BCM Dissipator build

[ace4059]

While this was a purchased BCM rifle, I figured it went under the custom build because there was a little machining involved. I tried to use the KISS principle.

Ive always wanted a dissipator upper but wanted a quality built one, not the lower tier companies that offer the pre built dissipator upper. I did not want this to be over gassed, and did not want the true rifle length gas system so I settled for a faux dissipator style setup.
My stipulations were it had to have a gas port on the smaller side, and both gas blocks had to be pinned. Listen up Colt and BCM. It would be nice if one of you would offer a factory built rifle like this. It would have been cheaper and not to mention less time consuming. Ive been working on this for about 10 months and finally got it completed to my liking.

It started life as a standard BCM 16" midlength.
I used the band saw to chop the FSB, sling swivel, and bayonet lug off the midlength gas block. I then smoothed it off with a belt sander and touched it up with a roloc pad. Then recoated it with a little hitemp black baked on paint.

Then I used a spare FSB from another BCM upper. The barrel was tapered on the end where this FSB would go, so it was loose and had to be built up on the inside of the FSB. I welded two small tack welds at 12 o'clock and hand filed them to a tight and perfect fit. This made the inside diameter of the FSB .745 instead of the orginal .750

I tappered a hole in the bottom of the faux FSB to use a set screw so the FSB would be aligned and be held in place while the tapered pin holes were to be drilled. I sent the barrel off to a guy that had a jig to align the FSB so it would not have any cant to assure the rear sight would be close to centered as possible and he drilled the holes.

I installed the triangle hand guard catch (sorry dont know the exact name) behind the faux FSB and threaded the hole where the gas tube would orginally go if this was the functioning FSB. I used a screw to hold the triangle cap on since I did not want it floating and spinning around the barrel. Everything was installed back to factory and I used a magpul rifle length hand guard.

I did modify the hand guard to accept a M-lock quick disconnect swivel. For that I used a flat end mill bit in a drill and went to work chewing through the plastic.

Hopefully you like it. I haven't decided if Im going to put an aimpoint t-1 on it.







Since I am left handed this is where I like the quick disconnect.


The front sight lined up fairly well and I had to adjust the windage a little for 100 yrd zero. I orgnially had a magpul plastic flip sight on it and it was almost dead center compared to the photo. The troy sight had to be adjusted quite a bit more over to the right. But all in all, I am happy


Modified FSB. The one pictured was for my KINO build. For the dissipator build, I left on the swivel and bayonet lug.





Only parts I added to the BCM rifle was the magpul furniture, BAD ASS safety lever, BCM ambi charging handle, and Norco ambi mag release. Has a surefire light with arson machine m-lock mount and troy fixed rear sight.

[E_Johnson]

I like it. Clean and classy. It would definitely look good wearing a t-1, but any good red dot would round it out nicely. How do you like the fixed stock?

[joedirt199]

That is exactly how i would have built mine. Fixed moe stock and moe handguards. Looks great.

[ace4059]

I chose a rifle length buffer tube and spring for softer recoil and smoother shooting. I didnt want to switch over to the A5 tube and buffer system for a collapsible stock. I actually wanted an A2 stock but could not find a quality one instock at the time I was looking for one. I settled for the magpul stock which turned out to be a good selection and I am pleased with it. I probably never would have tried it, but its another great magpul product.

[operator81]

Looks great. I went the PSA route for mine and swapped out the flattop upper for an A1 upper, just cause that long sight radius was begging for iron sights. Planning on going the MOE Rifle stock as well.

[Slvr Surfr]

Nice boom stick! I also almost pulled the trigger on the Spikes Dissy, but never did. I love the look. I ended up just getting a 20" rifle to scratch the itch instead.

[black22rifle]

Just in case anyone is interested in a non spikes mock dissipator, ADCO offere a service where they turn down the barrel profile past the FSB to .625 and pin a FSB making it a dissipator. For the people willing to shave down a carbine or mid length FSB.

[ace4059]

Just in case anyone is interested in a non spikes mock dissipator, ADCO offere a service where they turn down the barrel profile past the FSB to .625 and pin a FSB making it a dissipator. For the people willing to shave down a carbine or mid length FSB.

But that takes the fun out of building it yourself. If I didn't have the tools and knowledge then that would have been my next choice.

I would have loved adding the carry handle with sights to the dissipator but I have a BCM 20" rifle already set up that way. Didn't want two rifles almost identical.