Case annealing and neck tension

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LeftySixgun

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I didn’t want the 375 H&H Virgin case stretch thread to take a tangent. I’m new to the belted magnum cases. Is it a good idea to anneal the case necks on these larger bottle neck cartridges like the 300 & 375 H&H, the 416s…?

Also, is there an ideal amount of neck tension on these larger cases? If so, how much?
I deliberately fired 4-5 rounds while keeping the same single round in the magazine to see if recoil would set the bullet back, and it did! And by a pretty good bit, about .050” if I remember correctly. This was a 300gr RN FMJ by PPU, NO CANNELURE. Do you use a taper crimp die for this issue?
 
This is certainly not scientific, and I recognize that both the “neck” surface area and projectile weight are on the extreme end, but I have been annealing 600 NE, and other large NE cases, after every firing. The annealed cases’ grip on these heavy projectiles when deconstructing ammo with my homemade 2 foot long kinetic bullet puller is very impressive. Pulling 10, or so, is enough to deserve a rest.
 
BayouRobert said:
This is certainly not scientific, and I recognize that both the “neck” surface area and projectile weight are on the extreme end, but I have been annealing 600 NE, and other large NE cases, after every firing. The annealed cases’ grip on these heavy projectiles when deconstructing ammo with my homemade 2 foot long kinetic bullet puller is very impressive. Pulling 10, or so, is enough to deserve a rest.
Click to expand...
Good question I have then. I wanted to pull down some 375H&H ammo and noticed that it took very little effort to pull the bullet with an inertia hammer type method.
 
Interesting. I had some 7x57 and 270 Win Remington ammo. They both shot like shit so I decided to pull the bullets. Some cartridges took one smack with the kinetic puller and others took several real good smacks. So the I annealed the cases and resized them. Reloaded them with the same powder that they came with. Both calibers had reduced groups by 1/2.
 
Graham Hunter said:
Interesting. I had some 7x57 and 270 Win Remington ammo. They both shot like shit so I decided to pull the bullets. Some cartridges took one smack with the kinetic puller and others took several real good smacks. So the I annealed the cases and resized them. Reloaded them with the same powder that they came with. Both calibers had reduced groups by 1/2.
Click to expand...
Thats every bit of inconsistent neck tension!! And in that case, annealing will fix.
 
I have always crimped my 458 lott with the normal reloading dies- taper crimp. Never had a problem. I think you need to crimp the 375 even if you are using it for longer range plainsgame. So I would say anneal and try to get your crimp as consistent as possible so you retain accuracy.
 
LeftySixgun said:
I didn’t want the 375 H&H Virgin case stretch thread to take a tangent. I’m new to the belted magnum cases. Is it a good idea to anneal the case necks on these larger bottle neck cartridges like the 300 & 375 H&H, the 416s…?

Also, is there an ideal amount of neck tension on these larger cases? If so, how much?
I deliberately fired 4-5 rounds while keeping the same single round in the magazine to see if recoil would set the bullet back, and it did! And by a pretty good bit, about .050” if I remember correctly. This was a 300gr RN FMJ by PPU, NO CANNELURE. Do you use a taper crimp die for this issue?
Click to expand...
@LeftySixgun
The best crimping die on the market in my humble opinion is the Lee factory crimp die.
This applies a crimp similar to that from the factory and the projectile DOESN'T need a canuler.
Bob
 
I have a LEE factory crimp die coming. The seating/crimp die and set up to crimp is only consistent if the case are all the same length. That would mean Id have to trim the cases after each firing. The thing I noticed about this cartridge is that they grow/stretch as bad a s a 30-30 case...even after just one firing.
But I am enjoying this larger cartridge and the rifle.
 
I have mainly wildcat and oddball cartridges that I reload and I need my brass to last. I therefore anneal everytime I reload to minimise the risk of cracked necks and shoulders. As others have said, the Lee factory crimp is superior to other options. It will crimp any projectile with or without cannular. With my 416WSM using donor 325WSM brass the bullets are seated with the cannular a long way forward of the crimp.
20250127_175628.jpg
 
As others have already posted, the Lee Factory crimp die is by far the best on the market. It's the best $30 you will spend on reloading gear for big bores.

If you have a caliber they don't list as standard in the Lee Factory crimp die, they will make a custom die for you. Order the die on their website, and when you get an email confirmation of the order #, mail them an EMPTY UNPRIMED case with a bullet seated in the case, plus a small note with the part # and order #, and your custom crimp die will usually arrive in 2 weeks.

The LFCD starts at $15, most standard calibers are $20, 404 J and 416 Rigby are $50.

leeprecision.com

Factory Crimp Die

Collet Style Crimp Die. Incorporates a collet to apply a rifle type crimp to the case. Makes these very difficult to crimp cartridges a delight to reload. Bullets do not need a crimp groove, as the collet is so powerful it will form one. NOTE: This die is not carbide.
leeprecision.com leeprecision.com

Just understand, by crimping the case you are working the brass harder, which makes annealing that much more important.
 
In addition to annealing and the Lee FCD to give more bullet "grip" is to remove your decapping pin/ expander ball from your sizing die and spinning it in your cordless drill with ultra fine emery cloth to incrementally remove tooling from the expanding ball diameter until you find your desired tension. I am hesitant to even use the word "remove" basically it is just polishing the expanding ball. Go easy and check often; a little goes a long way. The last one I did was for my 270 wsm and +/-.0005" was perfect.
 
Graham Hunter said:
Interesting. I had some 7x57 and 270 Win Remington ammo. They both shot like shit so I decided to pull the bullets. Some cartridges took one smack with the kinetic puller and others took several real good smacks. So the I annealed the cases and resized them. Reloaded them with the same powder that they came with. Both calibers had reduced groups by 1/2.
Click to expand...
I wonder if you could use the Lee factory crimper on unfired factory ammo just to be sure of neck tension? Any objections?
 
steve white said:
I wonder if you could use the Lee factory crimper on unfired factory ammo just to be sure of neck tension? Any objections?
Click to expand...
I know several people that have done this exact thing. It works to varying degrees depending on if there is any crimp put on by the original manufacturer.

If the factory ammo uses a bullet that has a canelure, most often it's already been crimped.

If the bullet used in the factory ammo doesn't have a canelure it can still benefit from crimping, but usually only a light one. Go slowly and test for accuracy. If you bend the jacket excessively your accuracy will fall off quickly and you'll start to see signs of higher than normal pressure.
 
LeftySixgun said:
My crimp die arrived last night. I’ll set it up today or tomorrow.
Click to expand...
@LeftySixgun
Make sure you follow the instructions.
It's easy to over crimp and put a big groove around the projectile.
How do I know
Easy, I thought I knew more than the expert and screwed it down another full turn. When I pull the bullet ( after much hammering) I found a nice big indent all the way around the projectile. I guess the experts knew best. Don't try and crimp Barnes or other monos, it don't work.
Bob
 
steve white said:
I wonder if you could use the Lee factory crimper on unfired factory ammo just to be sure of neck tension? Any objections?
Click to expand...
@steve white
No reason you can't.
You are inserting a live round any way.
Just be careful not to over crimp.
Bob
 
Bob Nelson 35Whelen said:
@LeftySixgun
Make sure you follow the instructions.
It's easy to over crimp and put a big groove around the projectile.
How do I know
Easy, I thought I knew more than the expert and screwed it down another full turn. When I pull the bullet ( after much hammering) I found a nice big indent all the way around the projectile. I guess the experts knew best. Don't try and crimp Barnes or other monos, it don't work.
Bob
Click to expand...
Thanks Bob, I’ve got it set about 3/4 of a turn total after touching the shell holder. I’ll crimp one tomorrow and then pull it and check for a ring in the bullet. I do know that the collet is NOT closed up fully where I have it set right now.
 
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