05-08-2011, 11:07 AM
pinzgauer Wrote:You really need to learn to measure the right seating depth for your rifle.
PG is spot-on. I use a Sinclair Action Comparator, and have measurements (in my rifle, obviously) for two of the bullets you listed. The 120g SMK and 120g Hot-Cor both have configurations (shorter ogives, or tip-to-ogive?) that prevent simply loading to magazine length. In my Satern barrel, The SMK's COAL to just touch the rifling is 2.216, and the Hot-Cor is 2.160. Loading either of these to a straight 2.260 would lead to significant jamming into the rifling.
I believe this is represented in the load data that AA provides, as their recommended COAL for the 120g SMK is 2.220. Based on my own measurements, that isn't just a number they picked out of the air; there's a reason they included the COAL column rather than stating that all bullets could be loaded to magazine length. Since the other bullets you're using aren't listed, you need to gather that data from your rifle.
I would attribute the "sometimes works, sometimes not" aspect to variations in bullet ogive length (I think that's correct terminology). When measuring using bullet comparators, I've found variations of at least +/-.007 (ironically, most recently with Sierra 120g SMK's), which would change a load from jump to jam if the chosen seating depth doesn't have enough margin built-in.
I'm certainly not guaranteeing that you don't have something else going on; as mentioned, you may have a legitimate lack-of-throat issue. However, there isn't enough data to conclude that yet. If you make some OAL measurements and find that you're significantly shorter than expected, that would be an indicator; so would the recommended chamber cast. But since you need a OAL gauge/comparator anyway (IMHO), I'd start there.