510 Whisper Build Advice (Stock/Bottom Metal/Magazines/Twist/Barrel Length)

[Airwolf...]

Hi all,

After my first and mostly successful foray into custom bolt actions with my 338 Lapua Improved build, it's time to start the next one. I have decided to build a 510 Whisper bolt action. I was wondering if anybody could help with some questions regarding parts selection for this build. So far, I have purchased the action, which is a Remington 700 footprint Long Action that supports 4.050" magazines.

• Will 510 Whisper cartridges fit in a 338 Lapua Magnum AICS magazine? For my 338 Lapua Improved build, Fritz at Black Canyon Customs machined out the shoulder guides of my MDT 3.850" AICS magazines and I am curious if I would have to have something similar done for these to fit, if at all.
  • Is there any point to using 4.050" magazines that have a max COAL of 3.970"? I see that the 750 AMAX load on SSK's load data has a COAL of 3.620" and a standard CIP AICS magazine allows 3.740". It's always nice to have some extra room to work with, but if it is going to make everything else a pain, I won't bother.
• Are there any chassis-style stocks (like the MDT ACC Elite or MPA BA etc) that accept 4.050" AICS magazines? I have not been able to find any.
  • If no chassis style stocks would work, what stock would you recommend? I would prefer to keep it at or less than $700 if at all possible.
• What length barrel would you recommend? I am happy to SBR the action and go with a short barrel. I was looking at the SSK load data and they are using an 18" barrel. I think this is a bit long for my needs, as I was planning on developing my loads with Vihtavuori N110 and it is a very fast burning powder.
• What twist rate would you recommend for a 510 Whisper? I see that Maker Bullets offers a 1000gr 50 BMG Subsonic REX and a 900gr 510 Whisper Subsonic REX that both have a recommended twist rate of 1 in 10.

Thank you in advance!

 

[Dirty D]

I haven’t built one (yet) but looking at the specs I would assume that a CIP length magazine would be the easy button. The COAL is listed at 3.34” with a 750 grain bullet and the CIP magazines are 3.8”