First suppressor. Getting hard/sticky bolt lift

[HOLLYW00D]

Got my first suppressor out, and am experiencing hard bolt lift and case head swipe. Same can used for both rifles/scenarios below:

• 6.5 Creedmoor - 140gr Barnes Match Burner over 41.6gr H4350 in a new Lapua case
  • Hard bolt lift starts after 5th shot
  • Hard bolt lift goes away 5 shots after suppressor is removed
  • Round primers
• 6BR Norma - 105gr Barnes Match Burner over 29.5gr Varget in a new Lapua case
  • Hard bolt lift starts after 5th shot
  • Hard bolt lift goes away 5 shots after suppressor is removed
  • Round primers

Maybe the chamber is getting coated with a layer of carbon from the backpressure and not allowing the next case to grab the chamber walls, letting the case slide/press into the bolthead?

Is there a way around this? Maybe something as simple as more neck tension?

Thanks for your help.

 

[Diablo7]

Interesting, watching...

 

[ahlgringo]

reduce your load by .5 grain and see if it resolves with the suppressor on.

Never had an issue, but if I am gonna hunt with a can on, I work up a load with the same can on. It will obviously change back pressure a bit. If you were already "hot" it may be enough to now show signs of overpressure.

 

[HOLLYW00D]

The strange thing is, neither of those loads are anywhere near hot.

 

[zrodwyo]

I had an issue similar to this on a 7mm WSM. It would start blowing primers after 5-10 shots only when suppressed with factory ammo. Clean the chamber and it would be good for another 5-10 rounds.

I think it was thunderbeast who told me the issue was most likely a tight neck in my chamber. Increased carbon fouling around the case neck caused by the silencer creates an over pressure situation. Not unlike a carbon ring.

 

[Lawnboi]

Are these new barrels?

 

[HOLLYW00D]

Are these new barrels?

Yes:
6.5 Creedmoor = 86 rounds prior to can
6BR Norma = 0 rounds prior to can

First firing on new brass.

No flattening of primers at all. Hard bolt lift, and case head swipe, disappears 5 shots after can is removed. To restate that: I still get hard bolt lift and case head swipe for 5 rounds after the can is removed, but after that the bolt lift is normal and no swipe on brass. The opposite is true when mounting the can: with the can mounted, hard bolt lift/brass swipe starts after the fifth round (not immediately with the first shot).

 

[Lawnboi]

Yes:
6.5 Creedmoor = 86 rounds prior to can
6BR Norma = 0 rounds prior to can

First firing on new brass.

No flattening of primers at all. Hard bolt lift, and case head swipe, disappears 5 shots after can is removed. To restate that: I still get hard bolt lift and case head swipe for 5 rounds after the can is removed, but after that the bolt lift is normal and no swipe on brass. The opposite is true when mounting the can: with the can mounted, hard bolt lift/brass swipe starts after the fifth round (not immediately with the first shot).

I had a similar problem with a fresh barrel in 6.5cm and a gemtech tracker. It went away after 120 rounds but left me really scratching my head before that. I have a few reasons to believe that the bullets eventually smoothed out what needed to be from the chamber job.

It’s not the first time Iv been left with pressure at what I’d consider mild charges on a fresh barrel either.

Might also add what can.

 

[HOLLYW00D]

Thanks. I'll put a few more rounds through the barrels and see how they behave afterwards. The can's a CGS Hyperion, and it's a beautiful thing.

 

[Lawnboi]

Thanks. I'll put a few more rounds through the barrels and see how they behave afterwards. The can's a CGS Hyperion, and it's a beautiful thing.

Let us know what you figure out or if more rounds did it.

 

[HOLLYW00D]

Forgot to circle back to this...
Same can, same 6.5 Creedmoor load in the barrel I originally had issues with = no problems now
Same can, same 6.5 Creedmoor load in a brand new factory barrel (Sig Cross) = no problems
*shrug* beats me, but I'm happy.
Thank you @Lawnboi and everyone for weighing in!

 

[Sled]

Did you ever bore scope the barrel to see if there were any anomalies?