AR Sponsor
[ARCHIVED THREAD] - Thoughts on the CMMG Guard? (Page 17 of 25)
|
Quoted: also, anyone done a integral build on this design yet? seems ideal... could do an mp5sd ported at2" plan too. set screw it to not bleed off when you dont want too... aweeeeeesome saouce |
|
Quoted:
Yes, I'm planning on doing that. I have two 8" Guard uppers built from barrel / BCG combos. I bought my first set to make sure I would like the system. Bought a second set to do an integrally suppressed configuration. I already have an old LRM integrally suppressed upper that is standard blowback and plan on getting the 2nd Guard barrel turned down to work with that suppressor. |
|
Quoted: Assuming your piston carrier has the same cam pin path as a standard DI gun, then no. The Guard carrier uses a shorter cam path compared to a DI gun. (I was thinking the same thing when the Guard first came out; wanted to integrate the Guard bolt with a Rock River PDS upper. Only after I bought a Guard did I find out this small yet important detail!) barrel length... last i read, or remember readin was mp5sd is like 2". (for 115s) can drill and thread some set screws to close up ports when you running heavier stuff... post pics when you do!!! i added 5/8-24 threads further back on my pak 9 ak, think i gonna form 1 a big subgun type can... or maybe just thinner normal with good volume so it stays under handguards |
|
Quoted:
What bbl length makes 115 g SAMMI spec ammo subsonic?? What bbl length for 124g? |
|
Quoted:
@amphibian W the difficilties w the ejector and also w suppressing do you think that a guy would be better served w a tuned blowback (w proper buffer & spring for it, 16" gun for semi auto PCC shoots? Also consider that if you just go to the 'A5' length buffer tube you can use pretty much any 'tuned' blowback spring and buffer and put it in the Guard...although you should go lighter to achieve less reciprocating mass....just like what I'm doing now.... EX: Many praise the 9mm hydraulic Kynshot doing wonders for their blowback 9mm AR setups. I'm using that same buffer in a DELAYED blowback setup...however with the Guard gotta use the A5 length tube since the Guard uses the bolt / carrier setup vs a solid bolt. |
|
Before I built my Guard upper, I swapped out the buffer system on my SBR lower to an A5 tube, Griffin SOB buffer, spacer, and Tubbs flatwire spring. While I have no complaints, after reading all of the other posts here and in other threads about the hydraulic buffer, I just can't help but feel I'm missing out.
Does anyone know if there's any Memorial day sales that would include the blitzkrieg kynshot 9mm hydraulic buffer? If not, I may wait until Black Friday. I probably won't see my suppressor out of jail until Christmas time anyway, so I'm not in a big hurry to be making changes. |
|
so, who has these combos for the cheapest price at the moment?? i think i may use wifes bonus money haha...
also, on a different forum some guy said there is some short stroke piston kits made by someone else? i 30 second googled it and found nada... guard seems more ideal for the integral build i imagining, but i am always open to more ideas |
|
Quoted: What bbl length makes 115 g SAMMI spec ammo subsonic?? What bbl length for 124g? |
|
Quoted:
I’d be surprised if any realistic barrel length makes factory 115g or 124g subsonic. Most velocity specs are out of pistol length barrels of around 4” or so, and both bullet weights are normally supersonic out of those barrels. Quoted:
Quoted: What bbl length makes 115 g SAMMI spec ammo subsonic?? What bbl length for 124g? |
|
About the Tuning Kit that CMMG sells, does it add weight to the bolt, or are the weights in the kit lighter than those included in the Guard bolt?
My 5" barrel and bolt are still back ordered, but my plan is to run this suppressed semi-auto using Mean modified Pmags on an unmodified standard 223 AR carbine lower with a standard carbine spring and H3 buffer. Do I need the tuning kit to do this? |
|
Quoted:
Is CMMG selling complete uppers? I would like to use my BCM sbr lower with arc mags. Optics planet carries them too: https://www.opticsplanet.com/s/cmmg |
|
Quoted:
About the Tuning Kit that CMMG sells, does it add weight to the bolt, or are the weights in the kit lighter than those included in the Guard bolt? My 5" barrel and bolt are still back ordered, but my plan is to run this suppressed semi-auto using Mean modified Pmags on an unmodified standard 223 AR carbine lower with a standard carbine spring and H3 buffer. Do I need the tuning kit to do this? No, you don't need the tuning kit. CMMG recommends it but I don't like using any of the weights. I don't like adding more reciprocating mass. I think the optimal way to fix it is to delay the unlocking by changing the angles of the bolt. (which is what I did if you've read my posts). However, I can see where adding weight is easier and a reversible change so it makes sense to do it that way for the masses. Maybe when they are bored, they will offer different bolts for delaying the unlocking instead but I think they are too busy keeping up with the demand they have now. |
|
Quoted:
Yes, as well as barrel bolt combos. https://www.cmmginc.com/product-category/uppers-and-lowers/uppers-uppers-and-lowers/ Optics planet carries them too: https://www.opticsplanet.com/s/cmmg Looks like their prices have really gone up. They are selling Mk3 uppers for more than I got my complete rifle 5 years ago. So much for salad days.  Looks like $700 plus $60 for a couple of mags.
|
|
Quoted:
Thank you. Looks like their prices have really gone up. They are selling Mk3 uppers for more than I got my complete rifle 5 years ago. So much for salad days. Looks like $700 plus $60 for a couple of mags.I seem to recall it used to be $350 retail for the 8" and now $375. The 5" is at $350 now. Initially, they never offered the 5" for sale individually, you had to get a complete upper or complete gun. |
|
Quoted:
I never paid attention to the complete rifle or upper prices. I just got their BCG / BBL combos and a stripped lower initially. I seem to recall it used to be $350 retail for the 8" and now $375. The 5" is at $350 now. Initially, they never offered the 5" for sale individually, you had to get a complete upper or complete gun. |
|
Quoted:
Unless things have changed, they don't include a weight with the Guard BCG. No, you don't need the tuning kit. CMMG recommends it but I don't like using any of the weights. I don't like adding more reciprocating mass. I think the optimal way to fix it is to delay the unlocking by changing the angles of the bolt. (which is what I did if you've read my posts). However, I can see where adding weight is easier and a reversible change so it makes sense to do it that way for the masses. Maybe when they are bored, they will offer different bolts for delaying the unlocking instead but I think they are too busy keeping up with the demand they have now. |
|
Quoted:
Thanks Amphibian. I'll look back in the thread and find where you are doing that. Quoted:
Quoted:
Unless things have changed, they don't include a weight with the Guard BCG. No, you don't need the tuning kit. CMMG recommends it but I don't like using any of the weights. I don't like adding more reciprocating mass. I think the optimal way to fix it is to delay the unlocking by changing the angles of the bolt. (which is what I did if you've read my posts). However, I can see where adding weight is easier and a reversible change so it makes sense to do it that way for the masses. Maybe when they are bored, they will offer different bolts for delaying the unlocking instead but I think they are too busy keeping up with the demand they have now. Latest update on my blog site here: http://c3junkie.com/?page_id=538#section4 Basically, I got the 40SW BCG/BBL combo and using the 40SW in 9mm. You can clearly see the angle is less pronounced on the 40SW to deal with the higher pressure round. 
I was hoping it would NOT work in 9mm UNsuppressed and WOULD work suppressed and it did exactly that. 
Then adding suppressor: 
Now swapping to the stronger 556 Tubb flat spring and still works with the 40SW bolt. 
I also loaded a live round then inserted a fully loaded 30 round Endomag into both of the setups above, firing bursts with no malfunctions 2x each. This is to apply the maximum amount of resistance to the bottom of the carrier. The issue now is whether or not the ejector spring is going to hold up. The .40SW uses a new rounded ejector. I used to have a .45 ACP gas operated upper by RMW. He cut the face of the ejector to have an angle to help kick the brass out at the correct angle. I'm guessing CMMG is basically doing the same thing here but by making it rounded they don't have to deal with 'indexing' of the pin. The spring appears to be identical to the proprietary spring used in the 9mm and 45ACP Guard. So I would think that using my preferred buffer/spring/tube combination would result in a short life but that is yet to be determined. I first ran the 40SW BCG in .40SW to get that dialed in. I then did the testing above. So the ejector spring probably has about 300 rounds of mixed .40SW and 9mm run through it. It seems weaker than out of the box but not weak enough to be replaced yet. 40SW is higher pressure than 9mm so I would think it should die faster in 40SW than 9mm. It will be amazing if for some reason going to a rounded ejector extends the ejector spring life. Maybe less surface area contacting the 9mm case.? 
As previously mentioned, I think changing the geometry of the bolt lug angles is better than throwing more reciprocating mass at the issue.....just like changing the locking piece on an MP5. I do see it being a logistical problem for CMMG though.. Many customers will say they want something 'optimized' but the second it chokes on cheap ammo UNsuppressed, it will get a black eye. So easier to sell their weight kit for the carrier since it is less expensive and reversible. Check out my blog site in the link above if you care to read more details. |
|
Quoted:
I was hoping it would NOT work in 9mm UNsuppressed and WOULD work suppressed and it did exactly that. http://c3junkie.com/wp-content/uploads/2019/06/300BLK-A5-9mmKynshot-40SWBolt-NoCan.jpg |
|
Quoted:
How come? Quoted:
Quoted:
I was hoping it would NOT work in 9mm UNsuppressed and WOULD work suppressed and it did exactly that. http://c3junkie.com/wp-content/uploads/2019/06/300BLK-A5-9mmKynshot-40SWBolt-NoCan.jpg Look at how close the cyclic rate is unsuppressed before it jammed after adding the suppressor .... they are very close. To contrast that....: On my site, Configuration 1: Unsuppressed: 622 RPM Suppressed: 686 RPM So 66 RPM increase suppressed w/ Configuration 1: I think that is relatively high for a 9mm SMG design that doesn't tap into the gas system. (Gas operated 556 and ~200RPM increase is common). I typically see about 30 RPM increase on SMG's when adding a suppressor. For some reason the Guard is higher. As documented on my site doing Configuration 2. I did not anticipate this and while it ran great unsuppresssed, it was a single shot when adding the suppressor. Configuration 3, I tried to address this issue by modifying the bolt lug geometry specifically for suppressed as seen below. Below is the modified 5.45 Bolt that I tuned specifically for suppressed usage...it would not work without the suppressor.  But as you know I then had all the ejector spring issues. Then I modified the bolt provided by the other C2 that is clearanced to work with the fixed ejector.  I think I was impatient and ground the angles too much and it still worked without a suppressor. (still does work perfectly with and without a suppressor to this day).....I have been hesitant to go grinding on another bolt since that is pretty much an irreversible change. I also wanted to run the ground on bolt for an extended period to see how much wear I would see considering I removed the case hardening (BTW, it is doing very well and see no high spots). 
So with Configuration 4 (40SW bolt running in 9mm), it is like my early Configuration 3 testing where it only functions suppressed with the modified 5.45 bolt which I really liked till the ejector spring crapped out on me so fast. Again, as mentioned on my site, I would think since the 40SW which operates at a higher pressure than 9mm would kill ejector springs even faster than 9mm. Again, the spring in my 40SW bolt looks identical to their proprietary 9mm/45 Guard ejector springs. It will be amazing if just rounding it makes it last longer. I'm tempted to either round a 5.56 ejector like they did and put it in a 5.45 bolt with lugs ground to be like the 40SW and see how long it lasts....or for that matter just run the 40SW bolt in 9mm for a while and see how it holds up... In conclusion, I think it is fantastic that this system allows us to do these types of mods of delaying the cycling relatively easily. It would be my hope that at some point CMMG will offer suppressor 'optimized' bolts rather than just throwing more reciprocating mass at the problem....but I love options and there are plenty with this system. Way more than anything else in existence. |
|
Thanks for all that great info Amphibian! I'm not sure I'm reading right though. You are using a 40S&W bolt and a 9mm barrel extension? If the bolt lugs are a different angle on 9mm compared to 40S&W, aren't the extension lugs different as well. The different bolt face diameter isn't an issue? |
|
Quoted:
Thanks for all that great info Amphibian! I'm not sure I'm reading right though. You are using a 40S&W bolt and a 9mm barrel extension? If the bolt lugs are a different angle on 9mm compared to 40S&W, aren't the extension lugs different as well. The different bolt face diameter isn't an issue? As mentioned on my website, I have full auto UZI open bolts that have been opened up for use with 40SW and they still work with 9mm for the full size and MINI UZI. Based on that as well as several other guns that work w/ both 40SW and 9mm with a barrel change, I had anticipated it working with the Guard as well which it clearly does so far.... Now, I'm sure CMMG probably won't support what I'm doing but that is another discussion. |
|
Quoted:
The extension lugs are the same. As mentioned on my website, I have full auto UZI open bolts that have been opened up for use with 40SW and they still work with 9mm for the full size and MINI UZI. Based on that as well as several other guns that work w/ both 40SW and 9mm with a barrel change, I had anticipated it working with the Guard as well which it clearly does so far.... Now, I'm sure CMMG probably won't support what I'm doing but that is another discussion. |
|
Quoted:
The extension lugs are the same? Same as a standard extension or a guard 9mm extension? I haven't seen one in person yet, do the guard extensions have a angle cut on the lugs aswell to match the bolt? Additionally, I took a picture of my Guard barrel from the bore and the extension lugs look standard to me. 
|
|
Quoted:
Their patent does show angles on the extension however, I could have sworn I've seen a post by someone from CMMG saying they were standard. Just because the art in a patent references certain things doesn't mean it goes into production that way. Additionally, I took a picture of my Guard barrel from the bore and the extension lugs look standard to me. http://c3junkie.com/wp-content/uploads/2019/06/GuardExtension.jpg Interesting though, as you'd think that would wear much quicker than if the lugs were tapered the same angle to increase contact area, but it doesn't seem to be a problem. That would be a fun machining step to set up... |
|
Quoted: That's what I thought. When the Guard first came out, one of the reps on here said they were using standard extensions. Interesting though, as you'd think that would wear much quicker than if the lugs were tapered the same angle to increase contact area, but it doesn't seem to be a problem. That would be a fun machining step to set up... I would have thought I should see something by now. |
|
I've bought a Banshee 300 pistol with the 5" barrel and the CMMG Micro/CQB RipBrace. From what I've read, a lot of people are using longer buffer tubes with hydraulic buffers. I really don't want to swap to a longer buffer tube as I really like how short and compact this gun is. Is there an known optimum hydraulic / buffer spring / weight configuration for Banshees with the CQB RipBrace? Reliability un-suppressed AND suppressed being the priority, with smoother recoil impulse being a nice addition. I'm not expecting it to be as smooth as my MP5's, I just want the best shooting experience without sacrificing reliability. |
|
Ok, in regards to the 8 inch barrel kit CMMG is selling. What rail are y’all using? I will have a tri lug on it, so I’d like the rail to end right at or very close to the start of the threads.
If at all possible, anti rotation tabs. I don’t care if its keymod or mlok. |
|
Quoted:
Ok, in regards to the 8 inch barrel kit CMMG is selling. What rail are y’all using? I will have a tri lug on it, so I’d like the rail to end right at or very close to the start of the threads. If at all possible, anti rotation tabs. I don’t care if its keymod or mlok. Highly recommend the BCM rails. I have four of them now. |
|
Quoted:
I have the 8" with an 8" BCM rail (because I had an 8" rail sitting around). The muzzle is 1/4" from the end of the rail. So I used an In Lead We Trust extra extended 3-lug, it's perfect. About .5" longer than a normal 3 lug. So I have the right amount sticking out and get to run a 1" longer rail. Highly recommend the BCM rails. I have four of them now. Quoted:
Quoted:
Ok, in regards to the 8 inch barrel kit CMMG is selling. What rail are y'all using? I will have a tri lug on it, so I'd like the rail to end right at or very close to the start of the threads. If at all possible, anti rotation tabs. I don't care if its keymod or mlok. Highly recommend the BCM rails. I have four of them now. |
|
Quoted:
Ok, in regards to the 8 inch barrel kit CMMG is selling. What rail are y’all using? I will have a tri lug on it, so I’d like the rail to end right at or very close to the start of the threads. If at all possible, anti rotation tabs. I don’t care if its keymod or mlok. Buy the rail you really like, at the length you really want. Then buy the 16" CMMG barrel kit and present it all at home without installing it. Measure where the rail ends on the barrel and mark the barrel with tape or the like. Send to ADCO for cut and rethread and explain that you want the stepdown to the start of the threads where you marked. This will cost a bit more $$ and time, but it will allow you to have exactly what you want, with the flush fit that you want. If your barrel will be shorter than 7", then you can get the 8" barrel kit instead, and do the same. That will save you about $25. I've done this thee times now with excellent success using SilencerCo ASR mounts and a Hybrid suppressor, looks flush and very nice. I could have gone a little shorter because the ASR muzzle devices locks the Hybrid a little bit farther out than flush with the threads, like a 1/4" or so. |
|
Quoted: I have the 8" with an 8" BCM rail (because I had an 8" rail sitting around). The muzzle is 1/4" from the end of the rail (EDIT: INWARDS, the muzzle is 1/4" SHY of the rail). So I used an In Lead We Trust extra extended 3-lug, it's perfect. About .5" longer than a normal 3 lug. So I have the right amount sticking out and get to run a 1" longer rail. Highly recommend the BCM rails. I have four of them now. Thanks. This is what I’ll do. Can you verify that it is the extra extended? Reason I ask is you mention it being the extra extended, but the extended (not extra) is the one that is 0.5 longer. |
|
Quoted: @new21022 Thanks. This is what I’ll do. Can you verify that it is the extra extended? Reason I ask is you mention it being the extra extended, but the extended (not extra) is the one that is 0.5 longer. Extended base is 1.930? o.a.l. Extra extended base is 2.063? o.a.l. I ordered Extra Extended. It's 1/8" longer, and you MIGHT be able to get away without that, but I don't know what three lug you'll be using. I've tried the SiCo (external) and a Rugged (internal) both of those fit, and might fit with .125" removed, but honestly, I wouldn't risk it. Just get the Extra Extended. You'll love that setup. It's slick. |
|
Guys, I've read through this thread on the Guard and the other one in the M16 forum. I have a Spikes lower that is all setup for an RLL and a 11.5" 556 upper (standard carbine tube and H2 or H3 buffer). I would like to build a Guard or maybe a Banshee upper for use on this lower with the RLL and endomags. I'd prefer to not have to switch anything in the lower (other than the mag) when going from 556 to 9mm unless it really makes sense (significant increase in performance). I've seen some people mention one of the various Kynshot buffers and others mention another buffer (can't think of the name). Is there a lower receiver configuration that will work best with the RLL and going from 556 to 9mm? From what I've read, my choice of buffer will also determine the length of tube I go with.
Thanks for any help... I've done so much reading on this my head is kind of spinning. |
|
Quoted:
Guys, I've read through this thread on the Guard and the other one in the M16 forum. I have a Spikes lower that is all setup for an RLL and a 11.5" 556 upper (standard carbine tube and H2 or H3 buffer). I would like to build a Guard or maybe a Banshee upper for use on this lower with the RLL and endomags. I'd prefer to not have to switch anything in the lower (other than the mag) when going from 556 to 9mm unless it really makes sense (significant increase in performance). I've seen some people mention one of the various Kynshot buffers and others mention another buffer (can't think of the name). Is there a lower receiver configuration that will work best with the RLL and going from 556 to 9mm? From what I've read, my choice of buffer will also determine the length of tube I go with. Thanks for any help... I've done so much reading on this my head is kind of spinning. Check out section #1: http://c3junkie.com/?page_id=538#section1 |
|
Quoted:
Does anyone know if the BCG will work with mags other than Glock, specifically MP-5/40 mags? With double-feed mags, especially with fat rounds and flat nose bullets, the challenge is ramping the chamber enough to prevent them from jacking up between the lugs and breech, without sacrificing too much chamber support. It's been done in 9mm with Colt mags though, so with the right mag location and feed ramp you should be able to get a double-feed mag to work. https://www.ar15.com/forums/Industry/9mm-Guard-Barrel-and-BCG-working-with-Colt-mags/145-286362/ Take a look at the MPX feed ramps for inspiration 
|
|
Quoted:
Have you looked at my site? http://c3junkie.com/?page_id=538 Check out section #1: http://c3junkie.com/?page_id=538#section1 |
[ARCHIVED THREAD] - Thoughts on the CMMG Guard? (Page 17 of 25)
AR Sponsor