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Rougaroux22

6.5 Creedmoor short stroking

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Hi everyone! New to the forum. Searched around this forum and many others trying to find a similar problem to the one I am having and have had no luck. This is my 4th AR platform build, but my first in LR308. Rifle is in 6.5 Creedmoor. Build list below:

LOWER

  • Stripped Aero M5
  • Aero LPK
  • Geissele SSA-E trigger
  • Ergo Grip
  • DPMS Buttstock extension tube
  • JP Enterprises Silent capture spring Gen 2 Standard Version w/ 3 spring kit
  • Magpul PRS gen 3 stock
  • PMAGs

UPPER

  • Stripped Aero M5
  • Proof Research Carbon Fiber 20" CAMGAS 6.5 Creedmoor w/ gas tube
  • Superlative Arms adjustable gas block
  • JP Enterprises Full mass carrier w/ high pressure enhanced bolt
  • SLR 16 inch SOLO Ultra Lite KeyMod handguard
  • Cowl Induction Muzzle Brake – Gen 2
  • RADIAN RAPTOR-LT AR10 charging handle
  • Razor HD AMG / Vortex QR 30mm

 

So with the rifle fully assembled, I go to break in the barrel to the manufacture's recommendations. I decide this would be a good time to start adjusting the gas block. I am using the heaviest spring in the Silent Capture and starting with my gas block one turn from closed. I load one round into the magazine, send it home, and fire my first shot. As expected, the rifle did not cycle and I adjust my gas block one more turn open and repeat. My plan was to repeat this process until the bolt holds back on the empty magazine and then adjust an additional 1/4 of a turn open to account for pressure variations between different ammo.

However, I was never able to get the bolt to hold open on an empty magazine. I was getting a good ejection, but no hold open. The bolt would hold open when racked manually. With my gas block now wide open, my first remedy was to try a different magazine. Same problem. The next step I took was to try different ammo. Same problem. Rifle was well lubed and being cleaned periodically because that was part of the barrel break in procedure. I was running out of day light and packed up for the day.

Once arriving home I figured the first thing to do was a full break down and cleaning of the rifle. My next thought was to confirm that my gas block was aligned properly. After removing the block, the carbon ring seemed to confirm that the gas block was properly aligned. I used the HB industries gas block alignment kit to confirm alignment when reinstalling. 

Next trip out I was experiencing the same problems. The silent capture came with 3 different springs. I was running the heaviest spring so the next thing I tried was changing the spring down to the middle spring. Same problem. Then the lightest spring. Same problem. Decided to check the bolt catch next to see if perhaps it was not engaging the bolt. Tried firing while holding the bolt catch. Same problem. No lock back.

I am getting good ejection. Bolt and action are moving smoothly. Gun is getting cloverleaf groups. I thought maybe I could have a leak in the carrier. I called JP Enterprises and explained what was going on. He said that it their BCG run through such a strenuous process that it would be highly unlikely it was a leak in the carrier. He stated that PROOF's CAMGAS barrels are known to have port holes that are too small in diameter. Has anyone else experienced this?

Emailed PROOF Research next. He stated that the CAMGAS barrel was designed around running everything milspec or standard weights. He admitted that short stroking was a common problem with the CAMGAS when using silent capture, and that going lighter with the spring may have been counter-productive. He went on to explain that when the silent capture is put into a rifle with the CAMGAS system, your bolt unlocks earlier than designed and does not allow as much pressure to build through your gas system before sending the BCG back. His recommended fix was a heavier buffer (I'm running the standard silent capture instead of the heavy H2.) They make tungsten rings to replace the stainless ones to increase the weight of the silent capture essentially making it a H2/H3 buffer depending on how many you change out.

I was wondering if anyone else has experienced similar issues? Is there any other steps that I didn't think of to troubleshoot this? I plan on ordering the tungsten rings to try to see if I can get the rifle to cycle with increased buffer weight. I may even order a standard buffer spring/buffer combo to try first. I will update as this unfolds to hopefully help someone in the future. Look forward to any advice anyone has to offer. Thanks in advance!

 

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What’s the diameter of the gas port? Are you sure it’s short stroking and not bolt override? You may want to start with a traditional recoil system until your rifle is broken in to ensure proper mating of parts. Large frame AR rifles are much different than small frame that way. Also I believe guys have had issues with that gas block not allowing enough gas through, but I may mixing that up with a another. 

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Agree with Edge. Anytime you vary from standard you add more variables to the situation. From the sounds of it you can change the recoil system or the barrel. It sounds like both manufacturers have seen issues before in using the two together.

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I also agree with both above , try a std Gas Block & depending on the internal depth of you Receiver Extension , use the proper Buffer & Spring . You should measure the internal Depth & post it here , we get a lot of this type of issue .

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6 hours ago, Rougaroux22 said:

DPMS Buttstock extension tube

JP Enterprises Silent capture spring Gen 2 Standard Version w/ 3 spring kit

Superlative Arms adjustable gas block

JP Enterprises Full mass carrier w/ high pressure enhanced bolt

This is where you fucked up.  You complicated shiit with complicated shiit, and it bit you in the ass.

Use a standard recoil system, and use standard gas systems, and build a rifle that functions, first.  After that, get all fancy with the complicated parts, so it suit your needs/wants/desires, as it suits your shooting style.

Shiitcan all the fancy, complicated shiit, and start with a basic, functional rifle. Don't throw them away - they're already paid for - they're just not helping you right now, and only hindering you.  You diagnose one thing at a time, one part at a time - not a box of complicated shiit that will only fuk you up in the long run.  As it has here.

I know that hurts, being your first post an all, but go post an intro and tell us about you.  We're more inclined to helping people that want to be here, over the information whores that just post about the problem they have, then ghost everyone.  My $0.02...

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Looks like you were well on your way to figuring out the solution. You're on the right path. Uncomplicate it, then sprinkle some fancy back in piece by piece as 98 suggested. 

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Thanks for the responses everyone.

What’s the diameter of the gas port? Are you sure it’s short stroking and not bolt override?

I do not know the diameter of the gas port. I spoke with someone from PROOF today and he says he thinks it is .082? I do not think it is bolt override due to trying different mags and firing while manually holding the bolt catch.  

You should measure the internal Depth & post it here , we get a lot of this type of issue .

About 9 and 3/4ths internal depth. The silent capture sits up against the buffer retainer pin with the supplied spacer. Rifle will lock back on the bolt catch when cycled manually on empty mag.

You're right 98Z5V. After speaking with JP Enterprises and Proof I will be moving forward with the K.I.S.S. method. (Keep it simple stupid!) Standard spring and buffer on order. Will try that before throwing more $ on a standard gas block. I know the # of clicks to have the gas block fully open so I will run it like that with new buffer/spring and report back. The guy I spoke with from PROOF said the barrel is designed to run with standard equipment.The reason for going with the adjustable block and silent capture in the first place was it was recommended to help control the increased pressures of the Creedmoor as opposed to the .308; of course that was based on a standard rifle length gas system and not the CAMGAS. That's likely where I fucked up.

I wont be able to shoot the rifle again until next weekend. I'll update everyone with the results. Thanks again.

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30 minutes ago, Rougaroux22 said:

You should measure the internal Depth & post it here , we get a lot of this type of issue .

About 9 and 3/4ths internal depth. The silent capture sits up against the buffer retainer pin with the supplied spacer. Rifle will lock back on the bolt catch when cycled manually on empty mag.

Hold on, hold on, hold on...   Let's start saving money right here. You're running a rifle recoil system, so this won't be expensive, to get some standard parts...

Rifle receiver extensions all have the internal depth of 9 11/16" - so you're there.  Pick up any Armalite or DPMS compatible 308 rifle buffer {Armalite AR-10 Rifle Buffer, part # EA1090), and the Armalite EA1095 recoil spring.  Done deal, solid recoil system.  Aftermarket manufacturers generally don't screw the rifle recoil parts up - but don't trust aftermarket springs from unknown vendors right now.

Here are both parts, directly from Armalite - that spring lists as out of stock, but that's not always the case.  Call them on the phone...  I'll bet your order gets shipped right out.  $24 for both parts, combined.

https://www.armalite.com/product/ea1090-ar10-replacement-buffer/

https://www.armalite.com/product/ea1095-ar10-operating-spring/

Quote

The reason for going with the adjustable block and silent capture in the first place was it was recommended to help control the increased pressures of the Creedmoor as opposed to the .308

6.5CM is rated to a higher pressure than .308 Winchester, but that doesn't mean all the ammo out there is running at a higher operating (chamber) pressure.  That's due to the 30-degree shoulder on the 6.5CM over the 20-degree shoulder on the .308 Win round, primarily. 

I hope that info you got didn't come from other .308 shooters...  Here's what most people think...

308-shooters-densest-in-universe-700x434

You're doing good getting into this cartridge. 

308-65-ussocom-meme-700x467.jpg

Shoulda gone .260 Remington, though.  IMHO.   :thumbup:

Edited by 98Z5V

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Standard (meant, not special, heavier) Rifle buffers all weigh 5.4oz.  AR15 rifle buffers are 5.900" long.  .308AR rifle buffers are 5.200" long.  They both weigh 5.4oz. Tungsten gives the shorter Big AR buffers the same weight as the longer, smaller-caliber buffers.  DO NOT BUY an AR15 rifle buffer.  DO NOT.  Your gun won't cycle.

 

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On ‎11‎/‎29‎/‎2018 at 11:54 PM, 98Z5V said:

You complicated shiit with complicated shiit

Do you sell shirts yet that have your saying, "Don't complicate shiit with complicated shiit"?

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Took 98Z5V's advice and swapped out to a standard .308 buffer/spring. Quick summary is i'm still having the same problem ? Standard gas block on order.

A few others things I noticed that I can add to help piece this puzzle together, however they be nothing:

  • Spent casings have a lot of powder residue by neck
  • 2 faint scratch marks down the casings on fired brass
  • I find that the bolt starts to not move very well in the bolt carrier after only around 10 rounds.

Brother in law has a very similar build, except he is running a low mass carrier. Going to try the new gas block when it arrives. If that doesn't work, i will try using his BCG. If neither works I need to call PROOF back.

That's all the new information I have for now. Will update when I have more. Cheers. ?

 

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I'm probably way the heck off cause I don''t know all that measurements of which parts go with what stuff and I didn't read all the other post that in depth. So if I repeat something don't get all bent over me. Been in the hospital all day with my wife sitting with her. just trying to relax but here's a 2 cent shot how I look at this problem. But maybe no solution.

There is some fancy video on you tube talking about under gas or over gas based on where the brass is getting kicked out. If its to slow, port to small, I think it's at 5 oclock? To fast at 2 oclock, just right at 3 oclock. So where does your brass go? If its at 3 oclock and not locking back maybe not the right parts. Heck I don't know . Just a food for thought. Maybe one of the other guys could out a nickel thought on this.

A short story, I had a 260 cal that would short stroke but would function fine with one load at the low end, like 38.0g 4350 and a 123g bullet. Soon as you added more powder the rifle short stroked. It had all all the standard buffer and spring and A2 stock, rifle length gas system, 20 inch barrel. What I figured out was the gas port was to small 080. As more powder was added, the bullet speed increased. When it did, the bullet left the bore before enough gas went through the gas port to the BCG to operate.  I had an adjustable gas port and had it wide open as well. So, I drilled it to .092 then it worked and even had to turn the gas port down and use it like it should be used. 

You could have all the right parts, just not enough gas. But I don't know nothing most of the time anyway.

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Happy New Year everyone! Small update.

I was able to shoot the rifle this weekend running the standard buffer/spring along with a standard, non adjustable gas block. Long story short, nothing has changed and the rifle is still short stroking. Starting to think the port is undersized or something is going on with the BCG. Growing increasingly frustrated ?

Emailed Proof with an update and will call JP Ent tomorrow. Will let everyone know if I come up with anything else. Open to suggestions.

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2 hours ago, Rougaroux22 said:

Happy New Year everyone! Small update.

I was able to shoot the rifle this weekend running the standard buffer/spring along with a standard, non adjustable gas block. Long story short, nothing has changed and the rifle is still short stroking. Starting to think the port is undersized or something is going on with the BCG. Growing increasingly frustrated ?

Emailed Proof with an update and will call JP Ent tomorrow. Will let everyone know if I come up with anything else. Open to suggestions.

Happy New Year to you too.

If your std spring and buffer are correct for the application and you're gas system is non adjustable and fitted correctly then your next step will be looking at your gas port.

I'm surprised that the guy from the barrel manufacturer cannot quote you the gas port dia, FFS, they made the barrel, I'm sure they don't just randomly pluck a drill bit to drill each gas port., he should know.

Anyhow, slip the gas block off and measure, accurately, the dia of the gas port. Just a little FWIW, I built an upper in 243 Win, similar case capacity, and bore dia to your 6.5 Cm, and had to go out to .095" to get it to run.

There's a whole bunch of physics going on when you start tapping gases or fluids off of a supply, pressure reduction across the dia of the gas port, dwell time, (the amount of time the gas has to transfer across/through the gas port), and one that is focused on rarely, the smaller the dia of the supply, (bore dia of the barrel) vs the gas port dia the bigger the difference in the pressure drop across the gas port.

All the best:thumbup:

 

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1 hour ago, 308kiwi said:

If your std spring and buffer are correct for the application and you're gas system is non adjustable and fitted correctly then your next step will be looking at your gas port.

^^^ This, right here. 

You have a 20" 6.5 Creedmoor barrel with a Rifle +2" gas system.  That's gonna have to be a giant gas port, because that's way down on dwell time.  20" barrels don't need Rifle +2 gas...  Rifle gas is way more than sufficient for a 20" barrel.

For comparison - which should be very, very close between 6.5 Creedmoor and .260 Remington - here's the details on my .260 Remington barrel:

Wilson Combat .260 Remington Tactical Hunter barrel, 20"  rifle gas,1:8" twist.  Recessed 11-degree target crown.  416R stainless. 

Gas port diameter is 0.071".  Weight is 1205 grams/42.5 oz/2.65lbs.

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5 hours ago, 98Z5V said:

You have a 20" 6.5 Creedmoor barrel with a Rifle +2" gas system.  That's gonna have to be a giant gas port, because that's way down on dwell time.  20" barrels don't need Rifle +2 gas...  Rifle gas is way more than sufficient for a 20" barrel.

 

 

^^^^^^^^^^Ah, I didn't read/figure that, yep, I would be seriously looking at this, your dwell time is probably well short of what it needs to be.

So first things first, ditch the adj gas block, you don't need it...........yet.

I think you'll find the solution by sorting your gas port.

The whole issue that Proof Research is trying to resolve is the issue of extended length, (more than 20"), barrels using rifle length gas systems, creating excessive dwell time and violent unlock, extraction and ejection, the same happens with the little brother rifle, 223, with extended length barrels but the volume of gas involved is far less so the issue is a lot less apparent and most people don't even notice.

So, why I said you don't need your adj gas block yet is, if you at a later date suppress the rifle you may need it then to balance the gas system.

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We need gas port diameters from this guy, @308kiwi:thumbup:  Gotta know that number, before anything else can take place.

I'm thinking I'm not happy with my .260 gas port diameter, myself, at 0.071".  I want to drill it up.

I'm running a 147gr Hornady ELD-M projectile on a CCI-200 primer, reformed Hornady .308 Match brass, and 43.0 grains of a magnum powder - RL-22.  It functions fine, and gets great accuracy.  That's my final load on the 147s - until I start playing with RL-17...  Anyway...

I'm trying to make a load with the 140gr Hornady ELD-M with Accurate 2495.  Same brass, same primer, 35.0 grains of it.  It won't even cycle the BCG and get the brass out of the chamber - I have to pull the CH back, and fight it, to get the brass out of the chamber.  That load and powder should cycle this weapon.

First things first is get the 5.7oz buffer out of it, and try a 5.15oz buffer with the 140-load.  If it cycles - then I need two buffers.  Otherwise, that gas port is getting drilled up.

The shiit we go through...   :laffs:

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I'm about 6" of dwell time on this gun, at a 0.071" gas port.  This sucker will probably be going up.  I should probably be in the 0.090" range on it.  That means his 2" longer gas system, with around 4" dwell, needs to be over 0.100"...

P1060867.thumb.JPG.2fb79086c83c3ea3aca0675828847896.JPG

 

This is .308 info on port sizing, from a very reputable OEM manufacturer - this is all about dwell time:

image.thumb.png.4ea30f75eac49e3626faf1b4fa256fa1.png

Edited by 98Z5V

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50 minutes ago, 98Z5V said:

The shiit we go through...   :laffs:

:thumbup:

38 minutes ago, 98Z5V said:

This is .308 info on port sizing, from a very reputable OEM manufacturer - this is all about dwell time:

image.thumb.png.4ea30f75eac49e3626faf1b4fa256fa1.png

This chart is laminated and pinned on the wall in my workshop it has some of the BEST information available anywhere AND directly relates to what I said earlier re the physics of what goes on at the gas port, in particular the relationship of the bore dia vs gas port dia and the relationship of the bore, gas post dia and the length, (wall thickness of the barrel) of the gas port and of course that all important dwell time relationship.

38 minutes ago, 98Z5V said:

I'm about 6" of dwell time on this gun, at a 0.071" gas port.  This sucker will probably be going up.  I should probably be in the 0.090" range on it.  That means his 2" longer gas system, with around 4" dwell, needs to be over 0.100"...

P1060867.thumb.JPG.2fb79086c83c3ea3aca0675828847896.JPG

 

 

I'd agree, I went through this with my 243, like I've said, and ended up @ .095", it runs 100% and is a total pussycat to shoot.

It's all one great big balancing act, and the biggest problem is when the symptom is fixed rather than the cause which seems to be the norm with the AR family, people don't get the right info, and this includes manufacturers in some cases, and just keep changing poop until it runs, I call this process 'swapnostics'.

I am a firm believer in 'start at the beginning' and as far as cycling issues with these rifles is concerned that is the gas port.

 

Edited by 308kiwi

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3 minutes ago, 308kiwi said:

It's all one great big balancing act, and the biggest problem is when the symptom is fixed rather than the cause which seems to be the norm with the AR family, people don't get the right info, and this includes manufacturers in some cases, and just keep changing poop until it runs, I call this process 'swapnostics'.

I am a firm believer in 'start at the beginning' and as far as cycling issues with these rifles is concerned that is the gas port.

 

Concur  - COMPLETELY!  You think the biggest thing is the gas port - and I agree with that.  Now I'm about to go South on you...   :laffs:

I think the biggest thing to START with is a recoil system that will handle the pressure and power of these bigger cartridges.  First.  If your recoil system isn't gonna handle it, then you compromise everywhere else to make it work...   5.4oz buffer, minimum, if you're going crazy on a load, but optimum at that weight for normal charges, for the Big Frame AR, just to start with...   You have to have a spring that's matched to that, too.  Hell, the entire system was designed around that principle.  Once you've got that - it's all about dwell time and pressure - which is all about gas system length and gas port diameter.

I wish I could work in your shop, brother.  Even on a vacation.  We could fuk some shiit up. :lmao::banana:

So many companies these days are literally "cheaping out" and building the cheapest buffers they can (means, tungsten and stainless is expensive, compared to steel and aluminum), so they "under-recoil" these things, and come up with a screwed up spring to "kinda" make it work.  Directly downstream of that is making their gas ports right - or not.  They often don't.  People bitch, and think they need an adjustable gas block to tame down this vicious over-gassed .308 Win AR round...  and here we go. It was never over-gassed.  It was always "under-recoiled" because it was cheaper to build that way...   :thumbup:

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Fair call, and one would think that would be the easiest thing to get right but it seems not to be so, simply going by the number of times the topic of buffers and springs comes up on here.?

11 minutes ago, 98Z5V said:

I wish I could work in your shop, brother.  Even on a vacation.  We could fuk some shiit up. :lmao::banana:

 

Make a trip here as your retirement present to yourself and I'll show you the kiwi  "number 8 wire"  solution to every engineering problem ever encountered. :thumbup:

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1 minute ago, 308kiwi said:

Make a trip here as your retirement present to yourself and I'll show you the kiwi  "number 8 wire"  solution to every engineering problem ever encountered. :thumbup:

:laffs:   I.   AM.  IN!!!   :banana::thumbup:

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Small update:

I measured the gas port this evening and it is at .082. My brother in law has a similar build and I will have the opportunity to try a different BCG this weekend to gain some more insight. May try to swap uppers/lowers/bolts/bolt carriers, etc... to hopefully help to eliminate some more things in the troubleshooting process. Anything else I should be trying or be looking at? I want to eliminate everything else before I bring the barrel in to widen the gas port. Thanks everyone for the continued responses. ?*cheers

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