Hitting pressure with suppressor on.

[haisardao]

Question for all, I have good, accurate load for my 7 SS, Berger EH 175 gr over 61.5 RL26 @ 2850 out of a 20 inch benchmark barrel. I've shot it multiple times no issues. Today I decided to screw my suppressor in for the first time, my velocity increased 50 fps and got a heavy bolt lift, and ejector mark. Accuracy also decreased.
Took it off and back to normal. Rounds loaded the same way, same batch, same lots on everything. Have you seen this happen before? Thanks

 

[WanderingGoatie]

It increases pressure on my loads as well. When I put one on my 6.5 Grendel it ejects at 1 o'clock but without it ejects at 3. Bolt action 204 I get cratering of primers. 243 I had to reduce powder grains. I've noticed that certain suppressors add more back pressure but more aggressive calibers tend to do more for increasing pressure. Example being 243 has higher spikes than 7-08, 7-08 spikes more than 308 etc.

 

[Mark37082]

How hot was it when you were shooting? You may have been on the edge of pressure and a combination of heat and the suppressor pushed you over.

 

[haisardao]

How hot was it when you were shooting? You may have been on the edge of pressure and a combination of heat and the suppressor pushed you over.

That's a good thought, It was 103F. I've shooting this load all summer just to make sure RL 26 didn't act funny for an upcoming hunt in NM. Load with no suppressor has been dandy up to 106F, I'm not gonna use the suppressor now, I don't want to mess with my load.

 

[Mark37082]

That is quite toasty for a temp sensitive powder like RL26.

 

[lancetkenyon]

61.5gr RL26, 175 @ 2850 from a 20", 106°F....and surprised you are seing pressure when you add a suppressor.
Hot load to begin with.
Then you increase temps up to 106°.
Then you add some pressure by adding a can.

Recipe for overpressure loads.

I have found RL26 to get squirrelly when near max loads and temps climb above 85°. You exceeded every one of these signs and then stacked them in my opinion.

I always work up a load with the can on if I plan on shooting it that way.

 

[haisardao]

61.5gr RL26, 175 @ 2850 from a 20", 106°F....and surprised you are seing pressure when you add a suppressor.
Hot load to begin with.
Then you increase temps up to 106°.
Then you add some pressure by adding a can.

Recipe for overpressure loads.

I have found RL26 to get squirrelly when near max loads and temps climb above 85°. You exceeded every one of these signs and then stacked them in my opinion.

I always work up a load with the can on if I plan on shooting it that way.

I understand your point, I have been shooting this load at the same temperature without issues. My pressure ladder shot at 100F had a light bolt lift at 62.8 gr.
I admit I did not factor the suppressor in, working up the load with suppressor on makes sense, still learning my way around it. Thanks for the input.
H

 

[lancetkenyon]

Being in AZ, I tend to shy away from RL26 unless it is a late season round ONLY.
That being said, my 184 Hyb load with RL26 in my 24" suppressed is running 2940fps with a near max load.

I would back it down 1.5gr amd work back up to your 2850fps node.

 

[haisardao]

Being in AZ, I tend to shy away from RL26 unless it is a late season round ONLY.
That being said, my 184 Hyb load with RL26 in my 24" suppressed is running 2940fps with a near max load.

I would back it down 1.5gr amd work back up to your 2850fps node.

Thanks, makes sense, I think I'm reserving this load for the fall. I'll use my 7 RM with H1000 for August in NM

 

[QuietTexan]

You exceeded every one of these signs and then stacked them in my opinion.

X2.

Any (and I many ANY) pressure signs on the unsuppressed loads? Makes me wonder if you're so far into pressure that you're at the point you lose traditional signs and are about to lose a primer pocket in a spectacular fashion. Spooky things happen when the pressure spike is enough to move the chamber walls, all casehead signs can go away.

 

[haisardao]

X2.

Any (and I many ANY) pressure signs on the unsuppressed loads? Makes me wonder if you're so far into pressure that you're at the point you lose traditional signs and are about to lose a primer pocket in a spectacular fashion. Spooky things happen when the pressure spike is enough to move the chamber walls, all casehead signs can go away.

Unsupressed loads shot perfect, zero pressure signs, consistent velocity. Tight primer pockets, no case head expansion.

 

[Bob Wright]

Thanks, makes sense, I think I'm reserving this load for the fall. I'll use my 7 RM with H1000 for August in NM

Lance won't steer you wrong!

 

[FEENIX]

61.5gr RL26, 175 @ 2850 from a 20", 106°F....and surprised you are seing pressure when you add a suppressor.
Hot load to begin with.
Then you increase temps up to 106°.
Then you add some pressure by adding a can.

Recipe for overpressure loads.

I have found RL26 to get squirrelly when near max loads and temps climb above 85°. You exceeded every one of these signs and then stacked them in my opinion.

I always work up a load with the can on if I plan on shooting it that way.

This!

 

[cohunt]

Suppressors DO change the pressure curve (especially with supersonic loads)-- thats why almost all AR shooters use an adjustable gas block.
Each suppressor is different too- some increase the pressure more than others.- it depends on baffle design and volume.

I'm not sure it actually increases the max pressure that much, more than it holds the pressure in the barrel longer so you are "uncorking" the pressure cycle earlier without a suppressor.

It may well have to do more with the temps and the rl26 too-- probably a compounded issue