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Old July 8, 2005, 07:55 AM   #1
cdoc42
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Neck turning problem

I've been reloading for over 25 years and have never experienced this situation. I neck-turned some Winchester .300 WSM cases, loaded them with 62.0 gr of IMR4320 behind a Hornady SST 150gr, fired by CCI LR primers. Fired them off, then resized. I noticed there was very little resistance as the expander plug pulled through the case. Usually this is a hassle and requires lubrication of some sort. I took a Hornady SST bullet and hand-fitted it into the mouth of the case. It met case resistance but the bullet seemed to start to seat itself deeper than in cases I had not neck-turned. One case out of 20 actually allowed the bullet to drop right into the body of the case as though I had never resized it. Repeated attempts to resize made no difference. I took a previously loaded round and removed the bullet with my impact hammer. One small whack and the bullet popped out. usually I have to hit the hammer several times. Could it be that my neck-turning operation removed too much external brass and upon firing the case expanded to such an extent that I cannot resize to accept the .308 bullet?
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Old July 8, 2005, 11:35 AM   #2
zeisloft
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doc, how many times has this brass been through the mill?
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Old July 8, 2005, 11:51 AM   #3
brickeyee
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Neck turned cases often require a bushing type die to get the neck sized back for the next go round.
Redding makes 'regular' style dies that use inserts (as opposed to bench rest dies used with an arbor press).
If the gun you are reloading for does not have a tight neck chamber, turning necks is not likely to be very prodctive with regular brass.
Brass made from a longer case and sized down creating a thicker neck than needed can be turned to match the chamber.
Neck turned cases are normally only neck sized to preserve the tighter chamber fit of the case body while providing suitable neck tension.
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Old July 8, 2005, 01:41 PM   #4
LHB1
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cdoc42,
Sounds like you have reduced the thickness of neck to such that your std sizing die is now too large and does not reduce diameter enough to fit tightly on the bullet. Don't worry, it's a common situation. As another poster stated, you just need a sizing die that will take sizing inserts. I use Neil Jones bench rest dies and arbor press but I think Redding sells such dies for std reloading presses. Measure the thickness of neck metal, double it (for both sides), and add diameter of bullet. (Alternatively, measure neck diameter of reloaded round using turned neck case and desired bullet.) A sizing ring about .003 smaller than this diameter should work well if I remember correctly. Note that with such a setup you no longer need the neck expander button on the sizing die.

Good shooting and be safe.
LB
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Old July 8, 2005, 03:22 PM   #5
cdoc42
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Zeisloft, the brass has been fired no more than 4 times. Usually I fire them (at least on practice rounds) until the necks split. Never bothered with annealing.

Since this problem has not occurred with brass I did not neck-turn, I most likely will not invest in the dies, etc., discussed herein. I'll just chuck the brass and stick with non-turned brass I have. I'm getting 100-yard groups under one inch with 130gr and 150gr bullets. Being nuts, I guess, I wanted to see if neck-turning would drop that even further.

Thanks for your info.........
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Old July 10, 2005, 09:04 AM   #6
cdoc42
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Well, I fired off 15 rounds of neck-turned and 10 rounds of ammo that was not neck-turned. Both hit 2 inches high at 100 yards, dead on at 200 and 3 inches low at 300. I haven't chronographed them but I can't find those stats in any book I have. It doesn't seem to make a difference if the bullets aren't held as tightly in the neck-turned cases (?) Interestingly, I also was able to simply pull a bullet out of one of the loaded cases with hand grip-pressure - I dumped that one into the recycle mode.
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Old July 10, 2005, 10:32 AM   #7
brickeyee
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Powders do not all behave the same way with low neck tension. Some operate just fine, while others do not burn cleanly and can even have erratic pressure spikes. The bullet starts moving and can even be stopped when engraving the rifling causing very high pressures and a possible blow-up.
This is the explanation Norma has for various blow-ups in older surplus firearms.
Low neck tension is not an issue if the bullet is already into the rifling, but this is not a great idea for anything but benchrest/target rounds. Unloading can dump powder into the action and leave the bullet in the chamber/throat. Luckily the next round rarely chambers.
Neck turning is used to improve the concentricity of bullet to barrel. By reducing the clearance between the neck and the chamber walls and using a neck sized case the round fits with very little play in the chamber. Unless great care was taken during chambering it is seldom very useful.
Tight neck chambers are made to allow the use of regular brass with turning necks. The tight neck is not as beneficial as much as the ability to turn necks to have a clearance of only 0.001-0.002 on a loaded round. That is 0.0005-0.001 per side and ensures the bullet axis is very nearly parallel to the bore before firing.
Many stock guns do not have the high accuracy chambering needed to really benefit from neck turning. There have been experiments with forming cases from a longer parent case to provide increased neck wall thickness. The thicker necks are then turned to match the chamber dimensions found. The improvement was not very significant since most of the weapons had lighter weight barrels to start with and were not target grade.
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Old July 11, 2005, 07:45 AM   #8
cdoc42
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Thanks, brickeyee; too bad this type of information is not available as one ponders the decision to invest in various equipment to improve accuracy.
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