Hi you all,

Long time reader, 2nd time poster. Completely new to AR's. I appreciate any help.

I bought three AR's (go big or...something)
1. colt 6720
2. upper BCM 16" light weight middy with MI ss12g2
3. for my father: upper BCM 16" LW mid with Centurion Arms C4 12"
I'm still waiting on the lowers for the two uppers and using the colt lower in the meantime.

My dilemma is my father just informed me the he wants iron sight only and he expects accuracy (long time rifleman and korea vet.). However, I don't know how to get a front sight mounted on a 12" rail without having the sight move with the FF rail. I looked into buying a fsb and installing it on the front, but that is beyond my skill level, so I would have to pay a gunsmith to do it properly and that is money I'd rather save if possible. I understand the changes in accuracy with a front buis on a FF is relatively inconsequential for combat engagements, but my dad will be a target shooter only and I want him to have a good experience. I've already decided that an LMT A2- style sight will be best for him, but the front sight is beyond me.

1. Can I buy a gasblock or similar that securely mounts to the barrel in front of the rail (no gunsmithing required), then attach a fixed front sight to it?
2. Is there a front sight that mounts to the barrel (aside from a standard fsb)? The barrel doesn't have taper pins and I'm not about to drill into it.

I believe, the barrel diameter is .625, not .750.
If, in your experience, you have found that the decrease in accuracy is hardly perceptible by the common man, then I'll probably go with DD or Troy fixed front.

Thanks,
Dan