7WSM and long action ?

[Kalashnikov]

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.

 

[dwm]

The detachable magazine length of the short action Savage model 16FCSS is 3".

 

[Kalashnikov]

I am 'estimating' the COL with the 162 A-max seated -.284" into the case neck to have a COL of around 3.5".

 

[Blacktail2]

I have a custom 7wsm built by Chris Mathhews on a Stiller Predator short action with a watts extended magazine.My O.A.L. to the lands is 2.974 with the amax.This combo works with a little room to spare in the Watts box.

If you measure from the start of the boattail up .284(which the min. i like to have)you get a O.A.L. of about 3.029.I don't were you got the 3.5.

My 7 shot the amaxs ok but it liked the 175mk and the 176 Cauterucio the best.

 

[Kalashnikov]

My O.A.L. to the lands is 2.974 with the amax.This combo works with a little room to spare in the Watts box.

If you measure from the start of the boattail up .284(which the min. i like to have)you get a O.A.L. of about 3.029.I don't were you got the 3.5.

The 3.5" may be a bad estimate. I won't argue 3.029" - thank-you. What is the OAL with the 175 SMK's ?

 

[dwm]

Now we are getting somewhere. Would a 3" detachable mag be ok then with the proper throat?

Would this be close enough, does one really need a long action?

Then what about the 168 Berger and maybe even the 180 Berger? (I'm kind of hijacking your thread, but it is to the same question ...)

 

[Blacktail2]

Kissing the lands lightly 2.965 loa. The base to ogive(which is a better measurement) is 2.311 with the 175MK.

 

[RockZ]

I made a dummy round with the beginning of the bearing surface of a 168vld just to the neck/shoulder junction and it measures 3.13" OAL.
Hope it helps.

 

[Kalashnikov]

Kissing the lands lightly 2.965 loa. The base to ogive(which is a better measurement) is 2.311 with the 175MK.

Is the 2.965" OAL for the 175 SMK when the bullet is seated max .284" into the neck ? If so, looks like a LA may not be required after all..tnx

 

[Kalashnikov]

I made a dummy round with the beginning of the bearing surface of a 168vld just to the neck/shoulder junction and it measures 3.13" OAL.
Hope it helps.

Yes thank-you. It looks like a 3.1" short action would pretty much accomodate these bullets just fine...interesting...

 

[Blacktail2]

I just measured the max O.A.L. that will fit in the watts box,and its 2.995.This is a short action.If you need more, than the long action is the way to go,or the Savage.

Kalashnikov,
The 175mk load is seated about .350 into the neck.

 

[Kalashnikov]

What kind of velocoties are you guys getting with your 162 A-Max and 175 SMK's ? Loads ?

Maybe the M700 SA with Wyatts box extended magazine is the way to go....

Good info. tnx

 

[JeffVN]

I'm getting 2,900 fps from my 7WSM with the Sierra 175 smks using a 26" Kreiger 9 twist barrel and a overall length of 2.860" My load is 65.0 grains of RL-25 or 66.4 grains of H1000 (a little slower - 2,875).

My current set up is magfed from AI magazines through a Surgeon Short Action.

JeffVN