300 BLK tumbling?!?

[jeep78]

Ir you want to try stuff, try the same can and ammo on another gun, one that was factory threaded.

 

[RHelton10]

Ir you want to try stuff, try the same can and ammo on another gun, one that was factory threaded.

Good idea, unfortunately I only have the 1 barrel at the moment. I may take it to the gun shop and have him take a look at the crown but I'm going to go by and shoot another weight first to rule that out.

 

[Burdy]

Lots of people think they don't have a baffle strike... But they do. It can be extremely difficult to tell and under some circumstances require disassembly for confirmation.

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[jeep78]

Is your ammo subsonic in a 16" barrel? If so, it will be real slow out of your short barrel.

Too slow, and it will not stabilize.

 

[jpm2953]

I don't see how you could be tumbling at 17 yards and not be getting baffle strikes

 

[z.chance]

With 1/2-28 threads, there is basically no crown on the barrel, so I wouldnt even worry about that.


My theory is that you are hitting paper with a pointy, slow moving bullet. Its tearing the paper instead of punching a clean hole in it.

 

[Burdy]

With 1/2-28 threads, there is basically no crown on the barrel, so I wouldnt even worry about that.


My theory is that you are hitting paper with a pointy, slow moving bullet. Its tearing the paper instead of punching a clean hole in it.

Not likely. You can put a spit wad in a rubber band and make a clean hole.

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[rOmiLaYu]

Is your ammo subsonic in a 16" barrel? If so, it will be real slow out of your short barrel.

Too slow, and it will not stabilize.

With any other caliber, I'd agree with you - but - 300BLK is a different animal. It is designed for total powder ignition in around 9" of barrel. So actually a 16" barrel could actually be slower than a 9" barrel given friction over 7" and the lack of propellant gases.

I've thought about this all day and am just as lost as I was last night. I guess my next step would be to fire it unsuppressed and see if it did the same thing. If not, my guess would be miniscule baffle strikes that intiate the keyholing. Why those baffle strikes would be occuring is anyone's guess. Lack of concentricity, loose can, shoulder off, and on and on.

 

[JFM33]

It is pretty common for subs to keyhole ,most factory subs are designed around a 16" barrel.
When ever I am doing a load development for subs or even trying Factory subs I always do them without the can to make sure they are not tumbling.What works in my 10" 300blk doesn't always work in my friends 16"upper.If there not key holing without the can then I should be good to go with the can.
It is usually because of low velocity ,or too heavy a bullet for the barrel twist.
Gas tube length will mainly effect the action cycling ,unless the port is drilled oversize which could cause a minor velocity drop.It also matters if the gas port was drilled into the lands or the rifling of the barrel.

 

[jeep78]

Define "subsonic".

Both 500fps and 1075fps are subsonic. I seriously doubt both will have the same exterior ballistics when fired out of the same gun.