Have searched crimp but yields too large, so please bear with me...

Have been reloading no crimp for AR and satisfied, until:

Was gifted a bunch of unidentified component 62 and 55 grain fmj bullets. Weight sorted (1.2 grains extreme variation) and separated bullets with lead running up out of the bases. Weighed powder for ladder testing. New, unfired lc brass. Got 3min groups from a 2 min gun. Yeah, not match bullets or gun, but:

Much, much less effort to seat than other experiences led me to redo and expand on a test once
Suggested to me:

Measure headspace, chamber round, remeasure headspace. Paralled previous experience in that there was 2 thou shoulder setback from chambering. What I added was seating depth measurement pre and post chambering. Limited time so only 5 rounds checked, but had seating depth change a thou or 2 BOTH directions.

Doubt crimping will make big dif in accuracy, but considering cause of ocd. Since I trim gauged from shoulder (typically less than 2 thou hdsp variance) would Lee collet or what be best for consistent crimp?

Know crimping won't be magic, but I hate having or introducing variation. Chosen loads not hot, so I doubt setback induced pressure spikes, but...

Thanks in advance....