7mm08 neck turning

I resized some 308 to 7-08. It chambered and fired fine w/o neck turning, BUT I got higher pressure. Because I was running 43.5 G of Varget behind a 120G Barnes TTSX, I blew out a primer. Freaked me out at first. Just be aware of how your load behavior will likely change by necking down.
 
I turn all my necks. No matter what rifle I am using or cases. If you are going to reduce the neck from .308 to .284. Then cut your neck first to clean up the neck and even thickness. I go to .013 for neck thickness for me, but you don't have to cut that much off your case if not wanted unless you have a reduced chamber. 1. cut your necks first before down sizing the necks. Otherwise you can get a donut in the neck by down sizing first then cut the necks. I do cut all my neck regardless of who makes the brass. That way I know that the neck is straight and even all the way around. 2. before cutting the necks, make sure your case are all the same length. That way you stop at the same point in each case when thinning the case. You want to stop at the shoulder of the neck to the case. Don't over cut the neck into the shoulder. 3. You will need to get bushing dies to effect the correct tension. So yes you have increased your steps in necking down cases from one to another. That is what I do to get cases for my rifles, because case can be hard to come by presently. The other is you are going to have to fire form the case afterwards anyway.
 
MY .02c worth is that before I would neck sized down from .308 to 7mm-08 I would first anneal. From there I would size the necks down using the 7mm-08 sizing die without the expander plug in the resizer. From there I would neck size using a Sinclair mandrel neck sizing die. After neck sizing I would turn the necks "until" the necks cleaned up ( usually .013-.014) or until they reached factory specs. My thoughts are that if one is changing the diameter of the neck from .343 thousandths of an inch to .315 thousandths of an inch, that .028 thousandths of an inch of brass has to go somewhere. From my understanding of the process the mandrel neck sizing die ought to move the brass to the outside of the case where the excess brass can be neck turned off. Using the expander plug of in the full length sizing die could leave a donut where it can be reamed out; but I only use the Sinclair neck sizing mandrel for neck tension.
 
I am dealing with new brass that hasn't be fire to start with. I been advise to cut the neck first before resizing the brass to a different caliber. I would think that would apply to any reduced sizing of the necks. The rifle I am really setting up on is a reduced chamber in the neck area and not a standard SAMMI chambering either. The 280AI case 7mm, and where I am going go to is 6mm. So the necks have to be cut and sized down before anything else is done. I agree with your steps, but I would do the neck cutting at it's present chambering before reducing the neck size to get away from the donuts. You have gotten me to thinking that maybe I need to run a sizing die in the case first without the expander plug in. Then use a mandrel to set the ID in the neck to be sure that the excess brass is pushed to the outside. I use FL Redding bushing dies, and set for a bump of .002 or so. The case needs to be trim to the same length so the neck cut isn't running into the shoulder or short of the shoulder. So I will put your input into my notes and see how that comes out. Interesting thoughts on procedures. That what it's all about. I will have to try it both ways and see how it comes out. Steps-Steps and more Steps. The art of reloading.
 
Swamplord said:
Blue Collar have Lapua 7mm-08 brass in stock

www.bluecollarreloading.com

Lapua 7mm-08 Remington Brass #4PH7095

Product Information Cartridge: 7mm-08 Remington Finish: Brass Condition: New Quantity: 100 Primed: No Primer Size: Large Primer Pocket *This is not loaded ammunition.
www.bluecollarreloading.com www.bluecollarreloading.com
Click to expand...
You can always play with necking down at some point in the future, but if I can get Lapua in the desired chambering, the search is OVER in my mind. I have learned by experience that, at least in .308, Lapua may be the cheapest brass per shot you can buy, as I have been unable, thus far, to wear it out with loads up to published max. Good stuff.

Rex
 
Staying within the manual load data generally safe and are go loads. You still have to work within those areas to come up with a good load. Me it's a different story. I generally push my loads beyond the reloading manuals. Grouping and fpe are the important things to do the job on the game you are hunting. Punching steel is a different thing, and it's not going to run off. I run a ladder test for two things. First to see that I am within the range of pressure, and see where the better areas of the loading range. There lot to work with in developing or configuration a load for your rifle. Purchasing brass already make for the rifle is a lot easier than going the other way. The long range match shooters kind of point the way to achieve better grouping. I have learned a bunch in front of this screen, with all the input here. Some good, and some bad. Learning to develop loads is never ending. Little tricks or steps help the grouping.
 

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