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Joined:
Feb 2025
Posts:
16
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FL, USA
Posted: 11/15/2025 4:00:55 PM EDT
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Wanting to build a new 9mm RDB upper to go on my CMMG lower. Im thinking about going side or front charging and a receiver without a rear charge handle. Trying to minimize gas when suppressed. budget is a concern because its an upper not normally going to be used. tying to keep handguard 7-8" long because the CMMG barrel will be 8". i dont think i will mind if the handle reciprocates or not I liked the Type Zero front charging handguard but its not available yet in 7.5" and i still need a receiver. I have also considered getting a side charging BearCreek 556 upper and converting it to 9mm RDB because the uppers are soo cheap. i would assume i can change the bolt for 9mm RDB. are there other any options that would be better? does the side/front charging uppers make a significant enough change in reducing gas? i might consider doing this to a couple others such as a .300 and my BRT CAR15SD because they could use some gas reduction |
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Originally Posted By Kingfish999: Wanting to build a new 9mm RDB upper to go on my CMMG lower. Im thinking about going side or front charging and a receiver without a rear charge handle. Trying to minimize gas when suppressed. budget is a concern because its an upper not normally going to be used. tying to keep handguard 7-8" long because the CMMG barrel will be 8". i dont think i will mind if the handle reciprocates or not I liked the Type Zero front charging handguard but its not available yet in 7.5" and i still need a receiver. I have also considered getting a side charging BearCreek 556 upper and converting it to 9mm RDB because the uppers are soo cheap. i would assume i can change the bolt for 9mm RDB. are there other any options that would be better? does the side/front charging uppers make a significant enough change in reducing gas? i might consider doing this to a couple others such as a .300 and my BRT CAR15SD because they could use some gas reduction You may get more answers in the AR15 rimfire/PCC section of the forum. |
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Originally Posted By Kingfish999: Wanting to build a new 9mm RDB upper to go on my CMMG lower. Im thinking about going side or front charging and a receiver without a rear charge handle. Trying to minimize gas when suppressed. budget is a concern because its an upper not normally going to be used. tying to keep handguard 7-8" long because the CMMG barrel will be 8". i dont think i will mind if the handle reciprocates or not I liked the Type Zero front charging handguard but its not available yet in 7.5" and i still need a receiver. I have also considered getting a side charging BearCreek 556 upper and converting it to 9mm RDB because the uppers are soo cheap. i would assume i can change the bolt for 9mm RDB. are there other any options that would be better? does the side/front charging uppers make a significant enough change in reducing gas? i might consider doing this to a couple others such as a .300 and my BRT CAR15SD because they could use some gas reduction You might look at the Devil Dog Concept side charge handle. I have several and they work quite well. |
Joined:
Jun 2025
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AZ, USA
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Bear creek makes a 9mm upper side charging I have their 5" BC9 runs great BUT they changed the rear adapter for the bufferless upper to make it shorter.... bolt doesn't go back far enough to catch the bolt catch... I plan to shorten their bolt and add weight to fix that... if your not going bufferless then just grab onea their side charger 9mm uppers and done deal https://www.bearcreekarsenal.com/catalog/category/view/s/upper-assemblies/id/940/9mm--right-side-charging I have this one, runs 100% https://www.bearcreekarsenal.com/9mm-5-parkerized-m4-barrel-1-10-twist-blow-back-4-sch-nrail-bufferless-upper.html |
Joined:
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WI, USA
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Foxtrot Mike is a good way to go if you want a prebuilt upper. But, if you're looking for a customized solution and you're willing to do a little parts modification, you can buy Foxtrot Mike Gen 1 handguards + forward charging handles and make them work with a mil-spec upper after some minor parts modification. With a PCC, you may not even need to modify the mil-spec charging handle, depending on the shape of the bolt's key. I used this approach with two .22lr uppers I built. Only part of this gallery will pertain to the handguard/upper receiver modifications necessary. CMMG/Foxtrot Mike Frankenbuild Gallery While the gallery shows cut-up standard charging handle, an uncut one can be used (along with modifying its latch or the receiver's catch cutout for the charging handle latch) to achieve dual charging (front/side + rear). There's an old thread with more info in the Pistol/Rimfire forum detailing that project. You can either use one of FM's handguards pre-setup for a charging handle, or you can modify one of their Gen 1 non-front charging rails to accommodate the charging handle. Handguard gas tube hole needs to be widened upward for this to work. Edit: missed you were going for a no-rear charging handle. Sorry if this doesn't help so much. |
Joined:
Feb 2025
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25
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FL, USA
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Originally Posted By mech-monsoon: Bear creek makes a 9mm upper side charging I have their 5" BC9 runs great BUT they changed the rear adapter for the bufferless upper to make it shorter.... bolt doesn't go back far enough to catch the bolt catch... I plan to shorten their bolt and add weight to fix that... if your not going bufferless then just grab onea their side charger 9mm uppers and done deal https://www.bearcreekarsenal.com/catalog/category/view/s/upper-assemblies/id/940/9mm--right-side-charging I have this one, runs 100% https://www.bearcreekarsenal.com/9mm-5-parkerized-m4-barrel-1-10-twist-blow-back-4-sch-nrail-bufferless-upper.html ya i ordered and got a Bear Creek upper side charger but in 556 so it will have bolt pin clearence neded for the CMMG RDB. i spent alot of money for the holidays so im trying to recoup alittle. still need to order a barrel and bolt, then modify the BCA carrier to accept a CMMG bolt which should be pretty easy I had been debating on getting a FM Gen1 handguard. Amphibian mentioned the front charge handle is not in the same spot as the gas hole, also the handguard keys into the reciever and i wasnt sure if that can be modified to work on a milspec or not. at some point ill probably buy the Gen1 handguard and modify it to fit one way or another. i think the barrel nut showed out of stock so i didnt order one yet. if the Gen1 handguard will work then ill order a 10.5" barrel from Amphibians store, if not then ill order a 8" CMMG barrel holidays and work have been crazy tho so its on hold |
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