Dreaded Donut

K

Kim Merrill

Guest
Does the donut located inside the base of the neck effect accuracy or S.D.? Do you remove it by using a inside neck reamer or running the expander mandrel for the neck turner back into the neck, push the bulge to the outside of the neck and then run the case back over the neckturner?

I have tried several different methods of neckturning (cutting into the shoulder more and less) but I still have a very small donut inside the case.
 
If you are shooting the 6PPC with 0,020" freebore or more and a bullet made on the 0.825, 0.790" or 0.750" jacket, the base of the bullet is not going to come anywhere close to where a donut would form.
 
Jerry,

The bullet is nowhere close to the donut. I am asking you experienced guys if you fool with it or just leave it go.
Reading between the lines of your answer is sounds like you do not mess with it.
 
What jerry says is true. I have reamed some out but don't anymore. At the time, I questioned (in my own mind) whether the donut would change the burn rate, and if there would be a differance firing one with a donut, backed up by one without. I still question that I guess.

Jerry,
what are your thoughts on that particular end of it ?
 
I don't believe that a donut has any effect on burn characteristics. This is just my opinion. I do have one chambering which has a donut almost a quarter-inch long and shoots lights-out.

They are hard to remove, the K&M tool will take out a teeny one but you need something more serious like a fluted reamer for big ones.

al
 
Kim ...

Kim Merrill said:
Jerry, The bullet is nowhere close to the donut. I am asking you experienced guys if you fool with it or just leave it go.
Reading between the lines of your answer is sounds like you do not mess with it.
Click to expand...

That's correct. We don't mess with it. ;)
 
Do-nut

Years ago, I had a .2430 chucking reamer that I used to remove do-nuts. Then I quit using it, and nothing drastic happenned.

I guess I agree with everyone else. Unless the base of the bullet actually goes down that far, it is a non issue in 100-200 yard Benchrest.........jackie
 
It doesn't hurt a thing, BUT...

...if you want to get rid of it, push the shoulders of your virgin brass back .025" BEFORE you neck it up and turn it. Turn to the junction of the neck/shoulder...no messin' with "slightly into the shoulder", "barely onto the shoulder", "changin' the radius of your cutter"...none of that garbage...when you fire it the first time with a full case of 133 it is blown back out and NO donut anywhere to be found...
 
Considering all the factors

The line of thinking is that the donut restricts the gas flow. That would be correct to some extent were there not a greater restriction ahead of the donut.
 
Kent Harshman said:
...if you want to get rid of it, push the shoulders of your virgin brass back .025" BEFORE you neck it up and turn it. Turn to the junction of the neck/shoulder...no messin' with "slightly into the shoulder", "barely onto the shoulder", "changin' the radius of your cutter"...none of that garbage...when you fire it the first time with a full case of 133 it is blown back out and NO donut anywhere to be found...
Click to expand...

Kent I'm a little unclear here :)

Are you saying to turn back and set your fireform headspace on the step of the neckturn? To the ACTUAL n/s junction?

Or just to fire the case with the extra 25thou headspace and let the casehead stretch back until it (hopefully) finds the boltface?

Or are you a "case greaser?"

al
 
jmaisto said:
Jerry,
what are your thoughts on that particular end of it ?
Click to expand...

The increase in pressure caused by a donut constriction would probably be unmeasurable. On an average 6PPC benchrest load, 29 grains V133 and a 65 Berger bullet, the base of the bullet has moved approximately 1.4" down the barrel before maximum pressure is generated (approx. 55,900 psi).
 
Thanks, to all for the response. I live in the deep south where we miss about 1/2 day of shooting a year due to cold weather. I do not have have extra time on my hands. I do not touch donuts with powered sugar on then so I think I will add these donuts to my list of DON"T touch them.
 
Francis;
I don't believe anyone was concerned about their bullets being seated that deeply, as I doubt any chamber is that shallow.
The other reason has been covered. ;)
 
I have found they don't hurt a thing if you bullets don't touch them, but for those cases that do- such as the VLD bullets, i use a chucking reamer just smaller than the bullet OD and chuck a case up in my lathe- I then slider the chucking reamer in by hand and use my thumb for side pressure and angle the reamer slightly. You can feel it bite and cleans the donut right up. They suck one cases that have the bullet go deep enough to hit them!
 
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