Modify triangle retention cap for MOE SL (slim) hand guard

wild cat mccane · July 10, 2018, 06:21 PM

Hello,

Does anyone have a link with pictures for modifying a triangle retention cap into the round cap? Possibly even a triangle retention cap on a round cap to help me modify my triangle cap to fit the MOE SL hand guard?

I have learned after purchasing the MOE SL hand guard that the original MOE hand guard fits both triangle and circle, but the SL only fits the round. I have also learned most uppers come with a triangle--just like my PSA.

It seems just as easy to modify (ie crudely cut) the triangle into fitting as it is to remove all the junk forward of the retention cap to fit on a round cap.

Ugh.

kymasabe · July 11, 2018, 07:22 PM

Is this on a mid-length gas system? If it were me, I'd pull the retaining cap and install a round one rather than butcher the triangular, isn't that hard to do. Remember, FSB pins are tapered.
PS: most of PSA's carbine length stuff comes with round caps.

wild cat mccane · July 11, 2018, 08:36 PM

Apparently all but one of PSA's mid lengths (one with the grey SL installed) comes with a triangle cap while the MOE SL hand guard requires the round.

I guess I could watch a few videos, but it seems like a lot of work on the more delicate parts of the barrel...

PawnWolf · July 12, 2018, 02:29 PM

When you order the new cap, buy a new set of pins while you are at it. Neither one are that expensive (and the pins are soft, so if you booger the ones coming out you will have the extras), get you a hammer and some pin punches, and you will be fine. And as kymasabe says, the pins are tapered and go out only in one direction.

marine6680 · July 12, 2018, 02:51 PM

You also need to remove the muzzle device as well.

I had to do the same thing on my PSA.

If you do not have the tools, then it will be a bit more expensive of a process. Having the tools on hand is nice to have anyway, even if you don't build. (I highly suggest the Magpul BEV block over the clamshell receiver clamp... It works so much better for working on barrels)

You could probably get the triangle cap cut down, and modify the handuard to fit over it. (It's not as simple as just cutting the cap, as the handguard has groves to fit around it, and those will interfere with the flat sides of the cap)

Getting the SL handguards put on is a bear in and of itself if you haven't done it before and worked out the trick to it. It would be worse with trying to modify the incompatible parts.

So really it is best to swap the cap.

The SL handguards are great though, so it's worth a little trouble swapping the cap.

Dragline45 · July 12, 2018, 03:03 PM

Would the BCM PKMR handguard work for you? I have had both Magpuls at one point and replaced them with the much slimmer BCM polymer handguard which I highly recommend.

Mobuck · July 13, 2018, 05:53 AM

Pulling the "front end" of an AR can be a 15 minute start to finish job OR an absolute nightmare depending on what you have to work with. Absolutely DO NOT use the upper for leverage when removing the muzzle device.

wild cat mccane · July 13, 2018, 07:04 AM

I took the upper to a gunsmith to remove the PSA flashider. It took this burly old guy all his strength.

So that problem is already dealt with

wild cat mccane · July 13, 2018, 07:06 AM

https://www.bravocompanyusa.com/BCM-...mr-mid-blk.htm

More expensive, but cheaper than getting the round retention cap.

Thank you for the tip.

wild cat mccane · July 13, 2018, 12:39 PM

Purchased the Bravo Company guard. Not thrilled it's key vs M-Lok, but oh well

Thanks

Mobuck · July 14, 2018, 06:53 AM

Does "key vs m-lock" make all that much diff if you're not "configuring for the mission requirements" on a regular basis"?

wild cat mccane · July 14, 2018, 07:26 AM

I actually won't be mounting anything to it. I just think the key holes look cheap.

Found this link to be extremely informative:
https://www.guntweaks.com/magpul-moe...---part-1.html

kymasabe · July 15, 2018, 07:30 AM

Some day you'll knock the tapered pins out of the front sight block and think to yourself "well, that was easier than I expected, why didn't I do this sooner and why did I compromise on what handguard I really wanted".
Congrats on the BCM guard, save the box so you can resell it on eBay next month.
And, I agree with you, I don't like the look of keymod, I much prefer MLOK.

wild cat mccane · July 15, 2018, 12:43 PM

Sounds like the MOE SL grip is still the largest of the B5 and BCM in circumference.

marine6680 · July 15, 2018, 08:13 PM

It may be big from raw numbers, but I find it feels smaller. I like the SL handguard a lot, and put them on my ARs that use the standard clamshell.

wild cat mccane · July 27, 2018, 07:49 AM

Welp, I've become the hand guard changing master

The Bavo Company hand guard won the feel contest. I might have been persuaded by not having to change out the retention cap.

However, there is a slight annoying with their product. It's 3 pieces with the top section being two. This creates a seam right down the center of the guard that does slightly attract the eye.

Oh, and there is a star emblem. I don't know why, but stars just remind me of those huge metal stars people put on their house for who knows what reason.

With that slight annoyance noted, I do recommend their hand guard.

July 10, 2018, 06:21 PM	#1
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	Modify triangle retention cap for MOE SL (slim) hand guard Hello, Does anyone have a link with pictures for modifying a triangle retention cap into the round cap? Possibly even a triangle retention cap on a round cap to help me modify my triangle cap to fit the MOE SL hand guard? I have learned after purchasing the MOE SL hand guard that the original MOE hand guard fits both triangle and circle, but the SL only fits the round. I have also learned most uppers come with a triangle--just like my PSA. It seems just as easy to modify (ie crudely cut) the triangle into fitting as it is to remove all the junk forward of the retention cap to fit on a round cap. Ugh. Last edited by wild cat mccane; July 10, 2018 at 08:35 PM.

July 11, 2018, 07:22 PM	#2
kymasabe Senior Member Join Date: June 10, 2005 Location: SW Florida Posts: 2,747	Is this on a mid-length gas system? If it were me, I'd pull the retaining cap and install a round one rather than butcher the triangular, isn't that hard to do. Remember, FSB pins are tapered. PS: most of PSA's carbine length stuff comes with round caps. __________________ God's creatures big and small, eat them one, eat them all.

July 15, 2018, 07:30 AM	#13
kymasabe Senior Member Join Date: June 10, 2005 Location: SW Florida Posts: 2,747	Some day you'll knock the tapered pins out of the front sight block and think to yourself "well, that was easier than I expected, why didn't I do this sooner and why did I compromise on what handguard I really wanted". Congrats on the BCM guard, save the box so you can resell it on eBay next month. And, I agree with you, I don't like the look of keymod, I much prefer MLOK. __________________ God's creatures big and small, eat them one, eat them all.

July 11, 2018, 08:36 PM	#3
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	Apparently all but one of PSA's mid lengths (one with the grey SL installed) comes with a triangle cap while the MOE SL hand guard requires the round. I guess I could watch a few videos, but it seems like a lot of work on the more delicate parts of the barrel...

July 12, 2018, 02:29 PM	#4
PawnWolf Junior Member Join Date: June 22, 2018 Posts: 7	When you order the new cap, buy a new set of pins while you are at it. Neither one are that expensive (and the pins are soft, so if you booger the ones coming out you will have the extras), get you a hammer and some pin punches, and you will be fine. And as kymasabe says, the pins are tapered and go out only in one direction.

July 12, 2018, 02:51 PM	#5
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	You also need to remove the muzzle device as well. I had to do the same thing on my PSA. If you do not have the tools, then it will be a bit more expensive of a process. Having the tools on hand is nice to have anyway, even if you don't build. (I highly suggest the Magpul BEV block over the clamshell receiver clamp... It works so much better for working on barrels) You could probably get the triangle cap cut down, and modify the handuard to fit over it. (It's not as simple as just cutting the cap, as the handguard has groves to fit around it, and those will interfere with the flat sides of the cap) Getting the SL handguards put on is a bear in and of itself if you haven't done it before and worked out the trick to it. It would be worse with trying to modify the incompatible parts. So really it is best to swap the cap. The SL handguards are great though, so it's worth a little trouble swapping the cap.

July 12, 2018, 03:03 PM	#6
Dragline45 Senior Member Join Date: November 30, 2010 Posts: 3,513	Would the BCM PKMR handguard work for you? I have had both Magpuls at one point and replaced them with the much slimmer BCM polymer handguard which I highly recommend.

July 13, 2018, 05:53 AM	#7
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	Pulling the "front end" of an AR can be a 15 minute start to finish job OR an absolute nightmare depending on what you have to work with. Absolutely DO NOT use the upper for leverage when removing the muzzle device.

July 13, 2018, 07:04 AM	#8
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	I took the upper to a gunsmith to remove the PSA flashider. It took this burly old guy all his strength. So that problem is already dealt with

July 13, 2018, 07:06 AM	#9
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	https://www.bravocompanyusa.com/BCM-...mr-mid-blk.htm More expensive, but cheaper than getting the round retention cap. Thank you for the tip.

July 13, 2018, 12:39 PM	#10
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	Purchased the Bravo Company guard. Not thrilled it's key vs M-Lok, but oh well Thanks

July 14, 2018, 06:53 AM	#11
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	Does "key vs m-lock" make all that much diff if you're not "configuring for the mission requirements" on a regular basis"?

July 14, 2018, 07:26 AM	#12
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	I actually won't be mounting anything to it. I just think the key holes look cheap. Found this link to be extremely informative: https://www.guntweaks.com/magpul-moe...---part-1.html

July 15, 2018, 12:43 PM	#14
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	Sounds like the MOE SL grip is still the largest of the B5 and BCM in circumference.

July 15, 2018, 08:13 PM	#15
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	It may be big from raw numbers, but I find it feels smaller. I like the SL handguard a lot, and put them on my ARs that use the standard clamshell.

July 27, 2018, 07:49 AM	#16
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,623	Welp, I've become the hand guard changing master The Bavo Company hand guard won the feel contest. I might have been persuaded by not having to change out the retention cap. However, there is a slight annoying with their product. It's 3 pieces with the top section being two. This creates a seam right down the center of the guard that does slightly attract the eye. Oh, and there is a star emblem. I don't know why, but stars just remind me of those huge metal stars people put on their house for who knows what reason. With that slight annoyance noted, I do recommend their hand guard.