I've had this receiver set in the safe going on a couple years at least, but never had any motivation to build it out until recently. Nothing special; just a TM lower and a blem upper. Filled out with regular parts, and a nitrided BCG from an AIM sale along the way.
When the Black Friday sales started showing up the weekend before Thanksgiving, I'd been talking to a couple friends, and had a couple customers contact me about building a .45 cal muzzle device within the span of maybe 12 hours. The bug bit, and I started fleshing out my .458 socom.
This is the finished rifle, for those of you with ADD:
458 takes a modified bolt w/special extractor and opened up ejection port, but otherwise uses the same parts as any other AR15. First order of business was to mill out the majority of the material needing removal:
Then I used a die grinder to blend those edges and chamfer the opening. Teppo Justu's print calls for cutting the bottom of the port much closer to the lower lug than I think is necessary, so I chose to deviate from their design and left more material at the front of the opening. This might cause problems with large heavy sub loads, but I can always open it up more if that's an issue. I also didn't make my opening nearly as wide as their spec, but chamfered the passage instead. The empties fling clear without any impact to the receiver.
Barrel came shiny, and I didn't want that, so I bead blasted it:
First range trip, I shot 15 rounds and let a buddy shoot it but he gave up after 2 shots. I lost my good 50yd target at the 45yd line when it ripped off the hanger at Bill's North (not Bill's Baxter North), so I don't have that group to share but it was rather impressive for a 3x tactical scope (was using a Vortex Spitfire 3x prism scope that day). Here's the first two shots out of the gun at 25yds to verify the optic was on paper, and then the 5 round group I shot at 50yds while aiming at the insect without a good reference point (it was a free target, since mine was down range and I didn't feel like buying more for a quick function test session).
Sorry about the blur, my phone doesn't like the dim firing line lighting.
All things considered - this being a load ripped off the web and reduced a couple grains just to function check the build; I'm pretty darn happy with the results.
After all, we're flinging these out of an AR15 chassis:
And here's a comparison between 77gr SMK's and 300gr Nosler BT's
But my function check did bring up a flaw I had overlooked; the extractor wasn't properly de-horned and was causing the brass to do odd things (like remain inside the upper after a full ejection cycle). After discussing it with the 458 guru's, I took a file to the fangs and brought the gun up North with me for a few more rounds of function testing. This proved all was well with cycling, but temps were low and wind was up so I didn't bother trying to zero the PA scope.
As the sales kept coming, the deals were ripe and I decided to give Rise Armaments a try with their RA-535 trigger. This thing is almost too nice to hide inside the receiver.
Likened to a 1911 trigger, this is shorter in both pull and reset than either of mine. It's silly short! I'm curious how this will handle the battering of the 458, and wouldn't be overly surprised if it ends up doubling, but we'll see...
Parts breakdown:
Brownells branded (Satern) 458 socom 16" 1-14 twist barrel/bolt/brake, A1/2 buffer tube kit, black nitride gas tube, low profile gas block
Raptor charging handle FDE
AIM bolt carrier
MI 12" M-loc rail anodized FDE
Magpul PRS stock, MOE+ grip, MOE VFG
Rise RA-535 trigger
Primary Arms ACSS 300blk/x39 ACSS reticle 1-6x24 scope
ADM Recon 30mm mount anodized FDE
KNS anti-rotation pins ceracoted FDE
Once I'm back on the mend after my knee surgery Thursday, I'll be out in the shop cooking up a new device for .45 cal.