Neck diameter too large after annealing?

[Mags]

Is there such a thing as needing to neck turn brass ONLY after being annealed?

I’ve run into an issue with my .25 Creed where I’m unable to chamber a loaded round with freshly annealed Alpha brass.

Pertinent Info:
- Chamber has a .289” neck
- Using a .282” bushing
- OD of a sized neck (unloaded) ~.281”
- OD of a sized neck (loaded) ~.288-.290”
- Seating resistance is normal and consistent

Unloaded sized cases fit without issue, but it seems that the case mouth is wanting to “flare” upon seating a bullet. I can replicate the issue using an expander mandrel as well. Could this be a result of over-annealing or over-sizing? Assuming that it is, what are my options for correcting?

All thoughts and insight welcome.

 

[Dusty Stevens]

Debur the case mouth more

 

[Fast14riot]

.289" chamber
.288-.289" loaded diameter.

I dont think its annealing that is your problem. Also, you may want to use a 285-286 bushing instead of the 282 for unturned brass, that's working the brass a lot. I like .003-.004" total clearance, so if you turn your necks to give a .285-.286 loaded dimension, your 282 bushing will be fine.

 

[BoydAllen]

I am not sure why you are using such a small bushing. All you are doing is over sizing the neck and using the bullet for an expander, which is probably the source of your problem. If you use a larger ID bushing, that gives you a .003 to .004 difference between your sized and seated neck OD I think that your problem may disappear. As it stands you have a difference of .007 to.009 which gains you nothing because with that much expansion you are exceeding the elastic limit of the sized neck.

Added a little later: I completely agree with the post above this one. I completely missed the whole neck clearance issue. You need to be running a lot more....IMO .004 would be fine, no less than .003.

 

[RegionRat]

Sounds like you are over sizing.

 

[Mags]

I am not sure why you are using such a small bushing. All you are doing is over sizing the neck and using the bullet for an expander, which is probably the source of your problem. If you use a larger ID bushing, that gives you a .003 to .004 difference between your sized and seated neck OD I think that your problem may disappear. As it stands you have a difference of .007 to.009 which gains you nothing because with that much expansion you are exceeding the elastic limit of the sized neck.

Added a little later: I completely agree with the post above this one. I completely missed the whole neck clearance issue. You need to be running a lot more....IMO .004 would be fine, no less than .003.

This was my initial thought as well. I’ll order a larger bushing to see if the step up between sized and loaded is less significant. I believe you are correct in saying that the bullet is acting as an expander given the difference in OD.

Is there any credence to the fact that this would only happen after annealing though? I used the exact same bushings/process with virgin brass and then on firings 2 and 3 without issue.

Edit to add: I’m not sure how .282” is considered a super small bushing? I see most 6.5 guys in the .289-.290 bushing range, so as a .257 cal wouldn’t .282-.283 make sense?

 

[Walt Krafft]

Your neck clearance is too small. You have been lucky so far, and double lucky your reloaded rounds don't fit. Do what Dusty said to make sure it is not a burr. The od of a loaded round should be .287-.2880 max. If it is .2881 or bigger you need to turn your necks.

 

[David Christian]

@Mags, have you measured the OD of a loaded round of virgin brass and compared it to this lot that you are having trouble with? I suspect you have brass flow into the neck which is giving you a larger OD.

 

[Walt Krafft]

Also check your case length. You have been oversizing and your cases may have grown too long.

 

[dellet]

I would question the annealing process. The cases fit before, but not after.

It is not stated if there was a difference in sized neck diameter of pre/post annealed necks, but a .282 bushing creating a .281 neck sounds like it’s being crushed and has no spring back at all

 

[fatelvis]

Just a thought.... Maybe the presence of a donut?

 

[Rope2horns]

Chamber has a .289” neck....maybe it does maybe it doesn't.

OD of a sized neck (loaded) ~.288-.290”........not enough neck clearance after seating a bullet. This is why sized unloaded cases fit without issue.

Imo you need to turn your necks for more clearance.

 

[Coyotefurharvester]

0.016" thick neck brass , is that correct. What is the neck o.d. of fired brass?

 

[fatelvis]

0.016" thick neck brass , is that correct. What is the neck o.d. of fired brass?

Very good question

 

[lawman29]

Okay let's do some simply math for all. Bullet diameter + neck wall thickness x 2 ~ equal loaded round diameter. Measure the thickness of your neck wall on virgin brass, fired, sized, annealed, etc add that to .257 for ~ loaded diamenter. From that you will know if something is amiss...

 

[carlsbad]

did you wet tumble your brass?

 

[6MMsteve]

I deburr my case nks quite a lot..especially the outside..if you look through a mag glass you may see some rolled brass at the nk...

 

[20PPC]

@Mags I had the same issue with a 30 BR.
I had 10 firings on the brass with no issues but after annealing I could not chamber the cases.
.332 chamber and brass was turned to .011 for a loaded diameter of .330 before annealing,
the rounds measured .3318-3321 after annealing .
Of course I didnt figure it out until I was at a 100-200 yard match and ended up having to share my wifes rifle to shoot the match.
I had to pull 200 bullets and return the necks this time to .0105 .
I haven't had any issues since but did drop my annealing time by almost 1 second.

 

[mikecr]

Annealing doesn't thicken necks.
It's something else

 

[Ccrider]

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.