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Posted: 8/9/2018 9:29:04 AM EDT
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I looked into getting a 9mm upper for my SBR lower a few years back. I was looking for something that would allow me to swap uppers, drop in a mag block, and go. Mag blocks that needed the bolt catch removed, ejectors that needed to be bent just right, tales of widened pin holes, etc. made me shelve the idea. If I wanted something dedicated, there seemed to be a few good options, but for swapping back and forth with an SBR lower, I didn't feel as confident.
I recently decided to look into the possibility again. I figured tech must have moved forward to allow something a little more 'plug and play'. The other day I saw the Mean Arms EndoMag here on Arfcom and was intrigued by the concept. As far as 9mm uppers, from what I read initially, the CMMG Guard upper can use a regular buffer/spring due to their radial blowback design, so if a Guard upper would work with the EndoMag, it would be exactly what I was looking for - swap uppers, insert mag, and go (just like I currently do with my 5.56 and 300 Blackout uppers). I contacted Mean Arms through their website and got an email back that they have tested the Guard uppers with their EndoMags and they work "without issue". I'm hoping they release a YouTube video showing this, as it would boost my confidence. So now I'm trying to decide between a few options from CMMG for an upper - 5" Banshee/Guard upper, 8" Guard upper, or buy a 8" barrel/BCG combo and build my own (I don't see a 5" barrel/BCG combo on their site). I was leaning towards the 5" upper initially, since it's the shortest they offer (isn't that the point of an SBR  ). From some videos I've seen, it almost looks like it would be too short for a rifle (not much room on hand guard to adjust grip or placement of a VFG) but fine for a pistol. I'm also nervous about having my hand that close to the muzzle. On the other hand, the shorter length would help keep OAL down if I get a suppressor for it. Since I don't see a 5" barrel/BCG combo on their site, their upper is the only option for this length.
I'm now leaning more towards the 8" upper. My 300 Blackout barrel is 8", so I'm used to that length already. I have the option of buying their upper or buying the barrel/BCG combo and building my own. I tried to find information online about the velocity differences between barrel lengths and it seems like there is a velocity jump between 5" and 8" (varies from barrel to barrel, ammo to ammo, but always seems to be a noticeable difference). I'm only going to be punching holes in paper and keeping handy for home defense, so I'm not too worried about any distance differences between barrel lengths. I don't know of anywhere locally that carries both, so I can't compare in person. Has anyone handled both? Did you buy one or the other? Pros and cons? I'm not going to be ready to buy until November or December, and I am still waiting to see a Guard upper with an EndoMag in action, so I still have time to research. Might be able to catch up with CMMG at a fun show between now and then, too. So basically, the above was my long winded way of saying "help me decide". |
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Quoted:
Running a suppressor? 5" Unsuppressed SBR? 8" Done. The way things normally go with the ol' gun budget, I'll buy or build a 9mm upper this year, but the suppressor will have to wait until next year (plus however long it takes the ATF now - my last one took 6 months). I was initially wanting the 5", and I think your logic is bringing me back around to that length. |
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Quoted: I like the way you think. The way things normally go with the ol' gun budget, I'll buy or build a 9mm upper this year, but the suppressor will have to wait until next year (plus however long it takes the ATF now - my last one took 6 months). I was initially wanting the 5", and I think your logic is bringing me back around to that length. You can also have the 8" cut to whatever length you like for the HG/can setup you end up with. Personal preference, but I like having the can tucked into the HG on a PCC. Would be easy enough t buy a 7" HG and run an 8" bbl for a year (plus 6 months for form 4 wait time) and then have the bbl cut to 4.5", toss on a 3-lug and tuck said can under the HG you're already running. |
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I think I'm going to need to find a place I can put my hands on both, with and without suppressors would be nice as well.
As far as I know from reviews I've read and videos I've watched, length seems to have no affect on reliability. I've never had a pistol caliber AR before, so I assume the type of blowback they use (vs rifles with gas tube length, barrel length, dwell time, etc..) keeps them reliable at any length? |
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I went with the 8" Guard setup. If I'm going to shoot 5", I might as well shoot my pistol. I also run a full auto Mini UZI SMG which has an 8" barrel. I run both suppressed. I load my own 147GR. 3.7Gr of Titegroup (I know max charge is 3.6) but here in FL it is still subsonic out of the Mini at 8" as well as my 10.5" full size UZI SMG.
I also consider the 8" Guard as a 'training' setup for my 5.56 setup which has a 12.5" barrel and Brevis P Ultra suppressor which is super short. That 12.5" barrel plus the Brevis is about 15". My 8" Guard + Gemtech MK9K suppressor is right around 15" as well. So I have the same amount of maneuverability with both setups. I'm still tuning mine but here is a vid of mine running full auto with a RDIAS and modified Colt mag block using unmodified Colt 9mm mags. I was trying to pull singles in full auto as well as then getting a feel for how smooth it is running short bursts. https://www.youtube.com/watch?v=cmAdCXDTUgc However, I've gone back to Glock mags for now but may just switch to the Mean Endo mags if they run as smooth as the Glock mags. I've found that the Glock mags require less force to strip rounds off than the metal Colt mags which means I have a bigger window of reliability in regards to tuning the setup to run as smooth as possible. So I will be curious as to how much force is required to strip the rounds off the Mean Endo mags vs the Glock mags. |
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