Broke another bolt.... your thoughts??

[Cajuntransplant]

Silencers don't increase chamber pressure significantly. You're not breaking lugs because of dwell time or port pressure (adjustable gas block). I'd wager you have/had a short throat. Measure the throat on the new barrel and load accordingly.

You think the chamber/throat was incorrect and that’s what was causing me to break bolt heads? Could you explain why or how that would cause the bolt head to break? I don’t follow.

[grayfox]

I think I have read that they do cause more back-pressure straight back onto the bolt via the barrel, increasing the thrust force backwards; this is different than more pressure via the gas tube. If that is so then that will put more rearward force onto the lugs...
Others more experienced with suppressors, feel free to correct this if it's not so.

[Cajuntransplant]

I think I have read that they do cause more back-pressure straight back onto the bolt via the barrel, increasing the thrust force backwards; this is different than more pressure via the gas tube. If that is so then that will put more rearward force onto the lugs...
Others more experienced with suppressors, feel free to correct this if it's not so.

Yes please chime in. I’m only planning on running suppressed with this rifle in matches and hunting. Right now my plan is to allow the mfr to exchange my barrel and bolt and if I can’t get 18” with rifle then I want a 20” with rifle gas. If they won’t do that and I’m stuck with the 18” and mid gas will a heavier buffer help control it better and manage the pressure?

[centerfire]

You think the chamber/throat was incorrect and that’s what was causing me to break bolt heads? Could you explain why or how that would cause the bolt head to break? I don’t follow.

Short throat is increasing pressure. You have pressure signs with a variety of similar ammunition exhibiting similar velocities.

Most suppressor manufacturers have done strain gauge testing for chamber pressure, at this point, and the pressure change from the suppressor is negligible.

[Grumpy]

Sounds like you are just too hot. You don't need to see pressure sign to be way above design spec. Like magnitude 10 -15,000 psi higher before it shows on SRP, higher w/match or mag primers).

Breaking an extractor, imo, can be DI related. But breaking lugs (most especially if it is one adjacent - imho) is too hot. Loading too long, short leede, tight bore, monolithic bullets like GMX. Cans, as discussed, can dirty a gun - not really via the tiny diameter gas tube but through the larger bore. They act like a longer barrels, and a longer barrel simply holds pressure longer, they don't really elevate chamber pressure.

Drop your charge a bit, then a bit more.

[LRRPF52]

Question for anyone still following this thread here....

If I can only do a direct exchange for my barrel and bolt and end up replacing it with the exact same thing.. then whats my next step to prevent the problem if it's based off the cyclic action being too fast and harsh for running suppressed? Since the factory ammo and my handloads are running same speeds and factory stuff shows a lot of high pressure signs, do I need to change buffer weights / springs to try to control the harshness of the cycling to eliminate the issue of breaking bolts? From what KLEM, LRRPF52, GRAYFOX and others have chimed in on here I seem to have an issue where (even the factory ammo) is too fast for my rifle setup and causing issues. I haven't pulled the barrel yet since I've been so busy with work and all, but if I can only do a direct exchange for the same setup (satern type II, bolt head, Mid Gas, etc) then won't I still have the same issues down the line unless I address how hard the gun is cycling? Taking handloads out of the equation... Factory ammo was averaging within just a few fps of my handloads but had ejector marks on every piece of brass, high SDs, a large ES, and erratic ejection patterns. Even if I get exchanged out and run same setup and only run factory ammo won't I have the same issues? Do I need to get a heavier buffer and then retune my gas system? Ideally I am going to try to exchange it for a 20" with rifle length gas and go from there, but if that isn't an option, what do I need to look into changing?

It takes adjustable gas and a heavy buffer just to get an 18" MLGS .094" gas port barrel running acceptably without being suppressed.

I have several 18" MLGS Grendel barrels with .076" ports, and I'll probably never suppress them even with the .076" port, unless it's a flow-through can.

For my CLGS 12" Grendel with .068" port and Bootleg carrier with 4 gas positions, I'm not that worried.

For an 18" or 20" RLGS with the normal ports, much friendlier for suppressing.

If you're going to shoot suppressed, you need to make sure you have a more ideal port location and diameter for that type of gas flow, because the suppressor acts as an accumulator/added barrel length.

18" MLGS are already very plug dwell heavy on the front end, so adding a can is like making a 20-24" barrel with a short gas system.

Open that port up to .094" at MLGS with such a system and you will get unacceptably-early unlocking and torsional forces on the bolt lugs, whether it's 5.56 or 6.5 Grendel.

The same thing happened with M4A1s with the KAC and other cans, and that was CLGS 14.5". Bolts broke all the time, which spawned the LMT enhanced BCG.