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Posted: 7/21/2010 7:28:38 AM EST
I have one of the M16A1 parts kits that have recently come on the market. Everything was like new, except for the handguards, which were well-used. They fit on the gun, but it is very tight, and they are a bit cockeyed when installed.

I bought some NOS military surplus handguards, and they don't fit at all. I can only get the left side or the right side on, but not both at the same time. Where they meet at the top in that metal triangular retainer piece; there is not enough room in there for them to both fit at the same time.

Is this common when putting new handguards on a gun? Do they have to be "fitted"? I would guess that filing the edges of the plastic down some where they meet in the triangular metal retaining piece would allow them to fit.
Link Posted: 7/21/2010 7:36:46 AM EST
Is the barrel nut fully tightened to the receiver ? If not, they will bind.

You sometimes have to wiggle the guards in place making sure they are level.
Link Posted: 7/21/2010 7:37:32 AM EST
Link Posted: 7/21/2010 7:49:15 AM EST
[Last Edit: 7/21/2010 7:49:44 AM EST by MaximRecoil]
Originally Posted By Hal143:
Is the barrel nut fully tightened to the receiver ? If not, they will bind.

You sometimes have to wiggle the guards in place making sure they are level.


Not yet (I'm waiting for a tool to do that). That probably explains why the well-used handguards are so tight and cockeyed when installed; but I think the NOS ones are going to have to be filed a bit either way because they won't fit together in the top triangular cap in the first place.

Originally Posted By mike_nds:
Sometimes I've had to file the mating surfaces at the front to allow both halves to co-habitat in the cap.


Thanks. I'll wait until I have the barrel nut completely tightened before doing anything, but I have a feeling I will need to file them either way.

Link Posted: 7/21/2010 8:11:49 AM EST
If the barrel nut isn't tight, unscrew it and pull the barrel. Then with the barrel off the receiver, try and put the handguards on. That'll let you know if you have an issue.
Link Posted: 7/21/2010 8:33:47 AM EST
[Last Edit: 7/21/2010 8:35:00 AM EST by MaximRecoil]
I know what is causing the well-used handguards to be cockeyed. The triangular cap is cockeyed. The hole in it is misaligned with the front sight base's gas tube hole by maybe 1/16" an inch. Not only does this cause the handguard to be cockeyed, but the gas tube isn't going to fit in there either.

That cap won't budge either. I've tried to twist it over slightly with my bare hands, and also tapping on it with a rubber mallet, and nothing.

This sucks, because that isn't something I can fix. It isn't something I caused either. I got the parts set from GunThings.com, which had the barrel already parkerized and the front sight base already installed, and that front sight base is what is clamping the misaligned triangular cap so firmly in place.

Ugh...
Link Posted: 7/21/2010 8:56:45 AM EST
Link Posted: 7/21/2010 9:08:59 AM EST
Originally Posted By HarlanNDS:
If you want to try more fixes at home, apply a penetrating lube on both sides of the front handguard cap, and let sit for a day. Then put the barrel assembly in a freezer overnight. Take out the barrel and use a deadblow hammer to move the handguard cap.



Try this. If you can get a slim pin or screwdriver in the gas tube hole, you might try to pry it over. 3 in 1 oil works if you don't have anything else.
Link Posted: 7/21/2010 9:14:05 AM EST
Originally Posted By MarkRSims:
Originally Posted By HarlanNDS:
If you want to try more fixes at home, apply a penetrating lube on both sides of the front handguard cap, and let sit for a day. Then put the barrel assembly in a freezer overnight. Take out the barrel and use a deadblow hammer to move the handguard cap.



Try this. If you can get a slim pin or screwdriver in the gas tube hole, you might try to pry it over. 3 in 1 oil works if you don't have anything else.


I have Break Free, 3-in-1, and WD-40. Which would be better?
Link Posted: 7/21/2010 9:35:24 AM EST
[Last Edit: 7/21/2010 9:36:58 AM EST by Hal143]
All good advice above.

The cap is probably just gummed up with dried cosmo/grease. It should move with a little coaxing.

Mark's right about trying the guards with the barrel off. I figured you were just putting it together to see how it looks.

I was doing the same thing last night and the guards wouldn't fit unless the nut was fully tightened. When I removed the barrel, and slid the nut rearward, the guards popped right on.


ETA: Try a little Kroil, gasoline or Hoppes #9 or other solvent. Then try the WD or CLP etc.
Link Posted: 7/21/2010 10:40:41 AM EST
Link Posted: 7/21/2010 12:39:27 PM EST
Originally Posted By HarlanNDS:
Originally Posted By Hal143:
The cap is probably just gummed up with dried cosmo/grease. It should move with a little coaxing.


The OP's barrel assembly is one where the FSB was recently installed on the barrel (along with the front handguard cap) by GunThings.com. The barrel is freshly parkerized. I don't think there is dried cosmolene or grease involved. The FSB is installed, with the front handguard cap tight between the back of the FSB and the barrel step. This tight fit is what is currently preventing the OP from getting the handguard cap to move.



Gotch'a, I see. Bummer.

Link Posted: 7/21/2010 12:49:42 PM EST
yeah, cap is probably stuck to the backside of the fsb from being parked while assembled...douse it in oil (PB Blaster would be best) and let it sit for a day or two then just grasp the fsb in one hand and the cap in the other and give it a hard twist..I wouldn't use a hammer to try and move it as it's only tin, and you'll probably bend it if you hit it.

Mark's idea of using something to pry it might work ...try carefully using as large a drill bit/nail as will fit into what's showing of the gas tube hole as a lever to move it in the right direction

I have had some that were pretty tight but all were eventually able to be moved by hand after they were broken loose from the fsb
Link Posted: 7/21/2010 1:13:39 PM EST
I have a GunThings, and the handguards did'nt go on any harder (Or EASIER, for that matter!) than they ordinarily do.
Link Posted: 7/21/2010 2:32:54 PM EST
[Last Edit: 7/21/2010 2:38:40 PM EST by MaximRecoil]
Originally Posted By gb15:
I have a GunThings, and the handguards did'nt go on any harder (Or EASIER, for that matter!) than they ordinarily do.


Well in my case, the handguard cap was not installed properly. Evidently, the person who installed the front sight base wasn't aware that a gas tube would have to be able to go through that hole in the cap and into the hole in the front sight base, else he would have aligned the holes before calling it good.

The handguards not fitting is a different issue, and is a problem with the NOS handguards themselves (some plastic will need to be filed), because the well-used handguards that came with the parts set do fit, though they are cockeyed (but that is because the handguard cap is cockeyed).

Originally Posted By crackedcornish:
yeah, cap is probably stuck to the backside of the fsb from being parked while assembled...douse it in oil (PB Blaster would be best) and let it sit for a day or two then just grasp the fsb in one hand and the cap in the other and give it a hard twist..I wouldn't use a hammer to try and move it as it's only tin, and you'll probably bend it if you hit it.


It is steel actually, but rather thin. I tapped on it with a rubber mallet. It didn't bend, but it didn't budge either.

Mark's idea of using something to pry it might work ...try carefully using as large a drill bit/nail as will fit into what's showing of the gas tube hole as a lever to move it in the right direction
That's one of the first things I tried, even before posting about it; but it quickly became apparent that it wouldn't work; and additional force would only deform the hole.

Link Posted: 7/21/2010 4:30:10 PM EST
Well, I got the handguard cap straightened out. After soaking for a while in WD-40, I made a makeshift wrench by cutting the triangular shape of the cap out of a piece of wooden board with a jigsaw. It worked without damaging anything, so now it is all aligned and the gas tube can go in there.
Link Posted: 7/21/2010 4:35:38 PM EST
Originally Posted By MaximRecoil:
Well in my case, the handguard cap was not installed properly. Evidently, the person who installed the front sight base wasn't aware that a gas tube would have to be able to go through that hole in the cap and into the hole in the front sight base, else he would have aligned the holes before calling it good.

I've had at least one brand new AR barrel from a major manufacturer come with the handguard cap on crooked. Since they normally rotate pretty easily I don't think it's something that most assemblers really pay attention to. The only thing unusual about your situation was the amount of effort that it took to get it moving.
Link Posted: 7/21/2010 5:17:54 PM EST
[Last Edit: 7/21/2010 5:18:08 PM EST by MaximRecoil]
I got the NOS handguards on now (only took a little bit of filing), and they fit good and are not cockeyed. So everything is solved (for the time being anyway).

Thanks for the help.
Link Posted: 7/21/2010 5:40:26 PM EST
Originally Posted By MaximRecoil:
I got the NOS handguards on now (only took a little bit of filing), and they fit good and are not cockeyed. So everything is solved (for the time being anyway).

Thanks for the help.


I'm curious, do you think it was parkerized in place? And if so, did the part blocked off behind the front sight base take the parkerizing OK?

I've just started doing some parkerizing, and was wondering about leaving things together and whether they would get covered.
Link Posted: 7/21/2010 6:11:39 PM EST
[Last Edit: 7/21/2010 6:11:57 PM EST by MaximRecoil]
Originally Posted By MarkRSims:

I'm curious, do you think it was parkerized in place?


No. Nothing "broke free" when it turned; it just turned with a lot of resistance, but smoothly and with no noise.

And if so, did the part blocked off behind the front sight base take the parkerizing OK?


The handguard cup and FSB are Colt parts, parkerized ages ago. I doubt that the FSB and cup were installed on the barrel when it was parkerized, given that they were already parkerized and they have a slightly different color and "quality" to the finish than the barrel's finish has (they are different from each other in color too). In any event, the finish on the back side of the cup (the side against the FSB) is perfect, even after being moved slightly.

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