Neck diameter too large after annealing?

[Dusty Stevens]

Man im all messed up on the 257stw. I size the cases with a 7stw regular fl cheap die then size the necks with a homemade bushing sitting in a 375 h&h die. Its a nightmare. Luckily i stopped shooting it many years ago

 

[Ccrider]

Man im all messed up on the 257stw. I size the cases with a 7stw regular fl cheap die then size the necks with a homemade bushing sitting in a 375 h&h die. Its a nightmare. Luckily i stopped shooting it many years ago

Dusty. You need one of these. A little case lube, one pass on a 7mm STW and you are good to go. Takes about 2 seconds.

 

[Dusty Stevens]

Dusty. You need one of these. A little case lube, one pass on a 7mm STW and you are good to go. Takes about 2 seconds.

No need man. I think i have 3 25cals left. I see them as actions and stocks waiting to be built if i need them. I wouldnt actually shoot one

 

[Mags]

Had the same problem loading .257 STW a few weeks ago. I had taken the plunger out of my non-bushing 257 die. Did not realize that the die was sizing down way more than optimal and then the plunger was opening the neck back up to .287 outside diameter.

Seated bullets and the bullet served to open the necks back up. Looked like a bell at the end and some would not chamber properly. Long and short of it- oversizing the neck was causing the problem.

Btw, I am necking down 7mmSTW to.257. My fired brass measures .291. Loaded round .289. I have been using .286, 287 and .288 in my bushing die. My guess is that my chamber is .292 although I have never seen the reamer print. I did not know to ask for it when I had this gun built back in 2007.

This is exactly the issue I’m having. Necking them down too far is a foregone conclusion at this point and then the step back up to .257 is too severe, thus “flaring” the case mouth.

My question now becomes, since all of my brass is oversized, is what is the best way to fix this? I can get a .254 diam expander mandrel and try to “step it” gradually to .2565 or I can try to turn necks (though I’d really like to avoid this if possible).

One thing to note, I am able to get brass to fit by chamfering a good bit on the case mouth, sizing up (with my .2565 mandrel), then back down with my .282 bushing and seating a bullet. Some loaded cases still have the slightest bit of resistance when chambering but they will close... any chance that firing will just blow it out and allow me to resize with a larger bushing next time around?

Thanks for all the help!

 

[Texas10]

Just a guess, but I suspect you over annealed the case mouth, as that is where the heat will concentrate. Case mouths being dead soft will yield excessively during seating. May return to useable condition after work hardening via a few cycles. Seat then pull a bullet, re-size, seat and pull again, then see if brass is uniformly yielding (no more flare at the mouth).

What is your annealing process?

 

[Ccrider]

I used a .245 mandrel to open the necks up and then loaded, fired, annealed, neck sized and then did a light neck turn. I could have resized with the expander mandrel but did not want to work the brass that much.

I am a novice that learned how to reload using this cartridge. Not a wise choice for a beginner but I figured it out.

Take heed to what Boyd told you. He and several others on this site, are experts. You need to get the correct bushing size. I would try 284-285. You can’t base what you are doing on what others are doing on with a different caliber and chamber on a different gun. Chambers are different in the same caliber. Neat thing is you know your specific chamber specs.

I tried trimming and chamfering the bell away. That will get it to where it will chamber and fire but makes a mess of your brass at the mouth of the case-thinner than the rest of the neck. So if you have to do this to get the brass to fire, don’t go overboard and be careful with your load. The round will shoulder off of the neck.

 

[Mags]

Just a guess, but I suspect you over annealed the case mouth, as that is where the heat will concentrate. Case mouths being dead soft will yield excessively during seating. May return to useable condition after work hardening via a few cycles. Seat then pull a bullet, re-size, seat and pull again, then see if brass is uniformly yielding (no more flare at the mouth).

What is your annealing process?

You are correct - it seems the brass goes back to normal after “work hardening” it. If I mess with it enough, as in size, expand, chamfer, seat, pull, and repeat, it will generally fit without much issue.

My general process for annealing is with my Annealeez... never had such an issue. But this time around I had a buddy use his AMP. Not sure what setting he used, but I can’t imagine it would be significantly different from Alpha 6mm or 6.5 Creed brass.

 

[hicap40]

Mags, did you ever solve your problem?

Still got mine