Range report on M16A1 repro - small problem

[Bill Hollinger]

AR-15 FRONT SIGHT HOUSING | Brownells


$34.99 for the A1

[RBruce]

Also, same part from Midway: DoubleStar A2 Front Sight Gas Block Bayonet Lug AR-15 LR-308 Steel

[fjruple]

Turns out that the 20" skinny A1 barrel came with a F marked front sight base. I guess that is the reason for shooting low, although I don't see how .04" could make that much difference at 25 yards. Should the H marked base solve my problem?

RBruce-- Check with the retro M16 folks over at AR15.Com - Your Firearm Resource. (AR-15, AR-10, M4 Carbine, M16, HK, SIG, FNH, FAL, AK-47, 50 Cal, M1/M1A, Handgun, Pistol, Training, Hunting, and More!). Many can re-install a new M16A1 FSB onto your barrel. Welcome to the AR retro world. Another source of addiction.

--fjruple

[browningautorifle]

Your pins may not line up correctly and you may not have a top dead center base. Your front and rear sights might have a tilt...that's what I'm eluding to when putting on a strange FSB. Taking them off in no problem. Pounding the pins back is no problem. Your sight may lean...

[RBruce]

OK, I understand, Jim. So how do I prevent or correct the lean?

[Bill Hollinger]

Put the sight base on and align it using two straight edge rulers and then drive the pins in. The chances are it will be fine if everything is milspec. Be prepared for canted sights

[browningautorifle]

Be prepared for canted sights

From what I've experienced, if the holes are already drilled but not for the barrel you have it may not line up. Don't know about Bill's method...I guess you'll find out.

[Brian Dick]

Get a tapered reamer, run it in and just clean up the holes after you line everything up to the best of your ability with the correct front sight base. Another little trick is to run some soft solder into the holes first, then clean up with a taper reamer and tap in the pins. It will keep the front sight base from falling back into it's old alignment and follow the new taper reamed hole. I've fixed many a canted AK front sight base too with this method. Many of them were made on Monday morning after a weekend of swilling vodka I think!

[jmoore]

Extra long taper pins can be easily had from industrial suppliers such as MSC.

I think those holes were drilled and taper reamed with minimal fixturing, including Colt military and civilian barrel assemblies. So the chances of having the holes line up are miniscule. Do as Brian Dick advises, but be careful to ensure that the base remains straight! Thinking I did a photo thread on such an operation a few years back on this forum. Should still have photos on P'Bucket at any rate, if needed.

ETA: Must be on drugs! No thread & no photos...It's all clear in inside me head, but pullng images from there isn't too feasible. Probably more elaborate than you want, anyway. Milling machine, right angle tooling plate for upper receiver, barrel muzzle center, front sight post hole locating tool adapted from dial heigth gage, etc., etc.