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Discussion in 'Black Rifle Forum' started by Dizzy Beaver, Jan 28, 2013.
About 5000. Give or take a few.
Not bad, not bad.
Pleased with the performance?
Thank you for all of the responses. I called Daniel Defense and they said that they are no longer selling bolt carrier groups for the foreseeable future as they are using them to create guns and won't have any extras to sell for a long time. While I wait to find a good quality bcg I'll keep searching for a small parts/spring kit.
Is this rifle for fun? If yes, you might try finding parts to have on hand, but in reality just shoot it. If something breaks fix it.
If it is a hard use rifle or used for defensive purposes, areas to address in any AR15 type rifle are the Bolt carrier group, staked gas key and quality MPI/HPT bolt from a reputable source. I would also look at the receiver extension locking ring (castle nut) and make sure it is staked. For the Bushmaster and my own piece of mind I would check the headspace and measure the chamber, but if it is shooting good with a variety of ammo, you are usually OK there.
Solid post from Surf, as usual.
If you can't afford an extra/replacement bolt carrier group right now, then get the carrier looked at by a reputable armorer, and make sure the gas key bolts are correctly staked. Buy an extra set of gas rings, an extra firing pin retaining pin (they can get lost easily if you're not paying attention), and some quality lube. I'm partial to SLIP 2000 for lube.
Here is a basic repair/spare parts kit.
That's what happens when you buy cheap crap that's "just as good as"
Although, I am curious. What did you have and what broke?
Thanks or the link, Warp. I ordered a kit.
Good call everybody who suggested looking to make sure that my gas key is staked. There are dents in it as if they went through the motions, but they don't even go all the way to the bolts. I suppose I'll have to learn how to stake that myself.
Okay. I think it's ready now. I replaced all of the parts (except the Eotech) with parts from Daniel Defense. That oughtta do the trick!
The older model Bushmasters are solid.
Get a set of detents, springs, gas rings and an extractor.
You should be set for 10K+ rounds.....
The following are with me on any outing:
As noted, when a bolt is bad it will often fail pretty early on. If it gets past 1/2-1k or so it's not likely to fail before you pooch the barrel (ie., 10-20k). Certainly extractors - and, more often, extractor springs - fail but the complete bolt will have you covered there. Ditto the rings, but have never had rings fail. All my carriers are Colt; I've never had one fail and believe a carrier ought to outlast five to ten barrels....maybe more. I keep reading about how a cam pin ought to be included. Funny, but I've never broken one and some of mine have been run hard. Cam pins will often look awful after 10-20k, but they just don't seem to break. Instead, it's the bolt that will let go around the cam where it's weakest. Have never had the firing pin retainer fail....but imagine they can get lost.
Firing pins don't often break, but they do crater from perfs if you get into a bad lot of ammo (or alot of steel case). Inexpensive.
Despite alot written about changing springs the only M16 spring to cause an abrupt failure for me has been the hammer spring. Indeed, I've had them fail on a number of semiauto firearms. They are inexpensive. If you pay attention to the other springs, look for hammer/disco wear suggesting a weak disco spring, look for action spring shortening, etc springs should not leave you in a lurch. Ie., you ought to be able to see the failure coming. The reason I bring a hammer spring is b/c it's failure (FTFire) can be abrupt. In a pinch, switching to ammo with softer primer cups will get you going, though.
Mags. Well, you know why it makes sense to have extras.
If I travel some distance to a shoot I might bring other unlikely to fail parts mentioned, maybe even a LPK. Not everything that can break will shut you down. I had a dust cover spring go, didn't even notice till after the shoot.
We have 2 Bushmaster M4 style rifles in our mix. One has less than 1000 rounds through it. The other has seen about 8000 rounds with 6000 of those being in a hard use environment. It had an issue a few years ago with some Georgia Arms reloaded ammo. Some of the GA ammo would not chamber fully. The GA ammo ran fine in my Mini-14 and our Colt Match Target Sporter. I just figured that the Bushie had a tight chamber. No other issues have been observed.
I do not think Bushmaster makes bad rifles, but in the current market there are usually better rifles available for the same money. At the time we bought ours, DPMS was the only other readily available option and when a Colt could be found it cost $300 more than a Bushmaster. If We needed another AR in the stable, the M&P 15T that Clyde Armory has for $999 would be hard to pass up- free floated 5R goodness for under a grand is a good deal. By the time one puts a FF rail on a 6920, he has $1300 into it.
I have been shooting AR's since the early 1980's and other than magazines, I have never had to repair anything. I will say that there have been a few rifles over the years that were junk and I got rid of them but out of any rifle that turned out to be reliable, I never had to replace anything but magazines or mag components. The only repair items that I have are a couple of ni-boron coated BCG's (just in case). Heck with springs and pins, I just bought the whole unit.
If you've never replaced at least the gas rings, then you either don't shoot that much, or aren't paying enough attention to your weapon.
Gas rings generally last 2-3,000 rounds before they need replacing. Extractor springs are 5-10,000 rounds, and should have the insert and O-ring (if needed) replaced at the same time. Bolt heads are 10-15,000 rounds if they're well made, or earlier if they are not.