I'm reloading 7MM-08 (not that it matters) and have been neck resizing only. I've read that periodically you need to full length resize cases after you neck resized a number of times.

I've got a couple of questions.

1. If a case forms to your chamber when you shoot the gun, why would you ever need to full length resize? I understand why you need to periodically trim the case length, but why would you have to occasionally full length resize.

2. If you do need to occasionally full length resize, how do you know when you need to do it? How many times can you neck resize only before you need to full length resize?

firstshot
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Make your first shot count!

quote:

I've got a couple of questions.

1. If a case forms to your chamber when you shoot the gun, why would you ever need to full length resize? I understand why you need to periodically trim the case length, but why would you have to occasionally full length resize.

2. If you do need to occasionally full length resize, how do you know when you need to do it? How many times can you neck resize only before you need to full length resize?

firstshot
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Make your first shot count!

RULE OF THUMB...
F/L resizing is most important for hunting ammunition. Not only do you want 100% reliability, there is no way to keep the gun squeaky clean and a tight case fit under normal circumstances will not give you that reliability under field conditions.
Secondly, F/L sizing IMO is directly proportional to the loads intensity: higher pressures = greater case expansion.
Lastly, if all else remains trouble free, F/L size about every fourth to fifth reload.
To avoid any doubt, I use and recommend case gauges by Sinclair...it either fits, or it doesn't and you will "see" when it is time to trim.

The only time I ever do a full-length resizing is with new brass before the first loading.

Depending on your load, your gun will tell you when to FL size. IT's fine to neck size only, and it's generally better for accuracy. But there will come a time when the bolt is sticky coming up for removal, or when closing the bolt on a round. Then you need to resize. But, make sure you aren't oversizing, adjust your dies so it JUST sizes enough for yor chamber. The poster about hunting cartridges has a point about proper feeding, so if you're reloading for hunting, not a bad idea to resize for that.

I FL size most calibers I shoot w/ the exception of about three and I have to FL size them when the bolt gets stiff while chambering. Sometimes you have to bump the shoulder back alittle. Like another said, I would definitely do FL sizing on my hunting ammo.

Good Luck!

Reloader

I reload for 12 different cartridges and neck size them all, but occasionally your shoulder won't get bumped back. Then it becomes necessary to full length size the cases to restore the shoulder since neck sizing dies don't usually touch the shoulder. Best wishes.

Cal - Montreal

I agree with the above posters for bolt action rifles. Necksizing is all that needs to be done for same brass in same rifle.
For semi auto rifles, I will full length size each time. Locking mechanism isn't as strong/sure as a bolt action's. Out of battery firing is possible, and dangerous.
My two cents
muck

Thanks to everyone for the info!!!!

firsthost
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Makey your first shot count!

I'll go with muck.

I agree with ricciardelli,..I FL when they come out of the bag. NK sizing will most often make them last longer than the primer pockets will.