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Necking down 7.62x51

Discussion in 'Handloading and Reloading' started by 119er, Jan 27, 2013.

  1. 119er

    119er Well-Known Member

    I am going to neck down a handful of Lake City 7.62 to 7mm-08. This is a small change and I assume this should be a simple process. Any tips or tricks?
  2. rcmodel

    rcmodel Member in memoriam


    Case lube, run them through the die, and trim them when you take them back out.

  3. Reloadron

    Reloadron Well-Known Member

    I've done it exactly as RC mentioned. I never had a problem. Only did about 100 cases till I got some 7mm-08 brass. The only possible issue I have read about with doing it can be read about here. Again, it worked fine for me and I didn't neck turn the neck ID. Again, it went just fine on what I loaded.

  4. tbob38

    tbob38 Well-Known Member

    Just check neck thickness after forming.
  5. hueyville

    hueyville Well-Known Member

    It is that easy. Other option is to start with 30-06 and form them in steps down to your chosen caliber. It will give you enough neck thickness to inside ream and outside turn to get.an almost.exact.fit of neck to chamber. It does require a chamber cast and some math to get there. I hope when I pass someone does not find the hundreds of 30-06 head stamped ammo and think they hit the mother load for their rifle. It could actually be one of at least ten different cartridges.
  6. fguffey

    fguffey Well-Known Member

    Necking down 7.62x51

    I am going to neck down a handful of Lake City 7.62 to 7mm-08. This is a small change and I assume this should be a simple process. Any tips or tricks?

    "Any tips and or tricks? Yes establish good habits, measure the length of the case before you neck the case down then measure again after necking down, There are many reloaders that believe the neck gets thicker and or thinner when necking up and or down"

    I am a serious reloader, I have forming dies, my favorite forming die is anything that is related to the 308 W like the 308 W forming die and the 243 W forming die, the 308W and the 243 W are the most versatile of forming dies because they are short, The first time I formed 7.7 Japanese from 30/06 cases I paid for the 308 W. forming die.

    I have a 300 Win Mag trim/form die, I will be forming 200 8mm 338 from anything longer than the 338 Winchester Mag, point, I need a short magnum forming die, trimming the 300 Win Mag forming die will serve both purposes.

    F. Guffey
  7. dprice3844444

    dprice3844444 member

    just make sure you check the manuals to see if there is any difference/mention in case capacity info as to avoid any over pressure problems
  8. fguffey

    fguffey Well-Known Member

    "It does require a chamber cast and some math to get there. I hope when I pass someone does not find the hundreds of 30-06 head stamped ammo and think they hit the mother load for their rifle. It could actually be one of at least ten different cartridges"

    Agree, back when everyone was talking about how bad things were going to be I was accepting good deals on new cases from Pat's Reloading in central north OHIO. New pull down 30/06 match LC cases for .08 Cents each, I also purchased new pull down cases from a dealer in Houston for .07 Cents each. The military pull down cases do not have 30/06 stamped on the head of the case, I have formed 7.7 cases from 30/06 R-P just to show the shooter/proud owner of the model 99 it could be done.

    I am not the fan of reloading ahead, when time comes there will not be a lot of loaded ammo to shoot or pull down. the 'hit the mother load' will be in brass.

    F. Guffey
    Last edited: Jan 27, 2013
  9. 119er

    119er Well-Known Member

    Thanks for the info. I will compare them to the factory brass I have and start the loads low again.
  10. lightman

    lightman Well-Known Member

    You should have no problem with one caliber step. Lube it, size it, trim it, load it, and shoot it. Going several caliber differences could require reducing neck thickness. Lightman
  11. hueyville

    hueyville Well-Known Member

    Fguffey, I do not load that far into the future either. But considering all the rifles I have of which the 30-06 is the parent case, just 40 or 50 rounds of pet loads for each times the number of calibers and rifles results in a lot of '06 headstamp ammo. Each batch goes in a MTM ammo box clearly labeled as to what it is. But some folk are not versed enough to figure it out. I can see Bubba being handed a 50 round box clearly marked .338-06 a-square and trying to close the bolt.on his rifle with one, God forbide Bubba is a big strong hillbilly and actually gets the bolt closed. Maybe his brother gets the box marked .270 Win. He will have really crappy results but should not blow himself up. Same with 25-06 and .280 REM. I also neck a lot of .308 up to .338 Federal. All this is just tip of the iceberg. Odds are when all that ends up in an estate sale and the buyer wants to keep the nice boxes and drops the ammo in ziplock baggies the possibilities are mind boggling.

    I too am a big fan of forming dies. Some of the intermediate steps of a.multistep task I can use standard dies. For some reason I have a set of .250 Savage dies that get involved with quite a few recipes. Another reason for a commercial annealing machine and hardness tester. It is plain goofy the things we do. On rifles I could have never gone down the road of obsessive behaviour and purchased the best match ammo available for each rifle and be dollars ahead and much more time to shoot. Only problem would be the voices in my head telling me if I weren't so lazy that 400 yard group might be a tenth tighter.
  12. docsleepy

    docsleepy Well-Known Member

    Going from .308 to 7mm08 -- that's exactly how I get brass for my 7mm08. I actually PREFER it becuase then the neck ends up a bit thicker and for accuracy, I *want* a tight neck fit. (Why do you think we make our 6PPC brass to have only a .001 clearance at the neck? To reduce ANY movement!)

    Works great. I painted red paint on the headstamp to help me keep track of the fact that they weren't really .308.

    Besides, .308 is readily available at many target ranges on the ground, and I've found it was cheaper brass to buy than 7mm08.
  13. TwoEyedJack

    TwoEyedJack Well-Known Member

    I have done this with success. Just make sure you adjust your press to cam over or you won't move the shoulder back enough. You will also need to ream or swage the primer pocket. Once that is done, it loads just like 7MM-08 brass.
  14. fguffey

    fguffey Well-Known Member

    I will assume the press being used is a cam over press.

    Then I go to the rational for ‘caming’ over, “Just make sure you adjust your press to cam over or you won't move the shoulder back enough”, The case body/shoulder juncture on the 308W (7.62x51) is 1.559 from the head of the case, the case body/shoulder juncture on the 7mm08 is 1.559 from the head of the case to the case body juncture. I could use the .400” datum back to the head of the case but that has never worked before when it came to ‘rationale’.

    Again, what is wrong with knowing the length of the chamber first? I would suggest neck sizing with a full length sizer die first, then attempt chambering the neck sized cases,’IF’ the neck sized cases did not;would not chamber, ‘THEN!"’ I would START moving the shoulder back ‘slowly’ by adjusting the die down to the shell holder, stopping long enough to attempt chambering the case being sized. Once the case chambered I would suggest stopping long enough to measure the gap between the bottom of the die and top of the shell holder. Because I use the humblest of tools, the feeler gage, to adjust the die off the shell holder I am not required to make wild guestimates in fractional turns converted to thousandths, or degree converted to thousandths, I go straight to the verifying tool, the feeler gage.

    I was thinking/wondering, “Who has a set of instructions for a cam over press??? besides me. Then I wondered, ‘How is it possible a reloader could own a press and not be able to determine if the press was a cam over or a jam-over, cram-over or a lock-up press, of the last three options, none of the 3 options is a characteristic of a cam over press. Again, I have Herters, lots of Herters, all of my Herters cam over. I have RCBS Rock Chuckers, none of my Rock Chuckers cam over. I can ‘fix’ them to cam over, problem, reloaders believe the Rock Chucker cams over.

    Then there is the increase resistance to sizing due to number of times the case has been fired. not easy to get past the reloaders that believe the case does not get ‘fully grown’ until it has been fired at least 4 times, the same reloader believes it is possible to take a fired once and neck sized 4 time case back to minimum length by full length sizing to start over, back to resistance to sizing increasing because of the number of times the case has been fired.

    The amount of effort required to size/form a case is variable, nothing like starting with a new case, if for no other reason than to determine the length of the chamber from the bolt face to the shoulder of the chamber. Agaoin, rational, if the reloader knew the length of the chamber the reloader would measure the length of the case from the head of the case to its shoulder to determine if it would chamber, if after sizing the case will not chamber the reloader could start the preverbal wild guestimates of turns converted to thousands based on the 14 threads per inch or .071428” advance per turn.

    Cases that are stubborn to size wild require addition effort, to increase effort by screwing the die down to increase the presses ability to overcome resistance to sizing. EVEN THEN! It is possible to determine if the case whipped the press or if the press shipped whipped the case.

    30/06 to 308W, again, I am a case former, I form cases, I form cases I never intend to fire, it is a small price/sacrifice for a few of my 30/06 new unfired match cases to to pay or give up their place to become test cases. An impossible concept for a reloader to understand, the 30/06 case body/juncture is 1.948” from the head of the case to the case body/shoulder juncutre, the 308W distance from the case head to the case body/shoulder juncture is 1.559, the difference in the two lengths is .389”. I would think a reloader would be an expert case sizing reloader by the time they moved the shoulder back, .389”. Me? I would adjust the die off the shell holder to PREVENT sizing the case to minimum length Until I determined the length of the chamber, I size cases to fit, reloaders fire to fit? Reloaders have the same press, die and shell holder, I use the companion to the press, the feeler gage, I do not insist the press cams? over, the shoulder I form is not the came shoulder I started with, when forming 308W cases from 30/06 cases the shoulder of the 30/06 did not move, it became part of the case body, the neck was trimmed and part of the case body became the shoulder.

    To appeal to the ‘neighborhood acceptance’ I could have said ‘bump’, but as I said there is a lot going on when I use the press, die and shell holder, my case body and shoulders do not do a lot of traveling.

    F. Guffey
  15. blarby

    blarby Well-Known Member

    I've done this- it works just fine.

    Once we run out of 7-08 brass for my wifes rifle, I won't be buying any more.
  16. jerkface11

    jerkface11 Well-Known Member

    On once fired brass you may need to anneal first.
  17. GLOOB

    GLOOB Well-Known Member

    The case necks will often be thicker. I find my Hornady die sizes the necks too much to begin with. The necked down cases are a REAL bear to pull the expander through, even with lube. I hoped this would get easier on the subsequent loadings, but it didn't.

    I sanded the neck of this die for a good 30-40 minutes using a drill, dowel, and some sandpaper, periodically checking the fit. Even after all that, it was still too tight for my liking on necked-down 308 cases; it was 3 times as hard to expand the cases as it was to size them. (And I still needed the die to size enough on my necked-up 243 cases, so I couldn't go much further!)

    So I got a Lyman M die for expanding, which makes it easy as pie. Effortless with no lube. Of course, I'm loading cast bullets, so the M die stepped flare is also greatly welcomed. And the theoretical reduction of case stretch/trimming is added cake.

    Other options to consider are a neck reaming setup. Or one of those adjustable collet neck sizer dies... but then you'd need to sort your brass and adjust the die for the headstamp.
    Last edited: Jan 31, 2013
  18. 119er

    119er Well-Known Member

    I have a wilson trimmer. I'll see if I can get a reamer setup for that. It may be time to also make the next step and start turning the necks too. I plan on having a Rem. 700 rebarreled for .284 Win and sizing up Lapua 6.5x284 brass back to .284 so the reamer and neck turner will be handy anyway. My plan is to get real technical about dimensions with that rifle. For the 7mm-08 I plan to move to lapua .308 Palma necked down to .284.
  19. rcmodel

    rcmodel Member in memoriam

    If you ream, don't neck turn.

    If you neck turn, don't ream.

    It's one or the other.
    If you do both, there will be nothing left!!

  20. GLOOB

    GLOOB Well-Known Member

    Interesting. I was just reading up on the Wilson neck reamer, since you mentioned it, and since I have one in the attic, somewhere.

    It sounds like you are only supposed to ream the first third of the neck, because the reamer actually makes the brass a couple mics LARGER than bullet diameter. This is to aid in bullet seating. That wouldn't solve the expanding problem that I was experiencing. That also wouldn't do any good for removing "donuts" from necked-up cases.

    I guess a neck turning setup would be the only way to truly uniform these converted cases?

    OTOH, I guess if your neck is thick enough to begin with, and the tool can be adjusted deep enough, you could ream the entire neck. Then resize and still have neck tension. Anyone have a Wilson reaming setup?
    Last edited: Jan 31, 2013

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