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Magnum AR Project
- Thread starter Masczek
- Start date
It's been awhile, but I finally got around to taking some pictures of the carbon fiber rifle. It's 10lbs 11oz (if I remember correctly) as it sits in the pictures. The side charging upper really makes this platform a lot better IMO. I've had 100% reliable ejection with this upper, very pleased with how it's turned out so far. I also tried shooting it suppressed, the ammo I had that day was already loaded a bit hot. It started showing a little bit of pressure signs with my handloads, so I switched to some 180gr factory ammo I had and it seemed to work better. I've got several loads worked up now, I'll be taking it out this week to see which one it likes the best.
I built an AR 10 in 338 RCM. I use 6.5 PRC brass necked up.
Its 18" light fluted barrel weighs 7 lbs ll oz. Without scope.
Wanted something different, It makes a nice handling hunting cartridge with heavy bullets larger game.
Its accurate with 160 gr Barnes to 250 gr hunting bullets at 2575 with RL 26.
Its 18" light fluted barrel weighs 7 lbs ll oz. Without scope.
Wanted something different, It makes a nice handling hunting cartridge with heavy bullets larger game.
Its accurate with 160 gr Barnes to 250 gr hunting bullets at 2575 with RL 26.
Attachments
Anything special on the rifle other than the boltface and barrel?
I have been considering this setup in the back of my mind.
300 WSM
22" X-Caliber Barrel
+2 Rifle Length Gas Port
Superlative Arms Gas Block
Alexander Pro Fab Side Charging Upper (modified by me)
Kaliber Tech Lower (my design)
Rise Armament RA-434 Trigger
Standard Rifle Buffer and Spring
Smoke Composites Stock, Grip and Handguard
Tier One Tactical Bipod
Maven RS3.2 5-30x50mm Scope
I'm building one in 6.5 PRC as a range gun, it will be another month or so before it's complete.
It's a 5oz buffer. I have a 9oz I'm going to try when I get out and shoot either today or tomorrow. The one load I quickly put together was 2840fps, 190 berger vld, 61.5gr of H4350. This load was a bit hot, and the recoil was more than I'd like. I currently have several loads put together with 180 berger elite and various weights of H4350, we'll see which is the most accurate and go from there.
Nope, you can buy the KAK magnum bolt, or complete bolt carrier, and upper reciever, together for the easy button.
Or use, Your AR 10 upper reciever ejection port is opened up a bit on bottom of the ejection port, but you can do that with hand tools.
Barrel can be ordered, KAK used to have 300 WSM in stock and complete uppers, rifles, but no more.
I used a new Wilson Combat AR 10 barrel in 338 Federal and rechambered it to 338 RCM...this is fast and easy, if you are capable of chambering a barrel.
No line no waiting...no barrel profiling, barrel extension installation, gas port drilling, no threading.
Your rifle will be finished the day the in stock barrel arrives, about 7 days, from conception to finished project.
Reamers are purchased from PT&G or Brunos has some in stock for fast easy purchase.
You can make at 6.5 RCM (PRC) from 6.5 CM, OR 6mm RCM from 243 AR10 barrel, 7 mm RCM from 7mm-08. 30 RCM from 308 Win, 338 RCM from 338 federal, 358 RCM from 358 Win from existing chambered AR 10 barrels. Just order the length and twist you want and reamer.
Brass is made from 6.5 PRC cases.
This is the AR 10 338 RCM, 10 lbs 12 oz with the heavy 25X scope for accuracy testing, not need for hunting, and 7 lbs 11 oz without optics.
Rifle length gas, 18" fluted barrel stainless barrel.
Standard carbine lower taken off the 308 Win, nothing changed.
Handles full power 338 RCM load data from loading manuals.
So anyone interested in building a magnum on AR 10 there are alot of options in calibers to make one suitable for you.
Rifle length gas, 18" fluted barrel stainless barrel.
Standard carbine lower taken off the 308 Win, nothing changed.
Handles full power 338 RCM load data from loading manuals.
So anyone interested in building a magnum on AR 10 there are alot of options in calibers to make one suitable for you.
Attachments
Finally got out and got a load developed, here's what I'm using so far:
300 WSM
Norma Brass
Also Hornady Brass
180gr Berger Elite Hunter
59gr H4350
CCI 250 Magnum Primers
Averaging 2790 fps
COAL 2.955 (about .010 off the lands)
I'm not the best shot in the world, but managed to get a .73" group at 100 yards. I'm going to get some more loaded up and head back out to get some 5 and 10 shot groups. I think with a little more practice and some better brass prepping, I can get down to around .5" at 100 yards.
I got up to 2900 fps with 62.5gr, but slightly worse grouping, just barely under 1". This was toward the end of the day, so I might have been flinching a little bit as well, those loads were feeling a bit stout. No pressure signs though, so I could have kept going if I was looking for speed.
300 WSM
Norma Brass
Also Hornady Brass
180gr Berger Elite Hunter
59gr H4350
CCI 250 Magnum Primers
Averaging 2790 fps
COAL 2.955 (about .010 off the lands)
I'm not the best shot in the world, but managed to get a .73" group at 100 yards. I'm going to get some more loaded up and head back out to get some 5 and 10 shot groups. I think with a little more practice and some better brass prepping, I can get down to around .5" at 100 yards.
I got up to 2900 fps with 62.5gr, but slightly worse grouping, just barely under 1". This was toward the end of the day, so I might have been flinching a little bit as well, those loads were feeling a bit stout. No pressure signs though, so I could have kept going if I was looking for speed.
A guy on our local gun board did a couple 0% lowers and uppers over the summer, built around an Omen long action magazine (3.500" OAL). He casted the first lower, but the uppers and subsequent lowers were billet. Oregon recently outlawed all PMFs without serial numbers and BGCs, so it pretty much put a halt to his projects, but he did have success and a lot of fun.
I figured it was on the low end since it was one of my starting loads, my manual says 47,600 psi with 58gr of IMR4350, Hodgdon says 54,900 psi with 59gr of H4350.
This is for hunting, I wanted to be shooting at least 1" at 100 yards and the bullet going at or over 2750 fps with whatever was the most accurate. I'll probably play around with my 62gr load in the future and see what kind of groups I can get with that. That load was going about 2900 fps.
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