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Hi All, I have a new .243 and a new 7mm-08. After purchasing new brass for each; I've been given some previously-fired 7mm-08 brass and some once-fired .308 brass. I would expect some more once-fired .308 brass occasionally, in the future. I am interested in necking these down, as needed - mostly to .243, but occasionally to 7mm-08. I've been looking through various forums on doing this and here are the steps I've come up with: 1. Resize to 7mm-08. 2. Trim and debur. 3. Inside neck ream with a 7mm-08 pilot. 4. Resize to .243. 5. Trim and debur. 6. Inside neck ream with a .243 pilot. Are the above steps right ? I'd have to invest in a case neck turner with a couple of inside reamer pilots, but, I have a 100+ rounds of this stuff already sitting around, perhaps more in the future. Thanks, Mark | ||
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Although it is sometimes necessary to reduce the thickness of the neck walls when utilizing .308 brass for .243, most rifles have somewhat oversized chambers so no thinning is necessary. It will depend on the particular brass (military brass is usually thicker) and your particular rifle, but very few I have worked with need brass thinning. You can tell immediately: Just seat a dummy bullet into a reformed case (that you have already tried in you chamber and which chambers without resistance) and try it in your rifle's chamber. If it chambers without resistance, then your neck thickness is fine. As an intermediate step, it is fine to run the .308's through the 7mm-08 sizer (with the expander ball removed) prior to going through the .243 sizer for final. Don't make the mistake of screwing either sizer further into the press than necessary for the finished shell to enter your chamber without resistance -- you'll just be creating excessive headspace by pushing the shoulder back further than necessary. Brass that has been fired more than once will probably benefit from annealing. This is a whole 'nuther subject that I won't go into here. | |||
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I would caution you to be very careful with the segregation of your ammo. Sticking a .243 round in a 7-08 would probably just be a little embarassing, however if you can fit a 7-08 round in a .243, reloading could stop being as much fun as it used to be. Aim for the exit hole | |||
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If you have trouble, STOP and Anneal the Case Mouths. Unless you have "Tight Chambers"(like in any Remington "V"-series rifle) there is probably no need for anything elaborate in the Neck "Thinning". After you have a few Cases made, Seat a few Bullets(make sure they will clear the Lands) and slide the Case into the Chamber without using the Bolt. Then ease them back out with a Cleaning Rod. If they are "tight", then you either did not get them FLRed or the Neck needs Thinning. You might want to consider "Marking" the Case Head with a unique indicator to help with Sorting between the 7mm-08s and 308Wins in the future. Best of luck to you. | |||
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I don't know all your circumstances but why not just post and add for once fired 243 and once fired 7mm-08 brass. Seems like a lot of trouble for fairly common brass. Mike Legistine actu quod scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.  What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
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Eh? What trouble? . . . Jeremiah Johnson | |||
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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 lube 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. | |||
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If the .243 chambered easily, I'd assume it was good to go. To be sure, you can load say a 75% load into the resized case along with your bullet of choice and fire it. If the measurement of the fired case acrost the neck is greater than the loaded round, you're good to go. Another way to check it is if a bullet slides easily into the neck of a fired case, you're good to go and didn't even have to use a measuring stick.  (don't tell Woods or HC that I told you about using the bullet as a check for neck expansion )Aim for the exit hole | |||
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+++, Couldn't have said it better myself. If your military brass doesn't result in necks that are too thick, then it is highly unlikely that any commercial brass will give you a problem. Watch out for split necks in the first firing or two. If they start showing up you'll need to anneal prior to the reforming process. Annealing will also allow the cases to be formed with less force. But it is easy to screws up the annealing process, so look for some clear direction on how to accomplish it. | |||
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The head stamp on this brass is: 308 WIN C B C - which is sold under the Magtech label, I believe. Resized to 7mm-08, with a bullet seated, the O.D. measures ~ 0.312", checked at 4 spots around the neck. Resized to .243, with a bullet seated, the O.D. measures ~ 0.274 - also checked in 4 spots around the neck. | |||
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 X2. Never had to turn necks when down sizing .308s and never saw pressure signs which might be from tight necks. But it might happen so be prudent.  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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I got my first 7-08 back when it was still a wildcat. It had a tight neck and I had to neck turn .308 brass but did not when I necked up .243 brass. Aim for the exit hole | |||
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Yep, that's the difference in a custom wildcat chamber carefully cut with a minimum dimension chambering reamer and a factory chamber hogged out with maximum dimension reamer. | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Resizing .308 to 7mm-08 or .243
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