I had been looking at these {if you have the pinholes allready  it should be easy posts} for months and finally gave in and got a PRI front sight.

Holly cow are these a bitch to install
1 (first you have to remove your front post (my Bushy had to be torched to let the pins go)

2 I realized that Bushmaster finishes WHOLE barrel assemblies (so Know I had 2 shiny metal bands on the barrel)- I even tryed to order it without the post and the guy said you can just remove it yourself [thanks a lot- know I have a moly baked on barrel finish]

3 then I put on the PRI only to realize that the damn thing uses HUGE allen screws rather than pins-

4 now I got out the dremel and begin hacking 2 channels for the screws to fit in (no more depth just width is needed).

5 Then I fitted the sight like 6-8 times before your grooves were big enough for the allenscrews to fit.

6 sit back and enjoy (1 PRI post- cost:
$179
+ losing the nice barrel finish to the Baked on crap
+ 30- 60 nice fine [near invisible] little Dremel splinters- I swear I've probably gotten a lifetime supply of "iron" from these little suckers over the years- which is why I avoid dremeling steel at all costs- especially with the tungsten rotary milling bit (like this job required)- The tungtsten high-speed steel bit makes almost microscopic fibers out of the metal that are about 2/10ths of an inch long- OUCH  

I was also barreling the rifle and the combo wrench slipped and now I have a nice huge gash in the back of my hand from the workbench and 3 blood blisters from who knows what

It just hasn't been my "best" night.

Ah, the joys of 'shade tree' gunsmithing![BD]

I'm in the market for a flip up front sight. Luckily my carbine doesn't currently have a front sight. That make the job a bit easier. I didn't know that the PRI uses larger diam. alen screws than standard. That could cause problems, I may have to pay my Smith to fit the front sight, OR I may just send it to GG&G and have them install theirs. Its cheaper (installed) than the PRI is uninstalled.

They aren't large for allen heads but they are about twice the diameter of the original barrel pins.

The Bushmaster pinholes line up pretty close to the PRI, but my Model 1 Sales barrel was totally different.  (both require alterations but it is a bit easier to elongate [using the word loosley as the holes need to be nearly .22inch long] the Bushy holes than to make new ones).

The problem comes from the fact that the pin holes in the original front sights are never in the same place twice. A round hand file used to sharpen chain saw chains is a good way to open up the cuts in the barrel. For a gunsmith with a mill, it is very easy to make a pass with a ball end mill. But us basement gunplumbers have to find alternate means. The chain saw file works well. Also, this is a problem with the gas blocks for the .750 diameter barrel. The PRI sights that the thinner .625 barrel have practically no allen screw area that requires fitting.

I started out as a "Production Machinist" in 1969, right out of school, and through the years I've been a welder, millwright, machinist, auto/truck mechanic, and machine maintenance mechanic...

A few years back, my doctor wanted me to have an MRI...But first, they x-rayed my eyes...Then they canceled the MRI...

I have microscopic steel splinters in my eyes...They can't be felt, don't affect my vision, and can't be removed...

But if I went under an MRI, all 3 of the above would occur... [:(]

Word to the wise: Safety Glasses don't always stop everything...If your doctor says "MRI", get your eyes x-rayed first...

WOW thanks for the info- I've gotten these splinters in my eyes (but maybe my contacts have kept them off of my retinas).

PRI's are $190 with the .625 ID and $180 in the more popular .75in ID.