MNGunTalk.com

BigBlue wrote:

Ghost wrote:Did you get your trigger?

No, no word on that yet. I guess the 3-5 week estimate was not actually accurate. No big deal though.

At least you can do a before and after review on the trigger

So my free time and a decent day finally coincided. Got the new AP rifle out for it's shakedown. Had to adjust the SA adjustable gas block and sight things in. Both went well. The SA instructions for tuning the gas block were easy to follow. For sighting I just threw on a cheapie red dot sight I had lying around because I still haven't decided on a permanent optic, nor does my budget have funds for one yet.

I'm blown away by by the consistency of the groups at 50 yards. This picture shows three groups taken between sight adjustments. The three in upper right, two above the bull and the one in the bull and the one to the right. This is with a red dot that covers the bull at 50 yards and me shooting with a spring-clamp-on bipod on a wiggly bench. I think this AP setup is going to be a spectacular hunting rig when done. The rifle is quite tame on recoil which was not what I expected. Very little muzzle lift and my shoulder wasn't unhappy at all.



What didn't go as well was the Precision Gamma muzzle device. I tried to follow the verbal instructions AP gave me about it, which was: hand tighten, then torque to 35 ft-lbs with the wrench, then continue clocking to desired alignment with logo down. I lubed up the crush washer and hit it with the torque wrench. Got to 35 ft-lbs without issue. But then realized the logo was 270* from where it needed to be. Tried to tighten more to make up that 270* but no way was it going that far without cranking on it WAY too much. So at this point I have a used crush washer stuck on the end of the muzzle and no device on it. I'll have to use a Dremel to cut it off. Hopefully AP will send me a replacement crush washer. Next time I'll try setting the torque wrench at 35 but monitoring how far it rotates and stop when correct clocking is reached even if I don't hit 35.

BB

Are you using any rocksett with the muzzle device?

Ghost wrote:Are you using any rocksett with the muzzle device?

No.

Just following up with latest status...

Called AP yesterday. They were happy to send out a couple more crush washers for the Precision Gamma. The guy claimed that I should have been able to continue tightening the device far enough to get it clocked correctly. When I told him that the crush washer was already deformed so much it was oval shaped and sticking out he said that was normal. Said you can't over-tighten them because when they reach their max deformation the crush washer will crack. Huh. Doesn't sound like the type of advice I want to follow.

When I get the crush washers I'm going to try things slightly differently. First, instead of clamping the receiver in the vice blocks I'm going to get some non-marring vice jaws and remove the handguard so I can clamp the barrel directly. Then, I am going to set the torque wrench at 35 ft-lbs but when the device is clocked right I'm going to stop even if I haven't quite gotten to 35.

As to the rocksett question, I asked them and they said they do not recommend rocksett or threadlocker for muzzle devices. They said use anti-seize.

BB

Pics would help but it does sound normal to me.

Not much to take a picture of at present. I've removed the device. The crush washer is still on there because as it deformed it now doesn't come off the barrel threads. I'll have to dremel it off. I did use a pliers to bend it back to circular (from oval shaped) in hopes that would be enough to allow me to unscrew it, but no go.

What's the 'sounds normal' part? That the crush washer deformed to an oval shape? If so, that's unfortunate. Pretty ugly looking.

BigBlue wrote:Not much to take a picture of at present. I've removed the device. The crush washer is still on there because as it deformed it now doesn't come off the barrel threads. I'll have to dremel it off. I did use a pliers to bend it back to circular (from oval shaped) in hopes that would be enough to allow me to unscrew it, but no go.

What's the 'sounds normal' part? That the crush washer deformed to an oval shape? If so, that's unfortunate. Pretty ugly looking.

The crush washer deforming a bit. Remember it has to crush to work and that means metal has to move somewhere.

Since I squeezed it back to round with the pliers there will be no pics of that. Think of an oval. Two sides stayed 'narrow' and were still no wider than the muzzle device and the other two sides squeezed out and stuck out past the muzzle device and barrel a couple millimeters. It looked like crap and I would not have left it that way even if it ended up clocked correctly.

I would assume in normal situations the washer would crush uniformly and just expand the circle.

BB

BigBlue wrote:Since I squeezed it back to round with the pliers there will be no pics of that. Think of an oval. Two sides stayed 'narrow' and were still no wider than the muzzle device and the other two sides squeezed out and stuck out past the muzzle device and barrel a couple millimeters. It looked like crap and I would not have left it that way even if it ended up clocked correctly.

I would assume in normal situations the washer would crush uniformly and just expand the circle.

BB

Ideally yes, but I have seen them oval a bit.

Holland&Holland wrote:Ideally yes, but I have seen them oval a bit.

This was ugly. Way too much sticking out unevenly. I'm wondering if it wasn't due to the armorer's wrench I was using that may have been so wide it covered two sides of the washer so it could only deform out the other two sides? I'll watch things closer next time.

I've also looked around for more info on installation and it seems there are about as many ways to install one as there are rifles. From grease to anti-seize to loctite to rocksett to torquing specifically to just doing it by feel... I think as long as it gets on and clocked correctly I'm going to call it good. Just as long as it doesn't loosen up over time and cause a firing problem I'll be happy.

BigBlue wrote:

Holland&Holland wrote:Ideally yes, but I have seen them oval a bit.

This was ugly. Way too much sticking out unevenly. I'm wondering if it wasn't due to the armorer's wrench I was using that may have been so wide it covered two sides of the washer so it could only deform out the other two sides? I'll watch things closer next time.

I've also looked around for more info on installation and it seems there are about as many ways to install one as there are rifles. From grease to anti-seize to loctite to rocksett to torquing specifically to just doing it by feel... I think as long as it gets on and clocked correctly I'm going to call it good. Just as long as it doesn't loosen up over time and cause a firing problem I'll be happy.

You are very correct about the many opinions on how to do it. The last one I did with shims and ended up at about 40 lbs to clock it right.

without rockset or other higher temp thread locker it will loosen up upon firing. I use precision shims, not crush washers especially if I am going to mount a suppressor.

striped1 wrote:without rockset or other higher temp thread locker it will loosen up upon firing. I use precision shims, not crush washers especially if I am going to mount a suppressor.

I'll keep an eye on it over time. I'd be surprised that a well-known maker of muzzle devices would recommend something that would lead to problems later. But then again nothing really surprises me any more.

BB

striped1 wrote:without rockset or other higher temp thread locker it will loosen up upon firing. I use precision shims, not crush washers especially if I am going to mount a suppressor.

What did you torque them to? I had one with a peel washer at 25 lbs that shot loose, I repeel washered it and went to 30 lbs and it has not let loose again.