450Bushmaster.net

HANG ON A MINUTE...HAD A REPORT OF LESS THAN ACCEPTABLE FUNCTION...GOING TO RE-CHECK WITH MORE THAN ONE MAG TO GET BETTER RESULTS...LETS WAIT AND SEE.

I just got one of these RZE Unimags today...going to test it with the 450b and 30RAR to see if it works with them. Company says it is currently testing their Unimag with several other calibers, so an expanded list that it works with should be forthcoming. Links to the info on them are below. I'll try this mag with the 450b and 30RAR probably Monday...I'll let you know what happens. I suggested to RZE that they check out these calibers themselves...they should at least be looking at the 450b, since they list the 458 Socom as compatible...similar dimensions, etc. I'll find out for myself in a day or two...

http://ross-zheng-engineering.myshopify.com/

http://ross-zheng-engineering.myshopify.com/pages/demo

I took mine apart, and it has a very clever two-piece, spring-loaded, articulating follower that apparently compensates for the varying case body profiles. The mag spring and base plate are standard AR style. The mag body is SS, I think (non-magnetic and sounds like steel). The mag body looks standard, but if you look closely there are subtle shape changes just at the top of the long dimension where the topmost cartridge sits. The feed lips look surprisingly far apart, but that does not seem to be a problem. The 450b rounds double-stack as do the 30RAR rounds, with eleven rounds fitting in the mag for both (not surprisingly.)

More later...

interesting, looking forward to your test results.

Might be interesting as a "keep in the truck glove box" mag. Seems that every time I head to the range with multiple calibers of AR's I usually forget one caliber mag.

I shoot AR's in 5.56/223, 7.62x39, 6.8 SPC and 450 BM. A one fit's all mag would be nice to have.

Apparently RZE felt your pain...

Ok...pre-range result for Remington R-15 in 30 RAR: Rounds load nicely into the mag, but the magazine is too tight a fit in the mag well for my taste, at least on the lower that came with my rig, which has paint on the inside of the mag well. Might just be my rifle, but not sure about that. The one I have is slightly odd...the lower is stamped as being a model R-30 and has Realtree Xtra camo dip (rather than Max-1), but the box and documentation that came with it says its an R-15...?? I haven't yet bothered to ask Remmy about that, but I will now! If you Google search the term "Remington R-30" everything comes back as something about the R-15...???

SO, tomorrow will be just the 450b function test.

Well, we seem to have a new, functioning alternative mag for the 450b! Ran it through my Remmy R-15 with the Max-1 camo dip. Tight fit in the mag well, but not excessively so...I think the drag on the mag was due to the camo dip overlap up into the mag well on my particular rifle. If I cleaned the paint out of there, I think the drag on the mag (hey, that rhymes!) would go way down, but I'm pretty sure this mag would still be somewhat snug fitting. That's just a minor complaint I have with my rifle, however.

Full and partial mags functioned just fine, no observed problems...didn't fire a large number of rounds, because everything seemed to work as advertised.
Bolt hold-open worked fine.
Top round position looked just right for the 450b, with the tip slightly "nose up" when held in the mag lips.
Manufacturer recommends loading the mag carefully, so that the rounds double stack correctly and the top round is centered in the mag lips. Did that, and it worked fine. Whooda thunkit?
I noticed while initially hand-cycling some rounds out of the mag that the mag lips were scratching the brass, so I smoothed them over with a 600-grit sanding stick and some metal polish on a Dremel wheel...problem solved.
Finish, construction and overall quality seem top-drawer.

Summary of my experience with the RZE Unimag: Quality product that works well with the 450 Bushmaster!

I've had good luck with mine using it with both the Bushmaster and Grendel. However I don't think Ive ever tried to load more than 5 round to this point... just haven't had a reason too

OH, and its a snug fit in my Mega lower, but IIRC it said that in the description when I ordered to not expect it to drop free.

I can get eleven 450b rounds in the one I've got, and the spring is just above bottomed-out at that point. In use, I think ten in the mag would be a safe number...I'll find out, I suppose.

One of the engineers at RZE sent me an email that indicated they're looking at tweaking the "inside the magwell" dimensions of the Unimag to deal with the slight variations in magwells that are turning up over the AR inventory. They're fine-tuning the design as they hear back from owners and testers as time goes by...I don't think they want to screw up a functioning design, but they are making an effort to get closer to dropping free.

Great News Commander!
Thanks for the update and test work!

Thanks! Glad to help. If you're interested in these mags, I would suggest buying a first one to check function in your rifle(s), since I could only test using my rig...dimensions do vary slightly.