Handguard removal

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Handguard removal

Postby SharpMSC » Sun Jan 01, 2017 10:12 pm

Hey everyone!

I just purchased a 450 upper from Walsh in Michigan. I'm not to fond of the handguard and wanted to change it. Was there any information on proper removal? I scrolled through some of the pages but couldn't seem to find anything.

Thanks
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Re: Handguard removal

Postby Hoot » Mon Jan 02, 2017 8:30 am

SharpMSC wrote:Hey everyone!

I just purchased a 450 upper from Walsh in Michigan. I'm not to fond of the handguard and wanted to change it. Was there any information on proper removal? I scrolled through some of the pages but couldn't seem to find anything.

Thanks


Welcome aboard Sharp!
If current production Bushmaster 450's use the same handguard as they did 7 years ago, then there should be a set nut between the handguard and the barrel nut. I put a Ridgid brand strap wrench around the handguard and hold the set nut tight with my grip to keep it from rotating, then loosen the handguard a turn with the strap wrench. After breaking it free, you can spin it off by hand. If its too hard to hold the set nut steady, reverse the setup and rotate the handguard with your grip instead. It should not take much to unscrew it.

I like the stock handguard for its simplicity and it not being a "cheese grater" design, but to each his own.

Hoot
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Re: Handguard removal

Postby SharpMSC » Mon Jan 02, 2017 3:36 pm

Hoot wrote:Welcome aboard Sharp!
If current production Bushmaster 450's use the same handguard as they did 7 years ago, then there should be a set nut between the handguard and the barrel nut. I put a Ridgid brand strap wrench around the handguard and hold the set nut tight with my grip to keep it from rotating, then loosen the handguard a turn with the strap wrench. After breaking it free, you can spin it off by hand. If its too hard to hold the set nut steady, reverse the setup and rotate the handguard with your grip instead. It should not take much to unscrew it.

I like the stock handguard for its simplicity and it not being a "cheese grater" design, but to each his own.

Hoot


Thanks a lot. I plan on switching to the magpul rifle length hand guard, its a preference thing I guess.
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Re: Handguard removal

Postby Hoot » Mon Jan 02, 2017 6:47 pm

I was going to post the link to the Ridgid No. 2P Strap Wrench I bought from Home Depot but apparently they do not carry it anymore. Did some quick searching and OMG, they have really gone up in price! :shock:

There are plenty of them in various states, available on Ebay. New ones run about $34.00 plus $5 shipping. They help loosen threaded pipes as well with no marring. Don't be fooled by all rubber strap wrenches like those ones in the auto parts stores. They're too stretchy. The Ridgid No. 2P is woven rayon or polyester with a rubberized coating for extra grip on shiny surfaces.

Hoot
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Re: Handguard removal

Postby SharpMSC » Fri Jan 06, 2017 10:50 pm

Hoot wrote:I was going to post the link to the Ridgid No. 2P Strap Wrench I bought from Home Depot but apparently they do not carry it anymore. Did some quick searching and OMG, they have really gone up in price! :shock:

There are plenty of them in various states, available on Ebay. New ones run about $34.00 plus $5 shipping. They help loosen threaded pipes as well with no marring. Don't be fooled by all rubber strap wrenches like those ones in the auto parts stores. They're too stretchy. The Ridgid No. 2P is woven rayon or polyester with a rubberized coating for extra grip on shiny surfaces.

Hoot


Looks like I might be bringing out the torch tomorrow, still having trouble even with the strap wrench and barrel nut tool.
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Re: Handguard removal

Postby Hoot » Sat Jan 07, 2017 7:25 am

SharpMSC wrote:
Looks like I might be bringing out the torch tomorrow, still having trouble even with the strap wrench and barrel nut tool.


A heat gun might be a better choice. You shouldn't have to use the barrel nut tool the screw the handguard off of it, but you absolutely need a way to immobilize the set ring (nut) or it will fight you loosening the handguard, heat or not. I put the receiver in a receiver block like this one:

Image

IMHO, the best one you can get as it supports the receiver on both the top and bottom. I clamp the block halves in a large bench vise to give me both hands free. You can take a pair of channel locks and a piece of leather between the jaws and the set ring to immobilize it. There's always a possibility that some "gorilla" at the factory over tightened the whole thing and galled the threads. If that's the case, your primary objective will be saving the barrel nut! If that's the case you may have to write off the factory handguard.

Hoot
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Re: Handguard removal

Postby MOOSE EARS » Sat Jan 07, 2017 8:04 am

I had installed a Hogue handguard on an upper using a cheap strap wrench, which later broke. I decided later, after a few years of usage, to change the handguard. I tried using large channel locks with heavy leather to protect the barrel nut multiple times and it just wouldn't budge. I was actually ripping the leather into shreds with the amount of force I was using. I'm not proud of my solution, but I finally used an 18" pipe wrench to loosen the nut, with minimal, although noticeable, marring of the nut. Since I don't plan to ever use this handguard again, it's no great loss.I'll probably end up giving it away.
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Re: Handguard removal

Postby dantheman » Sat Jan 07, 2017 8:31 am

What about using some penetration oil first?

A mix of 50% Acetone, 50% Automatic Transmission Fluid with a little Marvels Mystery oil thrown in for good measure, works better than just about anything commercially available.

This came from a post on a Welding Forum

"Machinist's Workshop magazine actually tested penetrants for break out torque on rusted nuts. Significant results! They are below, as forwarded by an ex-student and professional machinist, Bud Baker.
Don't forget the April 2007 "Machinist's Workshop" magazine comparison
test.

*They arranged a subjective test of all the popular penetrants with
the control being the torque required to remove the nut from a
"scientifically rusted" environment.


*Penetrating oil ..... Average load*

None ..................... 516 pounds
WD-40 .................. 238 pounds
PB Blaster ............. 214 pounds
Liquid Wrench ..... 127 pounds
Kano Kroil ............ 106 pounds
ATF-Acetone mix....53 pounds

*The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic transmission
fluid and acetone.*
*Note the "home brew" was better than any commercial product in this one
particular test. Our local machinist group mixed up a batch and we all now
use it with equally good results. Note also that "Liquid Wrench" is about
as good as "Kroil" for about 20% of the price. "

I can tell you that this stuff loosens up just about anything.

Dan
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Re: Handguard removal

Postby Hoot » Sat Jan 07, 2017 12:25 pm

I have both of those penetrant components. When I run out of Kroil, I'll give them a try.

There seems to be some confusion of terms.

The barrel nut holds the barrel to the receiver. It is often threaded to receive a handguard.
I have seen handguards that were threaded on one end to also serve as the barrel nut. Kind of a 2-in-1. I actually have one.

Bushmaster uses a small threaded on the inside, knurled on the outside, lock ring that you screw on before the handguard.
The lock ring allows you to index the sling stud in the proper position and then lock the handguard in place, like a jam nut.
Unfortunately, the term "jam nut" can be self prophesying. If you do not break the jam of the lock ring against the handguard,
you could damage the threads on the barrel nut that both of them are threaded onto. You could also cause the barrel nut to
rotate and kink the gas tube. Removing the barrel nut itself is a job for a barrel nut wrench only. Anything else is inviting
disappointing results. Some factory gorillas totally disregard the barrel nut torque spec when trying to get the gas tube holes
to align that last little bit of rotation. I had a Rock River upper once that was like that once. My entire 265 lbs of body weight
would not budge it. Wound up having to cut the nut transversely just short of the threads and pop it with a cold chisel. Had
to do that once with a muzzle brake that an inattentive owner allowed to rust in place. Very nerve wracking. Different story.

I suspect that depending upon who tightened the Bushmaster handguard and lock ring at the factory, it could be real easy to
break free or a real PITA. I must have gotten lucky on mine.

Hoot
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Re: Handguard removal

Postby plant_one » Sat Jan 07, 2017 1:36 pm

IIRC mine was a royal PITA to remove, i think they had some locktite on the threads between the barrel nut and the handguard.

i had to use a large pair of channel locks with a small piece of leather scrap wrapped around the lock nut to loosen that, but even then the handguard was a SOB with the strap wrench.


like hoot, i had it locked in the vice with a upper receiver block, although i have the Wheeler one, which is different from the style he posted - its more of a clamshell that goes around the outside of the whole upper.
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