MOVING the gas port?

[Foxfire]

Thanks guys for the info it helps a bunch.

Mine is a 16” model “1” ported at the carbine position. It cycled fine with supersonic handloads, but even after opening up the port to 0.125 and installing a JP adjustable gas block I still can’t get it to lock open with subsonic loads. (For me if it won’t lock the bolt open then it’s not cycling completely.) Even tried slower burning powders. AA#7, H110, IMR 4227, Win 680. My conclusion was that my port was just in the wrong place for subsonic loads.

320pf,
I was very surprised to read that you moved your port from pistol to carbine position. Is that upper dedicated Supersonic? Why did you move it out?

Fox

[320pf]

Foxfire,

I am interested in the super sonic capabilities of the 300-221 fireball. As I mention in my original post, I have three 16 in, 300-221 Fireball barrels. Two Olympic Arms and a Noveske. The two uppers with the gas port in the pistol position work well with subsonic loads. I have found that the best powder for sub-bonic loads for my barrels is 7.5 to 8.5 gr. of AA#-9 depending on the ambient temp. The powder burn rates and the speed of sound change with temp so if you want to have your loads running just sub-sonic you have to tune them for the time of year. On cold days the speed of sound is a slower but the powder also burns slower and usually requires a bit more powder than on hot days. So I have my sub-sonic load pretty much worked out.

Both barrels with the pistol gas port are 0.070 in. and work very well with the sub-sonci loads. The super-sonic loads work mostly pretty well but if I really start working the gun in rapid fire... sometimes the action cycles too fast and tears the rim off the brass and leaves the shell in the chamber. It seems that the pressures are too high when the action cycles. Moving the gas port to the carbine position will delay the cycling of the action allowing the bullet to move further down the barrel and lowering the pressure. I am hoping that this will improve the super-sonic performance of the 300-221 fireball.

Do you have any data on the super-sonic capabilities of your barrel? Loads velocities etc...

thanks,

320pf

[Foxfire]

Sorry, no data yet. I want to work out the kinks in subsonic first, sense that will what I'll primarily shoot.