375 Raptor question

[roysha]

Can someone tell me what the reason for the shortening of the neck on this cartridge is? And yes, the case length is shortened overall.
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[BK7saum]

First of all, your question is a little ambiguous as shortening the neck does shorten the case length (all else held the same). I will answer what I think you are asking, which is why they shortened the body (neck moved or pushed back) and subsequently shortened the neck.

The 308 has a neck length of roughly 0.303" which is still roughly 1 caliber lenth that has been a somewhat standard rule in cartridge design.

The .375 has a neck length of 0.275" and while shorter than a 1 caliber length neck, doesn't seem to present any problems with the case neck to be able to hold the bullet. Yes, they could have left the neck length longer and it would not have presented any problems with the cartridge.

I don't know the reason the cartridge designer had for shortening the body and neck, but I suspect it would be similar to the Creedmoor and other newer cartridge variants of the 308 case, which was to better able fit the magazine length constraints of 2.800"

Larger and/or longer ogive bullets required more length for bullets and the shoulder had to be pushed back to accomodate the changes.

The shoulder needed to be pushed back to allow for the case neck to better align or fit with the location of the bearing surface on the larger/longer 375 bullets. Since the shoulder was pushed back, the neck became longer than necessary and possibly extended beyond the bearing surface and past the ogive, where it was not wanted or needed and out of proportion to the bullet/cartridge.

There are bullets in some cartridges that cannot be used due to long ogives and magazine length constrictions.

300 HAM'R is one example. Only lighter, shorter ogive bullets fit and still give enough bearing surface in the neck to stay firmly seater.

358 winchester is another. Magazine constraints limit the bullets used with the full length case.

260 rem is another example. When developed, about 130 grain bullets were at the heavier end of what it was desigbed to handle. Since then, longer and heavier bullets have become more popular and more mainstream. The High BC 140, 142, 147 etc bullets do not fit well with a 260 case and standard 308 magazine length. The bullet is pushed very far into the case, sometimes beyond the leadig edge of the bearing surface.

If you were to get away from magazine length restrictions such as a single shot or modified bolt action with a Wyatt's extended box, there are a lot more options in bullets available and some slight performance gains to be had by seating the bullet out farther and doing additional load workup.

Short answer..., cartridge modification limited by .308 detachable magazine length(2.800"). Something had to give and shoulder /neck were moved/modified to better able make the cartridge work in those constraints.

[roysha]

Thank you for the response.

First of all, the body is not shortened because to fire form cases all one has to do is fire 308 rounds in the Raptor chamber. That is how we formed the cases. The body is perhaps blown out a bit, and the shoulder is perhaps a bit more sharp, but for all practical purposes it is the same length.

Since this cartridge is supposedly designed for use in the AR 10, as you stated, the magazine length is the limiting factor for OAL. Therefore, in my mind, the length of the case is rather irrelevant in regard to fitting and/or feeding from the magazine since the OAL is what it is regardless of how deep the bullet must be seated to achieve the required OAL.

It would seem to me that a longer neck would be more conducive to securely holding the bullet in place during feeding and recoil, especially in the autoloading AR 10 platform.

To simplify much question, why did the folks that "designed" the Raptor feel that a short neck was necessary when in the overall scheme of things all it does is create a bit more work to initially form the case. No big deal in the overall scheme of things. I'm just curious why a simple 375-308 could/would not achieve the same end result with a bit less hassle.