My back up ammo stocks are divided pretty much evenly between Q3131A and XM193 and I just ordered some more XM193.  Most of my shooting has been done with Q3131A or Winchester 55 grain white box.  I am shooting a 16 inch BM M4gery mostly to 100yards but will shoot a little out to 200 yards.  I'm looking for "Minute of Paper Plate" accuracy.  Right now my rifle is zerod at 100 yards with Q3131A.

My question is for people who have experience shooting these types of ammo, is there a problem switching between the different 55 grain ammo, should I re-zero etc?

I have not had to re-zero my irons or scope shooting between q3131a, the white box 55 grain winchester or the 62 grain power point plus. They all shoot almost exactly the same out to 100 yards anyways. Accuracy may vary after that I have no idea. I have no place to shoot that far.

over the weekend i shot a couple of different loads. 100yds 20"bbl  no cleaning throughout the time.


federal american eagle 55gr
federal xm 55gr
q3131a 55gr
black hills 68gr reman


and with some loads it would open up a bit  but all of it stayed well below 1.5moa

Quoted: My question is for people who have experience shooting these types of ammo, is there a problem switching between the different 55 grain ammo, should I re-zero etc?

I would always rezero.   Different bullet shapes will travel differently in the air.  

Even though Q3131A is supposed to be the same spec as the XM193, I heve noticed that the average POI between them is off by about an inch at 100 yards.   This is still within military specifications I'm sure, but the average POI is different.