Reloading novice here - I've got an RCBS Matchermaster FL die set that I've been using for a while but never explicitly tested anything with seating depth. This is for a 6.4 CM Tikka that was recently rebarreled with a Proof Match Contour 26" steel, machined from a blank by a gunsmith. I've picked up the Hornady OAL tool and Hornady bullet comparator set, and I'm going through the process of trying to find the lands on my setup using the same 140gr ELDMs I've been loading for this rifle for a while (with mediocre results due to my inexperience). The way I initially set up my seating die was just to match the COAL of the factory 140 ELDMs I shoot regularly. However, consistenly I find that with the OAL gauge I'm seeing a much shorter length for the lands vs the length I already load my reloads to (or to what box ammo is at).
In the comparator, I'm seeing this:
In the picture, the top is the OAL gauge's modified case at the lands, supposedly, and the others are as labeled. The last picture shows more clearly that there's scuffing on the ogive for basically all of them, but especially the longer ones. Those that measured 2.1915 are very difficult to cycle, and oddly that includes the factory/box ammo. I tried a couple, and one I had to smack the bolt back to get it out, while the other factory round cycled more or less normal. I do recall from a recent match shooting box ammo that I had some difficult cycling at times, but I thought at the time it was maybe heat-related or not to do with my ammo at least. Note also that when I loaded a dummy at the lands measurement, it cycled with no resistance.
In the comparator, I'm seeing this:
- OAL Gauge: 2.1075
- Reloaded 140gr ELDM seated with "4.30" on the die mic: 2.1915
- Factory 140 gr ELDM: Also 2.1915
- Dummy round loaded with 140 ELDM, die at "3.45": 2.1040
In the picture, the top is the OAL gauge's modified case at the lands, supposedly, and the others are as labeled. The last picture shows more clearly that there's scuffing on the ogive for basically all of them, but especially the longer ones. Those that measured 2.1915 are very difficult to cycle, and oddly that includes the factory/box ammo. I tried a couple, and one I had to smack the bolt back to get it out, while the other factory round cycled more or less normal. I do recall from a recent match shooting box ammo that I had some difficult cycling at times, but I thought at the time it was maybe heat-related or not to do with my ammo at least. Note also that when I loaded a dummy at the lands measurement, it cycled with no resistance.
- Why would factory ammo be so tight in this rebarrel? Is that an indication that my gunsmith spun the barrel incorrectly, or maybe they were to tight on the chamber? Should that be considered defective?
- Am I missing anything in my process measuring the lands, or would it be logical to find the lands and then just back off .020-.060?
- Is it even safe to send something like the shorter rounds pictured? How can I tell the minimum overall length that's safe?
