[myopicvisionary]

Yeah, home annealing is more art than science.

[Owen]

Yeah, home annealing is more art than science.

It sure is! I actually melted the neck on few. Switching from MAP gas to propane helped with that a lot. I need to think more finesse less Tim Allen.

Bullet (208gr A-max) and case with an assembled dummy round

[sethinde]

I have been looking for an AR for a while and have considered the 300 BLK. I also like my firearms chambered in 9mm. But I can't help but think that I need a rifle in 5.56/.223. I have found one that may fit the bill.

Since I know you like your CMMG I figured I would post this.

http://gunmartblog.com/2014/01/30/cmmg- ... -calibers/




The new Mk4 T series rifles are CMMG’s latest definition of versatility. With four different calibers and two different barrel types to choose from, the Mk4 T line-up has something for everyone. Whether looking for your first AR, defending the homestead, planning that next hog hunt or just wanting a fun gun to have around – the Mk4 T has you covered.

The Mk4 T is available in four different calibers, including 5.56×45 NATO, .300 AAC Blackout, 9mm and .22 long rifle. The 5.56mm and .300 BLK models are offered with either a 416 stainless or a nitrided 4140 CrMo steel barrel in a medium taper profile. The 9mm and .22 LR versions come standard with the nitride 4140 CrMo M4 profile barrel.

The Mk4 T includes an RKM11 KeyMod free-floating hand guard with a 1913 Picatinny rail on top. The KeyMod slots are found at the 3, 6 and 9 o’clock positions and offer shooters a low-profile mounting alternative to the M1913 Picatinny rail. For accessories that are not yet KeyMod compatible, users can purchase a separate CMMG 5-slot Picatinny adapter rail that can be easily attached to any of the KeyMod slots for optimal placement of the accessories.

CMMG Mk4 T Specifications:

Caliber: 5.56x45mm NATO/.300 AAC Blackout/9mm/22 long rifle
Barrel: 16″ medium weight tapered profile (5.56mm, 300 BLK)
Muzzle: A2 Comp., Threaded ½-28 (5.56mm, 22LR), ½-36 (9mm), 5/8-24 (300 BLK)
Hand Guard: CMMG RKM11 KeyMod hand guard
Upper Receiver: Forged 7075-T6 AL M4
Lower Receiver: Forged 7075-T6 AL AR15
Trigger: Single stage mil-spec style trigger
Furniture: A2 pistol grip, M4 butt stock with 6-position mil-spec receiver extension
Weight: 6.3 pounds (unloaded)
Length: 32 inches (stock collapsed)

PRODUCT Barrel Type Magazine MSRP
Mk4 T 5.56mm Bead Blasted 416 SS 1:7” Twist 30-rd PMAG $1,049.95
Mk4 T 5.56mm SBN Nitrided 4140 CrMo 1:7” Twist 30-rd PMAG $999.95
Mk4 T .300 BLK Bead Blasted 416 SS 1:7” Twist 30-rd PMAG $1,049.95
Mk4 T .300 BLk SBN Nitrided 4140 CrMo 1:7” Twist 30-rd PMAG $999.95
Mk9 T 9mm Nitrided 4140 CrMo 1:10” Twist 32-rd $1,149.95
Mk9 T .22LR Nitrided 4140 CrMo 1:16” Twist 25-rd R3 $899.95
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[Owen]

I have been looking for an AR for a while and have considered the 300 BLK. I also like my firearms chambered in 9mm. But I can't help but think that I need a rifle in 5.56/.223. I have found one that may fit the bill.

Since I know you like your CMMG I figured I would post this.

My AR is a Palmetto but I appreciate the info. CMMG is good stuff too.

After loading even hotter and having them not cycle I decided to open up my gas port. It's now .125". It should cycle subsonic bullets now. If weather plays along I'll find out Friday.

[sethinde]

Ahh, didn't know that. Sorry to hijack the thread.
Palmetto is good too.

[Owen]

Ahh, didn't know that. Sorry to hijack the thread.
Palmetto is good too.

No worries! In 'my' thread hijacking is allowed...

[Owen]

Back OT: I will be heading to Ommelanden this afternoon to test some more loads with the new gas port.

[cj45lc]

Are you still trying to use the 7.6 - 8.3 gr of powder with the larger gas port ?
Good Luck

[Owen]

Are you still trying to use the 7.6 - 8.3 gr of powder with the larger gas port ?
Good Luck

Nah, I had it up to 10gr before opening up of the port. More than 10gr was scaring me. That's why I started researching the subsonic loads not cycling.

There is a good write up here that I got the port opening idea from.: http://micromoa.com/?page_id=496. I decided just to open it up to the max because I can always get an adjustable gas block if I want to shoot supersonic but for now I want to get subsonic unsuppressed to work well. The port choking flow makes perfect sense to me. The upper came with a .09375"(3/32") port so started at .109375" (7/64") but went to .125" (1/8"). A lot of other 300 blackout uppers come in at .110". I have carbine length gas system not pistol length which also play in to it.

I am not able to go to the range today so I'll probably just build some up starting back in the 8gr range. I have some left overs from 9.2gr to 10gr so I just need to make the lower end. I like reloading so it'll still be fun! Plus I got a new Lyman kinetic bullet pullet so leftovers can be recovered. Only problem there is that the plastic tips can get deformed but they don't need to be pretty to shoot!

[cj45lc]

interesting to say the least