AR57 rifle+suppressor=No, why?


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bikemutt
August 22, 2014, 09:24 PM
So, I picked up an AR57 rifle upper (5.7x28) to add to my fun chest, and figured it would like a suppressor as much as the AR57 6" pistol does.

I was surprised, the POI shifted greater than 12" right and 12" down at 25 yards with the suppressor mounted, and accuracy MOL fell apart, not off the earth but meh.

I first tried this at 50 yards and could not figure out where the bullets were hitting which is why I dialed back to 25 yards.

I checked, no baffle strikes. Suppressor is a Huntertown Arms G22 with Kestrel core (rated for semi-auto 5.7). Ammo is FN 40 gr. and American Eagle 40 gr. both displayed similar characteristics.

Not a big deal, this one does not have to be shot suppressed to enjoy it, I just wonder why Mr. Yuck showed up with this combination. Thoughts?

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barnbwt
August 22, 2014, 11:17 PM
Twist rate? Maybe the can is slightly off-axis, but parallel, enough to impart inaccuracy but not enough to cause baffle strike (yet)? How much does the sonic crack contribute to the overall boom, in your estimation? I'm toying with the idea of an integrally suppressed carbine at some point in the distant future...

TCB

ugaarguy
August 23, 2014, 06:43 AM
I think you'll get better answers here in the NFA section.

bikemutt
August 23, 2014, 08:04 PM
Twist rate? Maybe the can is slightly off-axis, but parallel, enough to impart inaccuracy but not enough to cause baffle strike (yet)? How much does the sonic crack contribute to the overall boom, in your estimation? I'm toying with the idea of an integrally suppressed carbine at some point in the distant future...

TCB
There is one other firearm I experienced a significant POI change with; Ruger SR-22, it was pathetic how much it changed, same suppressor. I would have to say the suppressor is of minimal usefulness with this (57) setup since the rifle is not real loud to start with, which is why I'm more curious than concerned.

I guess I've become complacent with suppressors; if it has a threaded barrel it will be quieter and as accurate. Mostly true, but not always.

Ranb
August 24, 2014, 01:06 AM
It is probably baffle strikes light enough not to leave a mark. I've had this happen before.

I put a silencer on an AR57 last week; it was very nice, much less noisy than an AR in 223.

Ranb

Theohazard
August 24, 2014, 02:52 AM
How long are the threads on your AR 57? Most AR-style barrels with 1/2x28 threads have longer threads that are about .6" long. But most .22 cans are designed for the .4" long threads found on most .22 threaded barrels, so the silencer often won't butt up against the shoulder, which can cause baffle strikes because the silencer isn't properly aligned.

And some silencers might butt up properly against the shoulder, but the muzzle will be too close to the first baffle, which can be an issue with asymmetric baffles. For example, the Spectre II will still shoulder properly on an AR-style .22, but the bullet exits the muzzle so close to the first baffle that the bullet becomes unstabilized and can keyhole. The one time I saw this happen, the shooter was very lucky he didn't get baffle strikes.

You're obviously not getting baffle strikes, but my guess is your first baffle is too close to the muzzle, which is causing accuracy issues. A $10 spacer from Gemtech might fix your problem.

bikemutt
August 24, 2014, 08:35 AM
How long are the threads on your AR 57? Most AR-style barrels with 1/2x28 threads have longer threads that are about .6" long. But most .22 cans are designed for the .4" long threads found on most .22 threaded barrels, so the silencer often won't butt up against the shoulder, which can cause baffle strikes because the silencer isn't properly aligned.

And some silencers might butt up properly against the shoulder, but the muzzle will be too close to the first baffle, which can be an issue with asymmetric baffles. For example, the Spectre II will still shoulder properly on an AR-style .22, but the bullet exits the muzzle so close to the first baffle that the bullet becomes unstabilized and can keyhole. The one time I saw this happen, the shooter was very lucky he didn't get baffle strikes.

You're obviously not getting baffle strikes, but my guess is your first baffle is too close to the muzzle, which is causing accuracy issues. A $10 spacer from Gemtech might fix your problem.
I did install a spacer nut on the thread to expose 0.4" for the can. It's supposed to be a pretty good spacer: http://www.tractiongrips.com/catalog/i12.html

I've used one of these on a Kel-Tec PLR-22 without issue.

Theohazard
August 27, 2014, 01:37 PM
I did install a spacer nut on the thread to expose 0.4" for the can.
Darn. I'd thought for sure I had your problem figured out.

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