Another OAL Thread

[whiteoak11]

Howdy, first time poster and virgin reloader! I've got my setup and I've read enough to try out my first load.

Sako 75 Hunter in 7mm-08 w/ a fluted bull barrel

I've got the Hornady OAL gauge and comparator and I made my own dummy case with a round fired through the rifle. When I push the dummy into the gun, things get really tight (as you'd expect from a fired round) and then there's a distinct point at which I cannot push the case in any further. This is where I assumed I needed to be and took my measurement. 2.835" OAL. The TSX bullet sits with the second groove just barely covered at that location. Seems like a long OAL or is that ok? Also, how do I know that the depth that I pushed the case to is the same depth that my gun will chamber a real bullet to?

Thanks in advance.

[PA-Joe]

You push the case all of the way into the chamber using the red handle and hold it in place. Then you push the bullet up to the lands with the inner slide and lock it. Do this several times so you have the system down and get a consistent meaurement. Try several bullets. Then you measure the max ogive length. When reloading you seat your bullets a few 0.01's back from max. You may find that you have a long freebore and that you will have to limit your COL to what will feed from the magazine.

[Unclenick]

Whiteoak11,

Welcome to the forum.

So, you got your own oddball 5/16-36 tap and letter J drill (IIRC the drill correctly) to make your own gauge cases? Bunch of trouble, but I understand your motivation, since I did the same thing.

There are two potential problems that arose from my experience with that approach. One is that you have to be neck sizing other once-fired cases for the resultant maximum COOL (Casehead to Ogive Overall Length; I built that term from a kit) to be valid. If you try to use that number with FL resized cases or with new brass, you will seat out too far.

The other is that most commercial chambers (don't know if yours is commercial or custom) are imperfect and have a little runout off the bore axis. So, getting your gage case in with the headstamp oriented at the same place on the clock that it had when you fired becomes important. If it isn't a match you can, again, get an overlong number.

All that said, you will want to discover the best seating depth for accuracy for each bullet you use. Those usually don't touch the lands, so repeatable location is the most important thing. To do that with cases that headspace on the shoulder, whether you use a neck sized case or a new case, you can get a match by using the Hornady LNL case gauge inserts for your caliper adapter head and find a difference between the shoulder and ogive. As long as you adjust your seater to maintain that difference, you should keep the bullet distance from the throat at firing pretty constant.