User Panel
Posted: 12/23/2017 10:46:30 AM EDT
For those of you with SBRed standard lowers with mag blocks, it is possible to get those Colt pattern mags to feed a Guard Barrel and BCG.
Will get some pics. |
|
|
Nice! Have you test fired it yet?
|
|
|
|
Looking forward to seeing how it goes!
Curious...you didn't have to tweak the feed ramp at all? With mine I found the top was interfering with the bottom of the BCG a little. Hope all goes well with testing; if all this conversion takes is an adjustment to the mag catch notch then that's going to make lots of people very happy! |
|
|
Originally Posted By 60-Driver:
Looking forward to seeing how it goes! Curious...you didn't have to tweak the feed ramp at all? With mine I found the top was interfering with the bottom of the BCG a little. Hope all goes well with testing; if all this conversion takes is an adjustment to the mag catch notch then that's going to make lots of people very happy! View Quote Have a couple of pics but photobucket sucks. |
|
|
Originally Posted By badkarmaiii: So far, nothing done to AMM mag block feed ramp, removed ejector from block, raised mag notch .080", rounded front of mag follower. Have a couple of pics but photobucket sucks. View Quote |
|
|
Originally Posted By 60-Driver: Ok cool interested to see your modified followers. I've tried Promag, Uzi, and C-Products so far, all with unmodified followers. Of the three, the plastic Promag followers have been the best at letting the bolt slide over top an empty mag but the orange C-Products are a no go; bolt hangs up ever time. View Quote C-Products orange follower... |
|
|
Aha brilliant! I'll go try that with mine...
I ended up cutting a groove in the Promag follower to ease clearance of the bottom left bolt lug. Both the Promag and Uzi feed great now (manually...have yet to test fire as well) |
|
|
|
Need some clarification, did you raise the notch 0.080" in the mag block or the magazines.
|
|
|
Not speaking for badkarmaiii but I raised the notch in the magazine. A flat needle file will easily remove about .080" from the top of the notch. This allows the mag to sit lower in the magwell. Magblock stays the same.
|
|
|
|
That's awesome!
|
|
|
Franken-Guard: CMMG Guard 9mm barrel and BCG with Colt mag and block |
|
|
Originally Posted By badkarmaiii:
Franken-Guard: CMMG Guard 9mm barrel and BCG with Colt mag and block View Quote |
|
|
|
Haha we'll see....still trying to find a way to get this thing to work with a Lightning Link!
|
|
|
Can anyone analyze the audio and determine the cyclic ROF?
|
|
|
|
Awesome job! I like the work on the feed ramp. Need to do the same...I've been having feed malfunctions where the front edge of the case neck will catch on the front of the feed ramp and hang it up. I think I may try lowering the feed ramp entirely which should help that out.
|
|
|
Still considering modding a mag catch instead of all my mags.
Pretty easy to change out... |
|
|
I know right?! Need to do the same. A couple quick passes with an endmill and you're done. So much easier than spending an hour with a file and a bunch of mags...
|
|
|
|
|
|
Was that at Calibers?
|
|
|
|
Turned out nice! Forgot to ask...
-After chopping the barrel, which buffer did you end up using? Any tuning weights? -Any FTF/FTE issues come up in various configurations? (suppressed vs unsuppressed, semi vs auto, super vs subsonic, etc) -Which can were you using? |
|
|
-After chopping the barrel, which buffer did you end up using? Any tuning weights?
H2 buffer, no tuning weights -Any FTF/FTE issues come up in various configurations? (suppressed vs unsuppressed, semi vs auto, super vs subsonic, etc) Had one FTF with the subs, which are 135gr and below 125 power factor. -Which can were you using? Griffin Armament Revolution 9mm. |
|
|
NEW YOUTUBE VIDEO
Omega 9K with 5.9oz Armament LARB buffer and slightly softer-than-standard spring. Ammo was some cheap factory relaod stuff my buddy brought. I sold him my upper so now I gotta build another one. |
|
|
I was able to mod a bolt catch and Colt style mag block to work with my CMMG Guard upper. It feeds and ejects dummy rounds 100% (so far). The rounds, however, look really beat up.
I am using PSA mags and the bottom lug on the bolt doesn't hang but does make solid contact with the metal follower - I wonder if this will be a problem long term? |
|
|
The sharp back side of the bolt lugs are tough on ammo and brass but it works.
The PSA mags are Metalform, IIRC. Time will tell if it's a problem... |
|
|
|
Originally Posted By badkarmaiii:
The sharp back side of the bolt lugs are tough on ammo and brass but it works. View Quote I ask because I've been messing around with my 45ACP franken-Guard and experienced a couple of split cases so far. One of the lowers I'm testing feeds from HK USC mags and I noticed the lugs were getting hung up on the neck of the brass when I pulled the charging handle back. I would have to release the magazine to get the bolt back then reinsert to chamber a round. Best I figured, under normal cycling the lugs are scoring the brass badly enough to create a weak point that was failing under pressure. |
|
|
I've only seen scratches so far, nothing deep.
Maybe breaking the edges a bit would help... |
|
|
Yeah I might try that.
Also, next time out I'm going to chamber a round with a full magazine, shoot it, then pull the next round out of the chamber to inspect the brass. I'll see just how much scratching is going on under normal cycling. |
|
|
|
I'd probably keep it manual with a jewelers file. A few strokes should do it. If I broke out the dremel, I'd use a felt polishing wheel at most. I've gotten a little too froggy with the dremel in previous projects and ended up removing way too much material than originally planned, even with something as 'light' as Cratex That's just me.
|
|
|
Did a quick couple of passes with a file then finished up with some fine grit sandpaper. Huge difference! Bolt is going back easy now, no longer catching on the rim. It's still putting decent scratches in the bullet/brass but a huge improvement from before. I think I may do a little Flitz polish next and hit the lugs and bottom of the carrier to smooth things up even more.
|
|
|
Originally Posted By 60-Driver:
Did a quick couple of passes with a file then finished up with some fine grit sandpaper. Huge difference! Bolt is going back easy now, no longer catching on the rim. It's still putting decent scratches in the bullet/brass but a huge improvement from before. I think I may do a little Flitz polish next and hit the lugs and bottom of the carrier to smooth things up even more. View Quote Most of the work in a reliability package involves making parts smooth, or so my dearly departed mentor taught me. |
|
|
Yeah I finished up with polish on the lugs and bottom of the carrier. Night & day difference when manually cycling now. It is super smooth with zero binding. Plus the lugs are no longer gouging the bullet/brass. I definitely think it will make a difference in reliability & longevity. Will do a live fire test tomorrow.
Granted this is with the 45 but I'm sure it'll also help the 9mm when I get back to testing it... |
|
|
I was able to take my modded mag catch/Hahn mag block out over the weekend. It ran in semi & full-auto.
A few observations: 1. Because the slot in my mag block was filed to lower its overall height in the gun I found it best to insert a mag on a closed bolt. This kept the block from moving upward as the mag was inserted and from having the block's feed ramp from interfering with the Guard bolt. 2. Because I modded the mag latch to allow the Colt Mags to sit lower in the gun, I could not swap on my 5.56 upper and have it work properly. The modded mag latch allowed the 5.56 mag to sit too low and would not reliably strip and chamber rounds. Thus, while the gun is very soft to shoot (mith my A5 system and A5H2 buffer) the modded mag catch is not a long-term solution for those who want to be able to swap pistol/rifle calibers. My thoughts are that the only viable solution would be to mod the mag catch slot on the Colt mags OR wait for someone to provide a Glock mag block that has the height of the mag lowered a few millimeters to account for the altered feed height in the Guard system vs. the blowback system. |
|
|
Originally Posted By cbecker333:Thus, while the gun is very soft to shoot (mith my A5 system and A5H2 buffer) the modded mag catch is not a long-term solution for those who want to be able to swap pistol/rifle calibers. My thoughts are that the only viable solution would be to mod the mag catch slot on the Colt mags OR wait for someone to provide a Glock mag block that has the height of the mag lowered a few millimeters to account for the altered feed height in the Guard system vs. the blowback system. View Quote |
|
|
Originally Posted By jreinke: WTF dude! Swapping a mag catch takes less than a minute to do and is by far the cheapest and easiest conversion. View Quote ETA - Video |
|
|
That thing runs nice!
Well done! |
|
|
+1. Nice work. That's with an A5 system & A5H2 buffer correct?
|
|
|
|
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.