Tightness in Fire Control area of lower

[gesundheit]

I have a question on finishing the lower.

I was in the process of installed a Geissele ACT trigger on my lower. The trigger installs just fine, however the hammer is another story. I noticed that the hammer does not fall with enough force forward. In fact, initially it was stuck when the trigger was pulled. I manually pushed it forward about 10-15 times and it seemed to go forward in slow motion.

I suspected something wrong with the hammer pin holes so I took the hammer out to confirm and found them to be fine. But I did find

The semi-circle marks on both sides of the lower's front where the hammer was rubbing against the front of the lower. It seems like the lower has just a sliver of too much aluminum where the machined portion curves in the front. This is the area that is catching the hammer as it moves forward.

Since the camera phone was not taking good photos, I took the liberty of taking pics from Internet and drawing the offending areas in orange color to give you guys an idea of what area of the upper I am talking about.

My question is what would be the best way to remove this extra aluminum while keeping the finish somewhat smooth? I almost picked up a Dremel but thought I should post here before I start hacking away.

So what say you?

[MistWolf]

It would be best to first contact Aero and Geisselle to determine which, if any, part is out of spec. If either the lower or the hammer is out of spec, let the company take care of it for you.

You could take a file and remove the offending extra material, but you may not be able to keep the sides parallel and if you remove too much, the hammer might float side to side too much and possibly cause problems. In any case, before doing any cutting, make sure everything was properly installed. Here's a thread where I installed a Geisselle trigger (with photos) that might be of help
https://www.m4carbine.net/showthread.php?t=72111

Install the hammer without the spring and see if it swings freely. If it does, you might have had the hammer spring installed incorrectly. It happens quite often

[AKDoug]

It isn't necessarily an AP lower since the OP mentioned he used photos off the net to illustrate the trouble areas. However, MistWolf's suggestion is spot on. You need to contact the manufacturers and see if they will help first.

[gesundheit]

Thank you, Mistwolf (I read your thread and foundthe tip on flipping the lower very useful. I use the Brownells method of installing LPK with lower on a vice block) and AKDoug.

I will contact Geissele but before I take up their time, does anyone know what the width of the trigger supposed to be? I suspect my lower and hammer are overlaying each other in terms of milspec tolerances.