Re: Flattened Primers
I usually send this by private email and don't post it in the open. But here it is.
Adjusting a Full Length Sizer Die for a bolt action rifle.
PLEASE… Read through this a couple of times before attempting to do it. If any of this data doesn’t make sense to you STOP…! If there is any part of this you don’t understand… STOP…! The author is making observances about what he has done with his own equipment. Your equipment, dies, shell holders, rifle, cartridge brass and other components may be different. I can almost promise they are. If you do this, you are doing it on your own accord. I accept NO legal implication or obligation. As someone shooting wildcat cartridges I have some experience in changing factory settings ON MY EQUIPMENT. I have even made my own dies in the past. I caution against “beginners” doing this procedure. Wait until you understand the physics of what you are doing a bit more.
For years I struggled with neck sizing for my first benchrest rifle. Size “X” number times then bump the shoulder with a body die. I never had the comfort I was looking for when it came time to cycle the bolt.
While I was complaining at the “Firearms Industry Super Shoot” one year, a friend took me aside and told me that he would come back later that night after supper and help me with the problem. He said to leave everything as it was at the time. Since he had set several world records in the sport I did as he requested.
When he returned, he told me to get my brass and remove the firing pin from the bolt. He asked if I had a full length sizing die and I said yes. Since I was using a bushing die for the neck sizer I just had to pop the bushing out and use it in the F/L die.
He explained that the shoulder of the brass was pushing against the shoulder of the chamber and making it hard to chamber a round and remove it later. This I understood. But I thought the chamber would hold it close to the same length. WRONG… It doesn’t work like that. The case will keep stretching until it fills the chamber and the bolt handle doesn’t want to lever it loose. (I have since seen photos of a very high dollar rifle with the bolt handle knocked off because someone thought he wanted to neck size only.) But I’m getting off track…
Screw the sizing die in the top of the press as the instructions say. Then back it out 1 full turn. Lube a few cases properly. (I use Imperial Sizing wax. A little bit on a finger tip will lube 3 or 4 cases.) You can use 1 or 2 cases to get things close. But for the final settings you need to use a fresh case each time. Cycle a case through the die and press. Then try it in the chamber. (Having removed the firing pin, there is no trigger reset or spring pressure to give false “feelings”.) You want to screw the die down in 1/16th of a turn increments. That works out to roughly .0045”, (four and a half thousands of an inch.) As you approach the shell holder you will eventually find a spot where the bolt handle easily moves forward all the way and starts over on its own weight. This is what you’re looking for. You want the bolt handle to just start down on its own weight. I usually adjust mine for half way down. It makes it easier to cycle the bolt without disturbing the sand bags and changing your aiming position.
When you have found this spot, try a fresh case and see if it works the same. Usually after using the same piece of brass for several trials, a fresh piece will have more “spring” to it and you’ll have to give it a little more squeeze to make it the same. Remember, when you are sizing your brass, most people cycle each piece of brass only one time. It just makes sense to me to do it the same way.
After doing this another accomplished rifle smith showed me a little collar he made from an old barrel stub and a chambering reamer. By slipping this over the case neck and setting it against the shoulder you can reliably measure the amount you are pushing the shoulder back each time you pull the handle. By doing it the way I have outlined in the previous paragraph most of my brass is being pushed back between .0015 and .003”. This is what a lot of rifle smiths suggest as a benchmark for “bumping” the shoulder back. This way the brass isn’t being “over worked”.
NOTE : Some dies will hit the shell holder before they ever get down low enough for your chamber. I have had this problem with about half of the dies I have set up like this. Remove the decapping pin and expander ball assembly. I set the dies up in a toolmaker’s “V Block” and use a surface grinder to remove approximately .010” from the length of the bottom of the die. Most dies have a very large radius ground in the first part of the inside diameter. This part is not making contact with the cartridge brass anyway. But it is used as a legal stop gap for the manufacturer. By using this, the maker can say he has made the die to SAAMI specs. But this is not what your rifle wants. After you have the die altered and set up properly make yourself a note and put it in place with a rubber band around this die. Keep it with the die at all times. Make it say what rifle the die is for and what alterations have been made to it. Also record what temperature it is at the time of the settings. If you load in an 85 degree house and shoot the ammo at 12 degrees in a blinding snowstorm, there will be a difference. The difference in temperature will make the chamber and die difference be an additional .001” or so.
I have also started using shims cut to fit the 7/8 X 14 size of the die in the press. This way you can hold the movements down to as close to .001. MSC Supply carries these shims in assortments as well as in packs of all one thickness. Brownell’s and Sinclair’s also carry them. But the price mark up is substantial if you are getting several packs of shims.
If I’m working that close I also use a “Crow’s foot” wrench with an extension and a torque wrench to keep the settings all the same. Yes, it can make a difference when working close.
Good luck with your loading. I hope you set some records yourself.
