375 Raptor in MSR

[Bliksem]

I got a new to me Aero Precision M5 MSR in a trade but as I already have 1 each in 308Win and 358Win I am contemplating another barrel switch. Initially I looked hard into going with the 45 Raptor but the cost of brass and customized magazines dimmed my enthusiasm.

During my research I came across references for the 375 Raptor. The more I read the more I like the idea and am trying to locate a barrel and dies. I have some leads but have not had responses to my emails. (I can‘t call as I’m sitting in a conference trying to pay attention to a presentation on a subject I’m too familiar with.)

I have searched on this forum and the inter webs in general but can’t find but a few references to builds in the MSR platform. I‘m not interested in subsonic but would like to do cast of ~300gn at 2000fps. I’ll be looking at what offerings already exist on the Accurate site and start doing a design if needed.

Any thoughts/opinions?

Bilksem

 

[CWLONGSHOT]

I have a friend building one of a 308 bolt rifle.
CW

 

[popper]

Check Xcaliber barrels.

 

[Ian]

I guess Arne isn't actually having any produced? I know he's worked a lot with Lother-Walther and Steve Satern in the past, might look there for barrels.

 

[fiver]

CH4D is the first place I'd look for dies.

300 at 2K? hope your into recoil.
@275gr. at 1600+- ain't no fun in the lever rifles [especially the Winchester]

 

[Brad]

I can do 300 at 2K and have reasonable recoil. In a 9# 375 H&H. The 275 at 1600 is mild.

Now a 270 at 1600 in the Win 94? Oh hell no, that hurts!

 

[CZ93X62]

Tracking Brad's text, in the Win 94 38/55 a 250 grainer at 1300 FPS is docile. At 1500, it's firm and noticeable. At 1700, it's becoming substantial. The 44 Mag Win 92 with 240s at 1800 is becoming substantial, as well.

One of the best illustrations of heavier bullets' drastic effect upon recoil came from the 30-06 at about age 16. Dad, Leo Reyes, and I were out sighting in the venison tools and Leo brought along factory-level handloads in 150, 180, and 220 grain flavors. All jacketed, all ~50K PSI. From Dad's Model 70, the 150 grainers were an all-day load. The 180s were noticeably sharper in recoil. The 220s were impressive.

Lastly, my 9.3 x 62 shooting 250 grain bullets at 2650 FPS recoils noticeably less than do the 286 grain NosParts at 2400.

That usage in an MSR and its gas-operated action may stretch out and attenuate the recoil somewhat. I have shot a whole lot of M80 and Gold Medal Match 308 ammo in gas guns and bolters over the years, and the gas guns are easier on the shoulder.

 

[Ian]

A fiberglass-stocked M14 weighs like 12 pounds, too, although the checkered steel butt plate is a buggar.

Suppressors soak up a lot of recoil.

 

[CZ93X62]

Some portion of the gas jet pushing the bullet out of the barrel contributes to the felt recoil impulse as well--some estimates say 20%-25% of the total.

 

[Bliksem]

CH4D is the first place I'd look for dies.

300 at 2K? hope your into recoil.
@275gr. at 1600+- ain't no fun in the lever rifles [especially the Winchester]

Thanks for this info: they had the sizing die and Dillon trim die in stock so they are on the way to me.

 

[Bliksem]

Check Xcaliber barrels.

Thanks for this hint: I managed to get a 18” Xcaliber barrel from Omega rifles, it is on its way to me.

 

[Bliksem]

Thank you all for comments and suggestion. Yes, I understand recoil can be an issue but then again I won’t be shooting 100’s of rounds in a session. I’m quite familiar with the effects of pushing heavy bullets at high speed and do appreciate the input.

I have a barrel and dies on the way so soon this build will be done. The host upper is an Aero Precision that came with a 308W barrel that will be switched out. I’ll forgo a muzzle break at this time as I don’t favor them so a thread protector will be used.

Once I have the upper ready I’ll do a pound cast and based off of that order a mold from Tom @ Accurate.

some pics will be uploaded once the build is completed.

 

[fiver]

cool, I'll be following the process.

 

[Bliksem]

CH dies including FL sizer, seater and Dillon trim die with Lee crimp die and gas checks were waiting for me when I got home last night. Tracking shows barrel delivering later today.

 

[Ian]

Christmas in September!

 

[fiver]

Dammit,,,, that reminds me I need more 45-70 checks and a bag of 375's surely wouldn't hurt, since that cup is looking a bit low.

 

[Bliksem]

So this past weekend I prepped 209 cartridge cases, 1 split during the reforming.

FC 64 demillled cases were put through 3 steps in a Hornady Projector press. First die is a modified Lee expander with a self-made neck expander mandrel that opened the neck to .375”, 2nd is a Dillon power trim die and the third is a CH FL die.

The cases were then inside neck chamfered on a Lyman case prep center followed by being annealed. The cases were then SS cleaned in a Thumlers tumbler and dried in a mini oven.

Next up, pound cast to be able to design a bullet and order the mold from Tom @ Accurate.