I am sure I am not the first one to think of this but I am glad I did.
I am very new to AR's and a few months ago I ordered a complete barrel assembly direct from Bushmaster.  I have this "thing" about naked AR barrels so I innocently ordered the barrel with a Y-Comp.  I was very disappointed when it arrived.  Bushmaster factory installs Ycomps on post ban barrels by cross drilling and setting it with loctite and a rollpin.  It really looked cheesy to say the least.  Oh well, what could I do?  I couldn't really take it off with the big channel drilled across the bottom of the barrel.  Well, setting aside the whole issue of how OBNOXIOUS the damn thing is, the thing BLEW OFF downrange after about 150 rounds!  I mean it LAUNCHED!  It just sheared off the rollpin leaving a perfect outline of the barrel.....

WOW, if anyone ever doubts the pressures released by firing a rifle, here is the evidence!

Anyway, I really did not want to put the thing back on but I also did not want to spend any more money at the time.  I had the YComp opened up to @ .30 cal and that took care of the pressure and noise but I still had the ugly roll pin sticking out on both sides.  

The other day I was putting some tools away and came across my tap set and it got me thinking....I did not want to put cap set screws in the sides of the comp but what if I tapped the hole where the rollpin goes through?  Worked like a charm.  I opened up the hole to a #25 bit and tapped it with a 10/24 tap.  I then put 2 set screws in sideways so they met in the middle and gave each a "bottom".

Eventhough anything other than a threaded barrel is just a compromise, I like this compromise.  It looks better than a rollpin or sideways set screws sticking out and it is not as permanent as blind pinning.  I wish I never had Busmaster notch the barrel in the first place but I like the way this came out.

Would that qualify your upper as Pre Ban since you can now remove the break?
I thought they had to be permanetly attached.
Other than that, it looks like a good quality job.

The ban only applies to hiders, not breaks or compensators.

It only has to be permanently attached if the barrel is threaded.

what avatar???

IF the brake had been installed on a threaded muzzle, the brake would not have sheared the roll pinb they installed it with, this is a "loose fit" press on brake, no BS laws have been violated, no small fuzzy animals harmed... just some people that cain't read plane engrish!.

Rick, if you want i can zap that with the MIG welder... but it's not needed, y'all dun good!

The installation is legal, but is it legal to open up the brake to .30 at the muzzle?  I was under the conclusion that ATF had strict specs on what the muzzle diameter could be on a brake.  I could be wrong though.

Not on the inside diameter.  They only care about the outside specifically if it's a fake flash hider as to not allow bayonet or grenade launcher to be attached.

How LONG is your barrel?

If it's less than 16" w/the ycomp removed, then it's now illegal.

Anything less than 16" MUST have the brake (or even a f/h) permentantly installed.

I thought that the inside diameter was the sole difference between a brake and a flash hider???

I hope this doesn't happen with all Bushmaster Mini-Y Comps.  I just bought a brand new Bushmaster Model XM15-M4 A3 last week with the mini-y comp on it.

If the OD of the brake is the same as an A2 flash hider, it's considered a grenade launcher and therefore an evil feature.
ID is inconsequential.

I actually [b]like[/b] my mini-CompY on my Bushy M4!  That being said it's coming off the day the ban expires...

Why not the obvious choice of sending it back to Bushmaster and having them fix it?  I've got a Bushmaster AK Shorty with the AK muzzle brake on it.  No roll pin.  It has a solid pin that is welded in place.  Can't even see it.  Perhaps the barrel is threaded so they have to weld the pin in place?  I know that if it flies off like yours, its going back to the factory the next day!

Rick in Vegas,

Some food for thought - it's possible that by enlarging the i.d. size of the muzzle opening of your Comp you're 'modifying' an ATF approved muzzle device and therefore rendering it illegal. I don't know for certain, but that's a possibility you might want to investigate! I do know that part of what allows a compensator to function is a muzzle i.d. that's close in size to the bore diameter.

I posted here about replacing the compensator on my MT6400C (roll-pinned, smooth barrel) several months ago with the SOG ARMORY A2 look-alike legal comp. You might want to see if you can find that thread. There are pictures there (posted by another member) and instructions for covering up the lock-screw holes.

All of this probably important only if the ban is signed!