preferred LR308 bolt catch?

[98Z5V]

1 hour ago, ehall said:

I bought one of the BAD 308 Enhanced Bolt Catches, the one they market as Investment Cast.

 

 

Very legit part, and company, man.  I run a bunch of those on the AR15 guns. 

[josiahg52]

BAD parts are very good. Hope my criticism of the bolt catch in a large frame wasn't casting aspersions on their parts in general.

I have a bunch of their CASS and a few other control parts. I think I ended installing the bolt stop in an AR-15. I just wish they offered "standard" safety levers for their CASS and ASS.

Edited May 7, 2022 by josiahg52

[98Z5V]

2 minutes ago, josiahg52 said:

I have a bunch of their CASS and a few other control parts. I think I ended installing the bolt stop in an AR-15. I just wish they offered "standard" safety levers for their CASS and ASS.

They have an investment cast single-sided safety.

Nevermind - I see what you're saying now - regular M16-looking lever ends...   D'oh!  

[josiahg52]

1 minute ago, 98Z5V said:

Nevermind - I see what you're saying now - regular M16-looking lever ends...   D'oh!  

Yes! Ended up using the Colt ambis on my more traditional, "clone-ish" builds. Still, the CASS is a solid piece of kit.

[Harveyshot]

The third one I bought was the one that finally worked the way it should, the AR10A bolt catch from DSG Arms.

[josiahg52]

On 5/24/2022 at 6:09 PM, Harveyshot said:

The third one I bought was the one that finally worked the way it should, the AR10A bolt catch from DSG Arms.

That one worked fine for me also and was one that I recommended. Mine came with my rifle, though.

[ehall]

I bought a couple more Magpul LR/SR mags and some more ammo, and went back to the range to test for a bit. The BAD catch doesnt hold the bolt back with any of the 7.62x51 NATO rounds. Some of my .308 match ammo holds back partway on the Lancers (catches the BCG body not the bolt face), but doesn't hold at all on the Magpul. The Tulammo steel .308 holds everything back even with the gas block closed off a little (guess its the opposite of the .223 steel). I put on a suppressor can with no baffles, enough to create a little extra pressure, everything holds open all the time. At this point my theory is that the gun is undergassed, so I'm ordering a couple of steel weights to get some more movement from the JP SCS (relying on the adj gas block for precision). Will report back again after.

ps--the BAD is weird looking but its the easiest to manipulate so far

[Harveyshot]

As stated earlier, I bought the Armalite 10A bolt catch and it has worked great but I've only used Hexmags with it. No steel ammo, range won't allow it.

[shooterrex]

11 hours ago, ehall said:

I bought a couple more Magpul LR/SR mags and some more ammo, and went back to the range to test for a bit. The BAD catch doesnt hold the bolt back with any of the 7.62x51 NATO rounds. Some of my .308 match ammo holds back partway on the Lancers (catches the BCG body not the bolt face), but doesn't hold at all on the Magpul. The Tulammo steel .308 holds everything back even with the gas block closed off a little (guess its the opposite of the .223 steel). I put on a suppressor can with no baffles, enough to create a little extra pressure, everything holds open all the time. At this point my theory is that the gun is undergassed, so I'm ordering a couple of steel weights to get some more movement from the JP SCS (relying on the adj gas block for precision). Will report back again after.

ps--the BAD is weird looking but its the easiest to manipulate so far

I would open the gas port up a bit before I messed with the fancy recoil system.

A lot of folks here haven't had very much luck with that recoil system.

[ehall]

Wanted to post a follow-up: I reduced the weight of the JP SS from H2 to H1 and it ran perfectly for a few 2-round mags, then stopped working again. I swapped in an Aero rifle-length spring and buffer that had been reliable in the early build, and had the same thing happen. It seems that LRBHO works fine for a couple of mags until things heat up, and then it stops working, reglardless of bolt catch, magazine, or buffer.

I did a full inspection on the gas system--full disassembly of the SLR block, verified alignment, pipe cleaner down the tube, everything. No real issues that I could find so I oiled the parts and put it back together. Another test and the same thing happened again, but now I see that the block is leaking pretty badly. Current working theory is that the block holds tight when the gun is cold but expands more than the barrel once it starts getting warm. A little googling indicates that other people have the same problem with the SLR and LRBHO.

I have a couple of other blocks here that I can throw on to test but the Lantac Dragon is secured with Rockset and I am looking at other options first. If it is heat-related expansion then I will probably have to get a steel block to resolve.

[98Z5V]

The gas port in the barrel isn't big enough.  No matter how far you open an adjustable gas block up - it can't create more gas, in an undersized gas port situation.  Proof of this is that you had to go from an H2 to H1 buffer weight configuration.  You should be running H3 configuration.

Edited July 2, 2022 by 98Z5V

[ehall]

Well, I was doing it for testing, since some people were blaming the JP SCS. If I don't care about LRBHO (which I do) then I can keep the adj block about halfway with the JP H2 and it cycles fine, it just doesn't lock open at the end. It is possible that the gas port is undersized. I have a set of rod gauges to measure, and I'm going to ask Criterion what it is supposed to be, we'll see where that convo goes. In the meantime I'm going to seal the block and around the threads of the adjuster screw, see how that goes. If it still fails with no leaks around the block then it is very likely to be the gas port. Other possibilities are with the Lantac BCG (no evidence of leaking anywhere) or with the buffer extension. Or who knows what.

Also to keep this kind of on-topic, the FCD ABC/R is what I am currently using because it has the smoothest finish whereas the cast pieces are thicker with rough surfaces.

 

[98Z5V]

9 minutes ago, ehall said:

It is possible that the gas port is undersized.

It isn't just possible - it IS undersized.

I'm not giving this information out because I'm just guessing at it, and don't know what I'm talking about. 

I'm GIVING you this information from experience, time on this platform, and alotta $$$ spent getting my own shiit right.

I'm directly TELLING YOU what the problem with your gun is, and you can take it or leave it. 

You can fuk around with this thing as long as you want.  You need a larger gas port.  You've already proven it by what you've stated.

Enjoy your gun.

[98Z5V]

@ehall, read this, and think about it for a minute...

A giant ship's engine broke down and no one could repair it, so they took it to a Mechanical Engineer with over 40 years of experience.

He inspected the engine very carefully, from top to bottom. After seeing everything, the engineer unloaded the bag and pulled out a small hammer.

He knocked something gently. Soon, the engine came to life again. The engine has been fixed!

7 days later the engineer mentioned that the total cost of repairing the giant ship was $ 10,000 to the ship owner

"What ?!" said the owner.

"You did almost nothing. Give us a detailed bill."

The answer is simple:

Tap with a hammer: $ 2

Know where to knock & how much to knock: $ 9,998

Lessons to Learn

The importance of appreciating one's expertise and experience ... Until

The words "it's easy" and "that's all", should be set aside. Why? Because maybe the experience is the result of struggles, experiments and even tears.

Like the picture above:

If i do a job in 30 minutes it's because i spent 10 years learning how to do that in 30 minutes. You owe me for the years, not the minutes.

(If I can finish a job in 30 minutes, it's because I spent 10 years learning how to do it in 30 minutes. You paid me for those 10 years, not 30 minutes).

This sentence reminds me of someone’s advice on respecting and wisely respecting the work of others.

There I also learned to see people ...

When they do not respect others, at the same time he has humbled himself.

Expertise and experience, that's expensive.

Unfortunately, our people still look down on that.

[jtallen83]

1 hour ago, ehall said:

In the meantime I'm going to seal the block and around the threads of the adjuster screw, see how that goes.

Please don't put any gooey stuff in there, it needs rounds to seal it with carbon, that's why you don't see any fancy seals in the gas system, the carbon will do it. 

[Matt.Cross]

I've got the exact same SLR GB on 3 rifles, 2 of which are new rifles, and none of which have the SCS. Have never had an issue with either leaking or LRBHO on any of those 3 rifles.

What I'm hearing is that you don't want to believe the folks who have told you the SCS is an issue. The odds of it being a factor are far higher than the odds your gas is block causing the issue. 

Also, as has been stated, your gas port size is well below what it needs to be for function's sake.

[ehall]

1 hour ago, Matt.Cross said:

I've got the exact same SLR GB on 3 rifles, 2 of which are new rifles, and none of which have the SCS. Have never had an issue with either leaking or LRBHO on any of those 3 rifles.

What I'm hearing is that you don't want to believe the folks who have told you the SCS is an issue. The odds of it being a factor are far higher than the odds your gas is block causing the issue.

I replaced the SCS and still the same failure.

I also have the same Titanium block on another 5.56 AR and it doesn't have any problems there. I use that gun more, with a larger variety of ammo, so I expect it is carbon sealed, whereas this gun does not get used much and the ammo is generally better.

[98Z5V]

@ehall, how about listing the barrel specs.  Length, gas system, gas block journal size. I can pretty accurately tell you the range that the gas port diameter should be in, if I have that information.

[98Z5V]

Just now, ehall said:

I replaced the SCS and still the same failure.

Because, the gas port is too small...

[ehall]

Just measured it at .079. Its an 18" with the rifle-length gas. That would put it on the small side.

https://criterionbarrels.com/products/large-frame-ar/dpms-pattern-308-hybrid-barrel-rifle-gas-chrome/?v=7516fd43adaa

I am also checking the throat of the gas key and a couple of other things while its apart.

 

[ehall]

https://www.snipershide.com/shooting/threads/possible-undersized-gas-port-in-criterion-barrel.7016262/

[98Z5V]

8 minutes ago, ehall said:

Just measured it at .079. Its an 18" with the rifle-length gas. That would put it on the small side.

18" rifle gas needs 0.090"~0.095" to run correctly, with a proper recoil system.  IF, it's a 0.750" gas block journal diameter, AND H3-weighted recoil system.

That's been the issue the entire way through this thread, when you go back and look at everything - not bolt catches.

This is also exactly why your adjustable gas block does nothing after 1/2 way open. 

Edited July 3, 2022 by 98Z5V

[ehall]

I'll open it a little but I'm not looking to get into H3 sizes. I have the AGB to deal with it but I'd prefer to stay in the middle of the range instead of swinging between the extremes, if possible.

One thing from that other thread: "most 308 ARs are pretty overgassed because people expect them to run military ball which is significantly underpowered compared to good commercial 308." I'm seeing the problems with 7.62x51 spec NATO ammo and some .308. The steel case stuff and some of the other ammo has had fewer issues. No issues cycling any of it like some people were complaining about it in the other thread, and I am larger than most of those. I'd like to get to the edge where NATO works reliably with H2 and stop. I'll try to figure that out and post another followup after.

Edited July 3, 2022 by ehall

[98Z5V]

Believe whatever you want, from whatever source you want.

Read this, in the meantime.

 

[98Z5V]

56 minutes ago, ehall said:

One thing from that other thread: "most 308 ARs are pretty overgassed because people expect them to run military ball which is significantly underpowered compared to good commercial 308."

FWIW, just so you know - Most factory .308ARs are NOT overgassed, at all.  They're under-recoiled, because it's cheaper to produce that way, and serious gas-system compromises are made in order to run those buffers that are too light.

For real.