I finally got my .375 Raptor assembled and some range time with the Lehigh 250gr controlled fracture bullets. I'm very impressed so far.

The .375 Raptor is simply a .308 Winchester necked up to .375 and shortened some to function better in a magazine fed semi-auto.

The case is formed with one pass through a FL CH4D .375 Raptor die. Then trimmed to 1.865.

.308 case left.
Formed/ necked up case center (Not trimmed).
Trimmed loaded .375 Raptor cartridge right (250gr Lehigh).



There needs to be a slight modification to the Magpul LR mags. The guide ribs on the inside, need to be filed down a little. Once this is done they load at full capacity. A 10 round Mag holds 10 rounds of .375 Raptor as does a 20 round Magpul LR Mag.

I'm getting 2500fps from a stainless X-Caliber, 18", 1-10 twist barrel. Which works out to about 3400 foot pounds of energy at the muzzle!

I used a higher power optic for load development. I'll be switching it for a quality 1-6x or 1-8x.

Here are the first 5 shots with the 250gr Lehigh's at 100 yards.





Without a scope adjustment, just for kicks I sent three to the 200 yard line. This is the first three shot group I fired at 200 yards.

I then made a scope adjustment and fired a 2nd three shot group at 200 yards. This put me on at 200 yards and 2 1/2" high at 100 yards.



I then did a little math, held 4 MOA in my Impact 32 MOA reticle and fired a three shot group at the 300 yard line. Had a slight breeze and it was cold. Could have been me on the trigger. Super great vertical, had some horizontal stringing. I guess I couldn't ask more from a semi-auto big bore.

Very nice. velocity is a bit unbelievable. I barely get 2600 fps w/168 out of a 20" 308 barrel.

30 years at a reloading press. 30 plus wildcat chamberings. It's all about the powder, barrel and bullet choice. Been there done that.

Find a different powder and reduce your bullets bearing surface. Fire it up with a magnum primer and stretch that velocity out.

I run my 6.5 & 6mm Creedmoor's with magnum primers. Screw H4350. RL-17 will give you a minimum of 105 fps more than H4350 with the same charge.

Last week I contacted HD Custom and ordered some of their lathe turned bullets with minimal contact bands like the Lehigh's. I ordered the 256gr "Sledge Hammer" and the 248gr "Hammer Hunters". I expect a bit more velocity out of the .248gr "Hammer Hunters".

If I was slinging the 250gr Sierra Game Kings I would expect a bit more than 2400 in velocity.

But it is not control feed.

What does she weigh?

Looks good a caliber that capable of hunting any thing is NA.

It is good that people are developing the MSR concept past the 223 and 308.

I have 4 MSR's I prefer others for hunting but that is just me.

The 358 Win gets 2200 fps with a 250 grain bullet, so you only need to get a 13.6% increase in velocity with the larger cross section bullet.

Getting 105 fps with a 140 grain bullet out of 6.5 Creedmor is a 3.87% increase

Some bullets arrived today that I had ordered awhile back. Looking forward to getting some loaded up when time permits.

256gr "Sledge Hammer" (Left)
248gr "Hammer Hunter" (Right)

I finally got the ball rolling on my 375 Raptor build. I already have a set of CH4D dies and an AERO M5 receiver set. My form 1 has been submitted and a 12" X-Caliber barrel is in production. Geissele SD-E trigger, SLR Helix 308 Handguard, Young Manf bolt headspaced by X Caliber. Been scouring bullets and reforming brass while waiting.

FL
I just finished my 375 Raptor Bolt gun using a 700 action and a 20" X-Caliber barrel. The gun loves 43 gr of 10X behind 270 grain Speer boat tails. It will give you 2480 fps and will keyhole at 100. Right now I am loading up some Nosler 260 solids for buff in a coupe months.

quote:

Originally posted by T Agg:
FL
I just finished my 375 Raptor Bolt gun using a 700 action and a 20" X-Caliber barrel. The gun loves 43 gr of 10X behind 270 grain Speer boat tails. It will give you 2480 fps and will keyhole at 100. Right now I am loading up some Nosler 260 solids for buff in a coupe months.

I’m not following you. Key holing to me means an unstabilized bullet that is tumbling uncontrollably and hits the target sideways. Definetly not a good nor accurate thing. Do you mean clover leafing? Where 3 shots are touching or making 1 ragged hole?? This I would definetly be interested in. Btw, how long did it take to get your barrel from X caliber? I am about 6 weeks in and getting anxious. They told me 12 when I ordered it. Just curious. Thanks

That looks like an awesome little cartridge .It's very powder efficient for the velocity vs powder
Burned and the amount of power you get .I have been thinking of making a 375-06 not much difference .That 375 raptor would be a nice addition to my 260 Remington ar10 !

Sorry for the confusion, one ragged hole. This bullet and powder combination is perfect, great accuracy and no kick. The barrel took 3 months to get.

Nice to see the results people are getting with their 375 Raptors. The 300 yard group shown has outstanding vertical dispersion and given the wind reported, horizontal stringing can be expected.

I am waiting on a shipment of 200 and 235 Volmer bullets to play with and weather permitting going to be doing some terminal tests into gelatin and solid object within the next month. Past shooting into gelatin at 25 yards with a 270 grain was just like a train going through Smart Car so going to place the gelatin blocks at 100 yards as well.

(I am Arne who designed the round, don't get on forums much so most people just email me.)

quote:

Originally posted by FLUndertaker:

quote:

Originally posted by T Agg:
FL
I just finished my 375 Raptor Bolt gun using a 700 action and a 20" X-Caliber barrel. The gun loves 43 gr of 10X behind 270 grain Speer boat tails. It will give you 2480 fps and will keyhole at 100. Right now I am loading up some Nosler 260 solids for buff in a coupe months.

I’m not following you. Key holing to me means an unstabilized bullet that is tumbling uncontrollably and hits the target sideways. Definetly not a good nor accurate thing. Do you mean clover leafing? Where 3 shots are touching or making 1 ragged hole?? This I would definetly be interested in. Btw, how long did it take to get your barrel from X caliber? I am about 6 weeks in and getting anxious. They told me 12 when I ordered it. Just curious. Thanks

Barrel delivery times seem to be running 8-12 weeks because every barrel is being made custom to individual customer's unique preferences. I know X-Caliber is very busy making 375 Raptor barrels from when I speak to them almost weekly.

The 18 inch 10 twist 5R is probably the most popular with some people going as long as 22 inches.

quote:

Originally posted by TXFCLASS:

quote:

Originally posted by FLUndertaker:

quote:

Originally posted by T Agg:
FL
I just finished my 375 Raptor Bolt gun using a 700 action and a 20" X-Caliber barrel. The gun loves 43 gr of 10X behind 270 grain Speer boat tails. It will give you 2480 fps and will keyhole at 100. Right now I am loading up some Nosler 260 solids for buff in a coupe months.

I’m not following you. Key holing to me means an unstabilized bullet that is tumbling uncontrollably and hits the target sideways. Definetly not a good nor accurate thing. Do you mean clover leafing? Where 3 shots are touching or making 1 ragged hole?? This I would definetly be interested in. Btw, how long did it take to get your barrel from X caliber? I am about 6 weeks in and getting anxious. They told me 12 when I ordered it. Just curious. Thanks

Barrel delivery times seem to be running 8-12 weeks because every barrel is being made custom to individual customer's unique preferences. I know X-Caliber is very busy making 375 Raptor barrels from when I speak to them almost weekly.

The 18 inch 10 twist 5R is probably the most popular with some people going as long as 22 inches.

I cannot wait. I ordered a 10 twist 12" for my SBR .375 Raptor. Looking for 200 yards max range. Spoke at length with Arne about it before ordering and he agreed that it will be a sledge hammer at my intended ranges. Sourced some ready to load brass and have been busily reforming 7.62x51mm brass but hit a snafu with the trimmer situation. To my knowledge Giraud is the only person making a trimmer for it and its oly available as a full power trimmer, not as a triway. This means a $500+ investment in just the trimmer. I can buy alot of brass ready to load for $500. I may still do it but I have to think about it a bit more.

The Giraud Trimmer is a heavy duty precision model that not only trims, but chamfers the inside and outside of the case mouth. I use it for my match ammo.

CH4D sells the Dillion Trim Die for use with the Dillion Power Trimmer if you want to use in a Dillion or Single Stage Press.

On any load data, be observant of differences in case capacity due to the thickness of the parent brass. I used Winchester Commercial brass in all my development as a baseline. Also, once fired and resized, case capacity will be slightly greater than the first forming.

Arne

A ballistic comparison of the 375 RAPTOR to other semi-auto big bores created using JBM Ballistics