450Bushmaster.net

Hello all,

New to the site but not to shooting, reloading, or ARs in general.

I'd like to use these magazines:
https://www.cheaperthandirt.com/product/c-products-defense-ar-15-30-round-magazine-223-rem-556-nato-no-tilt-follower-aluminum-gray-3023002179cpd-766897411083.do?sortby=ourPicks&refType=&from=Search:

but I'm having trouble searching the site and finding a reliable tutorial for converting these to 13-round .450B magazines. Should I mill the follower as-is? Replace it? Add a single-round follower adapter and reduce to 10-rounds? (clearly the last is the least desireable option to me).

Thanks!
jkpq45

I don't think I've heard of anyone fitting 13rds of 450 in a mag. I believe the old polymer sig mags were good for 11 or maybe even 12, with little or no modification. Most converted 30rd 5.56 mags are good for for 9-10.

And I assume the SG556 magazines are vaporware now?

Any other magazines that can fit 10+ rds of .450b?

Yep, the older SIG556 mags are kaput...they did hold 11/12 rounds variously, mag to mag. Haven't heard of any 10+ since them.

commander faschisto wrote:Yep, the older SIG556 mags are kaput...they did hold 11/12 rounds variously, mag to mag. Haven't heard of any 10+ since them.

12 all I can get in a Sig.

jkpq45, Apparently I was wrong about 13 round mag, however, the thread you bumped up for the modified CP mags is dated about the time CP was still around. They went out of business and some time later were bought by someone. The person/people that bought them changed a few things around with most of the mags. They are now CPD, and chances are the current mags aren't the same as the old. I have a few CPD 5.56 mags I can play with and see what happens, but chances are it wont be more than 9-10 rounds. The biggest issue with our round working in 5.56 mags is case geometry. 458 Socom has a more "in-tune" case geometry, hence why it loads and works better in .223/5.56 mags.

The curved 30 round mags don't work too well with the straight wall 450 BM cases, which tend not to go around the curve, hence the general limitation on the number of rounds you can get in one and still have them feed reliably. I prefer the straight 20 round .223 / 5.56 mags. Most any good brand will work, and I have used both metal and polymer. You don't necessarily have to change out the followers either. The last round will center on the magazine lips just fine.

My suggestion is to try some magazines you may have on hand without making any modifications and see if you run into problems.

If all else fails, take multiple, lower capacity mags and practice tactical reloads.

Well I played with the CPD 5.56 mags and I could stuff a total of 12 in it. However the top round was pushed up out of the mag at over 30 degrees, with 11 in it it was a little better but still not good. I'm going to play with it a little bit more but I doubt it will function with more than 9 or 10. Another thing I looked at were my ASC 9rd 450 mags. I noticed that they have dimples in body so it will limit capacity. I might take one of those and drill em out to see what happens. Maybe.

So I got around to modifying mags. I had a Military issue 30rd aluminum mag w/ tan follower, a CPD 30rd stainless mag, and the ASC 9rd or 10rd (can't remember) 450B mag.
Both the 30rd 5.56 mags now hold and feed 12rds of 450B. I still have to take them to the range and actually shoot them, but they should work. After messing with them for a while, I don't think 13rds is going to work. Mainly because of the spring length when compressed. You could probably cut a turn or two out and then pull it part, but then your losing spring power, plus springs don't usually last long at that point.

With the ASC 450B mag, I drilled out the dimples, but it didn't really help anything. When they put the dimples in, it compressed that whole area, so they follower gets wedged in at that point. For what they cost, I don't think I'll be messing with them any more.

Bmt85 wrote:So I got around to modifying mags. I had a Military issue 30rd aluminum mag w/ tan follower, a CPD 30rd stainless mag, and the ASC 9rd or 10rd (can't remember) 450B mag.
Both the 30rd 5.56 mags now hold and feed 12rds of 450B. I still have to take them to the range and actually shoot them, but they should work. After messing with them for a while, I don't think 13rds is going to work. Mainly because of the spring length when compressed. You could probably cut a turn or two out and then pull it part, but then your losing spring power, plus springs don't usually last long at that point.

With the ASC 450B mag, I drilled out the dimples, but it didn't really help anything. When they put the dimples in, it compressed that whole area, so they follower gets wedged in at that point. For what they cost, I don't think I'll be messing with them any more.

Please report back on how they work after you try them at the range. As I noted earlier, I have not had much luck with 30 rnd mags due to feeding problems going around the curve.