[ARCHIVED THREAD] - A2 and A4 Front sight base differences

Posted: 1/22/2009 4:49:53 AM EDT

Will a barrel with an A2 front site base match to a flat-top upper without sighting issues? If I'm not mistaken, most flat-top barrelled upper assemblies use the A4 F-marked front sight bases. I'm wondering if I should plan a front site base swap if I mate an A2 barrel assembly to a flat-top upper. Thanks.

Posted: 1/22/2009 2:16:23 PM EDT

[#1]

You will most probably need an extended front sight post when using an A2 FSB with an A4 upper receiver. Several manufacturers use A2 FSBs with flat-top receivers. Bushmaster comes to mind. RRA makes an .040" extended front sight post that works well.

Posted: 1/22/2009 3:08:33 PM EDT

[#2]

The F marked FSB was designed for carbines whether they be flat top or fix carry handle. Non-F marked FSBs can be used with either but you may need a taller FSP with standard FSBs. F marked FSBs can be used with flat top rifle lengths as well.

Posted: 1/23/2009 3:55:05 AM EDT

[#3]

Any idea as to whether or not the GI issue A4s have 'F' front sight bases?

[ARCHIVED THREAD] - A2 and A4 Front sight base differences

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[ARCHIVED THREAD] - A2 and A4 Front sight base differences

[ARCHIVED THREAD] - A2 and A4 Front sight base differences