7WSM and long action ?

[depopulator]

I am considering building a 7WSM specifically around the 162 A-MAX,.625 BC) or Berger 168 VLD,.643 BC) and 1-10 twist barrel.

I want to maximize the powder capacity,and velocity) of the case, so the plan is a cartridge overall length based on these bullets seated to a maximum .284" into the case neck,or less - what is the minimum I can get away with ??). I will also have the barrel/chamber throated so that the bullets would touch the lands when seated to this cartridge COL.

Lastly, I do want to use the magazine of the rifle. I suspect I cannot use the magazine on a short action with this proposed COL,whatever that may be - not sure at this point - anyone ??). Therefore, I am considering custom chambering a new long action SPS or Savage 110,in 300 RUM as a donor action?) to this cartridge spec.

Any problems I may be getting into with this build ? Can I expect much of an improvement in performance over a short action with these bullets seated to 2.86" COL ? Any advice or thoughts would be appreciated.

 

[Jeffvn]

I am currently doing what you are talking about - runnning the 7WSM long-throated to accomodate longer 7mm bullets,I'm using the 175 Sierra smks). I'm running it out of a Short Action Surgeon repeater, and have no problems at all. I do not seat my smks into the lands, but the rest is the same. My loaded rounds are 3.090", leaving .223" of shank in the neck.

In hind sight my throat is a bit too long, and the bullets are seated too far out, as the lands move with this chambering and you will want to be able to chase them to maintin your contact with the lands. I think the proper shank length to start with is more like .285-.300 or - roughly 3.025" with your 162 A-Max, as this gives you plenty of room to chase the lands but still gives you sufficient length to maximize case capacity.

Live and learn - the good news with my Sierras is they can and do jump well. Hope this helps.

JeffVN