Been doing bullet testing in my CZ-527 (.223) and it has been doing something funny. It has always done it to some degree, but noticed it again today. As loads get hotter and/or bullets heavier, it shoots left. Back off charge or bullet weight and POI goes back right. What could be causing this?

This is natural and expected. The barrel acts a bit like an un-restrained hose with the water turned on. As the bullet weight increases or the powder charge increases the bullet will leave the barrel at a diferent part of the oscilation cycle and it usually progreses predictablly once the pattern is indicated. This impact movement is sometimes used to get two different bulllets to the same poi.

Von Gruff.

Let me expand the thought a little bit. Most rifles will very POI with different loads, I know and understand that. But this one is very consistent with what it does, and very predictable. It is odd to me that the loads do not string vertically with charge weight, but nearly dead horizontal. It just makes me wonder if there is a problem with the bedding, or bolt lugs, or something.

Diaginal stringing would be an indication of something with the bedding, or a barrel that was not propery relieved.

Have you checked the barrel channel. There may be a touch on the right side that becomes evident with heavier loads.

Von Gruff.

quote:

As loads get hotter and/or bullets heavier, it shoots left. Back off charge or bullet weight and POI goes back right.

Do you expect bullets of different weights to have the same impact point? It doesn’t always work out that way. Add a hot barrel and the possibilities are interesting.

The barrel could touch just a bit, I can't rule that out completely, but I sure don't see any evidence of it. Might relieve it a bit more just to be sure.

Barrel is light on this CZ, could just be a natural quirk. This little rifle, while not bad at all, does not not quite live up to the accuracy expectations I had for it based on what I had read on them. Just another one of those things that make me question it. Probably just got an "average" one though, and not one of the ones that folks brag on.

One good thing about it, being so predictable, is that I know exactly what to expect. Maybe I shouldn't be looking a gift horse in the mouth so to speak. At least I don't need to throw chicken bones to guess what is going to happen next.