Build Thread Small frame 308?

[Roymil666]

I'd like to build a small frame 308 lower and a few uppers eventually. Anyone have any experience with these. I know zev, pof, and dpms make variants; but there doesn't seem to be much consensus regarding these.

I've built dozens of ar15s and several large frame 308s so the building isn't the issue. I'm mainly concerned with compatability and reliability when choosing parts for this platform.

I'd like to potentially build a lower that I could swap uppers onto for 308, 8.6 blackout, maybe 6.5cm.

Thoughts and opinions

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[Stomper]

Rugar SFAR, maybe?

 

[Nosferatu]

By "build", I assume you mean assemble from parts on a stripped receiver?

I'm not sure there are many stripped receivers out there. Zev did something a while ago that I believe was compatible with DPMS small frame parts. That's all that comes to mind right away. Adams arms, maybe, did something as well? Someone else to look into.

I bought a Ruger SFAR about a month ago. So far, it's a fine shootin' iron! Ruger already did all the building and assembly work though, so probably not what you're looking for. They also aren't selling any of the proprietary parts yet.

 

[elitejake]

Having people that work for Barrett and zev/mega and Aero and Wilson in my personal phone. I've been blessed to get that same question answered without spending a ton of fruitless money.
Zev is about the top of quality you can get at the moment. Some of the Nemo stuff is spot on also. Christiansen arms and centurion or proof research for the barrels. Get a good single piece drop in trigger and high quality flat spring with a spikes buffer.

 

[Member 34319]

Saw a gentleman shooting the Ruger SFAR at TCGC a few weekends ago. Talked with him on it a bit and watched him shoot it. I think he had a primary arms LVPO on it. It was so small and thin I was really surprised. I'd think it would make a great starting point for something along what you want. I am not 100% sure if there are barrels available for swap though as I don't know if anything is priority on the Ruger. I've also seen a POF small frame. It was bulkier, not by much but the Ruger is certainly narrower. It basically reads as an AR from first glance. Only as you look longer you see the massive mag well.

 

[JGSFAB]

Handled on at SHOT, felt awesome. Came home and started building one in CREEEDMOOREE.
Bearcreek side charge upper (modded), Grendel barrel rechambered to Creed, very modified SOCOM BCG (AR10 firing pin).
I pumped about 20 round thru the printed prototype lower with decent function.... next week I hope to start carving a real deal lower out of alloy.

 

[Roymil666]

That's pretty rad. I can build one with my eyes closed but I can't BUILD one. You sir have impresses me. Keep us updated. I do think going from .308 to 8.6blk would be an easier feat for at least myself to tackle.

 

[JGSFAB]

Future plans...

 

[JGSFAB]

The give away is the rear pin nearly over the safety.

 

[msgriff]

Handled on at SHOT, felt awesome. Came home and started building one in CREEEDMOOREE.
Bearcreek side charge upper (modded), Grendel barrel rechambered to Creed, very modified SOCOM BCG (AR10 firing pin).
I pumped about 20 round thru the printed prototype lower with decent function.... next week I hope to start carving a real deal lower out of alloy.

View attachment 1414646

I imagine this is a one off personal build, but I'd be a bit concerned about bolt lug failure. .308/65CM max pressure is around 27000 psi higher than the SOCOM and other AR-15 cartridges that use the same bolt face. Another related issue with the small frame short action designs had to do with overpressure events. DPMS GII flutes the barrel tenon, SFAR ported the breech.

DPMS GII tenon flutes


SFAR ports to the rear of the handguard

 

[JGSFAB]

I seen that, the SFAR does use a proprietary bolt and extension that is beefed up.


Hoping some day they release the SFAR parts, bolts and barrels do wear out.
Till then I'll be hand loading conservative rounds, regular head space checks, etc.
POF has been building Small Frame AR10s (AR10x15? lol) for years now. The POF BCG goes for $400, not cheap but not gucci either.
I'm sure I can make a beefier SFAR style bolt and extension as well. But for the $ and time I'll go with the POF.
Somewhere I seen one guy building TI BCs but IIRC they were more than the POF for just the carrier no bolt.

Even at 52K (Grendel pressures) the CM is more efficient, launching bigger bullets with more speed than the Grendel.
Is the .44 bolt that much stronger than a .473? Kind of more concerned with lug wear. I'll prob end up ordering the POF once I get it together.
I'm certain the dims will work, hammer/trigger/safety locations/mag length there really is only one right answer IMHO.

 

[msgriff]

I seen that, the SFAR does use a proprietary bolt and extension that is beefed up.


Hoping some day they release the SFAR parts, bolts and barrels do wear out.
Till then I'll be hand loading conservative rounds, regular head space checks, etc.
POF has been building Small Frame AR10s (AR10x15? lol) for years now. The POF BCG goes for $400, not cheap but not gucci either.
I'm sure I can make a beefier SFAR style bolt and extension as well. But for the $ and time I'll go with the POF.
Somewhere I seen one guy building TI BCs but IIRC they were more than the POF for just the carrier no bolt.

Even at 52K (Grendel pressures) the CM is more efficient, launching bigger bullets with more speed than the Grendel.
Is the .44 bolt that much stronger than a .473? Kind of more concerned with lug wear. I'll prob end up ordering the POF once I get it together.
I'm certain the dims will work, hammer/trigger/safety locations/mag length there really is only one right answer IMHO.

One of the guys at Mad Dog Weapons Systems re-barreled a SFAR in 27 RPR (6.5 CM based wildcat) last year. They just reused the factory barrel extension. They have a small blogsite with that build on it, plus they modified some mil-spec uppers similar to what you did.
The guy I know that makes small frame Ti BCGs are for the DPMS GII. Unfortunately those barrel extensions are larger than the AR-15's and won't fit an AR-15 upper like a SFAR will.
Grendel bolt failures at 52,000 psi are not unheard of. Lug failure was a major part of the discussion regarding Type 1 or Type 2 standardization. Unfortunately, the industry has gone with the Type 2 because of the extractor issue at the expense of lug strength. CMMG even thought Grendel pressures warranted a new AR design, The Resolute, which they call a mid-size AR.
Very cool stuff on you lower, I hope you keep us updated.

 

[Roymil666]

Definitely an interesting design for sure. I'm sure you could just swap the barrel extension onto an 8.6 barrel. I believe they use the same bolt as .308 and run lower pressures.

 

[JGSFAB]

One of the guys at Mad Dog Weapons Systems re-barreled a SFAR in 27 RPR (6.5 CM based wildcat) last year. They just reused the factory barrel extension. They have a small blogsite with that build on it, plus they modified some mil-spec uppers similar to what you did.
The guy I know that makes small frame Ti BCGs are for the DPMS GII. Unfortunately those barrel extensions are larger than the AR-15's and won't fit an AR-15 upper like a SFAR will.
Grendel bolt failures at 52,000 psi are not unheard of. Lug failure was a major part of the discussion regarding Type 1 or Type 2 standardization. Unfortunately, the industry has gone with the Type 2 because of the extractor issue at the expense of lug strength. CMMG even thought Grendel pressures warranted a new AR design, The Resolute, which they call a mid-size AR.
Very cool stuff on you lower, I hope you keep us updated.

How about POF ? As I read it they use different alloy like S7. It's certainly a high wear item either way.
Another idea is to ditch the .473 rim and swap to a SPC bolt. SPC carries a 58k max and a bigger powder volume. The 10 length mags make longer bullets (with longer loadings) a thing. SPC necked down to 6.5 would be simple, While we are wildcatting let's ackley it was well lol. Or at least the 30deg shoulder of the 224val.
Wow that was a rabbit hole...

I'm hopeful the SFAR makes small frames more popular and we get some SFAR parts available.
Either way I have the tools and time, I'm machining a billet lower anyways.

Lance Humbert on Instagram: "Another ridiculous PMF ..."

8 likes, 0 comments - Lance Humbert (@jgsfab) on Instagram: "Another ridiculous PMF ..."

www.instagram.com

 

[Snip]

A 308 case might barely fit in to an AR-15 magazine. You'd have to buy a custom lower and custom upper just to fit the round in. 223 on top and 308 mazine on the bottom.

 

[ilikegunspdx]

I'd like to build a small frame 308 lower and a few uppers eventually. Anyone have any experience with these. I know zev, pof, and dpms make variants; but there doesn't seem to be much consensus regarding these.

I've built dozens of ar15s and several large frame 308s so the building isn't the issue. I'm mainly concerned with compatability and reliability when choosing parts for this platform.

I'd like to potentially build a lower that I could swap uppers onto for 308, 8.6 blackout, maybe 6.5cm.

Thoughts and opinions

You say build as if your creating the recievers. Or are you just assembling parts?

 

[red442joe]

Tagged

Joe

 

[JGSFAB]

You say build as if your creating the recievers. Or are you just assembling parts?

Nobody sells a SFAR10 type receiver. I'm building a zero percent

 

[JGSFAB]

Making chips

 

[Snip]

Nobody sells a SFAR10 type receiver. I'm building a zero percent

That's pretty damn ambitious. Good luck to you.