AO M1 Carbine Front Sight Key Mod

I posted recently that I got a new Auto Ordnance M1 Carbine that I'm very happy with. It feeds and fires without a hitch and I've noticed that a likely reason for it's exceptional accuracy, 2" @ 100yds which is phenomenal for a carbine, is because it has a tighter chamber than my GI NPM M1 Carbine. This isn't a problem as it feeds my handloads just fine and I just love the idea of an accurate M1 Carbine.

Anyway, I decided to do some 200 and 300 yd shooting with it just for grins and I've started to notice that the very slight front sight tilt to the left it had with throws off my sighting picture at long ranges. It's not really that noticeable but I did have to run the rear sight a few clicks to the left of center to dial it in and now that I'm aware of it, it needs fixing. Never one to shy away from a chance to work on my weapons, I decided to tackle this job and straighten it. The normal way to accomplish this would be to clamp the action in an action block and turn the barrel a tiny bit to line up the front sight vertically. However, in this case I decided I didn't want to do that because the gas piston is attached to the barrel and so it would rotate out of alignment with the Operating Slide.

So, I pulled the front sight by driving out the pin and then backing it off the barrel and noted that it had a positioning key to lock it in place on the barrel. I decided to make a slightly offset key so that it would position the sight a few degrees to the right to straighten it up. This key is small, about 1/2" long, less than 1/8" high, and about 3/16" thick with a small round notch for the locking pin. A search through my scrap parts bin yielded a small piece of metal strap about the right thickness for the job. After a bit of cuttin, filin, and fittin I had a offset key that fit nice and snug and when I drove the retaining pin through the sight, rotated it perfectly to the vertical. So, I lubed it up, reinstalled the sight and now it sits perfectly vertical. All in all a nice little project accomplished.

A quick trip to the range demonstrated that I no longer had to adjust the windage those few clicks to the left and now 200 yd shots are surprisingly accurate. I should mention that even though this little carbine is exceptionally accurate, shooting it out at 300 yds is a stretch. The little 110grn round nose bullets traveling at 2000fps just run out of steam that far out and any wind will push them a fair amount. Still, it's a ton of fun to shoot and my long dormant supply of handloading components will be put to good use through it.

Here's a drawing of the standard key and what my offset one looks like. Note how the top portion of the key is biased over to the right a few thousandths:

Good info, thanks.

I had to tap my rear sight to the left as well. At just 25 yards, I made a 50 shot group that was about 2 inches to the right, and like 2 inches high. I expect the 2" high as I am just 25 yards away. So I tap it and then have to tap it back...so on and so forth...but now, my groups are centered.

I can't imagine making a tight group at 100 yards using these irons...so my hat's off to you.

I also didn't really absorb what you wrote in the OP so I am going to read it again. Also, are you using the stock rear sight, or did you upgrade to the Kensight?

Yes, I upgraded to a type II Kensight that's the same as those put on the carbines when they were arsenal rebuilt so that makes for a much better sight picture and the ability to adjust for windage. I don't think that the original flip sight has that good of accuracy in it. Plus, the 2" groups at 100 yds were done by my carbine, but not with me shooting it. You see, we have a younger shooter who's really into CMP competitions and good enough with his M1A to go to Camp Perry with it. He happened to be out at the range when I was sighting it in and came over to chat. I could get it to produce 3½"-4" groups with my old eyes which is the limit of my ability but I felt it had more accuracy in it so I asked him if he's like to give it a try.

He was the one with the young eyes, steady hands, and skill to make it produce the 2" group. He mentioned the slightly canted front sight (only a couple of degrees off center) that I'd noticed and said I could look into fixing that for better long range accuracy. He also told me at 100yds, it was the most accurate M1 Carbine he'd ever shot and we both agreed that it was a keeper. His comment is what actually turned out to be the impetus for me to go going and straighten out the front sight.

BTW, I made it out to the range last weekend with my son and he has always loved my M1 Carbine so he was thrilled I got a shooter. At 27, he's got great eyes and was able to knock down some bowling pins at 200 yds with it off the rest. He agrees that it's considerably more accurate than my GI M1 Carbine and he managed to talk me into letting him shoot a fair amount of the ammo I brought for it that day. Oh well, kids are like that.

Looking back at the other thread, it seems you are the one who told me about the Kensight in the first place. I didn't make that connection yesterday .

Also, looking at your MS Paint images, I can't really tell what you did, they looked pretty close in appearance. Did you fabricate the new piece out of metal yourself, or modify the existing? Also, have you run across any aftermarket front sights for the M1 Carbine? I'd be interested in tritium, or day glow fiber optic...or something like that.

As I said in my post, I used, "...a small piece of metal strap about the right thickness..." to make the part myself. If you look at the bottom end view closely, you'll note that the top, thicker part is slid to the right just a bit. That's the part of the key that fits into the slot in the sight and by offsetting it a bit to the right, rotates the sight a few degrees to the right.

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