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Old August 21, 2011, 10:10 PM   #1
hobie01
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necking down .308 brass to .243 question

I understand that .243 brass can be made from .308 brass. I have a bunch of Win. .308 brass and would like to neck it down to .243 for hunting loads. I ran a couple of once fired .308 brass into my .243 die and the length came out 2.023 compared to the max case length listed in my #12 Speer manual of2.045. This case should not be too short, shoud it? My once fired .243 cases are coming out of the resizing die at lengths Rem. 2.049 and Win. 2.046 respectively. The thickness of the case mouth wall is .015 Rem., .016Win., and the necked dowm .308 Win. case came out of the die at.018. My question is should these be reemed and ,or done in more than the one step that I did? I can't think that the thickness is off too much,but I wonder about the length. The trim length is listed as 2.035 and my necked down length is 2.023. Will that be acceptable?
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Old August 21, 2011, 10:19 PM   #2
M.O.A.
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it should be fine but there will be others that know more about it than me chiming in .

i too would like to know how they turn out i want to neck down 308s to 6.5 creedmoor but that take a nother step of fire forming
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Old August 21, 2011, 10:35 PM   #3
PCJim
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I personally dislike the idea of taking any brass headstamped at one caliber and sizing it to another, whether 308 to 243, 10mm to 40S&W, 357Mag to 38spl, etc. It adds another opportunity for a potential screwup, whether at the bench or on the firing line.

While it is true the .243 developed from the .308 Win case and that you can reform 308 brass to shoot the 6mm projectile, why not instead try to trade the brass with someone who needs some 308 brass?
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Old August 22, 2011, 12:43 AM   #4
riverwalker76
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Whenever I form cases I always mark the caliber that I've converted to in a Sharpie Marker on the case itself. It takes 2 or 3 cleanings without wearing off.

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Old August 22, 2011, 01:45 AM   #5
Jimro
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Make sure you monitor neck thickness on those necked down 308 brass. If it is too thick it can bind in the chamber and massively increase chamber pressures. Best thing to do is to neck turn them to spec.

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Old August 22, 2011, 01:48 AM   #6
FrankenMauser
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Quote:
My question is should these be reemed and ,or done in more than the one step that I did?
Check your neck thickness. Compare it to brass that is know-good in your rifle. If you're more than 0.002" over, I would inside ream or outside turn (seemingly redundant descriptions, but that's what we call it ).

Unless you just want to square up the case mouths, don't trim at all, until after the first firing. After that first firing, you'll probably see that the case length has changed. Now, you can trim all of the formed cases to a uniform length.

Sizing the neck to .264", .277", or .284" between the starting and ending diameters would help prevent the loss of some cases. ...But it isn't worth buying a sizing die, just for forming. Your choices are a bit limited, any way. It's basically .260 Rem, .270-308 (maybe .270-257), or 7mm-08.

Quote:
I personally dislike the idea of taking any brass headstamped at one caliber and sizing it to another, whether 308 to 243, 10mm to 40S&W, 357Mag to 38spl, etc. It adds another opportunity for a potential screwup, whether at the bench or on the firing line.
Pay attention to what you're doing.
It's even easier to prevent that "potential screwup", when you don't own a .308. .308 brass is like 9mm and Herpes. You find it everywhere you go. Hobie may not even own one.

If you can't tell the difference between .40 S&W and 10mm, you shouldn't own one. If you can't tell the difference between .38 Special and .357 Mag, you aren't checking your ammo properly. If the issue is other shooters that may make the mistake... Tell them not to start grabbing random ammo, just because they think they own the place. Teach them how to be responsible with reloads (and formed cases).
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Last edited by FrankenMauser; August 22, 2011 at 01:53 AM.
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Old August 22, 2011, 06:22 AM   #7
lamarw
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Seems like a lot of effort when .243 brass is readily available and inexpensive considering the number of reloads you will get from it.

If you were developing a hard or almost impossible round to find or an experimental round, then the effort is understandable and more than justified.
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Old August 22, 2011, 07:38 AM   #8
243winxb
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Best to just buy 243win. brass.

One pass into a FL 243win die is all that is needed. Lube well. The expanded may be hard to extract from the sized neck. Lube the inside of the neck also. The length of 2.023" is OK. Maximum neck diameter of a loader round .276" If larger, outside neck turn. Military brass may form a donut @ the neck shoulder junction. The bolt may be hard to close for this reason from Lee>
Quote:
Forming vs. Sizing

Case forming dies are usually cut to size the case slightly smaller than the minimum SAAMI (Small Arms Ammunition Manufacturers Institute) dimensions, to account for the brass case's tendency to spring back after sizing.

Our full length sizing dies are cut to size the case closer to the middle of the SAAMI dimension, because that is where most rifle's chambers are made, and to size to the minimum would shorten case life. Whether or not our full length sizing die will work as a case forming die depends upon the chamber dimensions of your rifle, and how much spring back there will be when sizing the case.
Neck diameter was over .276" crimping the round in the chamber, causing excessive pressure. > [IMG][/IMG]

Last edited by 243winxb; August 22, 2011 at 07:59 AM.
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Old August 22, 2011, 10:05 AM   #9
Nevmavrick
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It seemed to me that Hobie was asking more as an exercise, than an actual need. I could be wrong.
The thickness of the brass at the neck would be more of practicality-factor than the shorter necks, tho' you may want to equalize the case-lengths.
With the necks...think of it as putting the same amount of brass in a smaller area.
I agree with the problems of mismarked brass, but as I load several wildcats, it can be dealt with. It's just better to use the right brass. The trade would be the best, and easier way.
Have fun,
Gene
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Old August 22, 2011, 11:07 AM   #10
Clifford L. Hughes
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hobie01:

When I was young and I knew more than the authors of the reloading manuals I blew up a 243 Wnchester. However, I broke several common sence practices. Frist, I pulled the bullets from a box of 7.62 match brass and then I necked the brass to 243. I interpolated the powder charge and I reloaded the necked brass without reaming the neck. I was shooting under a 106 degree day off the hood of my car. The rifle was scorching hot to the touch. When I chambered the round it took some pressure on the rifle's bolt. When I touched off the shot all hell broke. I blew the stock in three pieces and welded the bolt to the Mexica Masuer's receiver. The late P.O. Ackley replaced the bolt and I was back in business. I broke several rules but not reaming or turning the necks did play a part.

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Old August 22, 2011, 01:35 PM   #11
M.O.A.
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where might one get a good neck reamer from for a good price ?
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Old August 22, 2011, 02:20 PM   #12
FrankenMauser
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Quote:
where might one get a good neck reamer from for a good price ?
Pretty much any good reloading supplier will have reamers at a reasonable price.

Neck reamers are sold for most case trimmers on the market. In some brands (such as RCBS), they're sold as pilot reamers, to be used in conjunction with case trimming. For some other brands, they're meant to be used in their own step.

Reamers for case trimmers are generally about $7-20. It's pretty cheap, if you already have a trimmer (other than the Lee Zip-Trim, or Hornady Lock-N-Load).

I prefer to outside turn the necks, but that requires a larger monetary investment. Forster and Hornady hand-held neck turners get good reviews. Lyman and RCBS have kits for use with their case trimmers.
Overall, outside turning requires an investment of $50-90, just to get started (you may still need a pilot/mandrel for certain calibers).

And, the "best" method is a debatable subject. Everyone has their own opinion on the matter...
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Old August 22, 2011, 05:02 PM   #13
M.O.A.
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thank you for the links
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Old August 22, 2011, 06:11 PM   #14
F. Guffey
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http://www.rcbs.com/downloads/instru...ndTrimDies.pdf
http://www.midwayusa.com/Find?userSe...eck+reamer+die

Reamer dies are close to $80.00, the reamer that goes with the die run close to $80.00, not for everyone, but if centering the hole in the neck means anything, the reamer/die combination is the way to go.
Then there was Lee, he furnished a neck reamer in his Target Model reloading die set.
As I have said before, donuts are produced by bad habits, a builder/wildcatter/reloader was having trouble with 22/6MM Remington Ackley Improved rifles he was building, when fire forming he had 60% failures, so, I formed 20 22/6mm Remington cases using 30/06 cases and 25/06 cases, the neck required reaming when the neck was sized down to .243 and again when the 243 was necked down to 22/6mm Remington, long story short he had no clue as to the cause of the case head separations and did not understand the cases I formed for him required full length sizing after he determined the length of the chamber, he was happy with the 40 % that did not fail and I thought he was just luck, anyhow he told me none of the cases I formed would chamber.

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