Thread: Throat Erosion - New Barrel

First time I've taken the time to re-measure this but it certainly affects accuracy (group size) more than I thought, and ultimately down range kill shots.
So last December I upgraded to a carbon wrapped barrel. As part of the whole load development exercize, I obtained the OAL measurement and CBTO. From here I proceeded to trial seating depths until I got what I wanted - so standard procedure really.
Ended up with a .4 inch group at 100 so understandably pretty happy with the investment and result.
Last Sunday sees me up at the range with a couple of mates, and up I get to put a few rounds into a target just to reinforce the .4 inch group. Well .4 grew to just over an inchand a bit when absolutely nothing had changed with my components or process. This is after 200 rounds, a few of which were a bit hot but mostly pretty reasonable
Bit of head scratching had me re-measure my OAL and CBTO, and of course that wont change, but the jump to the lands certainly had. Where I was using a 40 thou jump, now its a 50 thou jump and the groups are shit.
Hopefully now that Ive fixed the problem.