Thread: Neck Tension Issue... I think

G'day team,

I've been discovering the highs and lows of reloading over the last 12 months or so.

My 7mmRM shoots pretty well. Recently I've been trying combinations of AR2217 and 162g ELD-X. Long story short, about 6 months ago I was doing some load development and had issues with excessive pressure when I was not expecting it so had about 30 bullets to "pull".

I pulled them all last night using the RCBS hammer thing. After a few, I noticed that about 1/3 of them were very easy to pull and the rest were very difficult. I'm looking for any thoughts on why this might happen and whether this could be the cause of the unexpected excessive pressure?

The bullets I pulled were loaded over two separate sessions with the same dies. I might have fiddled with the dies in between (it was a few months ago and I can't actually remember) but don't think I would have done anything too silly? Would I? All were loaded with twice fired Norma brass. All seated 0.020" off lands. All cases trimmed to whatever the right spec is. None were compressed loads. I can't think of any other variables off the top of my head? Oh, and no points for who can guess which of the projectiles below was harder to pull.

Thanks for any help in advance.

Elliott

Possible that one batch had been left a while before being reloaded. Sometimes the deposits inside the case neck harden and even corrode. Did you thoroughly scrub the insides of the necks before resizing and reloading?

Originally Posted by Woody

Possible that one batch had been left a while before being reloaded. Sometimes the deposits inside the case neck harden and even corrode. Did you thoroughly scrub the insides of the necks before resizing and reloading?

Didn't give them a good scrub, but they weren't left long before firing (couple of days max) and I had a good look inside the necks last night and they all looked in good nick - no corrosion just powder.

You say you may have set the sizing die diffently? If you developed your load initially with virgin brass did you actually run that brass in the sizing die before loading or not? If you did'nt, then on the second loading the sizing die may have produced different inside neck tension to the unsized virgin brass. Before resizing used brass it is a good idea to brush inside the case necks with a 7mm nylon or bronze brush. Also if you only resize the neck say half way down compared to full resize your neck tension will differ considerably.

Not the issue here but it is possible under the right conditions for bullets to "cold solder" themselves to the neck and that does cause pressure.
It was first noticed in the 20s with batches of experimental 3006 ammunition. It was known that tin not only prevented copper fouling in artillery pieces it actually removed it.
Tin washed projectiles were loaded to see if this worked in rifles and inital trials were good. Problems were encountered with stored ammunition producing excessive pressure, initally overcharging was suspected but pulling rounds showed that not to be true some had soldered to the case so the idea was dropped. The cfe powders incorporate a minute amount of metallic tin in the formula and that is sucessful.
Sorry it's a little off track but I thought it interesting

+1 for definitely running a brush down the neck before re-sizing. How many firings has brass been through ? have you annealed the brass ? After 2 or three firings the brass will harden & neck tension will get variable.
Did you by any chance weigh the powder aft you pulled the pills ? Worth doing for a few just to confirm you did not some how end up with variation in powder loaded.

Also, did you chamfer the inside of the neck mouth. If you trimned to length you must lightly deburr the inside and outside of the mouth. A good reloading manual will detail all the correct procedures.

Once an immunologist by any chance? Is the sizing die a bushing die or does it have an expander mandrel? You didn't change bushings or remove the mandrel (be pretty hard to seat into a case resized without the mandrel I'd imagine). Try seating a bullet back into the cases you pulled the bullets out of. Grab the press handle down close to the press to get a better feel of the resistance needed to seat a bullet. Pressure issues when you weren't expecting it? You didn't change primer brands or switch to a new batch of powder? are you keeping the brass trimmed regularly? you don't have a dodgy cheap electronic scale or a worn out old beam balance? Are you measuring your OAL off the ogive on all loads (i.e. OAL not creeping up)/checking for adequate shoulder bump after brass sizing.

Originally Posted by Woody

You say you may have set the sizing die diffently? If you developed your load initially with virgin brass did you actually run that brass in the sizing die before loading or not? If you did'nt, then on the second loading the sizing die may have produced different inside neck tension to the unsized virgin brass. Before resizing used brass it is a good idea to brush inside the case necks with a 7mm nylon or bronze brush. Also if you only resize the neck say half way down compared to full resize your neck tension will differ considerably.

Resized the virgin brass. But will definitely give the inside of the neck a good clean and make sure I'm resizing consistently, cheers.

Originally Posted by chainsaw

+1 for definitely running a brush down the neck before re-sizing. How many firings has brass been through ? have you annealed the brass ? After 2 or three firings the brass will harden & neck tension will get variable.
Did you by any chance weigh the powder aft you pulled the pills ? Worth doing for a few just to confirm you did not some how end up with variation in powder loaded.

Yeah will definitely brush the neck now, cheers. Two firings, brass not annealed. Powder weights were accurate.

Originally Posted by Woody

Also, did you chamfer the inside of the neck mouth. If you trimned to length you must lightly deburr the inside and outside of the mouth. A good reloading manual will detail all the correct procedures.

Yep, all well and truly deburred.

why are they seated so deeply????

also next time you go to pull some...seat them a TINY bit deeper first....it breaks any sealing tension and makes it a bit easier....I pulled 100 loads the other week...man some do take a few whacks till they let go.... most took 5-6 some 10....

Originally Posted by Micky Duck

why are they seated so deeply????

They're seated 20 thou off lands?

Originally Posted by yerimaginaryM8

Once an immunologist by any chance? Is the sizing die a bushing die or does it have an expander mandrel? You didn't change bushings or remove the mandrel (be pretty hard to seat into a case resized without the mandrel I'd imagine). Try seating a bullet back into the cases you pulled the bullets out of. Grab the press handle down close to the press to get a better feel of the resistance needed to seat a bullet. Pressure issues when you weren't expecting it? You didn't change primer brands or switch to a new batch of powder? are you keeping the brass trimmed regularly? you don't have a dodgy cheap electronic scale or a worn out old beam balance? Are you measuring your OAL off the ogive on all loads (i.e. OAL not creeping up)/checking for adequate shoulder bump after brass sizing.

- immunologist: once upon a time, yes
- dies are your stock standard rcbs dies
- none were Noticeably difficult to seat from memory, is there something that could cause some to be more difficult than others? How would I control for that?
- unexpected pressure in that I'd fired that charge before without any issue then that same charge caused very sticky bolt consistently after even though the charge was the same (yes, weighed extras from the same batch)
-primers and powder the same
-brass trimmed to spec
-beam scale is accurate as far as I'm aware. I calibrate regularly because science.
- measuring OAL off ogive for each bullet