223 donuts and how to get rid of them

[AdamJ]

I have a .248" neck chambered 223. I was using win. case, cci br4 primers and 24.5 gr benchmark under a 53gr hornady HPFB. SD was in the low 20s. OAL from the bullet ogive is 1.795", .015 off the rifling. The loaded neck dia was .246". I switched to lapua brass and loaded neck dia was .249-.250". Neck thickness was .013", I turned them down to .010 and loaded neck dia is .244-.245". I had to reduce powder to 24.3 and accuracy was real good. Fast forward 5-6 loadings and the accuracy was good but some unexplained fliers were showing up and killing a good group. Ran the some rds over the chrono and SDs were in the 6-7fps range. Chalked it up to a bad day. When I got home and started to resize I noticed as I raised the press handle that the expander ball would feel like it was going through a tight constriction and then slide up through the neck with normal ease. I measured some cases with a 6" micrometer and the necks started out at .221" and then at the base of the neck they went to .216-.217".
Can a donut effect accuracy, but not velocity? Is this a donut or am I crazy? What is the best way to get rid of this and keep using these cases? They have 5-6 reloads and tight pockets, plus I have a lot of time in these 50 peices of brass. Inside neck ream I guess? What is the procedure for doing this? The resizer die is RCBS standard, all my other dies are forster ultras including the ultra seater .223 die. All help would be appreciated, thanks.

 

[6BRinNZ]

Hi,

do the projectiles seat down into the neck shoulder junction? I understand donuts forming is pretty normal but is only an issue if you have to seat into it.

I found I had donuts when I sized brass that had been fired 4 times, basically the brass had been over worked and the same bush didn't squeeze the neck enough, so when I seated a projectile it fell in but stopped on the donut.

Other giveways for donuts were, suddenly blowing primers, inconsistent seating depth and unusual seating force needed towards the end of the stroke. After this I make sure I shoot projectiles that are well clear of the neck/shoulder.

I haven't used any tools to remove donuts, I understand K&M has a popular donut cutter and a friend has just bought a donut cutter for the sinclair trimmer, which seems ok.

 

[fastnflat1]

would it possibly be that you are not turning the necks down close enough to the shoulder? I ran into this with my 20BR. i hear you dont want to go too far into the shoulder due to making a THIN ring and eventually having neck-shoulder separation but at the same time if you dont trim far enough down you create doughnuts when firing. leave it to the pros to say for sure but you can save your brass by turning the necks on down to the correct neck-shoulder junction, resize, load, and shoot.

 

[Adam Morris]

Adam, a very good doughnut removal method is to neck turn(far enough) onto the shoulder and use the K&M carbide mandril that has little cutting teeth that will make short work with said offenders. BTW, I have had pressure and accuracy issues with tight necked guns when my cases developed doughnuts which went away along with the doughnuts. I've used the K&M tools, but not the sinclair tools mentioned above. I sacrifice a case to confirm the amount of brass cut away from the shoulder before neck turning all of the cases in the lot.

regards,

Adam

 

[Laurie]

There is something odd going on here - I suspect it's a result of your neck-turning practices. I've loaded and shot many thousands of .223R rounds over many years for half a dozen rifles and never had the dreaded 'doughnut' appear.

For a start, I would never turn .223 case necks down to 0.010" unless it was to match a custom tight-neck chamber. Even with a 'minimum SAAMI' chamber, you'll have excessive clearance and over-work the brass. In my experience, .223 responds very well to a mild clean-up turn if using good brass in a good match chamber. My current Lapua 'Match' brass is very consistent out of the carton with just a few outside of a total neck thickness range of 0.0125" to around 0.0133". I put anything outside of these limits into the practice ammo box, likewise any with more than 0.005" variation around the neck. The remainder, more than three-quarters of the total are separated into above and below 0.0130" categories based on the smallest reading of three around the neck. The thicker lot are turned to 0.0130", the smaller to 0.1250". I wouldn't turn any .223R case for a non-custom tight neck chamber down below 0.012", and would always prefer to have them thicker.

In a minimum SAAMI spec chamber, these 0.0125" and 0.013" neck cases need hardly any working of the brass using a bushing die and give good results with 90gn Bergers at 1,000yd. I've yet to see what the case life will be. Winchester brass in a much 'slacker' Wylde match chamber full-length sized conventionally with a Hornady sizer die lasted 7-10 loadings, necks becoming work-hardened and eventually splitting. Lapua gave several more firings, but work-hardening of the necks and shoulders is an issue with conventional full-length sizing and most rifle chambers long before the case-necks visibly fail.

Laurie,
York, England

 

[AdamJ]

Laurie, neck in chamber is .248. Loaded neck size with Lapua is .2495-.250, kinda tight, hence the need to turn necks down. After showing my cases to someone expererienced in neck turning he thought the real culprit was me not turning down far enough to the shoulder. Thanks for the help all.

 

[mikecr]

Have you confirmed that you even have donuts?