D-Ring Removal and FSB Shaving

[aaron_c]

Hey guys, I have a dremel tool and it looks like the D-Ring is going to be cut out and the FSB shaved in order to fit a 13" rail on my midlength gas system (maybe, haven't decided yet for sure). What types of bits and such do you recommend using to cut the delta ring, and to shave the FSB down? I saw some cutoff wheels when in the hardware store today but I'm told that these are some very tough metals on these two parts, so would I need a few of the cutoff wheels?

[Evil Colt 6920]

For the FSB, I used a hacksaw to cut the sight posts off (very easy) then used a grinding wheel in the dremel to round off and smooth it out. Thats the only cutting I had to do. Good Luck.

[mattw82]

I've had good results with the dremel cut off wheels and hard metals, but they tend to wear out quick or break. If you buy the replacement disks that come in the little tube, that should be plenty for the task you described. Ive cut off bayonet lugs and sling tabs no problem with one or two disks.

[Evil Colt 6920]

Honestly, dont waste your time with cut off wheels on a dremel unless its necessary. Cut off wheels break easy, get dull easy, throw cutting debris all over your work area and possibly put your eye out. I can get the posts cut off the gas block faster and cleaner with a hacksaw than a dremel cut off wheel. Just use the dremel for grinding/reshaping the gas block to fit under your rail. I just did this for the first time about a month ago, pretty easy. Getting the FSB pins out was the hardest part, its downhill from there.

EDIT: Im not sure why you are having to cut off the D ring. Is something seized up?

[outrider627]

I used a dremel for both. I completely wore out 4 fiber reinforced cutting wheels while cutting the FSB and 4 rough sandpaper drums for the final shaping. If I had something better like an angle grinder, I would've used it. The dremel is not ideal, but it works. I believe Dremel has wheels stronger than the reinforced fiber ones, but they might cost the same as a pack of reinforced wheels.

If you're cutting the FSB while it's mounted on the barrel, be sure to cover the barrel in some heavy tape. I wrapped mine in masking tape, and then a couple wraps of duct tape. The masking tape prevents duct tape residue from sticking to the barrel.

I can't stress this enough, use eye pro! Sometimes those dremel wheels break in half and will hit you in the face.

The first step before doing anything is removing the gas tube. Once that is out of the way, start cutting the FSB however you like. Be careful with the bayonet lug because it gets really close to the barrel. There's a thread in AR GD about cutting FSBs and I posted some pics there.

The delta ring is extremely easy. Rotate the ring 90 degrees so that the gas tube hole is on either side of the receiver, and then cut. Its easier to cut the delta ring through the gas tube hole. Don't try to cut it with the gas tube hole at the top, the rail gets in the way. Once you cut through the gas tube hole, cut the ring again on the opposite side so you can pry it off.

The spring can be pried off with pliers, but I think I cut it a couple times with a dremel wheel so it would bend easily. The steel retaining clip needs one or two quick touches with a cutting wheel so it can be easily removed too.

ETA: I forgot about the handguard cap. I unpinned the FSB, moved it forward, and then cut it enough so I could bend it and remove it. If you cannot unpin the FSB, you're gonna have to find your own way to remove it.

If you do unpin the FSB, when you go back to re-install it, make sure you have someone to help you. Put the barrel on something sturdy that will fit in the space between the barrel and surface. A piece of wood can work if you don't have a bench block. Use a big hammer and a 5/16 pin punch. Have your friend press down on the upper receiver as hard as he can, and then hit those pins like if you were Thor. A few good hits should do it.

[Evil Colt 6920]

I used a dremel for both. I completely wore out 4 fiber reinforced cutting wheels while cutting the FSB Exactly why I dont use dremel cut off wheels on anything I can cut easily with a hack saw.

Also, Im confused about the need to cut off the delta ring:confused: Is that really necessary?

EDIT: OK i searched and see this is only done if you dont want to remove the barrel... If you have a barrel nut wrench and torque wrench, Id suggest just removing the barrel and avoid all the cutting.

[Iraqgunz]

I used the reinforced heavy duty Dremel wheels tor remove everything. I purchased a large bulk pack from Walmart (IIRC).

I was able to cut the Delta assembly with two wheels or less if I recall.

[aaron_c]

Thanks for all the help! To answer one persons question, I'm cutting the delta ring off to install a free float rail (probably Troy TRX).

[Tweak]

the delta ring is aluminum so no hassle to cut. Why not just pull the barrel and removed the parts? If you chop the FSB you're best to remove it and do so then refinish it.

[aaron_c]

I can probably remove the FSB but I don't have the necessary tools to pull the barrel and properly reinstall is to the level that BCM can, so I'd rather not mess with removing the barrel.

[GI_Jared]

Use a hack saw or a 4" angle grinder to cut the bulk off of the FSB. Don't waste your time with the Dremel, get a nice little air grinder set up that takes all sorts of different attachments that can be made by any manufacturer. I use something similar to this package below and the small pads work great for grinding down the FSB and giving it a professional look.

This kit is on northern tool (http://www.northerntool.com/shop/tools/product_200305429_200305429) for $59.99 and has all the necessary items to get you started.
http://www.northerntool.com/images/product/images/157798_lg.jpg