I have an old Colt A1 pencil barrelled upper.  This is the front sight that is round and has 5 dents instead of the newer 4 on the A2.  The thing is so tight that I had to use a wrench on my front sight tool to turn it.  Must be rusted underneath.  I actually could turn it with the increased torque, but stripped the tits off of the tool in the sight dents.  I suspect the underside is rusted.  Have applied Kroil and other lube, but still tight and now I need a new sight tool.  Can the old A1 sight be replaced with a new A2 sight without problems or do I need the old style?

Where?who has the old style sight (unused)for the Colt?  
Do I need any other accessories (sprigs, etc)?
Who has A1 sight tools to repalace the one I just sheared off?
I still need a replacement A1 front sight for another retro build I am doing on an A1 even if the other barrell will take an A2 replacement.  

Thanks for your help! Alan

are you wanting to replace the whole fsb or just the sight post?


the sight post are similar other than the slots and shape, so the a2 will work in place of the a1 all the rest is similar. i ordered a a1 sight tool from brownells with other items but when i got it it was cheap looking, worse than potmetal.

if you are replacing the whole fsb you will need a gunsmith that knows what he's doing cause the fsb pin holes need to be drilled according to the bbl.

I think once i remove the front sight post with a wrench and clean out the rusted threads (I assume this is the problem) that I will only need a replacement post.  The sight tool looked like cheap white metal I need a really good one.  I will replace one with an A2 on a grins and giggles gun, but I still need to get an original round 5 dents one and sight tool for the retro rebuild I ma doing.  Thanks!

OKAY wher can you get a good quality A1 front sight tool?

Lots of folks have them, like Bushmaster, for $8:


I replaced my A1 sight on my pencil-barreled build with a A2 square style, and only because of my particular build, found it necessary to get a .030" taller one, but it screwed right in nonetheless.  Good luck, post pics when done!

To answer your original question, A1 and A2 sight blades are interchangable.

In fact, I've put A2 profile blades on all three of my pre A2 Colt uppers, so as to have uniformity in all my ARs.