Hitting pressure with suppressor on.

[338 dude]

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

No

 

[FEENIX]

No

X2!

 

[KH_Outdoors]

What suppressor?

 

[haisardao]

What suppressor?

It's a Banish 30 from silencer central.

 

[haisardao]

Thanks all for the replies, lifelong learning is a beautiful thing. I'll wait for the fall and start load development with the suppressor on, gives me an excuse to put and shoot more.

 

[lancetkenyon]

Thanks all for the replies, lifelong learning is a beautiful thing. I'll wait for the fall and start load development with the suppressor on, gives me an excuse to put and shoot more.

I bet dropping powder charge by just 3% and working back up will bring you back where your rifle likes to be. But hanging the can on the end can change more than just pressure. Definitely expect POI and barrel harmonic changes.

 

[haisardao]

I bet dropping powder charge by just 3% and working back up will bring you back where your rifle likes to be. But hanging the can on the end can change more than just pressure. Definitely expect POI and barrel harmonic changes.

Thanks! Yea, I was expecting shift of my POI not the rest

 

[SteveBurton]

I bet dropping powder charge by just 3% and working back up will bring you back where your rifle likes to be. But hanging the can on the end can change more than just pressure. Definitely expect POI and barrel harmonic changes.

Lance is the man and has lots of experience shooting in the heat. I also work a load up for my suppressed rifles with the suppressor on. Then I will shoot that load without the suppressor and record my scope adjustments to bring POI where I want it. I personally have not been able to just screw on a suppressor and have rounds group the same so might as well be safe and start from scratch.
I have abandoned using R26 as I found it to become inconsistent in anything over 95ish degrees here.
Depending on your barrel, you may have a hard time finding a good load. I have a 28N with a 26" 3B barrel and it will just not shoot well with a suppressor on it. I think I burned away 1/4 of it's life trying.

 

[Roughrice]

I've had barrels shoot fine with supressor on or off with only POI shift.
However, I have one carbon sendero lite that I developed a load for without the suppressor and ASSUMED I'd only have POI shift when I put it on.
Wrong assumption. My super small group went to hell when I put the suppressor on. I'm talking 3" group!
I had to re-develop a load for it with suppressor. It's good now with suppressor but barely ok without.
Harmonics...
Not happy but, ... Oh well.

Oops...A little off of the pressure topic.

Sorry to derail the thread...

 

[haisardao]

I've had barrels shoot fine with supressor on or off with only POI shift.
However, I have one carbon sendero lite that I developed a load for without the suppressor and ASSUMED I'd only have POI shift when I put it on.
Wrong assumption. My super small group went to hell when I put the suppressor on. I'm talking 3" group!
I had to re-develop a load for it with suppressor. It's good now with suppressor but barely ok without.
Harmonics...
Not happy but, ... Oh well.

Oops...A little off of the pressure topic.

Sorry to derail the thread...

Thanks. All good points, that's what I need to do. Good to know I'm not the only one making mistakes

 

[aschler]

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

The only way I can see the can increasing max pressure is the barrel bends so much with it on that extra pressure is required to push the bullet down the barrel but this seems highly unlikely. Pressure drops rapidly as the bullet moves down the barrel.