AJC1
Member
My buddy just picked up a 7-08. I have never converted brass from one caliber to another but I plan on using 308 ppu brass and changing it to 7-08. Any advice....
Friend project 7-08
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11MikeMike
Member
Never tried myself, but if I had to I’d FL size in a 308 die with the expander ball removed and see what you’re working with. Then run it through a 708 die?? Good question though. I’d like to know the solution as well.
Yeah, I used to make 25-06 brass out of 270 brass. Going from a 308 to a 284 (7mm) is about the same jump. I recommend a good lube like imperial, and a good strong O press with lots of leverage. Lube up and go slow. Taking the expander rod out of a 308 FL die will get you a few thousandths closer to start, so that isn't a bad idea at all. Then put in your 7mm die and just go slow. You might have to neck turn the resulting brass since it will thicken with the reduction.
troy fairweather
Member
In a fl die and done, military brass may need the necks turned.ppu was making 7-08 did you look for any.
If I were you I would just trim close to the specs for the 7mm-08 and just FL size with that die, just go slow. I were going to convert I personally would incorporate the following steps.
1. Anneal the brass
2. Lightly lube the brass and neck but not the shoulder or you will get sizing hydraulic dents because lube won't have a place to go. Also very lightly lube the inside of the brass
3. FL size the brass with the 7mm-08 dies go very slow so that you do not collapse the shoulders. Easy Peasy!
1. Anneal the brass
2. Lightly lube the brass and neck but not the shoulder or you will get sizing hydraulic dents because lube won't have a place to go. Also very lightly lube the inside of the brass
3. FL size the brass with the 7mm-08 dies go very slow so that you do not collapse the shoulders. Easy Peasy!
Ifishsum
Member
Converting should be as easy as just lubing and running it in the 7mm-08 die with probably a trim after. I've personally never had to neck turn or do any other steps with it. I use Imperial sizing wax, to me feels like just a little more effort than sizing a fired 7-08 case.
Agree you can just resize in your 7-08 die but....
It will probably be shorter than book numbers for 7-08. It may not size the entire neck.
I reform for 260 and agree with HowieG. Necking up works better, especially with a tapered expanding ball. Good luck finding 260 brass or the tapered expander. 243 brass could work but I haven't tried it. I don't have a 7-08 yet.
Numbers:
308 case #1 Lake City once fired
length before resizing: 2.008
sized in 308 die: 2.013
then sized in 260 die: 2.024
neck wall thickness before reforming .015 and after .016
case #2 same as case#1
length before resizing: 1.999 ( a little shorter than case # 1)
resized in 260 die without intermediate 308 sizing: 2.011
neck wall thickness before reforming .015 and after .016
If you assume about half the affect going to 7-08 instead of 260 then you might get about .007 length stretch which added to the 308 max of 2.015 only gets you to 2.022 which is barely short of 7-08 book - not enough to worry about. It will all depend on the dimensions of the 308 you start with and your dies . The .001 neck thickness increase should be no issue. I have a bag of PPU 7-08 and the necks are .013 thick so plan on .284 + .014 + .014 = .312 for your cartridge neck. All my 243 PPU brass has been reformed so not sure if that is .013 or if your 308 is the same. If it chambers and is within SAAMI you should be good. The extra .001 might actually be beneficial for you chamber.
Here is the neck issue from my trials of 308 to 260
Pic of the two trials
#1 has a little less neck sized than #2 presumably because the 308 sizing step bumped the shoulder a bit.
If they chamber and get blown out to your chamber, and resized again, you should be fine. The shoulder dimple in the pics did not prevent chambering for me. I used Imperial sizing wax. Sizing up from 243 avoids this. You just have to try it, measure, and check against SAAMI.
Good luck.
Can't wait to get a 7-08 !
It will probably be shorter than book numbers for 7-08. It may not size the entire neck.
I reform for 260 and agree with HowieG. Necking up works better, especially with a tapered expanding ball. Good luck finding 260 brass or the tapered expander. 243 brass could work but I haven't tried it. I don't have a 7-08 yet.
Numbers:
308 case #1 Lake City once fired
length before resizing: 2.008
sized in 308 die: 2.013
then sized in 260 die: 2.024
neck wall thickness before reforming .015 and after .016
case #2 same as case#1
length before resizing: 1.999 ( a little shorter than case # 1)
resized in 260 die without intermediate 308 sizing: 2.011
neck wall thickness before reforming .015 and after .016
If you assume about half the affect going to 7-08 instead of 260 then you might get about .007 length stretch which added to the 308 max of 2.015 only gets you to 2.022 which is barely short of 7-08 book - not enough to worry about. It will all depend on the dimensions of the 308 you start with and your dies . The .001 neck thickness increase should be no issue. I have a bag of PPU 7-08 and the necks are .013 thick so plan on .284 + .014 + .014 = .312 for your cartridge neck. All my 243 PPU brass has been reformed so not sure if that is .013 or if your 308 is the same. If it chambers and is within SAAMI you should be good. The extra .001 might actually be beneficial for you chamber.
Here is the neck issue from my trials of 308 to 260
Pic of the two trials
#1 has a little less neck sized than #2 presumably because the 308 sizing step bumped the shoulder a bit.
If they chamber and get blown out to your chamber, and resized again, you should be fine. The shoulder dimple in the pics did not prevent chambering for me. I used Imperial sizing wax. Sizing up from 243 avoids this. You just have to try it, measure, and check against SAAMI.
Good luck.
Can't wait to get a 7-08 !
Chuck R.
Member
I do the same for my .260 brass, just anneal them and run them into my .260 FL die.
Also with other calibers I've had better luck expanding up VS necking down.
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AJC1
Member
I dont have a way to anneal here. The brass is only once fired so at least it's not work hardened already. This is not going to happen for a few weeks because my buddy is moving, only a few miles but still. I'm sure his wife has other priorities other tha him getting his loading stuff set up. I think I'm going to use an extended hold time to help reduce spring back.
Blue68f100
Member
If you have a torch, a drill and some way to hold and spin the brass you can anneal. I did it using the torch, brick in a buck of water for decades. I was only doing 20 rounds at a time when needed. Though water is not needed it does cool the brass down so you can handle it sooner. Now days I have a machine and anneal all my rifle brass every cycle. I'm retired so I have the time.
I've converted 308W to 6.5 CM. It's a lot easier to do if the brass is annealed. The brass will also fire form quicker if annealed.
I've converted 308W to 6.5 CM. It's a lot easier to do if the brass is annealed. The brass will also fire form quicker if annealed.
I would prefer skipping on the big single jumps down. I made 25-06 from 30-06, but it wasn't fun. I have been thinking of trying 308 to 264 just because I have some 308. Probably neck to 284 first and then on to 264.
308 to 264 is too big of a jump for me. As far as going the other way and necking up, I never use expanders in my sizing dies. I have a Sinclair Mandrel Die and can get stainless steel expander mandrels for it in all calibers from 17 to 338 for ten bucks each. In fact, I do ALL my expanding now using that die. It's a great piece of gear.
Heck, I’ve made many hundreds of 243 from 308 in one pass through my 243 die. I make lots of stuff from other stuff. I’ve made several hundred 22-250s out of military 308 just for something to do. 260 out of 308 is not difficult, but I do run it down to 7-08 first. 308 to 7-08 is a slam dunk! I highly recommend Imperial die wax.
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AJC1
Member
Imperial is all I use.... there maybe others but why mess with success
Yep, nothing beats Imperial.
Ks5shooter
Contributing Member
You are gonna love the 7mm-08 my favorite deer round.
BWS
Member
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Fantastic chambering.
Here's a VERY quick 3 shot group. B&L 3-9X40,stainless SPS 7-08. 145G RCBS sil cast,med hard with a cpl grains over jacketed starting book load of Varget,hard jam. 3 shots,as fast as you can run'm up through the mag off an X bag rest @100.
Here's a VERY quick 3 shot group. B&L 3-9X40,stainless SPS 7-08. 145G RCBS sil cast,med hard with a cpl grains over jacketed starting book load of Varget,hard jam. 3 shots,as fast as you can run'm up through the mag off an X bag rest @100.
JFrank
Member
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AJC1
Member
If it were mine I would have bought the privi loaded ammunition as my stepping off point... I've gone that route for my first 308 and 6.5x55 rounds... unfortunately their sold out right now. I feel like their loaded ammunition represents a great value when starting a new calibre.
JFrank
Member
I have no idea if it's good or bad but it does exist.
Some sob bought all the rest.
No joy...
Some sob bought all the rest.
No joy...
stillquietvoice
Contributing Member
I sized some federal 243 win to 7mm08, loaded them 3 times as 7mm08, then tried to resize to 243, after getting a new 243 win, had some split necks, after annealing and rezizing, also the case necks outside diameters were several thousands under saami spec when going from 243 win to 7mm08. I have 308 cases, but haven't tried sizing down. Would think that the outside neck diameter would be a couple thousandths too thick and would need to be turned, they might not, but measure to be sure.
Same steps as I mentioned is also the way to go, I prefer to use a tapered mandrel when expanding.
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