fire forming for the 338-Lapua-inp.

Depending on your particular case you may need a false shoulder or jambing a bullet to hold the case back against the bolt face for fire forming, if your blowing a shoulder forward without holding the case back against the bolt face your actually blowing the base of the case back to the bolt face thinning the base of the case.

Thanks for that important factoid. I may have mistakenly concluded that this necessity, prior to C-O-W fireforming, had already been covered and was understood.
 
I have never put anything between the powder and the cream of wheat. Seems like a good idea if they are going to get shaken and mixed up.
Steve

Here's why I separate the gun powder from the cream of wheat. Many years ago (decades) I loaded shotgun shells and placed white baking flour in with the lead shot pellets in the effort to buffer the pellets upon ignition, keep the lead pellets rounder, and tighten up my patterns in a 20 gauge 870 LW with a fixed improved cylinder choke. All chokes were fixed in those days.

I experienced a high percentage of those shells that fired under pressured and under powered. The only difference in the loads was the white baking flour added to the lead pellets. There was only one conclusion, and I reached it pretty quickly. The flour was escaping the column of pellets, leaking around the shotshell wad, and then contacting and contaminating the powder charge. White flour contaminates shotgun powder and affects powder burn rate and pressure. I am utterly confident of that.

So that's why I separate gunpowder from the C-O-W today. I never added cream of wheat or any other ground grains or wheat/flour to my shotgun shells as a buffering agent after those experiences. I now separate pistol powders from the C-O-W with a single thickness of kitchen-type paper towel when C-O-W fireforming cartridge casings.

One additional consideration... My shotgun shells would remain loaded for weeks and months before firing. I was loading them for ruffed grouse and ring-neck pheasant. They were carried around afield and loaded and unloaded. So it's possible that a longer period of contact time and some rustling is required for the flour to contact and degrade the shotgun powder. I didn't like what I experienced one bit, and was fearful of a dud shell lodging inside my shotgun barrel. So I ended that practice without bulging my shotgun barrel.
 
Depending on your particular case you may need a false shoulder or jambing a bullet to hold the case back against the bolt face for fire forming, if your blowing a shoulder forward without holding the case back against the bolt face your actually blowing the base of the case back to the bolt face thinning the base of the case.

I am ready to start my fire forming. Just got my rifle back from straight shot Gunsmithing. I just tried my new 338 Lapua brass in rifle it did not feel snug when I closed the bolt. So how do I make a false shoulder. I have never done one before. I have three dies one should work. First die is a Lee 338 Lapua. Next die is a redding 40 degree neck sizing die that I found out from you guys would not work in my rebarrel money wasted. Last die was made by Straight shot gunsmithing who chambered and installed the 338 Lapua-AL. thanks for your help I really appreciate it, Joe.
 
Do you have the ability to remove your ejector? If so stack scotch tape on the back of a case till you feel the case snug up then measure the stack to see how far you need to blow the shoulder out, this will kind of determine your needed direction.
 
Put tape on the head stamp, tried to think of a better way to convey it clearly, your just wanting to built up layers of tape between the case and bolt face to see what your head space clearance is which will be the amount you'll blow your case out. If it's a few thousandths then I'd just load up and fire form, if it's more then you'll need a different strategy like expanding the neck to the next cal then sizing it down till you have crush then fire form, or load a bullet and jamb then into the rifle g to Holt the case.
 
if its a new barrel (which I am assuming it is since you are fireforming for the first time) I would rec loading up some std load 338 L ammo and shoot it. it will be good practice and help get some rounds down the barrel so the speed stabilizes out before you really start load development.

I shoot 300g SMKs out of my 338 L imp (the bergers don't like going that fast) and use the 300g nosler custom comp for fireforming. they fly great and are much less expensive. the rifle shoots well under 3/4 moa with the fire forming loads, so its not a waist.

if the std brass isn't indexing on the shoulder, you will have to do it off the bullet. basically loading them with little to no jump.
 
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