Subsonic 220 RN unstable in 8 twist bbl

[BK7saum]

Have a 300 whisper. Loaded some Hornady 220 round nose bullets to 1050. Shot them at 50 yards and am getting oval holes on paper.

I was under the impression that an 8 twist should handle everything up to the old 240 smks. The 208 amaxs are stable btw.

Any suggestions or insight why the 220s are not stable.

 

[country888]

Re: Subsonic 220 RN unstable in 8 twist bbl

I have 2 box's of these for my blkout. I have shot them, but they don't feed well in mine. A buddy of mine is trying them in his also. They are keyholeing in his also. With the 220 RN it's not the weight as much as the shape of the oive. Its just the bullet. Stick with the 208 amax or 220 smk's. The 208 amax or the 208 hornady HPBT match shoot great in mine.

 

[ChadTRG42]

Re: Subsonic 220 RN unstable in 8 twist bbl

Technically, the 220 RN should be stable in an 8" twist at 1050. Is your 1050 fps confirmed by chronograph? If you have not chrono'd it, I would bet it's running slower, and doesn't have enough speed to stabilize.

But, I have also seen a few blk out's not stabilize the Hornady 225 bthp, where the 208's do fine in an 8" twist. A 1:7" is needed for the 240's.

The 220 RN is for bolt guns. It will NOT feed from an AR-15 magazine. The RN hangs up on the feed ramps.

 

[BK7saum]

Re: Subsonic 220 RN unstable in 8 twist bbl

This is a 700 with a shilen barrel. I don't remember the exact chronoed velocity but it was real close to 1050 +/-.

I guess I'll have to get a new 7 twist barrel chambered. I have a mold for a 240ish grain cast boolit that I was hoping to shoot along with the 220 RNs.