Reloading With A Suppressor

CaptnC

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I'm not sure if this is the "best" forum for this because it has to do with a AR platform rifle.

I've only been reloading for gas guns for about 2 years....with a can...about 8 months.

Just recently decided to put together a suppressed Night Vision rig for my wife. So i got the ATN 4k Day/Night Scope (which didn't end up being as light as I thought). I tried a 16" barrel with a M-4 contour in 6.5 Grendel which shot fine (no pressure signs) until I screwed the suppressor on it. POI moved over a foot, plus group size went from MOA to 3MOA and major pressure signs on the case head.

So I scrapped the whole project because the weight was too much, plus the accuracy was not there.

I decided to go with a heavy short barrel for weight reduction and stiffness. So far the accuracy has been fine but I'm again see pressure signs with the can in place.

I had read that if a can was built right it wouldn't effect accuracy, but never seen anything about causing pressure signs on the case head. I normally run my AR loads over my Magnetospeed to get an idea where I might be with the pressure. But I don't have any barrel sticking out of the hand guard so I'm not sure where I'm at velocity wise.

I forgot my Caldwell with the sky screens...would have been a great day because it was over cast.

The suppressor is a Rebel SOS 30 Hunter (full length no sections removed) it's super big, 10" in total length. So my first thoughts is it should handle the gas fine. The same suppressor has worked without a hitch on a 26" barreled 6.5-06 (only shot at 100 yards) and another AR chambered in 7.62x39.

My current load is below Barnes listed max for 120gr TAC-X bullets. I also had 5 left over loaded rounds (120gr GMX bullets) that I have shot in three other AR 6.5 Grendel rifles without issue, other than not being accurate. Well...I put two in the mag and accidentally had a "double tap" because the recoil (and pressure) was well above expected and a pistol brace! Cant wait for my SBR "stamp" to get here!

SO Question;
Is this normal for a rig when adding a suppressor?

How does the suppressor effect the SD and ES????
Is it normal to have
 

CMP70306

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Sep 12, 2011
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247
I think the issue is more the fact that the rifle is over gassed and the increased back pressure is causing the action to unlock prematurely causing the issues you are seeing. I’ve run the suppressor on my 18” AR in .223 but I tuned the gas block so that it runs both suppressed and unsuppressed.
 

CaptnC

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I have just received a adjustable gass block and I'm waiting on a adjustable gas key.

I'm going to use the adjustable gas key on the recommendation of a buddy who uses them in this competition guns.

It might even be in the mail box as I type this. I actually planned to go check when I got back from the range but for got.
 

cohunt

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I also think it's over gassed-- Adj gas block is better than adj gas key-- the adjustable gas block limits the total volume of gas back through the whole sysyem, adj gas ket just limits the amount of gas through the key to the bolt/rings . I use a front click adjustable so handguard style wont matter and you have a definitive click amount for adjustments.
 

CaptnC

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Well I have both so I'm flexible on what to do.

I've never had to use either one, so I have no loyalty to any method.

The 16" barreled rifle I mentioned earlier had the Osprey Gas system on it, which really helped with recoil to stay on target, but once the suppressor was screwed on it was tearing up some case heads. Heavy ejector marks and you could easily hang a finger nail on the divot in the primer.
 

new2mud

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You can get a Wiser precision mount for the Magnetospeed and mount it to a pic rail on the side of your AR hand guard. Will not shift your POI, and it doesn’t care how much barrel you have sticking out.
 

azarcher10x

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You're definitely over gassed. I have an AR set up for predator hunting (and p dogs)and I'm shooting light rounds. .223 w/ 36 gr. VG's. With a fixed gas block and the suppressor, I would get double and sometimes triple taps. Going to the adjustable gas block cured it. I ended up only having the gas block opened about 25%. As for such a drastic POI, I'd check for contact in the suppressor. The POI shift I get between suppressed vs. unsuppressed, is in elevation.
 

new2mud

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BTW, I will sometimes have to develop a separate accuracy load for suppressed vs. unsuppressed due to harmonic changes of a heavy can hanging off the end of the barrel. I believe some of the folks running lighter suppressors like TBAC may not have to do that.
 

Okanogan

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Riverside, WA
I run suppressed on all my gas guns (.224 Valkyrie, 6.8 SPC II, 300 BO and .308) and develop the loads for them with the suppressor in place. I use a TBAC Utlra 7 and so far everything has shot at least as well with the suppressor as without it and most shoot better. I use a Labradar and the few times I checked unsuppressed, my velocities were slightly lower which might suggest a little more pressure with the suppressor. I tend to agree that you are likely over gassed as a big part of the problem. I have adjustable gas blocks on everything but the 300 BO which is a PDW. The adjustable gas blocks are a nice feature in my opinion.

When I got my GAP10 .308 the information that came with it recommended not pushing hot handloads through it if I didn't want excessive wear. I've tended to follow the same advice with my Craddock precision uppers as well, in part because they tended to shoot better at loads lower than max.

I haven't checked how the suppressor effects ES/SD with and without it in place. I usually have no problems working up a supersonic load with good ES/SD with the suppressor in place. My biggest challenge in getting good ES/SD has been when I attempted to load subsonic.
 

George Dean

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North East Ohio
I'm not sure if this is the "best" forum for this because it has to do with a AR platform rifle.

I've only been reloading for gas guns for about 2 years....with a can...about 8 months.

Just recently decided to put together a suppressed Night Vision rig for my wife. So i got the ATN 4k Day/Night Scope (which didn't end up being as light as I thought). I tried a 16" barrel with a M-4 contour in 6.5 Grendel which shot fine (no pressure signs) until I screwed the suppressor on it. POI moved over a foot, plus group size went from MOA to 3MOA and major pressure signs on the case head.

So I scrapped the whole project because the weight was too much, plus the accuracy was not there.

I decided to go with a heavy short barrel for weight reduction and stiffness. So far the accuracy has been fine but I'm again see pressure signs with the can in place.

I had read that if a can was built right it wouldn't effect accuracy, but never seen anything about causing pressure signs on the case head. I normally run my AR loads over my Magnetospeed to get an idea where I might be with the pressure. But I don't have any barrel sticking out of the hand guard so I'm not sure where I'm at velocity wise.

I forgot my Caldwell with the sky screens...would have been a great day because it was over cast.

The suppressor is a Rebel SOS 30 Hunter (full length no sections removed) it's super big, 10" in total length. So my first thoughts is it should handle the gas fine. The same suppressor has worked without a hitch on a 26" barreled 6.5-06 (only shot at 100 yards) and another AR chambered in 7.62x39.

My current load is below Barnes listed max for 120gr TAC-X bullets. I also had 5 left over loaded rounds (120gr GMX bullets) that I have shot in three other AR 6.5 Grendel rifles without issue, other than not being accurate. Well...I put two in the mag and accidentally had a "double tap" because the recoil (and pressure) was well above expected and a pistol brace! Cant wait for my SBR "stamp" to get here!

SO Question;
Is this normal for a rig when adding a suppressor?

How does the suppressor effect the SD and ES????
Is it normal to have
I'd suggest replacing the gas block with an easily adjustable one.
 

CaptnC

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To be honest I have not done any load development for this rifle. I used loads that I had worked up for the 16" upper i had.

My thinking was the shorter barrel (10.5") would be less likely to be over pressure compared to a longer barrel.

I have an Aoudad hunt that feel in my lap coming up soon and was thinking about rushing the little 6.5 into service.

The property will not have any long range opportunities so I wanted my wife to use it. I like the ability to record the shots.


A little quick video through the lens of my ATN HD2 on my 7.62x39 AR. Pasted on a bigger hog looking for a pit pig.

I've got time to swap out the gas block and give it try before the hunt so there is still hope.
 

John Klingenberg

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Nov 13, 2018
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Michigan
The can will radicalize your ES. Especially if you remove and put it back on often. It's best to just leave it on one gun. ARs ,in my experience, are not the best host for cans unless you tune them and leave it be.
 

cohunt

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yikes!!! the gas pressure is primarily based off of gas port location and port size, but back pressure from the suppressor adds to it also.
a 10" barrel can not have anything longer than a carbine gas system and it may actually have a pistol gas system--both of which have much higher gas pressures than a midlength gas system (which I would assume that your 16" barrel had--but it may have had a carbine gas system) -- see my pic below (it is for 223, but it gives you an idea of pressures vs gas length/port location) -- if you compare a mid length to a carbine, the carbine has 1.25x the pressure at the port, and a pistol gas has 1.82x the pressure at the port vs the mid-length system-- adding a suppressor is just like adding a muffler to a car, you produce back pressure

but you will also notice that the longer the barrel, the less the muzzle pressure --thus you would have a reduction in back pressure form the suppressor if you went longer, or an increase in back pressure with a suppressor for shorter length barrels

buy an adjustable gas block, and double check with your suppressor manufacture to see if it is rated for a 10" Grendel barrel

if you like shorter barrels, the best compromise is an 11.5 or 12" barrel with a midlength gas system for both the 6.5G and 6.8spc2 -- the 12" will still give you good muzzle velocities for clean kills but stay short enough to be handy in tight brush

Screenshot_20180130-140407.png
 
Last edited:

CaptnC

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Jun 21, 2017
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Location
Texas
The can will radicalize your ES. Especially if you remove and put it back on often. It's best to just leave it on one gun. ARs ,in my experience, are not the best host for cans unless you tune them and leave it be.
I dont recall off the top of my head how many bolt guns I have but I do know how many I have that are threaded!

One...6.5-06 that I built for my wife that I h the barrel threaded for a brake. I know my M1A is threaded but I've never tried to remove the flash hider.

I have one more suppressor coming and it will go on this 6.5 Grendel permanently. The can on it now will go back on my 7.62x39 AR that is crazy accurate!

cohunt,
Thanks for all that detailed info!

I am well known on the 6.5 Grendel forum as a hater of short barreled 6.5 Grendel's. Its was certainly not designed to be shot from such short barrels, but I built this one to reduce the weight for my wife. Maximum range it will be shot in a hunting situation would be 150 yards so the velocity loss is not a big deal.

My wife hates the pistol brace so I already submitted a Form 1 so I can put a normal AR stock on it. It's still not as light as I had hoped.

It is a pistol gas system...I wish it had been a carbine length. I could have used the Osprey piston system on it that I had.

Getting ready to tear it down now and install the adjustable gas block.
 

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