Well it is finally time to barrel the 09 action. I have decided on 280 or 280AI. My question is this, what twist rate is acceptable? I do not want to shoot a bullet any heavier than 140 gr in this rifle. After visiting several local smiths I have come away pretty confused on the whole bullet weight/twist thing. Also there seems to be some difference of opinion as to if the mag box is long enough. Any help would be appreciated. Thanks.

If you stick with the SAAMI max COL and like to seat bullets close to the lands then it's going to be very tight indeed in the magazine box. My O9 can just about fit 3.3inches If the rifle recoils an amount you run the risk of the round underneath the bolt getting bashed on the feed ramp. You can get recoil stops in the box but they don't stop the one under the bolt moving and getting a bashed tip.

This is what I suffer from with my 9.3x62 on an 09 so I offer it to you in the spirit of what to be sure of. Having said all that it shoots fine with a short COL and bullets a long way from the lands.

I have built several 280 AI rifles on various actions. You need at least a 3.340" magazine length for the 140 Partitions, and a 3.550" magazine for the 160 Partitions. This keeps the bullet base out of the shoulder area of the case. (Bullets seated into the shoulder area use up valuable powder space.) I assume the 09 action you mention is a 1909 Argentine. You can gain almost 1/4" more magazine length by lengthening the magazine to the rear. Don't lengthen to the front!!! Use a good barrel, such as a Pac Nor, Lilja, or Shilen. 9 inch twist is preferred for 140 gr and up bullets. Have your chamber throated so the bullet is about 0.010" off the lands, using a properly seated bullet in the case that allows the cartridge to cycle through the magazine. My 280 AI reamer is ground for this seating depth. (I prefer the 280 AI.) One of my clients took a Griz last year with his 280AI that I built. He was hunting Caribou, ran into a Griz, had a tag. This guy uses 140 Partitions for most hunting, but carries a few 160 Partitions in his pocket. So, after switching to the 160's, one shot anchored the bruin. Give me an email if you need more help. Good hunting! John (star@olypen.com)