Magazine Rebuild Compatibility List

[grammaton76]

So, I would like to start a magazine rebuild compatibility list project. Info will be collected in this thread, and collated into a Gunwiki article on this subject.

I shall kick off my own efforts on this some time tonight I think, but in the meantime some of you probably have info you could contribute.

Requested format of submissions:

1. Original magazine (description including capacity and make if available, would like pic too)

2. Converted-into magazine (description including capacity and make if available, would like pic too)

3. Which parts are compatible between the two (description, would also like at least one pic of a transitory state between the two mags)

4. Any modifications which were necessary in order to make it work (i.e. cut a notch in a mag, perhaps shorten a spring, etc. If possible, would LOVE to have a pic of each stage of the conversion work)

5. Any notes on tricks needed to get the mag apart... some mags are tricky.

Conversions I'm aware of that'd be interesting:

1. AR-15 USGI 20 <-> 30

2. AR-15 C-Products steel mag <-> USGI

3. Sig, Glock, etc... 12/15/whatever <->30/32/whatever (although silly for handguns, this is of interest to AR pistol caliber conversions)

4. Ceiner mags... the new vs the old ones.

Conversions I'd like to see tried:

1. Any drums which just so happen to function with a swapped spring or something...

2. For someone with access to a Beta-C... I'd like to know if you can replace the follower in an AR mag with the dummy rounds/follower things from the Beta-C and have a functioning AR mag. IF SO, the dummy rounds have become the AR mag's follower and you COULD rebuild using those dummy rounds as a follower and the rest of the parts of the Beta-C. Clearly, we'd need to see some good proof that the AR mag functions with the dummy rounds. I believe that even if you have to mod the AR mag's body to make this work, it'd still be a legal rebuild as long as the modded mag body functions in an AR, which it was designed for.

[DRM6000]

c-products ss to usgi, no problem

usgi 20 <-> 30, no go. floorplates are specific to each and don't interchange.

[69Mach1]

The follower in the Beta C mag will fit into a 20\30 round mag tube. The follower is just a bunch of dummy rounds.

[sigsauer887]

Regular followers are a no go in the Magpul PMAGS. Have to use original springs.

[CHS]

c-products ss to usgi, no problem

usgi 20 <-> 30, no go. floorplates are specific to each and don't interchange.

So use a magpul ranger floorplate. Problem solved

[grammaton76]

The follower in the Beta C mag will fit into a 20\30 round mag tube. The follower is just a bunch of dummy rounds.

Any chance you can take a video of reassembling a USGI 30rd mag using a Beta-C follower, then using that follower in a Beta-C? My one concern here is that the dummy rounds would eject out the top of the USGI mag, but they may have oversized it just slightly so that this isn't a problem.

Provided this works, I believe the coveted path to rebuild a Beta-C from a USGI mag has been found.

[grammaton76]

c-products ss to usgi, no problem

usgi 20 <-> 30, no go. floorplates are specific to each and don't interchange.

Hmm, what about followers?

Only one common part is required in order to facilitate a valid rebuild - hence why we may have just found a USGI -> BetaC path.

[DRM6000]

Hmm, what about followers?

Only one common part is required in order to facilitate a valid rebuild - hence why we may have just found a USGI -> BetaC path.

ooh right, forgot about those. i believe that the 20 rd followers are specific since the mags are straight. if i have time later tonight, i'll take some pics of the parts.

[spencerhut]

CZ-75b 16 Round to CZ-75SP-01 19 Round (follower)
CZ-75b 16 Round to CZ-75b 25 Round (Follower)

[grammaton76]

I don't have a beta-c yet to test, but I have learned some things:

The Beta-C's dummy rounds aren't like the PS90 mag's... they're 7-9 (my source was fuzzy) pre-linked dummy rounds. This means it will probably not play nice with CURVED magazines.

No big deal, this is why we're also documenting a clear-cut and legal path from a USGI 30rd curved magazine to a USGI 20rd straight magazine.

Rough outline for this project, assuming the follower won't work with a USGI 30rd mag:

1. USGI 30rd mutates into USGI 20rd.

2. USGI 20rd is rebuilt using the follower (dummy rounds) from the Beta-C magazine.

3. Beta-C magazine uses the (originally from a Beta-C) follower used in the hybrid USGI 20rd / Beta-C magazine.

Provided that the conversion process between each step is well and thoroughly documented (as I intend to), it should be very simple to print out the process chart to bring along with your converted-to-Beta-C magazine and kept along with the DOJ's previously stated opinion letter allowing for magazine rebuilds.

BTW, I have started on the compatibility chart, and will post the URL once I've incorporated a fair amount of the existing data.

[69Mach1]

I understand what you're trying to do with the Beta C-Mag rebuild, and I have thought about this before, but this is really a stretch. BTW, I did fit the follower (loose dummy rounds and a connected 2-piece follower) from the Beta C-Mag into the tube magazine body. The dummy rounds replaced the tube mags follower. A better approach is for some ingenious CA resident to make an adapter that replaces the Beta C-mags tower to lock a regular AR tube mag onto. Say an 11 round (high cap) tube magazine that you rebuilt from your preban high(er) caps. That lets it maintain the identical height as the AR Beta C-Mag tower. Then add extra dummy rounds if needed. The idea came to me when I saw the PMag mag capacity extension from another post.

[mvpatriot]

thanks for the gunwiki gramma, I just used the 922r spreadsheet last night!

[69Mach1]

Also note that preban Beta C-Mags have loose spacer dummy rounds and only the top two are linked together. The newer style (which I need to pick up) have two sets of linked dummy rounds. One 8 linked set and the other is a 9 round linked set. Each linked side goes down into each side of the drum when loaded. Those rounds can be de-linked. I hope you do figure a way to get an approval in writing for this type of rebuild. That would open up some great possibilities......HK94 drums and M1A drums.

[grammaton76]

CZ-75b 16 Round to CZ-75SP-01 19 Round (follower)
CZ-75b 16 Round to CZ-75b 25 Round (Follower)

Can you let me know if these are OEM CZ-75 mags? Probably stamped Mec-Gar? Just trying to be as thorough as possible.

[grammaton76]

Also note that preban Beta C-Mags have loose spacer dummy rounds and only the top two are linked together. The newer style (which I need to pick up) have two sets of linked dummy rounds. One 8 linked set and the other is a 9 round linked set. Each linked side goes down into each side of the drum when loaded. Those rounds can be de-linked. I hope you do figure a way to get an approval in writing for this type of rebuild. That would open up some great possibilities......HK94 drums and M1A drums.

Very good information! I think now that it'd be easier to do the migration with the old style mag follower/dummy round, to avoid mag body curvature issues.

Saaaayyyy... buddy, what're you doing with that old style follower setup once you upgrade to the new style...? Follower rental could legally facilitate USGI -> BetaC rebuilds... buy new rebuild kit, rent old follower, rebuild with old follower over two steps, restore new style follower as final step of rebuild process, return rented old style follower... life is good.

As for approval in writing for this specific rebuild path, it won't happen - Allison has learned that "58 DA's" is the only thing she should write to Calgunners asking silly questions now. However, I personally feel that this is close enough:

http://www.hoffmang.com/firearms/DOJ-large-cap-magazines-2005-11-10.pdf

The DOJ has issued an approval letter for all-new-parts magazines, including those with larger capacity than the original. No limit has been imposed of how many "degrees of separation" the current state must remain from its pre-2000 state. As long as it still functions in the original gun, the magazine remains (spiritually, if you will) your trusty original magazine provided that a clear migration path exists where the magazine is functional at each step along the way.

I will state that the need for function verification is not explicit in the DOJ letter, but is a reasonable precaution derived from the statement that no part of the original mag configuration is required to remain as the "soul" of the rebuilt mag - only that you can't change it all out at once or it isn't a rebuild. We can't say "...and then a miracle happens!" and replace all the parts at once at some point along the way. My goal with this list is to remove all reliance on miracles and create a list of a legal and viable rebuild paths.

Provided there's a stringently documented rebuild path, I am comfortable enough with the photographically documented rebuild process and this letter, to say it's legit...