So I am taking the plunge and getting into .375 Raptor which is .308 brass reformed into .375 and trimmed down. Bullets are from 270gr to 350gr and will feed from slightly modified PMags in DPMS format AR10 rifles.
My question is about opening up the case necks from .308 to .375. I have purchased a 2 die set from CH4D (FL Sizing and Seater) as well as an expander die body and 2 tapered end plugs, .30-.33 and .32-.37. I have never used one type brass to make another caliber so what is the exact procedure? Do you use the end plugs to open up the case mouth first before using the FL sizing die? Doesnt the sizing die have a mandrel with a ball on it that would open up the case neck to the necessary diameter? If so then whay are the tapered end plugs needed? One video shows a guy resizing 1x fired .308 brass in a single step (rockchucker press) into the .375 raptor case and then trimming it in a Giraud trimmer. I get the trimmer part, I am just wondering if I am unnecessarily adding steps with the 2 different tapered end plugs plus the FL sizing die. I dont want to tear up brass with split necks and would prefer to do it right in order to make the brass last as long as possible. Please educate me on this. Thanks

Yep expand then resize

I think the plugr are for expanding the neck in steps. maybe to keep from splitting the neck. I like to anneil before going up to far on the neck expanding. .060 thousands is not all that much

anneal, imperial sizing wax, have fun ... if you are riveting cases, needs more lube .. but, if you have a 338, then 358 expander, do it in 3 steps, you'll save more cases

btw, it MIGHT be easier to cut of 30-06 cases, anneal, then form ... i have zero clue as to how tight the case tolerances are as North American Sportsman, LLC refuses to actually release the cart to the public, claiming ITAR, etc ...

i've released about a baker's dozen to the world, as i wish people to be freely able to use them -- i ain't in the business, and i don't agree with proprietary carts -- EVER

Yes, and the best type of expander is the Lee because they are quite tapered on both ends, so it makes expanding easier. Expanders that are just little buttons make it impossible.
Milk the case up over the expander in steps, up and down; don't try to horse it open all at once.
Doing what you want is easy to do; don't fret.
Oh, making them out of 30-06; no. That makes a lot more work as you are forming a neck out of a body, which means that you end up with a very thick neck, which needs turning or reaming.
Just form the 308; it will be easier than you think.

See "SMACK" 375 Raptor in Modern Military rifles...otherwise all the above. Sizer must have an elliptical sizer button or a tapered one.

I've upsized/reformed 8 mm x 57, 9.3 x 62 and 35 Whelen cases into 375 JDJ in one pass using a Hornady 375 H&H sizer elliptical button then fireformed
and downsized/reformed 444 Marlin cases using 416 Taylor seater then sizer, then a 358 seater die and finally FL in JDJ sizer with an elliptical button. Those cases couple probably use some annealing, but I will never shoot them enough to test out.

Takes a while to figure out what speed to jerk the handle...too fast and you bang the **** out of your press, too slow and the brass refuses to cooperate and doesn't form well. I hardly anneal any more...case stretching, incipient head separation, and over pressure loads usually kills the case before the neck goes, but it does work well for some...it's NOT wasted time.

Use a nylon cleaning brush with Imperial wax wiped on to lube the inside of the case mouth and wax the whole case before the final resizing. (WIPE OFF the wax) Get a cheap Lee case spinner, a clean shop towel cotton or paper, spin the case in the rag but BE CAREFUL, those dam*** case holder edges will grab the rag and depending on the torque of the drill motor can cause a total wreck.

Good luck with the Raptor...it's actually a very neat AND older, tho' not highly utilized wildcat, whose time has arrived for some platforms.

I’ve taken the 280 to 416. Lube and tapered plugs and go slow.

I'd be concerned about using a 350-grain bullet with such a small case, worrying one might get stuck in the barrel

Yeah...but at ~1950 fs it whacks at almost 2900 ft lbs...big bullet, low velo...depending. Pretty stout for a close in pig gun...not too shabby.

I would rather have the 45 Raptor tho'...really BIG bullet Hahahahahaha

Good hunting

quote:

Originally posted by sambarman338:
I'd be concerned about using a 350-grain bullet with such a small case, worrying one might get stuck in the barrel

350gr matchking -- ... which means, in practical terms, a highly accurate solid in these velocities

UUUUOOOOO, Jeffe...that bullet's so long it might just go past the bullets max OD and fall right into the case... Would definitely end up a solid.

How 'bout a Woodleigh RN...or a nice specially designed WFN flying beer can made out of Tungsten or other "unmentionable exotic" material used at one time in certain "penetrator" rounds.

Good Hunring

Just for my curiosity, what benefit are you looking for in the .375 Raptor.
I know for a fact you can achieve 30-06 energy levels with 300 grain gas checked bullets.And that was with a 16" barrel!
roger

Because he wants to use them in an AR-10. Semi auto. 308 sized AR rifle.
FLU, I practiced some today for you; first, open them up to .35 caliber; that is very easy. Then I went to the 375 expander. I used Lee expanders, which are very tapered in order to make it easier. Lube well. Go slow, up and back, up and back a little more. Not all at once. Piece of cake.

quote:

Originally posted by dpcd:
Because he wants to use them in an AR-10. Semi auto. 308 sized AR rifle.
FLU, I practiced some today for you; first, open them up to .35 caliber; that is very easy. Then I went to the 375 expander. I used Lee expanders, which are very tapered in order to make it easier. Lube well. Go slow, up and back, up and back a little more. Not all at once. Piece of cake.

Exactly and thank you. I wanted a big bore AR for hog hunts. I had my mind made up on a 458 socom but the cost of ammo and reloading components along with specialty bolt is a turn off. Being able to use 308 brass and standard ar10 parts and mags that i already have is real nice. I already ordered a set of dies and expanders from ch4d and the cost was very reasonable. Only thing I still need is a barrel, it'll be $400 but thats the last piece.

I have a new 458 Socom I will sell you for a lot less than retail.... They use standard AR-15 parts and mags. And Starline has brass.
I like the idea of a 375 AR-10 though, too. I'm going to have to look into it. I can cut a chamber without buying a reamer; cut the body with a 308 and the neck with a 38-55. Hmm.
I did some research; it is a Very efficient cartridge. I noticed they cut the neck off to use 350 grain sub sonic bullets; something I definitely do not want to do. So leaving the brass the original length might work better.
Now I am thinking....I have an AR-10 that is a boring 308. (I have the first new Armalite AR-10 built)
I can make a barrel in a day......this is a bad influence.

One thing you can do with the AR-10 that you CAN"T do with the AR-15 is load up to almost twice the pressure and half again(or more) as much velocity.

My 450 Bushmaster tops out at ~39 Kpsi, the 458 Socom about 35 Kpsi and the 50 Beowulf slightly above 33 Kpsi...the 375 and 45 Raptors are good to 62 Kpsi, not to mention any built using the 450 Marlin case(already been done on a 10 and with other calibers) or the 458 WM case...OR any of the fat ones that fit in the double stack mags.

YES...this forum is very hard on the wallet challenged wildcatters.

Good Hunting

Yes, all good points. Now I will sell one of my 458 Socoms to pay for a new AR-10 in 375, but I will try to make it full length brass. I see no good reason for the cut off brass. As long as a 270 grainer will fit in the magazine. Shooting a 350 grain bullet real slow is a dumb idea for me.

ABSOLUTELY, DP.

Most of the iterations I looked at/designed/made dummy's for, had no trouble at 2.86" working through my various mags and all of the fat or belted mage cases were in the 70-85 gr volume area and according to QL and Powley did very well in the 50-58 Kpsi range. I liked the 450 Marlin, WSM and the 350 RM cases and used the 375 gr Nosler Part to keep the COAL within specs and for achieving the highest case volume. A bit nit picky but thats what "OPTIMALITY" is all about.

Good Hunting and keep us informed.