Creating tight neck brass for a factory chamber

[Alaskan338Lapua]

So here's my plan. I have a factory rifle with a factory chamber in 308 win. Now suppose I reformed 30-06 into 308 win and reamber the inside neck and then took some measurements and trinmmed the outside neck then voilla! custom fitted 308 win brass! has anyone else done something similar? As far as chamber measurements are concerned how accurate is a cerrosafe casting?

 

[trueblue]

Seems like alot of work for very little gain in accuracy. I do not have a 308 Win, but from what I have read, it seems to be an accurate caliber without going tight neck. I think there would be more to be gained with practice and load developement, and partial necksize the brass.

 

[Alaskan338Lapua]

It's a 1 moa gun, but for the heck of it and to see if I can squeeze every last bit of accuracy out of the darn thing. I was thinking about making a chamber cast and starting from there. Any better ways to do this?

 

[boomtube]

"..voilla! custom fitted 308 win brass! has anyone else done something similar? As far as chamber measurements are concerned how accurate is a cerrosafe casting?"

It works fine. May or may not help - of course, what is certain in reloading anything? - but the effort is challanging and can be interesting. I make tight neck cases for .308. .243, 22-250 and 6mm International from .30-06 and .35 Whelen. It doesn't make a huge difference in accuracy, nothing does after we get to a certain minimum group size, but every nit-picky thing helps.

I've found the hand held Forster HOT-100 neck turner to be easy to use and it does a great job. Got mine from MidwayUSA, not really expensive and has both a calibrated screw and carbide cutter with a nifty relief angle on the corner to reduce damage to the shoulders.

Cerrosafe is GREAT for chamber casts to obtain the actual chamber neck diameter. I'm cheap, usually use melted "Flowers of Sulphur", powdered sulphur from a drug store for a couple of bucks and it works fine but Cerrosafe is certainly the better casting material. (With either material, don't over-fill the chamber or you will find it locked into the bolt lug recesses!)

 

[Alaskan338Lapua]

You hit the nail on the head, all those little things add up. Alright then, we can craft a whole slew of short action cases from 30-06 brass, but moving on to bigger and better things, how about 300 win mag off of 300 H&H. If I remember correctley they both have the same head diameter but correct me if I am wrong. In the past I have tried to make 300 WSM of of some of my non-reloading friends 300 RUM brass but that diddn't turn out too well and the case capacity was severely reduced.

 

[BountyHunter]

IMO you are spending a lot of time "pole vaulting over mouse turds!" but your time.

Equate it to $1000 spinners on a yugo!

At the end of the day, you will still have a factory chamber, factory leade, factory barrel. Just how much do you realisitically expect to pick up in accuracy from the 1 MOA.

What is your runout now from your loaded cartridges?

What kind of ES and SD are you getting now from your present loads?

What is your 308 load?

How much are your current dies squeezing the case down of fired dimensions?

If way, off how do you plan to avoid squeezing down your labor intensive cases back to the same size as the ones you have now? NS only will last 3-5x before hard to close and FL sizing required. By that time neck hardening will be prevalent and will require annealing.

In other words, lot of other things you can do probably that will get you the accuracy IF the gun is capable. If the gun is not, then you can turn cases until the cows come home and it will still be 1 MOA.

However, your time and I would say no more effort than 10 cases to avoid too much dissillusionment.


BH

 

[davewilson]

been there, don't think it will make a bit of difference. put your money towards Lapua 308 cases.

 

[boomtube]

Re: Creating tight neck brass for a factory chamber
Different folks, different results. And just the learning is worth something it seems. Or, we could all just buy Laupa cases? (Which also will have to be annealed from time to time, even it's not immune to work hardening, or is it?)

The simplist method to insure minium working of the cases is (1) neck size with a Lee Collet Neck Die, and (2) use a shoulder bump die when chambering gets difficult. Seems simple to me but,...?

 

[boomtube]

Duplicate post...

 

[VON GRUFF]

As has been said it should be at the end of a long line of improvements,BUT take no notice of those who would disuade you from this learning process. I have gone down the same road with my 7x57 with the added quirk that the 7x57 has a 3 thou tapered neck. I used 5.56x57 cases that have a .028 neck wall thickness and I have been able to get the necks to .0185 for a .0005 clearance release on the mouth but the taper gives me an incremental release clearance to half the neck length as I use the Wilson neck dies. I did get a snug chamber cut when I built the rifle although it will still chamber factory (shudder) if necessary. It is a facinating part of our past time-obsession and so long as you keep meticulous measurements and records, have at it with coution and enjoy the heck out of it.

Best wishes, Von Gruff.

 

[Alaskan338Lapua]

Thanks VG, the experiance of forming, measuring, trimming, reaming and the associated tasks is definatley a good learning experiance. All in all I'm not shooting a BR match with this rifle. it comes down to pride in ownership and pride in the work accomplished. Reloading is one of three hobbies that I get enjoyment out of. Sometimes on a -60 degree day with only four hours of daylight there's nothing to do but kill allot of time at the table tinkering around. I'm going to start work, thanks for the advice fellas-338