I've only been reloading for about a year now,and with the help from forums like this one,I haven't had a great deal of trouble.That is,until this morning...
I'd loaded up some 7.5x55 with 168 grain MatchKings to approximate the performance of the GP11 surplus ammo.I loaded these to the same OAL as the GP11.Snuck out to the range this morning to test fire some loadings.And when I began to close the action of my K31,well,damn,I can't get to close.So I pull the bolt back(with some effort) and look at my round,and low and behold,I see rifling marks on it.Well I get to looking at my round and a GP11 cartridge,and can plainly see that the ogive of the GP11 is less than the matchking.Duhhhhhhh!So, a lesson learned.Back to the bench to seat these a little deeper.

I like the method described in the Nosler reloading manual to determine the maximum OAL of a cartridge in a specific rifle.

-First, take a spent piece of brass and put a small dent into the side of the case mouth. This case should have a spent primer and no powder.
-Using one of the bullets you want to load with, mark up the side of the bullet with a permanent marker.
-Put this bullet into the case with the dent on the mouth. The bullet should be firmly held, but it should not be as tight as it won�t slide farther into the case.
-Slowly, chamber this round and close the rifle action. The bullet will come into contact with the rifling and be pushed into the case. I find that when I remove this dummy cartridge from the rifle the bullet is not pulled from the case. However, this contingency is the reason for the permanent marker. If the bullet is pulled from the case there will be a visible scratch on the side of the bullet. If this has happened, push the bullet back into the case.
-This is your MAX cartridge overall length.
-I like to repeat this measurement at least three times to make sure I get a consistent measurement.
-There is some debate as to whether the bullet should touch the rifling or not, and how far pack you want to set the bullet. I like to be cautious and back off of the lands. However, in writing this I don�t recall how far off the lands the Nosler manual recommends. I like to allow plenty of tolerance in case a seating die changes without my knowledge or the rifle is dirty.
-Also remember your rifle probably has a magazine. Any ammo you load you will probably want to fit into the magazine, so you haven�t turned your repeater into a single shot. When I reload I often find that the magazine length is often much smaller than the cartridge overall length allowed by the chamber. I think on the order of 0.3 inches. However, I don�t complain because the rifle still shoots ~1 MOA.

At one point I tried the old method of �smoking� the bullet on a dummy cartridge and chambering it in the rifle, looking for rifling marks, seating the bullet deeper, repeating the process. The candle only heated up the bullet! No smoke� I tried a dry erase marker, but couldn�t discern the marks from the side of the chamber and the rifling.

The above method has been easy, and free! I got my cartridge OAL and didn�t have to purchase any expensive gauges.

Ben

Ben_wazzu-I have been using the same method of determining overall cartridge length for many years and find it as accurate as any.I don't hesitate to spend money on tooling if it will be beneficial but in this case extra tooling is not required.

[ 05-25-2003, 23:13: Message edited by: stubblejumper ]