AR 450 Bushmaster Mag Issues

[missionary5155]

Good evening
We have a good load that functions our 450 Bushy. But so far every mag we have tried with more that 2 rounds loaded will stove pipe the slug up at the chamber.
With 2 rounds the first loads, fires, ejects and chambers that second round with no issues.
Have tried different mags, bullet guides (the lifter in the mag), military, civilian.......
So what mag works ??
Thank you for any enlightenment you can pass on.
Mike in ILL-Nois till mid November.

[Dutchninja]

All standard mag springs?

The tip of the bullet gets jammed at / before the chamber at 12 o clock?

Or is it jammed at the mag / feed ram?

[cwlongshot]

I found some followers SUK!! Also dremil the front of the mag so case mouth passes ove without contact.

CW

[missionary5155]

Thank you cw...
The present follower we are "using" is a simple rounded channel centered in the magazine.
I have been searching for mags on internet and saw one for sale that had the front side of the mag lowered.
That could well be the issue.

Dutch.. Yes the round gets bullet turned up near vertical with the bullet tip before the chamber at 12 oclock.

[missionary5155]

Found a close-up of a Duramag front side. That gives a very good view of the cutting I need to work at.

[lawdog941]

Duramags work the best for me. Problem is getting them while in stock. Modifying looks like the most logical approach.

[ohen cepel]

I had to buy new followers, from Tromix maybe? Quality item, not a 3d printed product.

Then, had to Dremel down the front of the mag.

Took me a lot of effort/time to get my 450 going. NOT as easy as the makers say and that line about using "std" mags is totally wrong!

You'll get it figured out, just takes some trial and error.

[missionary5155]

Good morning
Do the Duramags hold bolt open after last round ?
Going to the bench and do some Dremel work on two older AR mags.

[cwlongshot]

Mine do. Yours should.

CW

[missionary5155]

As of yet I do not have any.

[lawdog941]

As long as your springs in your old AR mags are good, and are able to cut out the nose portion of them, they should work out fine. Give them a try and let us know.

[Dutchninja]

Try wolf extra power springs, when the bolts comming forward the back end is driven down a bit causing the round to hit at 12, the extra power springs puts more upward force on the round against the feed lips keeping it more level as the bolt sends it forward,

When I had started loading 300 black out sub Sonics 240 cast PC’ed lead, the nose and OAL made them very nose heavy. I thought it was wrong load, tried different powder all types of mags, and the did some slow motion filming with my phone and could see the back end getting jamed down, try the more power springs, and off to the races. I have dedicated mags for 300 subs and heavy heavy socom rounds.

It might help, not sure but their cheap you get three, and worth a shot. Hope you get it figured out.

[Dutchninja]

Also rifle carbine or pistol lenght gas system?

[missionary5155]

Howdy Dutch and thank you for the info !
It has a carbine length gas tube.
Heavier Mag springs... I would not have thought of that one.
Hopefully the rain stops sometime tomorrow and I can give the "groove cut" mag a try. Ran 7 dummy rounds through it after the dremel time and all cycled perfect. But I also understand that is nothing compared to the cycle speed upon firing.
10 rounds should give me a good idea if more needs to be done.

[gumbo333]

When I had a 450 Bushy I used a 5 round mag I got at Midway for a 500 Beowulf. It worked great, no problems, no adjustments. A 16" carbine.

[missionary5155]

The "cut" Mag worked great ! No standing up followup rounds. Good ejection and bolt pushed next round straight into chamber.

But now an issue I have known existed is causing some rounds to fail to fully chamber.
Been using Buffalo Rifle for load development with a 250 grain. Well the unburned "mummies" have always been there and now for sure they are an Issue ! 4 out of 10 rounds failed to fully chamber and the fired brass showed the "dents" near the mouth where the "mummy" was jammed into the brass. Forward assist was needed to fully seat.
As long as I was chamber brushing every two rounds no issues over the last two weeks but now it is time to look at another powder.
So what would you suggest with a 250 grainer ?

[cwlongshot]

AA#9

Is all I use for jacketed.

CW

[lawdog941]

Lil Gun works for me. No problems.

[cwlongshot]

Lil gun burns super hot in a M$R. Plus pressure spikes are probable.

CW

[lawdog941]

I haven't had any problems yet. Although I don't run and gun it. It's a hunting rifle, max 2 shots. Lil Gun is a hot burner, but common sense use, it works.

[cwlongshot]

Its more than just mag dumps. HEAT KILLS barrels faster, excessive heat should be avoided. But come even close to compressed and watchout! Hang fires and pressure spikes are on your addenda. Been there...

LIL Gun is for chasing every last FPS. I dont play that game.

[missionary5155]

CW Again thanks ACC #9 is a bunch slower than I was thinking..... I wonder how Blue dot or 4227 might get along ?
I also do not need much over 1600 FPS. I hunt river bottoms and my longest shot weather flintlock of center fire is a whopping 33 yards. Most are very close with 5-10 yards the normal. 55# recurve gets alot of use.

[cwlongshot]

AA#9 is a faster powder then lil Gun or 4227. (Unsure why this is a concern)

Or if its velocity that worries you.... My top 200g FTX load closes in on 2600 fps....

4227 is good RE7 too but enough gas for M$R is questionable but Id steer clear of Blue Dot in the 450Bushy. I LOVE IT, BUT It can be a "funny" powder too. I have tried most of these even some "vhitavoree" powders but 5744/#9 have been the cream for four different barrels.

CW

[SeabeeMan]

I run the Tromix followers with Lancer 10 rounders, giving me a 4+1 setup for hunting with the stop removed. 100's of rounds, never had a FTF.

[BD]

Caviat: I put this .450B AR together 12 years ago and haven't had to mess with it much at all since, so the info is based on what was available then. I use the older blue "single round loading" .223 hi-power followers in any mag and they all work fine. The plastic Sig 20 round mags also feed just fine with the stock followers. Lil Gun works great but does burn very hot. I primarily use surplus WC297 in cut down .284 brass with large primers. Mostly because I have a lot of it and it was cheap at the time. It burns clean and consistently and groups well with the 250 grain FTXs. Not so well with cast. 2" groups at 100 are about as good as I can do with cast. I often have 3 very close, with a couple of flyers. The FTXs are excellent. I once put 50 rounds into 1" at an 80 yard range in upstate NY while doing load work up with FTX and LilGun, and the last 10 where shot by another guy who was at the bench next to me and couldn't believe what he was seeing, (big bore ARs where not very common then). And I've shot quite a few 300 yd groups under 2" with the FTXs. Once I retire I will go back after the cast in the .450B to see if I can't cure the flyers, but for now I'm staying with what works.

[missionary5155]

Thank you everyone for all the input.
Looks like mags are the big issue. While we are in Peru this time will get a couple "real" 450 mags ordered. 4-5 rounds is all I will need as this rifle will be for hunting.
But we are 9 days from leaving back to Peru so today that barrel was oiled and wrapped and goes into storage tomorrow with a pile of other items.
So again thank you all for all the good info and discussion. I learned alot and I do appreciate your sharing with e and everyone else who was reading along the wealth and value of what is already written.
Mike

[Gtek]

I spent many an hour staring into magazines and working with just about everyone on the market. If scarring/chiseling long lines on brass does not bother you and working a little radius up front I would suggest the Lancer mags and polish bottom of lips and it is what it is. A.500" case sitting up between two lips that are supposed to have .378" cases alternating under each creates a little issue. What I have done and have been using for several years dare I say flawlessly off the bench and hunting and they also feed the Socom just fine, three rounds magic, four rounds pushing it and don't use. Take a PMAG plastic 10 rounder, disassemble and now the fun begins. I took a very sharp wood chisel and removed front separating rib on front internal wall of magazine to almost flush. Then wrapped 320 on pop stick and finished polish to flush. Wrap a 30-06 case or equivalent case diameter with the 320 and radius front top of magazine down in at 30 degrees in to a depth of .1875"/3/16", shooting for a .250" radius. Here is where a mill really helps with next and final, secure up follower (take spring off) level/level in vise. Then run down longitudinal center with a .500" ball bit to as close as you dare to deck height of follower. Yes it makes holes through in places on bottom and interior wall of ridge but does not affect operation in any way. Clean up scraping and sanding to personal needs, took an Exacto and scraped a chamfer in created holes and used 30-06 case wrapped with paper to polish and clean up top. Three round loading as said has been flawless, four really wanting to pop overriding plastic tension of mag top but can slap in and will run.
I walk in loaded with three in mag and two more mags on the front of me, nine rounds of that and a 1911 on my hip. If I cannot get out of stand and back to the airboat with that I guess it ain't my day!