450 bushmaster reloading

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Re: 450 bushmaster reloading

Postby 45Raptor » Thu Nov 26, 2015 3:39 pm

Hi everyone,
New to site long time reader but first time posting. Have a question about factory ammo for the wife's 450 bushy. During hunting this season she had chambered a single round multiple times do to not taking shot while hunting and ejecting shell replacing in mag and doing again. Other day noticed bullet was protruding about 1/4" past factory seating depth . I took out of her mag and was able to push back in with little finger pressure. Set aside for now until have time to mic a re crimp. Anyone encounter this issue with their reloads or factory ammo. My guess is for being charged multiple times caused this. Appreciate any response. Happy Thanksgiving to all.
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Re: 450 bushmaster reloading

Postby Hoot » Thu Nov 26, 2015 5:50 pm

Welcome aboard. The phenomenon you encountered has a long history in these pages. Your assessment as to why it happened is also spot on. When I hunt with my 450b, I ease the round into the chamber, following up with a bump or two to the forward assist to make sure it's in battery. I also rotate my round sequence in my mag when I remember, to distribute the number of pulling moments any one is subjected to. It is the nature of the beast. I highly recommend discarding the round, if you don't have a set of reloading dies. Maybe even if you do. Recrimping will not give the bullet, which has already had a degree of swaging, obtain the same amount of retention as witha case that has been first resized and a new bullet seated. Lead is soft. A copper jacket adds to the overall hardness, but once a crimp is applied to it in a specific area, it will collapse there, never to regain its original shape. That unaltered shape is half the equation in a good crimp. Live and learn...

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Re: 450 bushmaster reloading

Postby 45Raptor » Thu Nov 26, 2015 6:03 pm

Hoot,
Thank you for the information and experience. I don't have dies for this cal. As of yet but it is on top of my list. I'm an avid reloader when time presents itself. Next question is it was my first thought of over charging the round and had my wife slowly charge then use forward assist to complete. Every time she does it will not eject the round like the extractor is not grabbing the rim. Thought she may have not been putting enough forward pressure on the forward assist so I tried myself a few times and when I pull back charging handle the round remains chambered until you tip the gun barrel up then falls out??
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Re: 450 bushmaster reloading

Postby Hoot » Thu Nov 26, 2015 7:15 pm

45Raptor wrote:Hoot,
Thank you for the information and experience. I don't have dies for this cal. As of yet but it is on top of my list. I'm an avid reloader when time presents itself. Next question is it was my first thought of over charging the round and had my wife slowly charge then use forward assist to complete. Every time she does it will not eject the round like the extractor is not grabbing the rim. Thought she may have not been putting enough forward pressure on the forward assist so I tried myself a few times and when I pull back charging handle the round remains chambered until you tip the gun barrel up then falls out??


Another classic issue chronicled over the years. There are theories about this and they all have merit. I experienced this myself on my original Bushmaster upper. My theory among all the others is that the single extractor is the culprit. My factory 450b had a very generous chamber. Holding a round by the rim, I could lower it into the chamber and wiggle it side to side a small amount. I'm not sure why Bushmaster made them that loose, other than to add a degree of reliability to the extraction process once the chamber becomes dirty. True to form, I rarely if ever had a failure to extract a fired round in over 2k of reloads. I did experience a high degree of resistance to well lubed cases when resizing which testified to their expansion. However, I could never extract an unfired round, despite it falling out if I tilted the muzzle upward. My theory it that the extractor pulls the smaller unfired case on one side, tilting it ever so slightly in the chamber and making it bind just enough to overcome the tension afforded by the extractor spring. This does not happen with fired cases as they have already expanded to the chamber diameter after firing and despite having shrunk back away from binding (by design) they do not slop around.

That having been said, there are holes in my theory based upon your observation. In my upper, it did not matter whether I eased the bolt into battery of let it slam into battery. Neither unfired rounds would extract. In your case, I am wondering if your chamber is cut a little on the long side. Its not unheard of. If you ease the round into battery, it needs to run into the end of the chamber to stop the case from going forward enough so that the extractor can reach around the rim and fall into the extraction groove far enough that it takes hold of it. If the extractor is not cut exactly right, or if the chamber is too long to allow it that last couple of thousandths reach to slip over the rim, then it will not be able to thoroughly engage and hold on tight enough to pull the case out. Another theory: In slam chambering, the case is rear-ended by the bolt and bottoms out against the bolt face momentarily, allowing the extractor to grab properly. The other possibility is that the case may not bottom out against the bolt face during slam chambering, but scoots ahead of the extractor engagement point. However, as it races ahead of the bolt into the chamber all the way to the end, the case mouth encounters the lip of the chamber, stopping its forward travel and bouncing it backward back into the still advancing bolt, to the extent that it allows the extractor hook to engage it.

Not having a transparent chamber, these theories are just that, theory. Regardless of the reason, it is one of the issues resulting from shooting rebated rims, straight-walled cases in a semiauto action. Unlike their bottle necked cousins, they headspace on the mouth. All that verbosity adds up to no simple solution for your circumstance. I just got used to tipping my barrel upward and catching the unfired round as it fell out. If that is an uncomfortable situation for you and your wife, then you're going to have to get used to rotating your case sequence over the course of a hunting outing, assuming you have to load and unload a lot. It is as you observed, a cumulative problem.

FWIW, I am now in possession of a Bartz Manufacturing upper. The aforementioned issue no longer manifests in it. My observation of the bolt, barrel extension and chamber is that of having been more precisely manufactured than my stock Bushmaster upper. Tolerances are much better adhered to and the extractor firmly engages the rim regardless of whether I ease the case into the chamber or slam it in.
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Re: 450 bushmaster reloading

Postby 45Raptor » Wed Dec 02, 2015 6:46 pm

Thank you hoot been doing some digging through old posts and am looking at extractor being possible issue. I'll keep you posted on what I find. And try to keep my posts in relation with what is being discussed realizing this wasn't a reloading question . my apologies to all.
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Re: 450 bushmaster reloading

Postby ardenkent » Thu Dec 03, 2015 6:59 pm

I too have just experienced this failure to extract un-fired factory loaded cartridges.
Occasionally, there was an extraction of un-fired but never a failure to extract and eject upon firing.
I haven't measured the cartridge cases to see if they are short.
It is unnerving to tilt and catch but certainly confirms an empty chamber.
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