AR 308 BR Build.. Almost. Shortstroking.. Sometimes. Nearly a Postmortem.

[Br00D]

Hello everyone!

Hold on to your butts people, this will be a complete autobiography of this rifle's conception. A dense conglomeration of everything I think I know and learned through this process. Some platitudes, some bad jokes, some dirty language, a few tangents, and all the relevant indispensable links I can muster to find a place for. Will it be a lot to consume? Definitely. Will that help me find the answers I need? Hopefully, but probably not. 

I created this account back when I finished my rifle in March, since then I've had a lot of fun, spent a decent amount of money, and nearly tossed my rifle over the burm multiple times. It's been an arduous year long process of misery, excitement, bloody busted knuckles, and more excitement turned into a page of text. I'm here in order to receive knowledgeable smiths' opinions on my issues and to educate those who are thinking of building their own 308AR and embarking on their own journey of selffulfillment, walletemptyment, and to hear that ohsosweet 308 thunder echoing back at you from across the mountain ranges far far away.

First a bit about me. I am mechanically inclined. I have pieced 223s together with ease. I understand how the AR platform works to a liberal estimation of about 90%. I spent multiple months in deep binges of research on 308 specific history, parts, and methodology of use, function and compliance. I started with an 80% DPMS style 308 lower that was a "gift" and built up from there. I am by no means a professional nor am I an expert. Just a civilian enthusiast who has been hunting, shooting and upholding his second amendment rights for over twenty years, beginning at the age of five.

My purpose of use for this rifle was to be an accurate, supressor-ready bunker-proof truck rifle, inside 300 yards. I find it's important to build a rifle for a mission. It keeps you from looking at all the other badass gadgets available that are outside your mission parameters. Look at them, develop your purpose of use, and only buy after you've determined that purpose of use and for gods sake buy second hand whenever possible. Arfcoms equipment exchange is an incredible resource for the honorable, they don't put up with ANY BS that's for sure. You've been warned. First tangent out of the way.

After a lot of aforementioned work this rifle now cycles Hornady 168gr and 178gr factory loads reliably, however I am much more concerned in getting 145gr+ to function and that has been quite a problem indeed. 178 grain is just not stable enough out of a 14" 1:10 twist barrel nor does it like to be loaded into a KAC mag designed for 762NATO and 168 grain AMAX is great for hunting but very expensive to stockpile and relatively slow compared to lower grain ammunition out of a 14" tube. Purpose of use coming into play again.

USE THIS CALCULATOR FOR BALLISTIC STABILITY, hopefully before you purchase your barrel and determining the rifles purpose of use. MOVING ON.

If you are a person looking into building a 308AR, then you fit into one of three categories. Below are those categories followed by my opinion of the category.

1. For the budget minded, mechanically uninclined and gas impingement noobs, RUN. Run far FAR away, all the way back to 223 land. Be safe there, be happy there. Or buy a complete prebuilt functioning 308 and never look back. You might love it, but this $ht ain't for you.

2. For the people mechanically inclined who have never built a rifle before, building a 308 from scratch is like a twenty million piece puzz3d puzzle that you have to pay for piece by piece to really complete. Approach cautiously, you will find this post very helpful, and if it turns you away then that's probably best for everyone involved.

3. For the people who build rifles and have no issue building 308ARs. Well.. I envy you and wish we were close mates.

I'll catch you up on the important parts of the final build:

The links are functional to the corresponding product pages and all relevant info for troubleshooting purposes.

ALL underlined text in this post is either a link to information or photos.

Lower-
80% Arms Lower
Geissele SD3G Trigger - Changed down from a CMMG LPK
Strike Industries M4 length receiver extension
Tubb Precision AR-10 Stainless Steel Buffer Spring - Changed down from Sprinco Orange
KAK Industry LR308 Carbine Heavy Buffer

Upper-
Rhino Rifles 308 Upper Receiver - No link/Company ceased operations
Rhino Rifles Nickel Boron bcg - No link/Company ceased operations
Sprinco Dual .308 Bolt Carrier Extractor Spring Set
BA Hanson 14" Barrel/Carbine length gas
SLR Sentry 7 Clamp On ADJ GB
Griffin Armament 30SD Flash Comp

I believe everything else is extraneous but if you want the saucy extras that add up to personal preference, just ask.

I started this build with finishing an 80% Arms 308 Lower and installed a CMMG lower parts kit. I did not continue until I had actuated the safety at least 5,000 times. Read a book, actuate the safety, watched a movie, actuate the safety, disassemble, clean, oil, reassemble, actuate the safety, repeat repeat, etc. All this time I was research my next step. I found an upper receiver paired with a BCG from Rhino Rifles factory after they had shut their doors. These were very nice, very expensive rifles. I got the pair for a steal so I sealed the deal thinking sweet artifact from the DPMS I era. The upper came with an UPK installed. I ordered the Sentry7 GB and a gas tube from SLR, the Griffin 30SD supressor mount, and the only 308 14" barrel I could find through Ballistic Advantage.
I took my upper, bcg, barrel, gas tube, and gasblock to an AR friendly smith nearby to be assembled since the muzzle needed to be pinned and welded and because of the mismatched parts, headspacing needed to be checked after assembly. I had it all done at the same time which thinking back wasn't the greatest idea before getting the rifle dialed in. (no way to fully remove the gas block if it ended up faulty, luckily not the case) Upon receiving the upper I found that the feed ramps of the receiver and the barrel were not perfectly aligned, normal for parts not made for each other, but not to an extreme degree. It did make me think twice about returning to that smith since they failed to mention anything about it. (I will end up grinding the dual feed ramps into one large ramp sooner or later anyway, making sure they are mated perfectly)

At this point I have a complete rifle with iron sights. My buffer system consisted of a Sprinco orange extra heavy spring made specifically for a DPMS length receiver extension paired with a 308 SHORT heavy buffer stuffed into a cheap strike industries receiver extension. With my purchase from Sprinco I also got a dual extractor spring set and installed those to the bolts extractor. Do yourself a favor and don't buy anything from strike industries. If you're a child at heart and want a shiny toy, well fine then. You're excused.

NOTE/INFORMATIONAL TANGENT: I wanted the rifle as compact as could be so I chose to go the route of a DPMS style buffer system, NOT an Armalite style buffer system. The difference in length is 3/4" and it is VERY important that when building this rifle, one is 100% aware of the differences between the two systems as to not mix buffer components of either system. If you haven't heard of this or have and are still confused READ THIS NOW. Bookmark it, every time you find yourself looking at buffer parts thinking, "huh??" READ IT AGAIN. Smash that information into your brain until you're waking up from wet dreams of the information coming to you in your sleep. It's just one part of making the 308 AR function and is 1/3 of the heart of your rifle. It needs to be dialed in to your internals' weight, ammunition loads, and consequently the internal gas pressures exerted on your bolt carrier.. A well worded article on the subject CAN BE FOUND HERE.  Something I have learned through failure is that the gas impingement system in an AR works because of timing built in to the design of the components. TIMING. It's real. It's fast but it's a process that happens in stages, from multiple directions. SOMETHING THAT CAN'T BE SEEN IN THIS ANIMATION. Though that animation shows the cycle operation of the moving components in a flawless system, it fails to show where all of the forces are coming from. When you build from mismatched parts the tolerances of that design are getting kicked out the window and curbstomped on the street. Things tend to bind when they aren't operating in perfect synchronous harmony. For example in an improperly timed system, as is observed in a gas system with improper dwell time, when a round is fired, 62,000PSI of hot gas welds the cartridge in place, the bullet moves down the barrel and chamber pressure gradually decreases as the volume it occupies increases until the bullet passes the gas port. At that point the gas floods to the path of least resistance, the gas tube then the gas key, etc. THERE IS A FANTASTIC STUDY OF 308WIN INTERNAL BALLISTICS HERE.  Though I think THIS IMAGE from that page will suffice to demonstrate the action of a flawless system. In our flawed example however, consider the "gas port pressure" curve beginning its upward ascent at .7 or even .6 milliseconds, this change simulates changing the position of the gas port, aft of the barrel. Once the gas port is pressurized the bolt carrier receives gas and begins moving rearward, pressures inside the cartridge are now still falling from ~40,000PSI instead of an in-spec system ~15,000PSI, multiply that by the surface area of the cartridge touching chamber and it is truly an immovable object by the standards of your dinky little extractor clip with only 12,000PSI coming from the gas port. Though the bolt is attempting to extract the spent cartridge from the chamber it is STILL essentially welded into the chamber. So your BCG is receiving ~12,000PSI of rearward pressure vs the ~40,000PSI still applied to the insides of the spent cartridge which is in turn attached to your BCG via the extractor clip. That's a bind, and results in a situation that can be misdiagnosed as undergassing or shortstroking. Because the time it takes to release the pressure from the cartridge results in no rearward motion UNTIL the cartridge is released around the 15K mark. So the BCG only moves back with the pressure you've got in the system at that time. I've been told this could even be the problem I am having though I am NOT observing excessive damage to the rims of my cartridges and despite those claims my carbine length gas system is in spec with the gas port at 7.5" from the chamber with a dwell length of 7" from gas port to muzzle. I happen to have misplaced my link for dwell, but resources on it are everywhere. More on my issues in a minute. Well. Congratulations, you've completed your rifle but you've only just opened the box on your 20 million piece puzzle. Hopefully you've purchased all the pieces you need at this point to put it together successfully. ha 

I had/have two types of 308 magazines on hand. A few Magpul 25 round PMAGs and KAC 10 rounds. For the uneducated, the process to dial in an adjustable gas block falls along the lines of finding the point where you are sending enough gas to the gas key on the bolt carrier to lock it back on the bolt catch on an empty magazine. From there the bolt should strip extra rounds from the magazine reliably if they are available. Should. Start with a single round in an otherwise empty magazine and set the gasblock to position 1. Load magazine, throw the charge handle, fire. If the bolt doesn't lock back you need to open the block up some more and try again. (Position 1 is usually dedicated for suppressed fire only. Suppressors increase the amount of time your chamber will hold at maximum pressure before beginning to fall off, which means higher pressures for longer.) So, two clicks open to position 3, reload, throw the charging handle, fire. 

First problem of the build was encountered here. No matter how far I opened the gasblock I just wasn't getting enough gas to reset the bolt. The brass was in between stovepipes, failure to extract and two o'clock ejection. Please see the following photos: Extracted brass had deep grooves cut in line with the extractor, ovalled necks, carbon fouling on necks, and of course dents from stovepiping against the extra heavy orange buffer spring. I probably went through over 100 rounds attempting to diagnose the issue going between my supplier of the receiver/bolt assembly to arfcom. My upper receiver supplier told me that BA barrels are often out of spec and if my bolt was even locking forward my problem was most likely due to a chamber that wasn't fully honed. I measured and it was slightly smaller THAN WHAT I FOUND TO BE "IN-SPEC". I measured something along the lines of .46x" at the edge of the chamber, so I honed the chamber exactly as told (I trust him), but for half as long as told (I don't trust him that much). Manual extraction difficulty decreased, I could now semi comfortably hand cycle the rifle. Following recommendations by only the most knowledgeable on arfcom and against the will of my upper supplier, I replaced the one piece gas ring with a new unit from JP Enterprises. I also blew compressed air into my gas key to check for leaks, I did not find leaks. After someone on arfcom told me that the charge handle shouldn't feel like I'm pulling the weight of an elephant up a hill. I concurred and I tossed the extra heavy sprinco for a tubbs and my problems changed from a constant cycle issue to an intermittent failure to feed. Minor success, but a success nonetheless! I was beginning to feel the power, and I loved it.

I was now able to fire between 1-3 shots of decent Hornady American Shooter 308WIN 149gr ammunition. 168gr was now running, apparently, flawlessly. (I don't buy a ton of that stuff but I'm up to something like 80-120 rounds, no failures) People told me during wear-in of new parts, the rifle will become more and more reliable. I took that as a recommendation that I need to wear in my rifle. I went to SGAmmo and purchased a case of 300 malaysian surplus 762x51 146gr L2A2 ammunition. (NON-NATO)

After a week of living in the woods at my families cabin and blowing away ground squirrels in eastern washington it was clear to me that my rifles problems were not getting any better. I shot around 250 rounds having to hand cycle the bolt every. single. time. All the while I was turning up and down my gas block. That ammo was absolute crap, I knew that, but I got a bin with a good seal. Reviews state flawless function in other ARs and SCARs. My mission here is to get my rifle cycling 145gr and up. Lower is fine, but not the goal. Point is, the rifle should have cycled the ammo.

Before firing the last fifty or so malaysian 146grs a few weeks later, I decided to take old Tubb's advice and began clipping coils off of the buffer spring. I took a slow motion video of the bolt attempting to cycle and it definitely wasn't an overgassing problem. Sorry I don't have the video, I'll see if I can get it tomorrow. The bolt was failing to move far enough back to engage the bolt lock/release. So I clipped one coil, no change, two coils, it cycled two rounds of the malaysian before repeated failure, three coils, same result no progression, four coils and a complete wipedown and oiling of internals, it cycled over five rounds before a repeated failure to feed. I ran out of the malaysian surplus and had 50 more rounds of hornady american shooter, almost the same exact results. Sometimes it ran 8 in a row, others would require manual recharge 8 in a row. Increasing the gas, seemed to help, and then it didn't so I'd turn it back down and receive equally frustrating and confusing results. This last trial was performed mostly prone with an affixed bipod to maximize rigidity of the platform. I loaded a full magazine of ten rounds of 168gr hornady early this day and all ten cycled just fine.

I took the rifle hunting just this last month with 168gr hornady factory loads and it functioned flawlessly between five non-consecutive shots. 

This is about the point where most guys think of pulling the gas block off and checking the gas port diameter. Which is where I left my discussion at arfcom. I didn't want to touch my gas block unless I absolutely had to. And if you turn your attention to this thread here user clandestine has checked just about everything I have save the gas port however he ended up stepping the diameter of the gas port up from what I know to be in-spec around .070"-.076" for a 16" 308 carbine all the way up to .091"

What say you 308AR? 

Here's the complete album of photos I used on my post on arfcom.

I hope those here for information found my experience helpful and I hope those here to help weren't overwhelmed by the wall of text. I'm certainly tired after writing this, hopefully it was worded well enough for comprehension.

I appreciate any and all eyes on this puppy.

Cheers

Edited November 27, 2018 by Br00D

[jtallen83]

50 minutes ago, Br00D said:

This is about the point where most guys think of pulling the gas block off and checking the gas port diameter.

What is yours?

What is the inside depth of the receiver extension?

Has it been tried with a standard weight buffer?

What are you using for a BCG? just curiosity there......

[98Z5V]

^^^  Yep.  Need the internal depth.  It's needs to be 7.000" internal depth, and that's not a "ballpark figure" or a "minimum starting number" like one guy here awhile back thought.

Second - yes.  Get to the gas port diameter.  If you wide open that adjustable gas block, and it STILL won't function - with a proper recoil system - you have a gas port diameter problem, and you'll be drilling it up.  You listed an accurate description of how to tune an adjustable gas block, but that's not how you test one.  First round downrange is with a wide-open gas block - to see if it even functions.  If it doesn't function, because of a bad gas port diameter, you'll never tune it.  Ever.  Wide-open is always first.  Then, you commence to tuning it for your load.

We can pretty accurately tell you, right away, if it's too small, just by you reporting the number.

Edited November 28, 2018 by 98Z5V

[98Z5V]

My gas port diameter on this .308 Win 13.5" carbine gas barrel is 0.081".  81-thou.  You need to be pretty close to that.

During:

Final:

[survivalshop]

What was that word , loquacious ?   Good explanation though , thats for sure , much more than we usually get .Good job .

[98Z5V]

On 11/27/2018 at 7:01 PM, 98Z5V said:

My gas port diameter on this .308 Win 13.5" carbine gas barrel is 0.081".  81-thou.  You need to be pretty close to that.

 

Keep in mind - my "carbine" gas system on that gun above is AR-10 Carbine gas - which is AR15 midlength gas.  I have less dwell time, so my gas port is slight larger than something with more dwell time.  You should be pretty close to that 81-thou, though, slightly under...

Edited November 29, 2018 by 98Z5V

[Br00D]

On 11/28/2018 at 9:41 PM, 98Z5V said:

Keep in mind - my "carbine" gas system on that gun above is AR-10 Carbine gas - which is AR15 midlength gas.  I have less dwell time, so my gas port is slight larger than something with more dwell time.  You should be pretty close to that 81-thou, though, slightly under...

I appreciate the posts obviously. I've been really busy since I posted this. So apologies for not jumping right on this.

Tonight I decided to take my 308 apart and what I found really pissed me off, at both Ballistic Advantage and the gun smith who worked on my rifle.

.081" haha Take a look at these pics and tell me what you think. I measured with a caliper but the error is obvious. First few are at .080 and the last as close as I could get it to it's current diameter. And then followed it up with the precision cut feedramps done over at BA.

You get what you pay for I suppose. I'm going to be calling them and demanding this be fixed. Gonna be tough with a pin and welded muzzle capturing a gas block and a barrel nut on there but I'll post back when I know more. Including if BA will own up to their mistake and fix this sad excuse of a barrel.

[Br00D]

On 11/27/2018 at 3:31 AM, jtallen83 said:

What is yours?

What is the inside depth of the receiver extension?

Has it been tried with a standard weight buffer?

What are you using for a BCG? just curiosity there......

Buffer is a modest 5.3oz.

Receiver extension is 7" on the money.

BCG is a mate to the upper receiver from Rhino Rifles.

I really didn't want to pull the gas block off because of the muzzle being welded. That and I don't have a 1 5/16" crowsfoot wrench to retorque the barrel nut. 

As it stands now I guess I'll have some time to acquire that crowsfoot wrench.

 

I didn't mention why I was pissed at the gun smith. They didn't notice the gas port size before welding the muzzle. If I was a professional gunsmith with an FFL like they are and know what I know now, that would be a step in my process before doing a permanent change on a customers item. They installed my barrel without any anti seize. They installed my gas block and rail without any blue loctite. Basically the worst. Not including an optic, the rifle was in the ballpark of 2500 dollars. (The reason I went with a BA barrel) I won't be skimping like that again and I'll definitely be doing my own smithing from now on.

[98Z5V]

That's no way to measure a gas port, honestly - not trying to piss you off, so get that now.  You need to "pin it" with measured drill bits to get it right.  I can make a 0.030 difference in a gas port size, in how I hold vernier calipers to it. Insert indexed drill bits that fit - until you get the next one up that doesn't fit - and measure that one with the digital vernier calipers. Then go measure the last one that fit.  That's the only way you're gonna know the true diameter, without a precision pin-fit caliper that's designed for this small stuff. 

Gotta pin it, man, and see what it really is.

Your buffer is about as stout as it needs to be, in weight, and from that manufacturer, the length is right.

Blue loc-tite is never used on a gas block or rail.  Anti-seize is never used on a barrel nut.  Don't hate your "gunsmith" for that - those things are not used on those areas, and they didn't use them - from me, that's kudos for them for not fucking it up by using that stuff in those areas. 

I've done this before for another guy here that I didn't know beforehand - but I've done it for many guys that I DO know here.  If you want that upper receiver setup teched out and fixed, I'll do that.  Ship it, I'll find out what it's doing and FIX IT, and ship it back to you.  I'll go through whatever I have to in order to test fire it, with a  video (swapping uppers if I need to, if your upper doesn't mate to something I already have) - and when it runs, great, I'll send it back.  We're talking one working weekend on that, not weeks.

[Br00D]

2 hours ago, 98Z5V said:

That's no way to measure a gas port, honestly - not trying to piss you off, so get that now.  You need to "pin it" with measured drill bits to get it right.  I can make a 0.030 difference in a gas port size, in how I hold vernier calipers to it. Insert indexed drill bits that fit - until you get the next one up that doesn't fit - and measure that one with the digital vernier calipers. Then go measure the last one that fit.  That's the only way you're gonna know the true diameter, without a precision pin-fit caliper that's designed for this small stuff. 

Gotta pin it, man, and see what it really is.

Your buffer is about as stout as it needs to be, in weight, and from that manufacturer, the length is right.

Blue loc-tite is never used on a gas block or rail.  Anti-seize is never used on a barrel nut.  Don't hate your "gunsmith" for that - those things are not used on those areas, and they didn't use them - from me, that's kudos for them for not fucking it up by using that stuff in those areas. 

I've done this before for another guy here that I didn't know beforehand - but I've done it for many guys that I DO know here.  If you want that upper receiver setup teched out and fixed, I'll do that.  Ship it, I'll find out what it's doing and FIX IT, and ship it back to you.  I'll go through whatever I have to in order to test fire it, with a  video (swapping uppers if I need to, if your upper doesn't mate to something I already have) - and when it runs, great, I'll send it back.  We're talking one working weekend on that, not weeks.

Appreciate the offer, and maybe I'll take you up on it, but first I'm going to call Ballistic Advantage and have a word. I agree my measurement method was hardly scientific but I reset the calipers again and again to .080, held it to the port and observed. Though I may not have an accurate measurement of the current diameter, I think it's fair to say this gas port is out of spec. Would you not agree? Even .010 out of spec seems to me like enough to cause an issue.

I've heard many times that copper based anti seize is perfect for use on aluminum barrel nuts. Geissele rails prompt for anti seize and so does the JL Billet rail that was installed on this 308. I've also heard of moly grease, clp, synthetic oil, etc.

Though not particularly necessary or that effective, blue loc-tite is one of those above and beyond sort of steps that I would appreciate. Much like the accessories that include it on threads new in the package. KAC prompts for blue loc-tite on their rail screws. It's hardly permanent and with the correct allen key doesn't present danger of stripping.

Blue loc-tite on the clamp-on gas block, true, basically menial after cooking off. Red loc-tite or rocksett on the GB is something I will be applying myself, and again, you're right. Something I would rather request specifically or just do myself.

[Br00D]

Just following up that a 1/16" (.0625) SnapOn punch does not fit into the gas port. I'm thinking about running to the store and just grabbing a 5/64 drill bit and drilling it out as opposed to 1. Sending my barrel, muzzle, gas block and barrel nut to BA and trusting them and 2. Buying a 40 dollar carbide reamer. 

Thoughts? 

Edited January 8, 2019 by Br00D

[Matt.Cross]

6 hours ago, Br00D said:

Just following up that a 1/16" (.0625) SnapOn punch does not fit into the gas port. I'm thinking about running to the store and just grabbing a 5/64 drill bit and drilling it out as opposed to 1. Sending my barrel, muzzle, gas block and barrel nut to BA and trusting them and 2. Buying a 40 dollar carbide reamer. 

Thoughts? 

The carbide reamer is overkill. A drill bit is all that's needed. As for Loc-tite, I use both red and blue extensively in my work as a tool and die maker, I wouldn't put either on any part of an AR other than the lower. 

[308kiwi]

Very small dia carbide reamers have a tendency to break very very easily, removing broken carbide reamers from what is effectively a blind hole is a difficult task.

Totally agree with Matt Cross, a HSS drill bit of the correct diameter is all that is required.

 

[edgecrusher]

Also, put a wood dowel into the barrel, for safety sake

[Br00D]

Thanks guys, just got off the phone with BA. Kyle said the correct gas port diameter is .055"... so that basically matches my measurement of .058 and thoughts I could've been over a bit. 

[Br00D]

@98Z5V

What do you think? Should I take a #46 bit to it? Maybe just go easy on it and give it 5/64?

Edited January 8, 2019 by Br00D

[98Z5V]

7 hours ago, Br00D said:

Thanks guys, just got off the phone with BA. Kyle said the correct gas port diameter is .055"... so that basically matches my measurement of .058 and thoughts I could've been over a bit. 

WOW! Mine is 13.5" barrel, "midlength gas" for lack of a better comparison to "Armalite AR-10 Carbine gas" - damn close enough - and 0.081" gas port diamater.  That seems SMALL, for 2" of gas system down. 

4 hours ago, Br00D said:

@98Z5V

What do you think? Should I take a #46 bit to it? Maybe just go easy on it and give it 5/64?

I would punch that thing to 0.070" right now, just because the gas port is 2" shorter than mine - carbine gas versus midlength gas.  1/4" wooden dowel down the barrel as stated, drill bits out, go slow.  I wouldn't send it back for that. I'd take the Makita drill to it.

[Br00D]

14 hours ago, 98Z5V said:

WOW! Mine is 13.5" barrel, "midlength gas" for lack of a better comparison to "Armalite AR-10 Carbine gas" - damn close enough - and 0.081" gas port diamater.  That seems SMALL, for 2" of gas system down. 

I would punch that thing to 0.070" right now, just because the gas port is 2" shorter than mine - carbine gas versus midlength gas.  1/4" wooden dowel down the barrel as stated, drill bits out, go slow.  I wouldn't send it back for that. I'd take the Makita drill to it.

Sweet. I also bought a #50 (0.070).. actually the owner of the store just gave a few to me after I explained my situation. I'll check back in and post an update, I need to think up some way of lining my barrel up with my drill press now and keeping it level in the x and y.

 

Cheers

[Matt.Cross]

54 minutes ago, Br00D said:

Sweet. I also bought a #50 (0.070).. actually the owner of the store just gave a few to me after I explained my situation. I'll check back in and post an update, I need to think up some way of lining my barrel up with my drill press now and keeping it level in the x and y.

 

Cheers

If you have a pin gauge or drill bit that will fit in the current gas port, use it to line your gas port up to a drill bit in the chuck by eyeball. There's no need to 'fix' the barrel in place with regard to X and Y axis movement. You only need to keep the barrel from rotating under drilling conditions. A standard length drill bit will follow the existing hole without wandering, which is why you can do it with a hand drill as long as you keep the drill oriented roughly parallel to the existing drilled hole.

[Br00D]

4 hours ago, Matt.Cross said:

If you have a pin gauge or drill bit that will fit in the current gas port, use it to line your gas port up to a drill bit in the chuck by eyeball. There's no need to 'fix' the barrel in place with regard to X and Y axis movement. You only need to keep the barrel from rotating under drilling conditions. A standard length drill bit will follow the existing hole without wandering, which is why you can do it with a hand drill as long as you keep the drill oriented roughly parallel to the existing drilled hole.

I'm just really fkn worried about the bit breaking lol I feel like that would really end up being a bummer.

[Matt.Cross]

6 minutes ago, Br00D said:

I'm just really fkn worried about the bit breaking lol I feel like that would really end up being a bummer.

Use cutting oil and go slowly, moderate pressure on the bit, and you'll be fine. Don't get aggressive and you'll have no problems.

If you do break a bit...  You're not the first to have done it. Any competent gunsmith or machinist can retrieve the broken bit and finish the hole for you.

[Br00D]

1 hour ago, Matt.Cross said:

Use cutting oil and go slowly, moderate pressure on the bit, and you'll be fine. Don't get aggressive and you'll have no problems.

If you do break a bit...  You're not the first to have done it. Any competent gunsmith or machinist can retrieve the broken bit and finish the hole for you.

Nice that's a good idea. Thank you

[Br00D]

Figured I should update this thread. After drilling to .070 and recalibrating the adjustable gas block I'm shucking 145gr shells at 3 oclock reliably. Big thanks to all those who contributed.

[Sisco]

3 hours ago, Br00D said:

Figured I should update this thread. After drilling to .070 and recalibrating the adjustable gas block I'm shucking 145gr shells at 3 oclock reliably. Big thanks to all those who contributed.

Matt and 98 won’t steer you wrong.

[98Z5V]

7 hours ago, Br00D said:

Figured I should update this thread. After drilling to .070 and recalibrating the adjustable gas block I'm shucking 145gr shells at 3 oclock reliably. Big thanks to all those who contributed.

This makes me happy - thank you for the update. I mean that.