Modifying a Bushmaster AR15 feedramp to use soft point ammo...


PDA






anymanusa
December 27, 2008, 08:52 PM
Is this doable? Is this a good/bad idea? I've found where the contact/mushrooming problem is on the feedramp, I'm just not sure how good an idea it is to mess with it.

I have all the tools, and all the skill necessary (I think), I just wonder how viable it is.

Thanks for input.

If you enjoyed reading about "Modifying a Bushmaster AR15 feedramp to use soft point ammo..." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
RyanM
December 27, 2008, 09:15 PM
I wouldn't mess with it, myself. There's decent OTM ammo out there that expands and holds together as well as any softpoint. Plus ballistic tip ammo.

anymanusa
December 27, 2008, 09:37 PM
I'm just wondering if I could mess it up. I have about a 1000 rnds of softpoint, and someone offered to buy it, but I'd rather keep it and shoot it if I can do an hour worth of grinding work on the feedramp and make it work.

Thanks.

RyanM
December 28, 2008, 05:23 AM
Well, do you have M4 feed ramps or not? I wouldn't touch the M4 cutouts in the receiver at all. They're anodized, and grinding those will expose the soft aluminum underneath. The cutouts in the barrel... I doubt grinding those would "damage" the gun any, but I still would rather match the ammo to the gun, than match the gun to the ammo.

Also, is it denting the ammo to the point of it being unsafe to fire? You could just burn up the softpoint for practice, and get some OTM or ballistic tip ammo for hunting, home defense, SHTF, etc. Dented tips probably won't expand well, but the effect on accuracy is surprisingly low.

anymanusa
December 28, 2008, 06:01 AM
Are you sure that the feed ramps are a 'surface hardened' type treatment? If so, then I really don't think I should do any grinding on them. I'm going to check it with a magnet. I would've thought that it was a hardened steel piece.

M4 feed ramps? I doubt it. As far as making a gun work with ammo, that's what this thread is about. How feasible is it? I would like to be able to shoot sp out of it if at all possible.

I can see the point on the cutouts of the ramps where the soft point is jamming up against the feedramp, although I'm not sure if I could do what needs to be done to make it work right with the sp.

Thanks

anymanusa
December 28, 2008, 06:04 AM
After a brief bit of research, it would appear that I have typical 'rifle' feedramps, which are indeed cut into the barrel extension, and therefore the same material as the barrel, not aluminum.

Actually I found this:

My gun has an M4 barrel, but it looks like someone cut the ramps in the upper receiver with a dremel tool! That is most likely exactly what happened. There are a lot of uppers out there that do not have the cuts... hand cutting the upper receiver with a dremel is a quick way to make the conversion.

Granted, it may not look so great, but odds are (if they are actually doing anything) they will work fine. The most obvious fault with this method is that the cuts are not refinished and you see bare aluminum -- while there may be some surface hardness that is not there... you will wear out a lot of other things on the gun before you have to worry about any problems with "wearing" on the hand cut ramps.

If you are the kind of person that lays awake at night and obsesses over the dire thought that your feedramps were not refinished... well, hit one of the dealers on the site up for a new upper so you can relax

here:

http://www.m4carbine.net/showthread.php?t=193

Another possibility I will explore is the use of different magazines. I would much rather find a way to shoot sp ammo out of this rifle than buy another rifle just for that purpose. I'm into 'all purpose' rifles more so than specialty finicky rifles. This seems to be the only rifle that I have any problems with regarding sp ammo.

RyanM
December 28, 2008, 09:49 AM
After a brief bit of research, it would appear that I have typical 'rifle' feedramps, which are indeed cut into the barrel extension, and therefore the same material as the barrel, not aluminum.

Yep, that's what I meant. M4 feed ramps extend into the aluminum receiver, and it's a really bad idea to grind those. I personally don't think that grinding at the barrel portion of the feed ramp would negatively affect anything (as long as you get all of the metal grit out of the lockup area), but I'm no expert on ARs.

Anyway, just how badly are they mangling the ammo? If they're deforming the jacket at all, then the rifle is defective and should be sent back to Bushmaster. But if it's just the lead tip, I honestly wouldn't worry about it. Just keep that ammo in reserve for target practice, single feed only if it causes jams. Or you could randomly put a round of softpoint in your practice magazines, for stoppage clearing practice. In the long run, 1,000 rounds isn't a whole lot.

If it doesn't jam, and it's just the lead that's getting deformed, it's no problem. A smooshed tip will cost you about 1/4 to 1/2 MOA accuracy, tops. Not enough to worry about, in practice ammo.

Magazines may be an option, though. Magpul Pmags actually block the round from even touching M4 feed ramp extensions. Not sure about feed angle in general, but there's really no reason not to use Pmags.

Art Eatman
December 28, 2008, 12:43 PM
If there's a feeding problem, buffing with a cotton wheel and jeweler's rouge oughta cure it. "Grinding"? Uh-uh.

If the binding is from hitting low on the feed ramp, I'd at least mess with one magazine. Open the feed lips a tiny amount to get a wee bit higher feed-angle. Just a little such effort might end the problem.

I had a Bushie Match Target, vintage I guess around 2000, which didn't seem to care what I fed it. It was happy with soft points. So, I don't really know about later-model problems...

anymanusa
December 28, 2008, 01:34 PM
thanks for the replies. I will try using my pmag and see what results. It's not that I'm so worried about 1000 rounds, but I want the gun to shoot sp ammo.

I will buff on the ramps a little too.

anymanusa
December 29, 2008, 12:02 AM
All right. I tried the sp's in my pmag, and they seem to cycle just fine. I'll continue trying that route out to see how well it works. Just for kicks a also used a buffing wheel to smooth out the ramps a little.

Rexster
December 29, 2008, 12:28 PM
Bushies are popular patrol rifles with my fellow officers, and none have needed modifications to work with the 55-grain jacketed softpoint ammo we are required to use on duty.

If you enjoyed reading about "Modifying a Bushmaster AR15 feedramp to use soft point ammo..." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!