450 Bushmaster tight chamber

[lar45]

I recently picked up a Ruger AR in 450 Bushmaster. It shoots Hornady 250 FTX factory ammo great.
That's 5 rounds in less than.5" at 75 yds.
238819
So I'm working on trying to get some reloads to shoot. I started with some Speer 300 deepcurl with CFE BLK and after a few starting loads the gun locked up with a round partially chambered.
I had to use a range rod to tap it back out.
I scrubbed the barrel and chamber squeaky clean. Then tried dropping a factory round in. It stopped about 3/8" short and could be pushed in. They wouldn't fall out when the barrel was tipped up.
My hand loads we're the same.
I put the rifle back together and the rounds would chamber fully with the spring loaded bolt.
So... Do I just live with it, send it back, or ???

[bruce drake]

I'm following as I have this exact same problem with a 6.5 Creedmoor chambered AR10. works fine with storebought ammo but hates to feed loads made with reformed 308 brass unless I use an RCBS Small Die that puts the cartridges case head back to initial configuration. And once that bolt slammed forward and then it doesn't fully seat the cartridge, its a pain in the butt to then clear the chamber...especially when you forget your range rod...

Bruce

[WehrmannsGeweher]

Are you using Hornady dies and playing CLOSE attention to the OD of the crimp ? If you are going to shoot jacketed the Hornady is the most accurate. IME 450 ARs don't care for cast much either.

As for the CM issue, use factory brass and your problem will vanish.

[DougGuy]

I would shoot it some more, if it locks up with factory ammo, yes send it back.

[lar45]

I'm using Hornady dies and Starline brass.
I shot a box of reloads with Speer 300Jsp loaded with IMR4227 AND 4198 where everything worked great. I tried some Lil-gun with 250 XTPs and it worked fine. Today was with 300 deep curls and CFE BLK when it locked up.
After clearing the jam I tried some of the Hornady factory ammo and it jammed with it also.

[cwlongshot]

This is a valueable tool to your reloading bench.. Not always "NEEDED" but always useful.

https://tromix.com/product/cartridge-slotted-case-gauge/

I have had issue with pickups in 10 MM and more recently 38 Super. You do not notice the bulge at the base or its not much but enough to be a problem. This Case Gauge will tell you problem brass or problems with your re sizing setup.

Good luck,


CW

[Gtek]

Let's see if I am following this correctly. First fired factory worked fine, fired reload and jam, removed jam, factory round now jams?

[lar45]

Let's see if I am following this correctly. First fired factory worked fine, fired reload and jam, removed jam, factory round now jams?

I'm sorry if I wasn't terribly clear. I fired factory and reloads, they worked fine. Yesterday I tried a new reload with the Speer 300 DeepCurl and CFE-BLK. It jammed, cleared the jam and factory ammo jammed.
Cleaned the rifle and now it doesn't jam, but the loaded rounds, factory and reloads, will not fall freely into the chamber. I think that the chamber is too tight.

[lar45]

Just got off the phone with Ruger, they are sending UPS to pick it up.

[cwlongshot]

EXCELLENT experience with Rugers service! They will have you all fixedup quickly!

[tomme boy]

Bruce, your problem is you may need to neck turn the brass. When converting brass down to a smaller cal. this shows up all the time.

[Gtek]

Strange set of circumstances when hearing the chain of events, probably a good thing you stopped when you did. Maybe barrel removing itself from extension? Did you check fit with that new big projectile? Possible really steep pressure curve with with bullet touching on both ends? Nothing I can think of would decrease chamber dimension shy of a metallurgy failure being a tick away from a catastrophic failure. Curious, did you disclose hand load use? Very interested in outcome if real information returned.

[lar45]

Yes I checked the fit with the 300gn Deep Curl. I made up a dummy round, put it in a magazine to make sure it would feed, dropped the bolt, ejected and checked the nose for any rifling marks.
I never loaded anything hotter than book max for this rifle. The hottest rounds fired were the Hornady Black 250FTX.
I think that a metalurgy failure would expand under pressure, not get smaller.
I'm pretty sure that the chamber was just cut undersized. Maybe the reamer had been sharpened too many times.
Yes I did tell them about the reloads. I even wrote a letter to go inside the box so the tech working on it would have all the details.