Full Ambi AR Build

[stage20]

So, you're not a fan of drop in trigger groups?
I can understand milspec type triggers and springs would be a plus in a mad max situation. That BCM might be a better call.

Drop ins are good. Lot of folks prefer the pieces and parts. You won't have any issues with the CMC. I'd bet 99.9% there would never be an issue, but as far as self defense, my brain wouldn't go for a box trigger. That said I have a few range toys with box trigger and never had a hiccup I could blame on them.

 

[Themumfordman]

I’ve found I love the JP captured springs for more precision or long range builds - smooths out the recoil impulse a lot on semi-auto rifles, especially with larger calibers like 6.8 SPC, 6.5 Creedmoor and such.

I used a Maxim defense buffer for a while on a pistol build back a couple years ago with both an 11.5” 5.56 upper and an 8” cheap 300 blackout, and never had an issue with it. Neither of those had adjustable gas, and ran well even suppressed.

 

[850guns]

Box triggers are not really serviceable if they have issues, at least I’ve not ever tried to force one apart to try. Your mil-spec style component triggers would be a heck of a lot easier to clean mud or blood out of and change springs on if you were using them in a hard-core

 

[Shootist]

A little story, a few years ago at a bi-annual shoot week.
A friends Wilson Combat trigger ( a box Trigger) turned his rifle into a slam firing full auto.
No way to fix it in the field and when you released the trigger, it decided if it was going to keep firing or not.
Of course Wilson replaced it free of charge but it made that gun unusable for the rest of the week.

 

[850guns]

Most of my lowers are setup the same way with an A5 tube, an appropriate weighted buffer(usually H2), Radian safety, and either a Geissele 2 stage or Larue MBT.

I'm not sure how corrosion resistant all these different parts are, but a bit of maintenance and some CorrosionX will go a long way in keeping everything operational and looking good.

On a side note, the Mk2 from Griffin and the ADM lower share the same design DNA.

What calibers are you shooting ?

 

[850guns]

This is my DIY “Honey Badger”
Build. Base is a SiCo lower, BCM upper with the HB 7.75” barrel/gas system and brace/buffer. Has my standard SSA-E trigger, Radian safety, and I used a Midwest Industries wide 10” rail, which slides about 2.5 inches over the base of the suppressor, giving a lot more room for gripping and adding accessories. Only downside is it does get a bit warm when you’re running a few mags through it.

I probably should have started this thread as a pistol build.

I have a good rifle set up with A5 buffer and ambi controls but don't have a lot of rounds through it.

That said this Griffin Mk2 lower will primarily be sporting PWS Mk111 uppers in 5.56 and x39. But am currently searching for a 300blk upper.
This lower should also run my CMMG BANSHEE uppers in 9, .40, .22, 4.6.
AND run d.i. uppers in various barrel lengths and calibers.
And do it reliably!

Is it a pipe dream?

 

[Themumfordman]

Not necessarily, but you may have to be flexible on some things:

*Shooting suppressed in various calibers on the same lower, you’re almost certainly going to need adjustable gas systems on at least most of those setups.

*Pistol calibers with a magwell adapter don’t seem (to me at least) super dependent on buffer weights to the same extent, since they’re still basically a direct blowback system. If you rock something like a CMMG radial delay upper, that certainly would change things.

*A 22 conversion setup doesn’t use the buffer or spring, so that’s an easy one.

*From what I’ve seen in an AR platform, x39 beats the crap out of the gun with recoil far more than 5.56 or 300blk do, so that one may take more tuning if your build is done based on your AR calibers primarily. That said, I’ve not run the PWS in x39, so that may make a big difference.

My SBR lower I’ve run with all length 5.56 barrels from 10.3 up to 18 and with super shorty DI 300 blackout and piston uppers like the JAKL. I’ve had just about zero issues ever with that, and it’s using a Super 42 spring and H2 buffer. Also runs 6mm ARC and 6.8 SPC smoothly too.

My normal setup on that is a 12.5” DD carbine barrel & BCG with superlative arms adjustable gas and a Rugged suppressor. Freaking machine in that setup.

 

[Shootist]

I probably should have started this thread as a pistol build.

I have a good rifle set up with A5 buffer and ambi controls but don't have a lot of rounds through it.

That said this Griffin Mk2 lower will primarily be sporting PWS Mk111 uppers in 5.56 and x39. But am currently searching for a 300blk upper.
This lower should also run my CMMG BANSHEE uppers in 9, .40, .22, 4.6.
AND run d.i. uppers in various barrel lengths and calibers.
And do it reliably!

Is it a pipe dream?

I think running the MK111 & x39 uppers on the same lower are doable in theory, the same lower running the pistol cal uppers not so much.
Just my humble opinion.

 

[Themumfordman]

I think running the MK111 & x39 uppers on the same lower are doable in theory, the same lower running the pistol cal uppers not so much.
Just my humble opinion.

I don’t completely disagree. The biggest problem I’ve experienced with rifle lowers and pistol caliber uppers is the magwell adapters never seem to work super well, and I’ve had a lot of FTF and FTE issues while shooting. Even with basic buffers and weights I always had better success with a dedicated pistol lower.

 

[850guns]

Lots of good input. I appreciate all the input.

 

[850guns]

My SBR lower I’ve run with all length 5.56 barrels from 10.3 up to 18 and with super shorty DI 300 blackout and piston uppers like the JAKL. I’ve had just about zero issues ever with that, and it’s using a Super 42 spring and H2 buffer. Also runs 6mm ARC and 6.8 SPC smoothly too.

My normal setup on that is a 12.5” DD carbine barrel & BCG with superlative arms adjustable gas and a Rugged suppressor. Freaking machine in that setup.

Good to know.
I've been looking at the Jakl.
What's your opinion?
And have you tried it on other lowers?

 

[stage20]

Aside from magwell adapters not being ideal, the same lower can run any caliber, just keep a couple buffers on hand for tuning.

 

[Themumfordman]

Good friend of mine has one in 300blk. It’s okay, not my favorite setup. He had a heck of a time getting his gas system dialed in. I think honestly the gas port was undersized and he should have sent it back to PSA to fix. He worked with a local shop to tune it and it runs great now with a K can on it, but I don’t know that I’d get too excited about one.

His big deal was wanting a folding stock on a compact SBR setup. He has his on a cheap PSA lower with pretty stock parts and it runs fine now. Runs better on my SBR tbh…

Personally I’d save a bit and buy a Bren 2 and be much happier overall.

 

[joebagodonuts]

What calibers are you shooting ?

5.56, 6.5 Grendel, and .300 blackout. In general, the H2 runs them all well. With the shorter(11.5-12.5) barrels and a can the H3 comes out. It's mainly an ejection pattern thing with me rather than a recoil impulse issue. I don't think I'm a good enough shooter to appreciate the difference between an H2 or an H3, but I can appreciate not over-stressing the system if I can keep the same reliability.

 

[850guns]

I shoot left and like the ambi controls especially on a pistol. Also being able to change the ejection plays into my purchaces.

Get one of these lowers, and a left hand ejecting upper!

 

[850guns]

Almost all my parts are in. I decided a carbine tube, super 42 and H2, CMC trigger and LPK. Fortis locking castle nut and plate.And budget friendly ambi safety.

But those shorty buffer systems might find their way in my cart when I find a shorty 300 upper.

Oh, and the CMMG system i use doesn't use a magwell adapter, it uses modified Pmags and conversion mags for the 22lr.

 

[Themumfordman]

The CMMG 22 setup is freaking sweet. I ended up doing a dedicated AR-22 rifle with their bolt system, barrel and mags. Runs like a champ.

 

[joebagodonuts]

Got the Mk2 lower put together with parts from another lower. Slick design and everything went together without a hitch.

 

[Themumfordman]

Got the Mk2 lower put together with parts from another lower. Slick design and everything went together without a hitch.

That’s a solid setup! I got most everything ID’ed except the trigger and the handguard, which looks like a Geissele (?).

Curious - why did you go B5 grip but Magpul on the stock?

 

[joebagodonuts]

That’s a solid setup! I got most everything ID’ed except the trigger and the handguard, which looks like a Geissele (?).

Curious - why did you go B5 grip but Magpul on the stock?

That’s an 18” Noveske barrel in 6.5 Grendel, BCM upper, Geissele 15” rail, JP bolt

Lower is running the A5 with an H2 buffer and a LaRue trigger. I run the B5 since it’s a more vertical grip and I’ve got them on most of my other rigs so there’s some consistency there. CTR stock allows for the cheek riser and you can lock it in a position which takes out wobble.