You might try a different tritium front if you want tritium. Meprolights are pretty close in size to an original A1 front


http://www.amazon.com/Meprolight-AR-15-M-16A1-Tru-Dot-Sight/dp/B0002INGN8

Not sure on the width, but Ameriglo has finer adjustment:

http://www.amazon.com/Ameriglo-Most-Tritium-Front-Only/dp/B000OI81AY


If you want something with a smaller aiming point that glows in the dark you might be better off buying a red dot.



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