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+--- Thread: Need Help with 450 Bushmaster Troubles (/showthread.php?tid=24828)
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Need Help with 450 Bushmaster Troubles - Scouttracker - 08-18-2022
Ok ,I need some great minds to get together.
I have a AR style 450 Bushmaster, Anderson lower, Bear
Creek upper. I've had it for 3yrs now and shot quite a few deer
with it. Long story short I come into a bunch of
FMJ ammo and I wanted to reload it. So
off to the range I go to burn it up.
My problem is after 9 to 10 shots and it gets pretty hot it will not feed.
Let the gun cool back downtown touch and we go to 9 to 10 shots repeat.
Gas block is tight, cleaned twice, lubed, cussed, prayed, laughed, cried but shoot 9 to 10 shots and same thing . Anyone have any ideas ?
Need Help with 450 Bushmaster Troubles - VASCAR2 - 08-18-2022
Just a WAG but I think a rough tight chamber might be more prone to fail to extract once hot. Id polish the chamber or at least buzz it with a brass brush, oil and a hand drill. If the cartridge is being delayed from extracting it might zap momentum from the BCG thereby not having sufficient recoil energy to chamber the next round.
If the 450 isnt feeding from the magazine without being fired but hot Id inspect the extractor. The extractor might be tight fitting and when hot the case rim is failing to slide on to the bolt face while chambering. There is a mod to the ejector where you break the edge to permit large diameter cases to more easily feed.
https://bulletin.accurateshooter.com/2014/08/ar-ejector-mod-for-improved-reliability-with-larger-cartridges/
Need Help with 450 Bushmaster Troubles - CJW - 08-20-2022
I think Vascar is dead on ..as usual
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-21-2022
Thanks , I'll have to check out both suggestions.
Will inform with what I find.
Need Help with 450 Bushmaster Troubles - montana - 08-21-2022
[ATTACH=CONFIG]19051[/ATTACH] Don't do this. Always remove the ejector before you do any modifications to it. I have lightly polished the bolt face and put a slight bevel around the ejector edge. Make sure the ejector can be pushed flush with the bolt face. It is also good practice to replace any split rings when once removed..A bolt face that is undersized can also cause problems with function.
Need Help with 450 Bushmaster Troubles - Happy2Shoot - 08-21-2022
Scouttracker Wrote:Ok ,I need some great minds to get together.
I have a AR style 450 Bushmaster, Anderson lower, Bear
Creek upper. I've had it for 3yrs now and shot quite a few deer
with it. Long story short I come into a bunch of
FMJ ammo and I wanted to reload it. So
off to the range I go to burn it up.
My problem is after 9 to 10 shots and it gets pretty hot it will not feed.
Let the gun cool back downtown touch and we go to 9 to 10 shots repeat.
Gas block is tight, cleaned twice, lubed, cussed, prayed, laughed, cried but shoot 9 to 10 shots and same thing . Anyone have any ideas ?
Could you give more detail?
What exactly happens, down to the smallest detail?
I assume the last round fires, and extracts, and ejects. Then what? Does the bolt skip over the next round in the magazine? Does the next round get picked up but then nose dives into the feed ramp? Does the next round half feed into the chamber but gets stuck diagonal and the bolt crushes the case body half way up?
Do you run it dry, or wet?
How dirty is your gun after 10 shots?
Are you shooting pointy bullets or wide flat nose?
I have a 50 Beowulf. I've had to learn a few things.
More detail?
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-22-2022
More details. I'm running 7 round duramags. First seven rounds gun runs perfect , mag change shoot 2 rounds . Both rounds fire and eject, 10th round gets hung up halfway into the chamber.
Primer end angled down toward the magazine. Bolt hit case about .5 " above the cartridge base. ( almost like it jumps out. Of the mag.) I have 6 mag and it makes no difference in the order I use them. I tried running both wet and dry, that made no difference. Bolt and chamber is dirty but not filthy. After it cools and I clean it. It will do the same thing . I was shooting factory Remington 260gr FMj is when I noticed it. This bullet is a pointed flat nose. Then I tried Hornady Black 250gr fxt. This bullet is pointed with a red polymer tip. The shots that do shot and eject, eject between 2 and 3 o'clock. That's about all I can think of right now.
Need Help with 450 Bushmaster Troubles - Happy2Shoot - 08-23-2022
Do you think the bolt is running too fast?
It could be that the bolt gets the case started moving but jumps the rim and crushes the body?
What buffer weight are you running? Could you try a heavier buffer? Hmm, what kind of recoil spring are you running, heavy? Could you try a softer recoil spring?
Need Help with 450 Bushmaster Troubles - Happy2Shoot - 08-23-2022
You could also try smoothing / softening the edge of the magazine where the case mouth would rub when chambering a round. Put a ramp on it.
See where the case mouth is touching?
No need to do this.
![[Image: b6wk06W.jpeg]](https://i.imgur.com/b6wk06W.jpeg)
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-23-2022
Happy2Shoot Wrote:Do you think the bolt is running too fast?
It could be that the bolt gets the case started moving but jumps the rim and crushes the body?
What buffer weight are you running? Could you try a heavier buffer? Hmm, what kind of recoil spring are you running, heavy? Could you try a softer recoil spring?
Geissele Super 42 H2 spring and buffer kit
Need Help with 450 Bushmaster Troubles - Happy2Shoot - 08-24-2022
Scouttracker Wrote:Geissele Super 42 H2 spring and buffer kit
"The Super 42 Spring has a 15% stronger average return force than the standard buffer spring."
Try a regular spring and a regular ar15 magazine (aluminum Okay mag).
Do you have more forward and backward wiggle with the Duramags than a standard ar15 mag?
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-24-2022
Happy2Shoot Wrote:"The Super 42 Spring has a 15% stronger average return force than the standard buffer spring."
Try a regular spring and a regular ar15 magazine (aluminum Okay mag).
Do you have more forward and backward wiggle with the Duramags than a standard ar15 mag?
No wiggle that I noticed. But I'll check again,and try a standard spring next time at the range. Hopefully this weekend if I dont get called to work again . This working stuff keeps getting in the way .
Need Help with 450 Bushmaster Troubles - StoneHendge - 08-25-2022
Big bore AR-15s are like boats. The joy on the day you buy one is only exceeded by the joy on the day someone buys it from you (and in my case, the day when City Market (Kroger) had a dozen gallons of chocolate milk to sell for 10¢ apiece).
Signed,
A former 458 Socom owner
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-31-2022
Well folks I finally had a chance to try a few things ,(one at a time minded you) and my shoulder feels it .
Changed to standard spring & buffer. No change.
Tried 3 new mages . No change. But what I did deduct was it only happens when it hot and only on the feed cycle. So only 3 things get really hot after 5 to 10 rounds. Barrel, gas block and tube, gas key. Started process of elimination. Barrel is locked shooting hole for hole ,feed ramps were polished. No problem there. Seeking Precision adj gas block & tube. All tight and clear. Ejection was between 2 and 3 o'clock. No problem. That brings us to the gas key. Cold gas key is tight, as it heated up it became loose and pushed the bolt down with changed the feed angle. Gas key was staked but the company did a piss poor job. The way I found this was I put the bolt in the oven( at the advice of a marine armorer) . Tighten the key down and restated. Running like a champ. Thanks for everyone's in put. Hope this process helps someone else.
Need Help with 450 Bushmaster Troubles - VASCAR2 - 08-31-2022
Glad to hear you sorted it out. Id thought you could see evidence of gas leakage around the key but it makes sense metal expanding contributed to the malfunction. I think it is satisfying sorting out these issues with firearms, even if it takes a process of elimination.
I really appreciate you letting the forum know what you discovered!
Need Help with 450 Bushmaster Troubles - montana - 08-31-2022
Scouttracker Wrote:Well folks I finally had a chance to try a few things ,(one at a time minded you) and my shoulder feels it .
Changed to standard spring & buffer. No change.
Tried 3 new mages . No change. But what I did deduct was it only happens when it hot and only on the feed cycle. So only 3 things get really hot after 5 to 10 rounds. Barrel, gas block and tube, gas key. Started process of elimination. Barrel is locked shooting hole for hole ,feed ramps were polished. No problem there. Seeking Precision adj gas block & tube. All tight and clear. Ejection was between 2 and 3 o'clock. No problem. That brings us to the gas key. Cold gas key is tight, as it heated up it became loose and pushed the bolt down with changed the feed angle. Gas key was staked but the company did a piss poor job. The way I found this was I put the bolt in the oven( at the advice of a marine armorer) . Tighten the key down and restated. Running like a champ. Thanks for everyone's in put. Hope this process helps someone else.
Glad to here you got it figured out. If the gas key was that loose, then you were getting some severe gas leakage. I would keep an eye on the gas key since you reused it and the material will be a lot less when re-staking. I would have just replaced the gas key. Did you bed the gas key to the carrier? An easy test to see if the gas key screws are torqued properly is to do a reverse torque of 25 to 30 inch pounds. If the screws come loose, then it wasn't properly staked (50 to 58" pounds) to begin with. Always oil the screws to get a proper torque.Heat should not play a part with the gas keys coming loose if they are properly staked or didn't break.. I only use Michiguns OCKS(optimized carrier key screws) screws. They are designed to grab the staking material..http://www.michiguns.net/tool_new.php?product=ocks
Need Help with 450 Bushmaster Troubles - Scouttracker - 08-31-2022
montana Wrote:Glad to here you got it figured out. If the gas key was that loose, then you were getting some severe gas leakage. I would keep an eye on the gas key since you reused it and the material will be a lot less when re-staking. I would have just replaced the gas key. Did you bed the gas key to the carrier? An easy test to see if the gas key screws are torqued properly is to do a reverse torque of 25 to 30 inch pounds. If the screws come loose, then it wasn't properly staked (50 to 58" pounds) to begin with. Always oil the screws to get a proper torque.Heat should not play a part with the gas keys coming loose if they are properly staked or didn't break.. I only use Michiguns OCKS(optimized carrier key screws) screws. They are designed to grab the staking material..http://www.michiguns.net/tool_new.php?product=ocks
I ordered a new Fail zero bcg. Will rebuild the used one for a backup. But will check out that web site.
Need Help with 450 Bushmaster Troubles - montana - 09-01-2022
Scouttracker Wrote:I ordered a new Fail zero bcg. Will rebuild the used one for a backup. But will check out that web site.
Everything Michiguns makes is top quality. I use their staking tool (MOACK), gas tube bender throat gauge (5.56), reamers and other tools.. For checking barrel chambers and throats, nothing beats the PTG function gauge.. https://pacifictoolandgauge.com/641-function-gauges-nopix- Many new or factory barrels can have tight or poorly reamed chambers with out of spec throats.. PTG also has the best head space gauges on the market. I have had quite a few head space gauges I have sent back to other suppliers because they were out of spec. PTG head space gauges are second to none and have been spot on accurate.. Just expect to weight a very, very, long time getting them lol..
Need Help with 450 Bushmaster Troubles - VASCAR2 - 09-01-2022
Not to sling mud but jut to make an observation. This is a BCA upper and at their price point I would not be surprised if they are using low budget, suspect quality parts like carrier key bolts. Improperly torqued and staked carrier keys is not unheard of with AR-15s. My Son once worked for a Company that was lax on inspection until they got bit hard on substandard steel. The vendor supposedly sold the correct spec steel but when products started failing the company traced the problem to poor quality material. This incident almost bankrupted the company. They learned a lesson and started inspecting any incoming material for quality and insuring it was to proper spec.
I only mention this as I havent made an effort to be more open minded to suspect any part. There is even a differences in the quality of cotter keys for retaining firing pins on AR-15s. With so many products being imported and not knowing their true source of manufacture it is a reminder to really think out of the box when dealing with malfunctions.
Need Help with 450 Bushmaster Troubles - Scouttracker - 09-02-2022
VASCAR2 Wrote:Not to sling mud but jut to make an observation. This is a BCA upper and at their price point I would not be surprised if they are using low budget, suspect quality parts like carrier key bolts. Improperly torqued and staked carrier keys is not unheard of with AR-15s. My Son once worked for a Company that was lax on inspection until they got bit hard on substandard steel. The vendor supposedly sold the correct spec steel but when products started failing the company traced the problem to poor quality material. This incident almost bankrupted the company. They learned a lesson and started inspecting any incoming material for quality and insuring it was to proper spec.I agree, I have a couple BCA products . I usually buy them from people that are tired of trying to troubleshoot the problems. I replace most of the parts to get them to run . I dont know why ,I guess I'm a glutton punishment ??
I only mention this as I havent made an effort to be more open minded to suspect any part. There is even a differences in the quality of cotter keys for retaining firing pins on AR-15s. With so many products being imported and not knowing their true source of manufacture it is a reminder to really think out of the box when dealing with malfunctions.