6x6.8 suppressed. ##UPDATE## I have false pressure signs

3DHUSKER

3DHUSKER

Active member
6x6.8 suppressed who is shooting one?
Want to discuss the pressures you are seeing.
Seems that the load I have worked up is on the edge of too hot with a Suppressor or so it seems. First round seems ok then I get marks every time after that. Is anyone experiencing this? Getting ready to work on this and want input so i don't blow a bunch of supplies figuring it out if someone else has been there.

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With a SBR you might not. I am shooting a 22 inch barrel at 31.5 grains 8208 with the 58 grain Vmax, 30 grains 8208 with the 87 and 90 grain bullets, seated just off the lands. Those loads are good without a suppressor but with they are over or so it seems.

I am going to check my gas block also to verify I have just enough gas to cycle and lock back. I believe I set that when I built the gun.



 
What's the velocity difference of can on, can off. Shouldnt be more than + 15-20 fps. Also what are you basing your over pressure comments on? Is it velocity, case signs, ejector marks on brass, software program, what? Disclosure I don't have a 6x6.8 but Overpressure signs should be the same regardless of caliber.
 
OK I shot this today and discussed the issues with Ritch there may be other issues to address. He gave me some really good ideas and things to check. I will try to get these things done and let you all know what was going on.
 
Gas, DI.

Rain stopped before dark for a bit.... I had set the gas block like the paper work said, back out until it locks back and then another half turn to be reliable. That equaled 3 turns out and that is what it was set at where it made marks.

It locked the bolt back at 2 1/2 every time so i tried to turn down and other 1/4 and it didn't lock. Set it back to 2 1/2 and locked it down. I shot rounds back to back to back and less marks but problem still exists.

I have a few more things to check another day but made progress thanks to a phone call by master builder Ritch.

I love this caliber more and more every time I shoot it.
 
3DHusker,I recently built a 6.5x6.8,and I also shoot it suppressed. I can't get anywhere near the top powder charges with the suppressor. It will blow the primers out of the case,or stretch the primer pockets easily with Hornady brass.
I just started loading test loads at 3.0 grains off known maximum charges,and work them up until the brass shows signs,and so far I have found several different loads with 4-5 powders.

I bought 300 pcs of Hornady brass,and have tossed over 60 in the trash from high pressure problems trying to get this rifle to shoot the upper end charges. It isn't going to happen with the suppressor!
 
Good info here. I plan to try my new SAS Barricade on the 6x6.8 upper soon, so I will be looking back at this thread.

Just curious, which adjustable GB are you running Husker?
 
Tx, I got a few min tonight to run a mag through the gun with the block set at 2 1/2 and it would not pick up the next round. I had to give it a little more and ended up at 2 3/4 turns. Started getting marks again. I need to measure the brass and see if I am pushing the shoulder back too much also. Tools are at other place.

Anton, I am currently running a Barricade on mine along with a JPGS-5B gas block.

The suppressor has not mattered I have tried different ones including a couple of 30 cal that are in the front of the safe, same result.
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I shoot a 6x6.8, Savage build. I have not had any issues at all, with or without the can on.
The AR15 6x6.8 I built did not have any issue at all either. I ran an adjustable GB on that one.
 
##UPDATE###

Over sizing was giving me the false pressure signs, the suppressor had nothing to do with it.

Settled in at .002 bump back of shoulder to function correctly and no marks at the full 31.5 grains when using once fired brass out of my weapon.

Here is what was going on (the short version). I am using the CH4D Die.

Upon first neck down of the de-milled brass I was running, i set the die down till it hits the shell holder and was getting .009 head space, (never checked that till today). That resulted in false pressure signs. This de-milled brass came from military loads so it was sized to run in a machine gun with out issues and the brass would never be used again. It started out with lots of head space and my procedure didn't help. LOL.. I should have known better.

I then set up the die properly for my weapon to have a head space of .002 off a shot piece of brass out of my own weapon. That fixed the marks problem but I still needed to check the first neck down from the de-milled brass and see where i was at with the die set correctly on my shot brass. I ran a de-milled round into the die and had .006 head space (the properly set die is .004 long of hitting the shoulder resulting in .006) That is more than I want but I will probably live with that on the first firing as it will be .002 from then on out. So in short I was making the excessive head space problem even worse before.
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Hope this helps some one else out in the future that has a brain fart similar to mine.
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Glad you found out the cause. I couldn't think of any way that a suppressor would cause a pressure spike except maybe heating the rifle up
 
Originally Posted By: Redleg84Glad you found out the cause. I couldn't think of any way that a suppressor would cause a pressure spike except maybe heating the rifle up

Until now I had never had such a problem but this is my first WILDCAT gas gun and everything has been a learning experience with it.
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That being said I love it. It is truly a hammer on coyotes with the 55 and 58's and with a 90 Grain Nosler HBT it is a hammer on hogs and deer.

I see a Savage barrel in this caliber in my future also.
 
I'm setting the shoulders back on my 6.5x6.8 at .002",and it still blows the primers out before I get into the higher powder charges. I've played with the shoulder set back several times,and it hasn't made any difference with the Hornady brass. I've got some Federal brass,but haven't tried it yet.
 
I have never blown any primers out at all. As a matter of fact it shoots better now that I got all the bugs worked out when I run them at max load (little tiny bug holes). When I tried to load down it didn't do well, It likes to be pushed as the guys have said all along. Its taken time and bullets to get this thing working for me but it is worth it.
 
I haven't played with mine in a while,it's been too hot for any real testing. I'll get back to it in a couple months,and maybe I'll find something that will allow me to turn it up a little.
I'm not too concerned,I get decent velocities with several of the powders that I've tested with,and I have 3-4 other ball powders to test with it. I will only be shooting two bullets from this little rifle,the 100 gr AMax and the 120 gr Sierra Pro Hunter.
 


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