can anyone tell me what the different hammers are...I never noticed this before my new build has the rounded one ,the bushy has the notched one...bolt carrier feels like it is snagging a little on the rounded hammer....

The notched ones are the Colt [b]design[/b] and are meant to be used with the open bottom bolt carriers. If the hammer slips (or tries to follow the carrier closed) the hammer is supposed to catch the underside of the firing pin spool and lock the gun up instead of allowing full auto fire.

The rounded (neutured M16) hammers can also catch the firing pin spool if the firing pin spool is too large (M16 firing pin) or if the hammer sits up too high (mislocated H/T pin holes, short trigger, bad hammer cut).

I always recommend shrouded bolt carriers for the most reliability.

If your hammer is catching the FP then you'll see it it as a bent FP retaining pin.

Does the following sound right?
When you work the action (with the charging handle) with the trigger forward the carrier drags.

When you hold the trigger to the rear and work the action the carrier does not drag.

[edited for "sound right?"]

yes, the carrier drags going both ways.. the bolt carrier will actualy stop in forward motion with buffer spring pressure on it....?this does not happen on the bushy lower...probably be best to just swap out the hammer...

Compare the diameters of the firing pin spools first.

[url]http://www.biggerhammer.net/ar15/hammers/[/url]

Go here and all your questions will be answered.