• Frank's Lesson's Contest

    We want to see your skills! Post a video between now and November 1st showing what you've learned from Frank's lessons and 3 people will be selected to win a free shirt. Good luck everyone!

    Create a channel Learn more
  • Having trouble using the site?

    Contact support

Fun AR variant builds?

May I introduce you to the 375 raptor? its a wildcat based off the .308 win, so everything but the barrel is still standard .308, but it has some crazy nice properties. It was originally created as a short action option for hunting african dangerous game because of the legal requirements there for .375 cal and up.

its expressly designed for shorter barrel lengths too. Maker Bullets makes a 400gr copper monolithic for the caliber for subsonic use.


View attachment 8224925
The brass isn’t standard necked up 308 brass, is it? Don’t you have to neck it up in two or three steps, and then cut/trim a fair amount off of the end of the brass?
 
Being fairly new to the AR Platform, in the last 2-3 yrs I started with 9mm, 7.62x39, 223, 308 with a 2nd upper in 6.5cm, then another 308 pistol. While rushing to get a bid in on, what I thought was 6.5 creedmoor, I accidentally bought 6.5 Grendel ammo, had an extra lower, bought a barrel now it's just about assembled. Still need glass and Muzzle device. These 6.5s are really my 1st times straying from military cartridges. Smaller diameter bullets seem all the rage, but I'm intrigued with lager, I find the 338 Federal interesting. I'm just a Fud that enjoys tinkering with guns, mainly to be used for hunting.
 
I'm really enjoying making more specialized builds for my 5.56 guns. Started with a couple 16" guns (Carbine, Mid, Dissy), then did an 18", 11.5" and so on...

Now I'm working on 13.9" (lightweight) and 14.7" (Recce) builds concurrently, with different optics, accessories, and furniture to differentiate them. I expect they will replace my 16" guns as my go-to options for training and coyote hunting. I also have a 7.5" in the works for the hell of it. If it ends up fitting in my pack how I hope it will, I'll probably morph it into a .300 BLK.

My favorite guns are probably the trio of 18 inchers, in 5.56, 6.5 Grendel, and 6.5 Creedmoor. Shooting at 600+ yards is a delight with all of them, but the Grendel is definitely the "one". It's so easy to make first round hits, and it's just over 9 lbs fully loaded with a 3-15x and offset Holosun. I just wish ammo was easier to come by in my neck of the woods.

My brother has a JP 9mm 16" gun that is a goddamn pleasure to shoot. I didn't want to like it because I thought it was overpriced, but after running it through its paces in the desert with my Glock mags, I can't deny how fun it is.
 
Last edited:
The brass isn’t standard necked up 308 brass, is it? Don’t you have to neck it up in two or three steps, and then cut/trim a fair amount off of the end of the brass?
there are options to form it from .308 or other cases, it doesn't necessarily need to be fireformed or work the brass too much if you have the right tools
 
I didn't want another 5.56/Wylde, 300BO, 6.5G, 6ARC, or .308 build and assembled a 7.62x39 build with parts I had around and a POF 16.5" barrel when they closed them out. With Duramags, enhanced bolt/firing pin, and a Larue MBT (with extra power springs) it has been flawless. No adjustable gas block was needed. This was my least expensive AR to assemble and it gets the most attention at the range outside of my SBRs.

It's fun to shoot less expensive ammo.
I'm building off that same barrel. Talk to me about the rest of the build. How's the accuracy?
 
I built a 30 RAR, AR 15. It's accurate, low recoil running 155 gr Lapua a bit over 2400 fps, 12 twist repurposed 308 win barrel, chambered, cut, threaded, profiled, barrel extension installed, from bolt gun to AR 15...30 RAR. Uses 450 bushmaster bolt, and 450 bushmaster brass necked down...total cost $324.
 
I'm building off that same barrel. Talk to me about the rest of the build. How's the accuracy?
It’s a basic budget build for a budget round. I didn’t want a high end build for this so I went cheap with a generic Cero Forge Upper/Anderson lower/UTG Forerunner (Titanium barrel nut) handguard. Gas block is a non-adjustable steel (.750 set screw type) from Luth-AR. I know some folks say you need an adjustable gas block for the round in an AR. I bought one and didn’t end up needing it for this build.

For reliability with steel case/comm bloc surplus you want extra power hammer spring (https://www.blackriflearms.com/Enhanced-Power-Hammer-Spring_p_685.html) . That means no cassette triggers. I use a Larue MBT-2S and it sets off every time with the EP spring.

Use an enhanced firing pin that is a little longer to set off comm bloc/steel case.

BRA (https://www.blackriflearms.com/7.62x39BoltandEnhancedFiringPinCombo) and RTB (https://www.righttobear.com/7-62x39-ar15-bolt-completion-kit-enhanced-firing-762ekit/) sell them. I use the RTB bolt/pin and no issue. I keep a BRA pin as a backup if one breaks.

I’m using a Crimson Trace Series 3 1-5x24 FFP on top and accuracy is limited by the ammo I shoot (cheap stuff), so it’s been 1.5-2 moa at 100 yards with just blasting. I have no doubt the barrel is capable of better so I’ve recently picked up components to start reloading the caliber. I’d sworn I wouldn’t add another caliber to reload, but the POF barrel really impressed me even with crap ammo. I’ve recently picked up some brass cased ammo to see if I can get more out of it and I’ll use those empties to reload.

Magazines are another key component. The Duramag 28 and 10 rounders are all I use.
 
  • Like
Reactions: JS8588
ar45.jpg


Twas fun at the time, but I think the newer tech has passed it by.
Though there's something to be said for a magazine that even empty you could easily beat someone to death with.
 
  • Love
Reactions: x248716x
It’s a basic budget build for a budget round. I didn’t want a high end build for this so I went cheap with a generic Cero Forge Upper/Anderson lower/UTG Forerunner (Titanium barrel nut) handguard. Gas block is a non-adjustable steel (.750 set screw type) from Luth-AR. I know some folks say you need an adjustable gas block for the round in an AR. I bought one and didn’t end up needing it for this build.

For reliability with steel case/comm bloc surplus you want extra power hammer spring (https://www.blackriflearms.com/Enhanced-Power-Hammer-Spring_p_685.html) . That means no cassette triggers. I use a Larue MBT-2S and it sets off every time with the EP spring.

Use an enhanced firing pin that is a little longer to set off comm bloc/steel case.

BRA (https://www.blackriflearms.com/7.62x39BoltandEnhancedFiringPinCombo) and RTB (https://www.righttobear.com/7-62x39-ar15-bolt-completion-kit-enhanced-firing-762ekit/) sell them. I use the RTB bolt/pin and no issue. I keep a BRA pin as a backup if one breaks.

I’m using a Crimson Trace Series 3 1-5x24 FFP on top and accuracy is limited by the ammo I shoot (cheap stuff), so it’s been 1.5-2 moa at 100 yards with just blasting. I have no doubt the barrel is capable of better so I’ve recently picked up components to start reloading the caliber. I’d sworn I wouldn’t add another caliber to reload, but the POF barrel really impressed me even with crap ammo. I’ve recently picked up some brass cased ammo to see if I can get more out of it and I’ll use those empties to reload.

Magazines are another key component. The Duramag 28 and 10 rounders are all I use.
Glad to hear. I have my build almost complete with pretty high end parts including an LMT Enhanced 7.62x39 bolt, a Velocity Steel Case Trigger, and an enhanced firing pin from RedXArms. Upper is a Precision Firearms heavy walled billet and lower is a Dirty Bird ambi. Sounds like I'm going to enjoy this.