Alright, have some questions regarding zeroing after #38 installation.  Got the sleeve and mounted it, got the Aimpoint in the #22M68 and mounted that, sighted in irons first at 25 yards-right on.  On to 100 yards aiming at center mass, hits centered horizontally but all shots printed in the head.  Tried the Aimpoint, which is sighted in according to the irons and it's dead on at 100 yards.

I've adjusted my front sight up 4 clicks.  It's moving the shots towards center slowly.  How much further can I go??  (Obviously when the sight post pops out I've gone to far so I thought I'd ask before that happens.)  Is Bushmaster correct when they print in their catalog that Colt's are out of spec. with their sight heights??  Does one need to purchase the higher front sight post that Bushmaster is selling or can I keep adjusting my front enough to get my shots centered?

Thanks for any info.

I'd like to add that Steve at ADCO is a great person to do business with.  Prices seemed to be just a hair lower than other places and a $4 flat shipping rate sweetens the deal.  Was very patient with my myriad of questions regarding ordering procedures.  I sent the money order on a Tuesday afternoon from MN and had my items the following Monday afternoon.  

You may need the higher front sight post. I noticed that when I zeroed my M4gery after installing a Bushy carry handle, my front sight post base was extended above the flat of the sight tower where the post screws in.

Dosen't bother me because it is still secure, but next time I order from BM I'm throwing in a new higher front sight post to the order.

Lessons learned from Bushy.

According to Bushy the Colt A3 flattop sight plane is 0.040" higher than the Colt A2 sight plane.

So Colt uses a different front-sight/gas-block, Bushy in all their wisdom decided to use a A2 front sight and a lower carry handle on their flattops.

So when using a Knight, GG&G, ARSM, etc… BUIS on your Bushy you need to get a new front sight post from Bushy that is +0.040" higher. This puts your front sight post approx level with the protective ears, instead of below them like it should be.

Hope that helps, I bought the front sight post when I ordered my upper, but I'm going to replace my front sight post anyway with the GG&G tactical flip up front sight and I didn't get the Bushy carry handle anyway so long term the problem solved for me, and in the future if I decide to get a carry handle, I'll just get a Colt spec handle and no need to re-adjust zero to switch between my ARMS #40 & the carry handle. (Although I see no need to get a carry handle other than prosperities sake...)

Hope that helps

Thanks for the help.

I guess I should have explained that the rifle is a Bushmaster but it seems you guys caught on.  

Great, something else I need to order.  UGH.

Another question regarding the allen screws on the 22M68, how tight???  Loctite???

Thanks again

Colt make the carbine front sight higer because they should and must, do to geometry. The shorter the barrel the higher to the merging sight plane the front post must be. A higher front sight post housing is on all gov't M4's, the copy cats only give one ht. since it is cheaper and they didn't do their homework in the first place, nor do they sell to the US military or pass inspection.
Gov't rear sights meet one ht. std., Gov't front sights meet a spec ht. based on barrel length, that's about the long and short of it.
Good shootin, Jack