Custom COAL for 300 bergers in 338NM

[jrock]

I'm putting together a list of components to for my .338 NM build. Since it's custom, I am trying to decide which COAL I should use for the 300 gr. Berger Elite Hunter VLD's. I got the brass and bullets so I could play around with the measurements. I will be neck turning the brass. If I seat the bullet out so that the maximum diameter of the bullet is just above the neck shoulder junction to avoid a doughnut, the COAL is 3.7". This obviously doesn't fit in a long action internal box magazine.

I've read that turning the neck just into the shoulder eliminates the doughnut. If this is true, then I could seat to a 3.6" and use a standard internal magazine. I really want to use a standard long action DBM and am planning to go Defiance for both the action and their DBM. Am I on the right track?

Also, what distance from the lands are you finding that the 300 VLD works the best? The VLD's in my other guns work best placed less than 0.020" from the lands. Don't want to get a chamber with a free bore too long to seat in a DBM.

 

[sp6x6]

I have NM and shoot the 300 OTM's. I am .005 off lands at 3.670 COAL. That fits in my standard rem mag and I load same for my other that is AI mag fed, that has clearance in mag maybe 1/8 but never measured inside mag CIP 338. Mine are both Defiance rebels

 

[jrock]

Thanks 6x6. Why did you go with a Rebel action over the Deviant?
I called Wyatts about their 5 round .300 mags and they said it would work for the .338 NM but it may not be able to stack 5 rounds. I went with them for the 3.71" COAL they told me (over advertised 3.625" AI) for the .300 mags. That way I can swap it between guns without modifications. I like the ease of unloading and loading of a DBM. If I can only get 4 rounds in the mag, I think I'll play around with shortening the length of the mag.

 

[sp6x6]

I have 5 stacked in my mag with that bit clearance I would have to measure actual mag. The Deviant did not exist at the time. I live about 200 yrds from Defiance, just saw a bud that works there. He had his 338 ultra on a Deviant,was a packer nice looking set up.

 

[jrock]

sp6x6,
I've noticed after looking at cartridge and chamber specifications for the NM (attached) that the neck is not a straight neck. It is wider at the base of the neck than at the mouth. I'm measuring a wall thickness variance of 0.001" max measured at one point along the neck so I have not confirmed the neck wall thicknesses at mouth and base.

This is what I'm thinking,
1. turn necks makes even thickness
2. fire form cases would expand to chamber which is tapered and then the internal neck walls are no longer parallel.
3. I assume that FL sizing (with RCBS dies) would then carry the non-parallel internal neck wall dimension and cause uneven pressure on the bullet along the length of the neck.

Any thoughts?

 

[sp6x6]

My thoughts are i think you are over thinking it. I have one of the first Normas,from posts Ive seen they have been very easy to load for and inherently accurate. I had a bud look over what I was doing, I was maybe going to get bushing die and my loads where coming out pretty well, my necks where he said resonable. He has multiple WR in 1000 bench. He also has a 300 Norma improved for a hunting rifle as well as a 338 LAI.There are quite a few Normas in my area as I live next to Defiance and about 4 mile from Proof.There head stock maker has alot of rounds down the Norma.

 

[jrock]

That "inherently accurate" is one of the reasons I picked the NM. I checked the cases to see if there is a taper in the neck and if there was any it was within the 0.001" thickness variance so for all intensive purposes, I would say it's a uniform thickness from mouth to base. I guess the engineer part of me got the best of me this time. Sometimes it's best to just go out and measure it.

What improvement does your friend have on his NM? I've wondered if it's worth getting an improved reamer as the cost isn't much different especially since it's already so "inherently accurate".

 

[sp6x6]

I had notes on the 300 NMI but I cant find them, but he was pushing the 230 at a good clip where it hung right with 338 to 1200 type yards and I dont remember what he blew shoulder out to maybe 37 he is all about precision being a top 1ooo yrd bench competitor.

 

[Cuz]

Jrock,6x6 is right, the 338nm is pretty easy to load for. I skim turned some cases for mine, but they were pretty even to begin with. I do anneal the cases after each load. I think that keeps neck tension more uniform. I rebarreled a 338lm to norma to better fit in the magazine and velocity loss was minimal. It impressed me enough to order another action and barrel to build a second one.

 

[jrock]

I sent Norma an email and their reply was that the uniformity of their cases is great and neck turning will not yield much improvement if any. They suggested focusing on components and load testing over neck turning.

 

[Cuz]

One other thing i do on all brass is use a flashole uniformer.

 

[jrock]

I visually checked a handful of them and they the holes looked good. No burs on the inside as well. I ran a few through the primer pocket unifier and didn't get any cuts so I guess Norma has pretty good brass in those two areas.

 

[Cuz]

I have been loading the 300 gr otm bergers at 3.75 oal. This puts them right at the lands. Accuracy will hold 1/2 moa or better out to 660 yrds which is how far I have had a chance to test for groups so far. Velocity is 2770 from a 28'' barrel. I also load the 280 grn barnes lrx at 2800 fps. It is very accurate also. Point of impact at 200 yds is basically the same for both bullets so I plan to use the barnes at shorter ranges. The bergers are pretty rough on coyotes at 100 yds.

 

[jrock]

So the Wyatts DBM showed up tonight and I tired to fit the cases in and the first one fits but you can't fit anymore because the flute on the back sides of the mags indent too far to prevent the first case from being pushed down. So I'm back to square one.
I was planning to build on a HS precision stock and for some reason Stocky Stocks says not to inlet them for the M5 which is my next cost effective solution for a DBM. I didn't want to go with the M5 version as I'm afraid that when I'm packing my gun in the thick stuff a branch may catch the mag release as it sticks out.
I was thinking of going with an extended BDL and the Wyatts long magazine box and hope 3 rounds fit in. Less money and would be a 3+1 so plenty good for hunting.