sizing brass for 7mm-08

Ted47

Well-Known Member
What is the easiest / best way to form 7mm-08rem cases?

Would sizing up from .243 or down from .308 give better results, or is there other ways apart from new brass.

And would annealing help the process?
 
Size down and neck turn. It works out the same price as some 7-08 brass and you then have the kit to turn any Lap .308 into great 7mm08 brass
 
I bought 100 Lapua .308 cases and simply resized them in a full length 7-08 sizing die. The trick was to use Imperial Sizing Wax as the lubricant - very sparingly - to prevent stuck cases. No issues with case neck thickness or case lengthening and I have reloaded this brass some 5 times now.


KRS
 
I bought 100 Lapua .308 cases and simply resized them in a full length 7-08 sizing die. The trick was to use Imperial Sizing Wax as the lubricant - very sparingly - to prevent stuck cases. No issues with case neck thickness or case lengthening and I have reloaded this brass some 5 times now.

KRS

Lapua .308 cases aren't cheap, but anything will be cheaper than new 7mm-08 cases. This will work on any cheaper brand of new .308 cases as these are undersized to begin with. In fact you're only partially sizing the neck here with minimal body contact usually, so may not need lube at all.

The 7mm-08 case is 20 thou longer than .308 Max length so any converted cases should be OK for length. Necking down .308 gives more uniform results than opening up the necks of .243 cases but part of the neck remains oversize, which might cause tight chambering in some rifles. Bk has a point about over thick necks needing turning, but I would think that most sporting 7mm-08 chambers should have enough lateral clearance to take marginally reformed brass like this.
 
Lapua .308 cases aren't cheap, but anything will be cheaper than new 7mm-08 cases. This will work on any cheaper brand of new .308 cases as these are undersized to begin with. In fact you're only partially sizing the neck here with minimal body contact usually, so may not need lube at all.

The 7mm-08 case is 20 thou longer than .308 Max length so any converted cases should be OK for length. Necking down .308 gives more uniform results than opening up the necks of .243 cases but part of the neck remains oversize, which might cause tight chambering in some rifles. Bk has a point about over thick necks needing turning, but I would think that most sporting 7mm-08 chambers should have enough lateral clearance to take marginally reformed brass like this.

My M595 had overpressure from thick necks with unturned brass
 
My M595 had overpressure from thick necks with unturned brass

One way of checking there's enough clearance (without getting this far) is just to seat a 7mm bullet in the necked down .308 case. Measure the outside neck diameter of this with a 7mm-08 case which has been fired in the rifle. If the neck diameter of the dummy is no more than a couple of thou over that of the fired case then you can press on.
 
One way of checking there's enough clearance (without getting this far) is just to seat a 7mm bullet in the necked down .308 case. Measure the outside neck diameter of this with a 7mm-08 case which has been fired in the rifle. If the neck diameter of the dummy is no more than a couple of thou over that of the fired case then you can press on.

I made it simpler yet: I measured the neck thickness of a 7-08 factory casing. The brass I was forming from Lake City 308 had a thickness .0015 to .002" greater in the neck walls so I thinned the necks that much. Done.~Muir
 
I took my 308 to 7mm-08 reformed military brass reloads out today for a brief test before the snows hit us again. First, the brass looked great. Second, the Sierra Pro Hunter 120 grain over a starting load of Varget shoots. In a strong wind with my rolled up Carrhart jacket as my rest -a very loose rest- my blue fingers touched off three, 100M five shot groups averaging just a bit over MOA. I was pleased in the brass and the load, equally.~Muir
 
Back
Top