I want to add an ARM Inc #40 A2 buis to my Colt6920 carbine. I noticed that when ordering from bushmaster they claim you need to change the front sight post Note: This sight is designed to work in conjunction with the A.R.M.S. SIR System forends Due to the aperture height on this sight, you should order the .040 taller Front Sight Post. Does this apply to the Colt as well? I called Colt and they could not give me an answer. any help is appreciated.
…you will be just fine with the colt…it has the correct height FSB…i have an Arms 40 standard…and an Arms 40L-SP (same plane aperatures)…i really perfer to have the same plane aperatures on a carbine…check it out before you buy…
Your Colt should have an F marked FSB and be fine with the ARMS sight. Most commercial models including the Bushmaster don’t have the F marked FSB and therefore may require the taller front sight post. I have a ARMS 40 on my RRA and it did not require a taller front sight post. I also have a SIR system (which I’m looking to replace) and while the contours of the front of the BUIS fit together with the rear of the rail, neither effects the zero of the sight. I initially ran the 40 as only irons with a standard set of handguards with no problems.
-RD62
awsome info thanks. The guy from Colt actually called me back this afternoon,basically he siad they think I should be fine