Gas Gun: Having to Work Up New Load Removing Can?

[General RE LEE]

I am going to run my can on my bolt guns and run no muzzle device on my 6 ARC AR-15 build. Recoil on 6 ARC is negligible and I was getting a lot of back pressure with a can, even with adjustable gas block.

With my bolt guns, can or no can would change POI a little but it wouldn’t change accuracy of my pet handload.

Removing the can on my AR-15 opened up the accurate load I had developed in my AR.

Has anyone seen this before? Ever have to work up another load removing a can?

 

[FoggyScope]

I havent personally, i was listening to the hornady podcast about barrel tuners and they did say in their testing that adding large weights to the barrel (like a can) can change barrel harmonics. Sounds like most of the time its minimal, but depending on the barrel it can be major. Case by case depending on barrel manufacturing errors (everything has error of some kind) and how they all add up with the weight of the can influenced by the pressure created by the firing of the gun. So it could be that gun/ barrel combo is noticing it. In the ar specifically youre changing the gas system pressure dramatically with the can and my understanding is that can also effect dispersion (since you said the adj block didnt tame it down enough). So youre most likely right that it has changed something. If you have a different can you could try that. Or it may be possible to make a load (diff powder/bullet) that works more consistently for supressed/not.

 

[sierracharlie338]

IME adding/removing a can could show a bit of change in group size but it should not be a situation where the grouping would be drastically different to the point that a new load needed to be found. To be clear, I’m not saying it can’t happen, just saying I have not seen it. Only caveat here is if there was a minor baffle strike and removing the can alleviated that causing a change in flight path (that’s pure speculation though).

 

[Sccritterkiller]

The worse POI shifts I get with or without cans is with ARs..I think because so much of the barrel is free floated.

 

[Vern400]

Absolutely. Especially with a heavy can on a light barrel. Barrel harmonics change. What you saw is not unheard of.