220 Swift Improved?????

[brianwinzor]

SRHaggerty, MTBA'S prediction of 3600 with the 68 grain bullet is realistic, as in my 220 Swift AI I achieved 3,630 fps with the 68 grain Hornady in a 25.25 inch barrel.

However, my gunsmith achieved 3765 fps with the 68 grain Hornady HPBT using 47.0 grains of Norma 205 in my barrel, prior to sending it back to me after chambering. I had exhausted my supply of Norma 205, and could not access any more, but the other powders that were available in Oz in the mid 1980's could not get anywhere near that velocity.

I suggest you email Richard and get his view on the explosiveness of his 68 grain ULD bullet at around 3600 fps.
Brian.

 

[srhaggerty]

Brian, I did in fact do what you said and emailed him this morning. I think I will rebarrel it to AI, whether I shoot the 68's or some ballistic tip.

 

[srhaggerty]

MTBA,

If you backed that load off to reach 4300fps, how many rounds do you think that barrel would take?

 

[Kevin]

srhaggerty,
My barrel has had a lot of regular 220 swift shot through it with 50-55gr bullets and also a lot of 220AI with a mix of 40 50 52 and 55gr bullets. I really do not know which combination caused the most harm. The gun actually still shoots OK the problem is that I have the bullets seated as shallow as possible to get close to the lands. The 40's actually are not close they have about .1in freebore. Naturally the 40gr has the most powder. But if you did back it off to 4300 it would burn almost the same ammount of powder as the 55gr load. The same ammount of powder along with a smaller bullet should cause a little less damage than with the 55's. Case life would be very long thats for sure.