grinding fsb

[Quick Stick]

Guys, I'm wanting to install a Troy/Vtac Extreme rail on one of my uppers and with the length I want to go with, will need a low pro gas block.
Question is, will I have a problem with the inside diameter of this rail fitting if I grind my standard fsb?

I tried the search, but could not come up with anything. Thanks in advance.

[Surf]

It will fit.

Shaving front sight base for Troy TRX Extreme Battle Rail (http://www.youtube.com/watch?v=I5rPPyYdFUs)

[PrarieDog]

I agree it should not be a problem. Mine went just fine.

[Eric D.]

Just curious. what are you guys using to refinish your fsb after you grind it?

[Surf]

I have used various cold bluing and in the video above I use Aluminum Black by Birchwood Casey. It is more of a parkerizing finish and matches the AR finishes better. I have also used high temp bbq or engine paints, but the bluing or similar treats the metal better.

This is a still from the above video.
http://i225.photobucket.com/albums/dd60/SSDSurf/Misc/alumblk01.jpg

[Fried Chicken Blowout]

FYI, I got two of the S&W M&P15TS rifles that come with the Troy Extreme Rails and the gas block that S&W is using is NOT low profile enough to allow a rail segment to be mounted below the gas block. The rail segments us a continues nut bar that fits on the inside of the rail and provides a place for the screws to go into from the outside. This nut bar is the same length as the rail... So if you want to install a rail segment below the gas block for a vertical fore grip or AFG you will need to make sure you have clearanced the bottom of the gas block a bunch.

For my applications I had to use a 3.5" rail segment and cut the middle out of the nut bar. I would have preferred to use a 2" segment but there was not way to get the clearance I needed for that without changing the gas block or grinding on it.

[Quick Stick]

thank you guys for the information.
Surf, great video thanks!

[Dark5ide]

Thanks for posting the video link Surf--I´ll be needing to reference it again soon as BCM has 14.5¨ LWs back in stock.

[uwe1]

It will fit.

Shaving front sight base for Troy TRX Extreme Battle Rail (http://www.youtube.com/watch?v=I5rPPyYdFUs)

Surf,

Thanks so much for all the videos you've done on AR15 assembly and Glock armoring. I've seen some real old school ones on VHS, but yours are well done and easy to follow. Your vids give this bubba gunsmith a little courage!

Last Monday, I had my FSB removed on my DDM4 and exchanged for a lo-pro gas block/13" TRX rail. After seeing your video (and seeing the nasty scar from the pinning), my OCD got the better of me and I took the original FSB to task. It took me a little longer than 45 minutes because it was my first one. I also did the whole thing with a Dremel because my angle grinder has a broken wheel. The lo-pro gas block is now out and the shaved FSB has been re-pinned. The Aluminum Black worked great on the steel.

Tomorrow will be the test as I'll likely be heading to the range to send a few hundred rounds out to ensure that this gun will function. Thanks again for taking the time to educate.

[dakotalawdog]

Sure you wouldn't rather go with a low pro style gas block? It can be a bit of a PITA to punch out the taper pins, but with a big hammer, some heat and punches, its probably easier than grinding down a FSB. If you don't want to dimple the barrel (BCM sells a slick tool for that), you can pick up a clamp on style DD gas block. I've used several, they work great....

also... if your FSB has bayo lugs, be sure to grid them off too, if you want to mount a rail on the bottom of your hand guard.

[uwe1]

Sure you wouldn't rather go with a low pro style gas block? It can be a bit of a PITA to punch out the taper pins, but with a big hammer, some heat and punches, its probably easier than grinding down a FSB. If you don't want to dimple the barrel (BCM sells a slick tool for that), you can pick up a clamp on style DD gas block. I've used several, they work great....

also... if your FSB has bayo lugs, be sure to grid them off too, if you want to mount a rail on the bottom of your hand guard.

Some people go with the pinned FSB because it is generally a more secure method of attachment versus set screws on a low profile gas block. In addition, if your gun already had a pinned FSB, going to the lo-pro will reveal the scar on the barrel which is an exposed area of metal (not parkerized). Also, if you use the clamped gas block, it could be a very narrow fit under the Troy TRX Extreme rails (if you're planning to use those).

My FSB was already removed by the gunsmith and a low profile gas block was in its place revealing the huge scar from the pinning. I remembered watching Surf's FSH shaving video and re-watched it a few times, and then attempted it with great results. Afterwards, I removed the installed rail and lo-pro gas block, then replaced the pinned FSB.

I took the gun out and shot about 150 rounds out of it, some slow fire, some fast. Not one hiccup. Needless to say, I'm very pleased.

[Surf]

Uwe1 - I am very glad that you find the video's helpful. They are a bit long but I try to cover them in a manner that anyone with a little bit of DIY ability and the desire to do it can follow along easily. I am very glad to hear that your FSB came out well!

[localfiend]

also... if your FSB has bayo lugs, be sure to grid them off too, if you want to mount a rail on the bottom of your hand guard.

Or not...

http://i59.photobucket.com/albums/g295/localfiend/M4/full.jpg

http://i59.photobucket.com/albums/g295/localfiend/M4/front.jpg

:D

[Surf]

Or not...

http://i59.photobucket.com/albums/g295/localfiend/M4/full.jpg

http://i59.photobucket.com/albums/g295/localfiend/M4/front.jpg

:DThe OP is talking specifically about the Troy and VTAC Extreme BattleRails. For the longer version of these rails to fit the bayo lug needs to go.

[uwe1]

One thing I'll add about grinding the FSB is the "finish". I first used the cutting wheel of the Dremel to shape it, but felt that I wasn't getting as good control as I would like, so I used one of the brown grinding stone attachments. I was able to get a very consistent grainy looking, but even surface with that. I probably should have just stopped there, but I ended up using the sandpaper attachment and got the cut surfaces smoother.

It still looks great, but the smoother texture is a bit more shiny than the rest of the FSB and I don't think that it took the Aluminum Black finish as well as if I had left it more coarse. Fortunately the shinier part is under the rail so it's not too reflective.