Another .308 brass to 7mm-08 or .243 Thread


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beartooth91
June 11, 2010, 04:11 PM
Hi All,

I have a 7mm-08 and a .243. Since purchasing brass for both; I've been given some .308 once-fired and previously-fired 7mm-08 brass. I expect I'll be given more .308 brass at occasional intervals in the future. I'm interested in resizing some of them down to .243. I'm thinking -
1. Resize to 7mm-08.
2. Inside neck ream with a 7mm reamer.
3. Resize to .243.
4. Inside neck ream with a .243 reamer.

Is the above a safe, doable way to do this? I'd have to invest in a RCBS case neck turner and reamer pilots.

Thanks,

Mark

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grubbylabs
June 11, 2010, 05:59 PM
You could send me your 308 brass, that would be safe.:D

Peter M. Eick
June 13, 2010, 07:01 PM
I will comment that the only time I ever perfed a primer was when i accidently got a 243 case mixed into my hot 7-08 loads. If you do this, work up a load carefully for each different combination.

Brock K
June 13, 2010, 07:14 PM
Yes you can do it that way.. Or you could just skip the inside neck reaming.. In 20+ years of reloading i have never inside necked ream.. I have turned the outside but never reamed the inside.. If your gonna do this make absolutly sure you dont mix your 7-08 up with your 243's.. I shoot all 3 and most of them are 308 brass...

GW Staar
June 13, 2010, 11:20 PM
Hi All,

I have a 7mm-08 and a .243. Since purchasing brass for both; I've been given some .308 once-fired and previously-fired 7mm-08 brass. I expect I'll be given more .308 brass at occasional intervals in the future. I'm interested in resizing some of them down to .243. I'm thinking -
1. Resize to 7mm-08.
2. Inside neck ream with a 7mm reamer.
3. Resize to .243.
4. Inside neck ream with a .243 reamer.

Is the above a safe, doable way to do this? I'd have to invest in a RCBS case neck turner and reamer pilots.

Thanks,

Mark
My successful .308 to .243 conversion process is simpler and works fine.
1.Resize to .308.
2. Resize to .243.
3. Load, then fireform.
Neck ream only if a loaded cartridge measures too tight in your gun chamber's neck. If it does then ream inside the neck after it's resized (using a sizer without an expander) to .243.

DON'T REAM TWICE as per your steps! Too thin necks will result. Neck may then split first or second reload.

BTW Forster makes reamers sized to ream .243 brass before sizing, or after sizing. Don't know what RCBS makes.

Consider the following: Using a die with an expander ball, when the case is sized (expander ball is in the case), the extra neck wall thickness decreases the inside neck diameter. Then when you pull the die out, the expander sizes the inside of the neck to the expander diameter. Now the outside diameter of the neck gets pushed out. If it's too big, you might have feeding problems, but most chambers are big enough to handle it. No inside reamer is called for here. You could use an outside reamer, but the next paragraph is a better, easier way to go, IMO.

Using a die without an expander, the extra material is left inside the neck...therefore a reamer would be needed to ream inside neck diameter to the correct size to give perfect neck tension. The question is will the Forster or RCBS reamer be that perfect diameter? That's what you have to investigate.

Outside neck reamers are typically made for another purpose. Benchresters use them to make the neck thickness concentric (the same thickness) all around the case, so that bullet release is even all the way around. Not something most of us need, and may be outright dangerous to do in gas semiautos (like a Remington 25 or Dpms chambered for .243), where thin necks (especially at the shoulder) translate to failed brass. If you choose to use one on this brass be careful that you don't cut into the shoulder to much...easy to do with the shorter than factory necks you will experience.

beartooth91
June 14, 2010, 06:59 PM
Ok, here's some data from my 1st two (dummy attempts):


These 308's have a 3 letter stamping. The 1st letter is a "C" or an "O" or a "Q". I can't tell. The middle letter is a "B". I'm sure of that one. The 3rd letter looks to be a "C" or a "G".

1. I set up my Hornady 7mm-08 die for FL resize and ran a case in. Well lubed or so I thought. Much more force reqired to resize. Out it came. Measured it and it was approx .008 short (~2.017"), which surprised me ('cause I've never done this before).

2. Checked chambering and a little force was required to chamber the case. Tweaked the die in another 1/8th of a turn and sized again. Chambering was now, normal (easy). (Could it be the slightly shorter case required the additional 1/8th of turn ?)

3. Seated a bullet. O.D. of the case neck, checked in quarters is approx .004 thicker than standard 7mm-08 brass with the same bullet seated. Don't know whether this is a problem or not. Dummy round chambered as normal (easy).

4. I then took a 2nd case and repeated Step 2 (7mm-08 die turned the additional 1/8 turn in from where I normally have it set).

5. I then ran it into my Hornady .243 die, set up as normal for FL size.

6. This case was long (~2.046")! So, trimmed and deburred (to 2.035").

7 Checked chambering (in the .243!) and it chambered easily.

8 Seated a Sierra 70 gr HPBT MK to 2.625" (as I normally do 'cause this rifle has a long throat). Checked chambering and it chambers fine.

9. O.D. of the case neck (with bullet) is approx .004 wider (or thicker?) than with a standard .243 case with the same bullet. Again, don't know if this is a problem or not.

Brock K
June 14, 2010, 08:04 PM
You gotta remeber when you are sizing brass you are moving the brass into a new shape.. when you sized from 308 to 708 that extra brass moved down a little bit so there for you needed to turn your 708 die down slightly to bump your shoulder back alittle.. This is normal.. Also remeber the 308 has a longer neck then both the 708 and the 243 and the 243 has a shorter neck then the 708.. Load a few up and and fire them.. Once they are completely fireformed you will be good to go.. Actually your formed 243 case wasnt long at all.. ANSI spec for the 243 is 2.045 so you really didnt need to trim at all.. Now after you fireform them they will grow and that is when you want to do any triming if needed.. Brass will grow as you fire it..

beartooth91
June 14, 2010, 08:53 PM
Ok,

The brass head on these are labeled -

308 WIN

C B C

I believe these are sold (as loaded cartridges) under the Magtech label. Anyone had any experience reloading these?

**PS** The necked down dummy rounds, measured at 4 points around the neck are showing O.D.'s of 0.274 (for the .243) and 0.312 (for the 7mm-08). Am I good to go?

Brock K
June 14, 2010, 10:06 PM
Yup thats magtech brass and it is decent brass.. I have thousands litteraly mostly pistol and have no issues.. As far as you OD standard 243 is .276 and the 708 is .315 per ansi.. So you should be good to go.. You may have to outside turn them after your first firing.. Here is a pic of the diamension..

http://i980.photobucket.com/albums/ae282/stcroix63/ansi.png

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