If the extractor is the problem, what’s the fix? I may be experiencing the same thing. But I do swear by silk sweet lube.
450 bushmaster problems
- Thread starter That_FNG
- Start date
If the extractor is the problem, what’s the fix? I may be experiencing the same thing. But I do swear by silk sweet lube.
meketrefe
.450/400 Nitro Ex
It is simple. With these cartriges it is easi to ram the mouth into the step between the mouth and the freebore and unlike bottleneck cartriges that have the shoulder to support them even if it is a small one.If the extractor is the problem, what’s the fix? I may be experiencing the same thing. But I do swear by silk sweet lube.
The solution is simple in most cases. Take out the bolt and with both hands straight against each other how much force is needed for the extractor to open up and jump over the rim. Also make sure the ejector plunger does not have excesive force.
Both should allow the base to slide and seat flat on the bolt with some but not too much tension.
Of couser if you locate the base in an angle past the extractor you will force the round straight and give you an idea of how much the tension of the ejector plunger is alone.
The chamber has to fight both and bring the case back to a perfect rest where is supposed to headspace.
Some ejectors can be rough or have the spring, ejector hole or both slightly out of spec producing excessive tension.
The extractor should be a 7.62x39 (I found armalite to be very good for this) and if excesive tension is present have the spring and o-ring a bit conditioned by helping opening with a small screw driver priying open so slightly until you feel starts to open and close eaisier. Dont use s lot of force or might break the extractor.
Also if the inside tips of the extractor lip are too sharp this causes extra resistancr as the extractor edges bite in the brass of the rim so in this case just using a very fine file slooth all out to provide a smoot contact area with the bras to slide past the rim. Just very little so you dont loose engagement surface for the extractor, it is more to svoid the sharp edges and tips that put some scars on the rim but the extra force.
Some of these things might smooth out with time bit in this case we are helping these cartriges that are more sensitive to extra unnecessary tension.
I had pics about this procedure in the past. Not sure where they ended up.
Makes sense?
As always, great info.
That_FNG
.308 Win
Ok so had my gunsmith check it out. Headspace is within spec. Bolt and extractor is within spec. He used a scope and checked out the barrel. No burrs in the barrel. With or without a magazine present it still has the same problem. I’m stumped.
That_FNG
.308 Win
Everything regarding the bolt, extractor and barrel checks out with no problems. Could it be that the upper itself is out of spec?
meketrefe
.450/400 Nitro Ex
I posted a popular problem. You can go to 100 gunsmiths and they might twll you everything is on spec but what they dont know is how an AR works with this type of calibers.
So do yourself a favor and take the ejector and extractor off and chamber one slowly like that.
We have gone throuh issues lie this and some others dozens of times.
The process to debug the problem is known amd proven.
Like was said. Take of extractor and ejector off the bolt. Put in dummy round or spent case and slowely close the bolt. You will most likely find it closes smooth and easily. On my 450 the extractor spring was so hard it took chunks out of the case trying to grab the rim. Re assembled the bolt without the o-ring on the extractor and works smooth. Here is a video that might help.
Gonna take apart my .308 bolt when I get home.
Just pulled my .308 extractor. It had 2 bushings. Never seen that before. I took one off to start.
What make ?
Was it giving you problems?
Not too much but it wouldn’t always fully chamber the first round. I was figuring it was the buffer (I already replaced the spring). I dont remember the brand of the BCG. I bought it with my barrel. I’d have to look on my computer.
That_FNG
.308 Win
Tried that using parts from my friends windham weaponry’s 450 thumper. Still having the same problem.
odd question could it be the charging handle causing problems?
Twogunwilly
6.5 Creedmoor
yes
meketrefe
.450/400 Nitro Ex
Why someone elses parts?
remove the extractor and ejector plunger from your own bolt, the one the rifle was headspaced for.
Vinson57
.450/400 Nitro Ex
I have an upper from Bushmaster for 450 BM and the bolt head is of different dimensions than a 222/556 bolt. Enough so as to be noticeable. Could this be the issue? The bolt head where the locking lugs all, the end is thinner as maybe the 450 cartridge base needs more space. The BCG and Bolt came with the upper and marked with .450 as maybe not confuse with other ones.
meketrefe
.450/400 Nitro Ex
Of course is diferent. The bolt face is .473 in vs the .378 of the 223. Two differen roudns one much wider than the other.
Everyonw shouls be able to disassnle a bolt for cleaning includung removing the ejector and extractor and by the same token do this to do a simple headspace chek.
Othwewise do not buy an AR , IMO.
That_FNG
.308 Win
Replaced the charging handle with a new one and it seems to be cycling fine now with the dummy rounds.
Robin
.475 A&M Magnum
FNG, Can you get a picture of both charging handles together showing the difference. I'm a bit surprised that such a seemingly inconsequential part could have such a major impact on the bolt locking down all the way.
Robin
Robin
That_FNG
.308 Win
it came with the top one (radian raptor) and I replaced with the bottom one. (Standard mil spec)
I’ve cycled dummy rounds thru it 30 times now and not a single hang up.
Robin
.475 A&M Magnum
FNG, Is it shorter? Kind of looks that way. I just learned yesterday there is a physical size difference between 'Mil spec' and 'Commercial spec' and am hoping something I ordered will be compatible. Why they would do that is a mystery to me, just causes confusion and a lot of crap being sent out and sent back.
I'm glad it is working out for you and live fire will work equally as good!!!!
Robin
I'm glad it is working out for you and live fire will work equally as good!!!!
Robin
meketrefe
.450/400 Nitro Ex
you never tried to chamber a round with the receiver off and just the bolt before you went to the gunsmith?
you whould have known this from day one if you took the group apart. It cannot be just a short charging handle
and I don't see obvious marks from being stuck in the receiver.
I am still wondering why you had to hammer the round out of battery based on your original post.
In any case disassemble the bolt and plunger and clean the parts with a scotchbrite and then wipe them and
lube them and still make sure there is no extra tension from those parts.
These straight wall calibers will enjoy a smooth everything.
When reloading do not deburr a case much and only if you have to. That case mouth needs to be as square as it can be w/o catching
anywhere in the mags or ramps.
@meketrefe have you ever seen what I mentioned earlier? Two bushings on an extractor? I took one out and the rifle chambered fine after that. Still doesn’t like Magpul mags though. Someone at my range is giving me an Armalite mag to try.
meketrefe
.450/400 Nitro Ex
you mean two o-rings? If so that is a BIG mistake. Even if one leaves one orings the whole thing should open and close quite easily.
The tension can be tested by priying with a small soft steel tool like a cheap screwdriver or something.
@meketrefe I took one out and left one. It functioned fine after that. Now I wonder if I sent @dsdmmat all that brass for no reason lol.
meketrefe
.450/400 Nitro Ex
probably. lol. ... who sold you the group?
I can’t remember honestly. I did buy a generic bcg but can’t remember where from. I believe it was the same place I bought my Faxon barrel from. I might have it written down somewhere.