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Discussion Starter · #1 · (Edited)
My last AR .45 was a second pistol upper to go on the lower that my MP5 upper was on. It used the newish CMMG rotary bolt that is miles ahead of the old Olympic Arms .45acp blowback bcg/bbl system. The CMMG bcg is much lighter and requires less bolt and buffer weight to operate the gun all of which makes a smoother running AR. Unable to get the dpms slabside any longer [used them on 3 other builds] I looked around and found the Stoner sporter pistol upper and 15 inch handguard from midway. The stoner upper has a vertically larger ejection port [horizontally shorter] which should do fine for .45s. I had to enlarge the port on the dpms to get reliable ejection. I’ve got stuff on order and between covid and the holidays who knows when it will all arrive. Here’s my 8 in cmmg dpms upper and CNC greasegun mag lower with the stoner parts and my MP5 build. More photos when I get something else done.
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When I built an AR45 (16" carbine) last winter, CMMG's RDB system (yes, it DOES work every bit as well as he says) and CMMG's upper (already correct size port).
Would have to look again to see whose GLF (Glock Large Frame) lower, but runs like a singer sewing machine.
 

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Discussion Starter · #6 · (Edited)
Thanks for the compliment. I had built a forward charging sbr using dpms upper, CNC greasegun mag lower and Olympic stuff [the only .45 ar stuff around then] and decided to do another as an ar pistol. I initially built it with a pistol buffer tube and just a round handguard but after it was done I didn’t like it. So I decided to do a rebuild. I had the opportunity to fire an MP5 and while it cycled so fast I couldn’t hit much I loved the look and feel so I hunted around and found a guy selling MP5 parts. FYI, the rate of fire of the MP5 is control by the power of the ammo used, the hotter the load the faster it runs. There was a lot of tinkering to get it together. Had a machine shop turn down the bbl for the front sight tower and thread it for the vortex which acts like a jam nut. The charging handle was a challenge as it has a part that operates the bcg via a piece of drill rod and the front part that rotates to engage the bolt hold open notch. I wound up using a rifle rear sight drum as the pistol drum was too low. The rear sight base is screwed to the rear of the upper with a piece of oak as a spacer with a mp5 end cap cut to fit. The mp5 plastic handguard was a perfect fit on the Olympic bbl but I did shorten it a hair. The sbpdw pistol brace completes the look. It was pricey but works great and fits my long arms. The Here’s some pix.
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Discussion Starter · #8 · (Edited)
Hope this help explain what I’ve done. There are two parts of the charging handle that ride in the cocking tube. The front part has the oem MP5 knob in it, the rear part has an offset piece of drill rod attached to it which aligns with the enlarged gas tube hole and a modified gas key on the bcg. The two pieces have a bolt to loosely hold them together. Initially I had a small flat bearing between them but recoil destroyed it so now there is a teflon washer. I had to make it that way in order for the knob to rotate enough to engage the hold open notch. Of course the rear part stays in line with the gas tube hole and key. There is a spring in the tube to keep the charging handle pushed forward. To me thats the cool factor of the MP5, the slapping of the charging knob to load the weapon. Btw, the big piece of round steel in the gas tube where it comes through the sight tower is a lug bolt that I turned down to fit.
 

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I no longer have any hosted anyplace on the internet after I removed everything from Photobucket when they wanted Big Money for my pictures to be postable, and never found anyplace else to put them, son they are just In My Phone, have made it onto Facebook posts from time to time........ when appropriate to a discussion....
 

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Discussion Starter · #15 · (Edited)
Put my rifle together but haven’t gotten around to shooting it yet. I messed up and ordered 1/2 inch muzzle break indexing spacers instead of 5/8 inch. Looks super. Was working on clearing our overgrown farm property with my son yesterday and then today after church I rebuilt my broke sawzall as parts had come in Saturday. It had zero grease in it, no wonder it broke. Cutting stuff up to do a junkyard recycle run next week. We’ve pulled a dead hot water heater and 12 tires [4 with rims] off the rural 33 acre property so far. There’s at least the remains of 2 vehicles on it but as they’re in the woods so I think they will stay where they died.
 

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Discussion Starter · #16 ·
I just put a quick 30 rds through it off my deck and other than it not liking my swc loads with a few ftf’s it’s very nice. Liked my 200 gr rnfp fine. Light as a feather and dead on. I swapped my Burris red dot that’s on a quick connect mount from the cmmg 8 inch pistol bbl to the long bbl and it was still dead on. Going to be a cool pcc ipsc rifle. Photos soon.
 

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Discussion Starter · #17 · (Edited)
Photos. Tried another swc load with mixed results. I might need to break a corner on the feed ramp but I want to compare the 8 inch bbl to the 16 inch plus the Stoner upper might be an issue as my other .45 pcc builds use dpms uppers.
Done some more shooting and I’ve had 100% success with round nose flatpoint bullets. I’ll just have to save my swc for my revolvers and 1911s.
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Discussion Starter · #19 ·
Replaced the DPMS slabside upper with a Midway Stoner upper on my .45 acp CMMG rotary bolt short bbl upper. Finally got around to trying it out today. Simply swapped the Burris from the long bbl upper and hit everything I aimed at. Round nose bullets fed fine.
 

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Hey guys! I have decided my first build and the ball is rolling. I want to build an 8” ar45 with
CMMG MKG delayed blowback BCG and barrel kit (which I just received) with side charging handle. I heard there might be some issues with using the CMMG BCG. What recommendations can I get for upper and lower for a smooth build?
 
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