DLT
Silver $$ Contributor
I can feel it with my mandrel or the Lee collet die. If it’s not a tight neck chamber you can tell with a simple bullet drop. I don’t have any tight neck chambers
Please Explain Donuts to me
- Thread starter Dimner
- Start date
257ack
Silver $$ Contributor
splain donuts, well they are little round pasteries with a hole in the center. They go real well with coffee. seriously, I got them a few rounds after neck turning. My remedy was to re-turn the necks with a cutter that reamed out the donut in the necks. I really dont think that they mattered since I seated my bullets out past the donut. My opinion is they are caused by brass flow
MGYSGT
Silver $$ Contributor
I have a little different donut solve. I trim it off from the outside before I resize the case. I also chuck up my expnder ball and use emery cloth to reduce the size of the ball. I don't want to feel any resistance from it when withdrawing the cartridge from the die. The last thing I like to do is seat above the donut. If I do that the first step is not necessary. Does it all work? I sure makes me feel better.
Dimner
I do believe in Captain Crunch.
Good Doughnut
Bad Doughnut
Superb Doughnut
Bad Doughnut
Superb Doughnut
Buying a full set of pin gages that covers the range you asked about will usually require two sets; 0.250" and less, and 0.251" and up. The one's on Amazon that don't cost a king's ransom will typically come in 0.001" increments.
It's also important to understand the gages are either + or -. A plus gage is warranted to not be smaller in diameter than the nominal value, a minus gage is warranted to not exceed the nominal value. Add to that, the stated tolerance. These sets are are a great value but, I use a 0.0001" micrometer to verify the actual diameter of a pin, if it's really important.
Another choice is ordering tapered gages from Porter Precision that're available in 0.0005" increments, plus and minus, which should effectively handle the calibers you have in mind with a greater degree of resolution. Sure, they're $10 each but, that may be a lot less than two sets from Amazon where you'll never use 95% of the pins.
Vermont pin gages are another good source if you know precisely what you're after.
Donuts are also inherent to brass manufacture/design, as brass thickness tapers from webs all the way to mouths. FL sizing also moves brass forward(thick towards thin) into necks.
You've already chosen a cartridge that will require FL sizing.
If your seating bullet bearing through neck-shoulder junction, or FL sizing necks for some reason, then you should outside turn necks to remove or mitigate the issue.
Outside neck turning is way cleaner/better controlled than reaming.
You might also consider partial bushing neck sizing, so that you're not amplifying the problem with excess sizing.
You've already chosen a cartridge that will require FL sizing.
If your seating bullet bearing through neck-shoulder junction, or FL sizing necks for some reason, then you should outside turn necks to remove or mitigate the issue.
Outside neck turning is way cleaner/better controlled than reaming.
You might also consider partial bushing neck sizing, so that you're not amplifying the problem with excess sizing.
I haven't used an expander ball in any of my Forster sizing dies for many years and never tested their effects with regards to donuts. So, I'm not sure to what extent an expander ball might do work on donuts (different shaped expander balls can different effects). But, I don't think it would an affect that wouldn't really "hurt" anything. Given the way an expander ball works within a FL non-bushing sizing die, I think that an expander ball can actually be of some help. I still prefer using an expander mandrel to get better concentricity as I almost never seat bullets deep enough for the bearing surface to touch any donut.
Krogen
Gold $$ Contributor
I've been handloading for years, decades actually. In my vacuum I'd never heard of a brass donut until @urbanrifleman and I talked about freebore for .223 Rem and 80.5 gr Bergers. Intuitively, the donut doesn't sound good to me. I'd want it gone or avoid it altogether by seating beyond it.
But . . . . What's the real problem with seating into the donut? Increased neck tension? If it's uniform from case to case, is it a problem? I can see that tight neck chambers and neck-turning would be concerning. Bushing dies leave a kind of donut since they don't size all the way to the shoulder. Maybe not a "real" donut if the brass isn't thicker there. LE Wilson has made benchrest busing dies forever. Was this a problem all along? Or is it much ado about nothing?
Yeah, I have a lot of questions and little knowledge!
But . . . . What's the real problem with seating into the donut? Increased neck tension? If it's uniform from case to case, is it a problem? I can see that tight neck chambers and neck-turning would be concerning. Bushing dies leave a kind of donut since they don't size all the way to the shoulder. Maybe not a "real" donut if the brass isn't thicker there. LE Wilson has made benchrest busing dies forever. Was this a problem all along? Or is it much ado about nothing?
Yeah, I have a lot of questions and little knowledge!
Bushings do not cause donuts.
If you carefully set a neck mic, you can measure donut area with all new brass.
It builds from there with neck upsizing or heavy body sizing.
With a plan, donuts can be mitigated, at least to begin, with neck turning.
Donuts represent a variance in thickness. Thickness and hardness affect tension -if you bring it into tension.
Such is the case if you FL size necks (regardless of seating depth).
So if you partial length neck size, you can leave donut brass alone and out of affect. Then if you have normal neck clearance, you could seat bullet bearing right through donut area, no problem.
If you carefully set a neck mic, you can measure donut area with all new brass.
It builds from there with neck upsizing or heavy body sizing.
With a plan, donuts can be mitigated, at least to begin, with neck turning.
Donuts represent a variance in thickness. Thickness and hardness affect tension -if you bring it into tension.
Such is the case if you FL size necks (regardless of seating depth).
So if you partial length neck size, you can leave donut brass alone and out of affect. Then if you have normal neck clearance, you could seat bullet bearing right through donut area, no problem.
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ImBIllT
Silver $$ Contributor
1) A donut is an area in the case where the ID suddenly decreases. A gradual decrease in neck thickness isn’t really a donut, and exists in pretty much all brass that has not been turned. If you seat the base of your bullet above that point, then it really doesn’t matter. If you seat your bullet into the donut, then problems can arise.
2) 99% of donuts were formed by turning case necks thinner, and not going all the way to the shoulder, and then sizing the entire neck length. Because the last few thousandths of the neck weren’t turned, they are substantially thicker than the rest of the neck, and sizing the entire neck results in an internal ring of thicker brass and smaller internal diameter at the bottom of the neck. Some people claim that even when turning the entire neck, as the case grows, the unturned shoulder can end up in the neck of the case causing a donut. I suppose this is possible even in brass that has not had necks turned, especially when necking up, but it would likely be a smooth transition rather than the abrupt decrease in ID that occurs with donuts in turned brass. I wouldn’t exactly call that a donut, even if it could cause problems.
3) You can feel a true donut by rubbing a paper clip or tiny flathead screw driver along the inside of the case neck. With a bad one you can sometimes drop a bullet into a fired neck and it will sit on the donut instead of dropping into the case, but it will slide freely in and out of the neck. For an inconsistent case neck thickness such as might occur when necking up brass or in cases that have stretched a lot you might feel it when seating a bullet, or be able to adjust bushing size until you find that the bullet is loose at the case mouth but gets tighter as you push it in.
4) You didn’t ask this, but here are some ways to handle donuts, whether they are abrupt or gradual.
a) Don’t seat the bullet into the donut area.
b) Don’t size the lower portion of the case neck.
c) Use a die with an internal sizing button on the decapping rod, or expand necks with a mandrel after sizing.
d) turn case necks using a cutter that I’m has an angle and cut barely into the shoulder.
e) internal neck ream.
The above solutions work to varying degrees in varying situations. Sometimes you have to seat a bullet past the shoulder. Sizing the inside of the neck with a button or mandrel usually works great with a gradually increasing neck thickness, but not particularly well with an abrupt donut from turning. Turning into the shoulder slightly works pretty well for preventing donuts, but I’ve encountered reports that it doesn’t work all that great for already formed abrupt donuts. It also won’t make the shoulder the same thickness as the neck, so when the shoulder grows into the neck, you’ll still get a donut, even if it isn’t as bad as it could be. My opinion is that the best solution is to avoid sizing the bottom of the neck. It will expand to match your chamber wall. If you only size the upper potion of the neck, then a donut where the shoulder meets the neck will not be sized down enough to contact the bullet unless it’s very extreme, or you have very little neck clearance. Obviously most of these do not remove the donut, but they help avoid problems that donuts can cause.
5) For your specific situation, as long as your sizing die has a neck expanding button on the decapping rod I’m almost 100% certain you’ll never run into any problems. Most, if not all factory brass gets thicker as you go from the case mouth to the case head, even in the neck, and the vast majority of SAAMI spec chambers are larger at case shoulder junction than at the case mouth. In your situation I don’t think you have anything to be concerned with.
2) 99% of donuts were formed by turning case necks thinner, and not going all the way to the shoulder, and then sizing the entire neck length. Because the last few thousandths of the neck weren’t turned, they are substantially thicker than the rest of the neck, and sizing the entire neck results in an internal ring of thicker brass and smaller internal diameter at the bottom of the neck. Some people claim that even when turning the entire neck, as the case grows, the unturned shoulder can end up in the neck of the case causing a donut. I suppose this is possible even in brass that has not had necks turned, especially when necking up, but it would likely be a smooth transition rather than the abrupt decrease in ID that occurs with donuts in turned brass. I wouldn’t exactly call that a donut, even if it could cause problems.
3) You can feel a true donut by rubbing a paper clip or tiny flathead screw driver along the inside of the case neck. With a bad one you can sometimes drop a bullet into a fired neck and it will sit on the donut instead of dropping into the case, but it will slide freely in and out of the neck. For an inconsistent case neck thickness such as might occur when necking up brass or in cases that have stretched a lot you might feel it when seating a bullet, or be able to adjust bushing size until you find that the bullet is loose at the case mouth but gets tighter as you push it in.
4) You didn’t ask this, but here are some ways to handle donuts, whether they are abrupt or gradual.
a) Don’t seat the bullet into the donut area.
b) Don’t size the lower portion of the case neck.
c) Use a die with an internal sizing button on the decapping rod, or expand necks with a mandrel after sizing.
d) turn case necks using a cutter that I’m has an angle and cut barely into the shoulder.
e) internal neck ream.
The above solutions work to varying degrees in varying situations. Sometimes you have to seat a bullet past the shoulder. Sizing the inside of the neck with a button or mandrel usually works great with a gradually increasing neck thickness, but not particularly well with an abrupt donut from turning. Turning into the shoulder slightly works pretty well for preventing donuts, but I’ve encountered reports that it doesn’t work all that great for already formed abrupt donuts. It also won’t make the shoulder the same thickness as the neck, so when the shoulder grows into the neck, you’ll still get a donut, even if it isn’t as bad as it could be. My opinion is that the best solution is to avoid sizing the bottom of the neck. It will expand to match your chamber wall. If you only size the upper potion of the neck, then a donut where the shoulder meets the neck will not be sized down enough to contact the bullet unless it’s very extreme, or you have very little neck clearance. Obviously most of these do not remove the donut, but they help avoid problems that donuts can cause.
5) For your specific situation, as long as your sizing die has a neck expanding button on the decapping rod I’m almost 100% certain you’ll never run into any problems. Most, if not all factory brass gets thicker as you go from the case mouth to the case head, even in the neck, and the vast majority of SAAMI spec chambers are larger at case shoulder junction than at the case mouth. In your situation I don’t think you have anything to be concerned with.
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searcher
Gold $$ Contributor
Yes - the neck tension will no longer be as uniform once you start to have doughnuts as the doughnuts themselves vary in size, thereby placing different stresses on each bullet - making each loaded round less the same as one another. This is because not all brass walls are uniform and they stretch at different rates, pushing the brass flow to the neck in varying amounts. That is the first problem. The second is that unless the doughnut is perfectly round, you start having concentricity issues as your bullet is no longer in a straight axis to the bore. Then - if you are using flat base bullets, it has been said (would have to be bad doughnut) the doughnut can bridle the edge of the base of the bullet or pressure ring (if such bullet has one), creating gas escaping unevenly when the bullet exits the bore. I'm not sure about the last one - but I firmly believe in the first two - as they are measurable in different ways such as using a gauge to measure bullet extraction and using a concentricity gauge. I know you are not asking - but to rid a case of a doughnut, annealing, then using an expander mandrel is probably the best, short of using an inside reamer cutter - which I prefer. I would only try to rid a doughnut if my bullet needs to be in that space.
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S
same Looks as when I used to neck up Winchester 243 brass into 260.
I have some cases that have been reloaded several times but have not been neck turned. For some time I noticed that while seating a bullet they meet noticeable resistance at a point and the bullet seems to "snap" in and then seats with normal pressure again. I've often wondered about the presence of donuts but never actually looked to determine if they were there. It certainly sounds like I've got some THICK donuts.
Yesterday, I received my package of 21Centry mandrels, lube & accessories. It looks like I'll be venturing into the next level of this game. I thought that my annealing machine would be my last venture but now realize that there is no end. LOL
Yesterday, I received my package of 21Centry mandrels, lube & accessories. It looks like I'll be venturing into the next level of this game. I thought that my annealing machine would be my last venture but now realize that there is no end. LOL
urbanrifleman
Site $$ Sponsor
The only cure for the donut is to not be near it.
6.5 forever
Silver $$ Contributor
This will be my next project. Last night I seated bullets in uncharged cases until I could not feel the doughnut. Then I chambered it and there are no marks on the bullet.
Next I will finish loading at that length and test fire.
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