284 Win Reamer Specs

[ChrisNam]

I currently shoot 1000y BR and F Class with the 168 gr Sierras or Bergers in a 1:10 twist 30" barrel chambered in a straight 284 Win. Unfortunately I do not have the reamer specs, except that I know that the chamber has a 0.315 minimum turn neck.

I've always used 7mms chambered specifically for the 168 gr bullets. I've always enjoyed very good accuracy with the 168 grs, but no barrel ever wanted to shoot the 150 gr bullets. I presume the throats have always been to long.

Some time ago I ordered a Pacific 284 Win reamer with a 0.315 neck and a 0.120 freebore.

It appears that with 6mms the consensus has recently moved towards a shorter freebore - for the 105/107 grs it used to be, if I recall correctly, 0.100to 0.115, while recently some, including it appears Dave Kiff, advocates a shorter 0.80 to 0.90 freebore.

What should the freebore be for:
1. 168 gr Sierras / Bergers in a 1:10 twist
2. 175 - 180 gr Sierras / Bergers in 1:9 twist?

I will greatly appreciate any advise.

 

[ronemus]

I shoot the 162 gr A-Max,similar in size to the Sierras) and find that a .270" freebore will put the bottom of the shank just above the neck/shoulder junction. The .284 neck is long enough that a 0.400" freebore is possible if you want to maximize case capacity. Anything between those limits should work well. I'll be interested in the results of your search for reamers; the barrel I'm shooting now was chambered over 30 uears ago and will have to be replaced soon.