TackDriver284
Handloader
- Feb 13, 2016
- 2,533
- 2,054
I deprimed 50 cases of Lapua brass for the 300 Win Mag to prep it for neck turning. Brass necks is too thick and causing high pressure. Cleaned the body and inside necks then set up the BenchSource to anneal it, just the glow method is sufficient enough since it works for me, threw away the Tempilaq long ago. Cleaned the necks again with some Kroil, and full sized ( non bushing ) all the brass, and used a .307 steel mandrel to open the necks to make it easier to use the neck turner mandrel afterwards. I removed the buttons from all my full sizing dies long go, don't like them. Got some Imperial wax and a qtip, lubed inside the necks and tried to run the neck turning mandrel that I had purchased from K&M last week, did not want to go in easily as usual. It was so hard to run the brass into the mandrel for some reason. I bought the V2 mandrel since they no longer have the V1 mandrel but I am still using the V1 die that I had for a long time. K&M modified their new mandrels and a new die called a V2 that does not use a stop screw that is screwed in to the bottom of the mandrel which helps stop the case mouth from smashing into the bottom of the die once it bottoms out, but this new mandrel does not have a screw stop. I was exerting lots of pressure on the ram and Redding Boss that I can hear the studs creak that the working table is bolted to. Felt the case bottom up into the die pretty hard, thought maybe the case mouth may have deformed, but luckily it did not. I never exerted that much pressure ever like that neck turning other brass for other rifles, this is a first. I used 3 different lubes, which are the Imperial wax, 3 in 1 oil, and powder graphite and none of that worked well. I was getting irritated after doing 15 pieces of brass and thought real hard on what will work or just stop what I'm doing. I pulled another lube off the shelf, which was the thick RCBS case lube, the one you put on a roll pad, never used that lube for like 30 years. To my amazement, that lube did work with like 80% less effort. Not sure why the others did not work, strange. In the picture, the left mandrel has the screw stop and the new mandrel on the right does not. I continued to lube inside each case neck with the RCBS, and ran the neck turning mandrel in all the 50 pieces of Lapua brass. Next was setting up the new cutter in the neck turning tool, used a 28 degree cutter, since the 300 Win Mag has a 25 degree shoulder. I calculated how much material to remove so I set it up to remove .0015" giving me .003" clearance. I lubed inside the necks and turned all the brass. After each brass was turned on the electric drill, followed up cleaning the necks with fine steel wool, and cleaned the inside necks with a rag and a little screw driver. Resized a turned case, and got one AccuBond and seated it in the turned Lapua case, and measured the neck diameter, voila its exactly the same measurement as the Norma with a loaded round which is .335" giving me .005" clearance. Recent measurement was .338" and SAMMI specs is .340". Measured each brass neck thickness and each one measures .0135" on 4 to 5 points on the neck, perfect concentricity all around on all the brass neck. I'm happy it paid off. Variation on the Lapua necks was not good before turning, it was measuring from .014 to .0155" , not concentric at all. Beat myself up at the bench today, at least I got it done. Testing with Lapua brass will not happen at this time since I already started on the Norma brass and it was shooting pretty good, just a little more tweaking the load and get some range time and I'm sure it will work. Putting the neck turned Lapuas on the back burner for now. I hope I never need to turn any more brass for the 300, but I still have half a box of virgin Lapuas left. 
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I'll do that hopefully this weekend, swamped with work for the next several days. Will keep you guys posted.
