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1/22/2020 12:12:56 PM
Posted: 1/18/2015 8:36:15 PM EST
what are the differences between "F" marked uppers and non "F" marked ones? How about front sight bases? Just got two from PSA and they seem to be indifferent as far as compatibility. A little guidance please. thanx TG
Link Posted: 1/18/2015 8:40:42 PM EST
[Last Edit: 1/18/2015 8:41:43 PM EST by OverScoped]
F marked front sight bases are to be used with a Flat top upper and a detachable carry handle.



Sometimes you can get enough adjustment out of a non f marked front sight base to make it work, and if you have to, you can get a different sized pin.

Link Posted: 1/19/2015 9:38:48 AM EST
[Last Edit: 1/19/2015 9:39:26 AM EST by warpig8654]
Originally Posted By trenchgun:
what are the differences between "F" marked uppers and non "F" marked ones? How about front sight bases? Just got two from PSA and they seem to be indifferent as far as compatibility. A little guidance please. thanx TG
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The uppers aren't F marked. That only applies to the FSB. The F marked FSB is .04 taller than the non F marked variety.
Link Posted: 1/19/2015 5:14:21 PM EST
[Last Edit: 1/19/2015 5:15:39 PM EST by j3_]
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Originally Posted By warpig8654:


The uppers aren't F marked. That only applies to the FSB. The F marked FSB is .04 taller than the non F marked variety.
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Originally Posted By warpig8654:
Originally Posted By trenchgun:
what are the differences between "F" marked uppers and non "F" marked ones? How about front sight bases? Just got two from PSA and they seem to be indifferent as far as compatibility. A little guidance please. thanx TG


The uppers aren't F marked. That only applies to the FSB. The F marked FSB is .04 taller than the non F marked variety.

PSA has sold in the past upper receivers with and F stamped/ engraved in the side of the upper around the area where a normal forge mark is.
Only difference in the ones I got were painted T marks opposed to non painted one on other upper from them
Link Posted: 1/19/2015 6:31:56 PM EST
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Originally Posted By j3_:


PSA has sold in the past upper receivers with and F stamped/ engraved in the side of the upper around the area where a normal forge mark is.
Only difference in the ones I got were painted T marks opposed to non painted one on other upper from them
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Originally Posted By j3_:
Originally Posted By warpig8654:
Originally Posted By trenchgun:
what are the differences between "F" marked uppers and non "F" marked ones? How about front sight bases? Just got two from PSA and they seem to be indifferent as far as compatibility. A little guidance please. thanx TG


The uppers aren't F marked. That only applies to the FSB. The F marked FSB is .04 taller than the non F marked variety.


PSA has sold in the past upper receivers with and F stamped/ engraved in the side of the upper around the area where a normal forge mark is.
Only difference in the ones I got were painted T marks opposed to non painted one on other upper from them


I caused some confusion here. An F stamped upper is machined by manufacturer FN. An F stamped / marked FSB is regarding the height of the FSB. Two different things. I appologize for the confusion.
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