Let's talk about the "dreaded donut"

[Trickymissfit]

How much would a guy expect to pay for a pin gauge or set of gauges?

If I am understanding all this correctly, that is the only way to tell for sure if we have these donuts or not.

What other types/kinds of inside reamers have you all used to remove these donuts. I've now seen the Forster one that goes in the turner, I've seen the K&M ones that are part of the turning mandrel, but what about stand alone ones?

Again, thank you all for the responses.

steve,
you can buy small sets that start from about .030" and go all the way upto .250". It sorta varies, but nearly all sets are .001" apart. Quality also varies a bit, but if the set meets Federal standards your OK. But rather than just buying a complete set of gauges, you can also buy individual pins. I used to do this all the time, and rework them. Most pins are made of full hardened A2 (known to be an extremely stable material), and are ground round to within 10 millionths and on size within 50 millionths. You can buy them from Enco and many other outlets.

For about $35 dollars you can also buy a set of small hole gauges that will do the samething. They are round, and expand to the hole diameter. You then measure them with a micrometer. There's also a set that has one end flat, and these are the ones to get. I bought mine out of the Enco catalog
gary

 

[Ackley Man]

I have to outside neck turn the new brass before firing so it will fit in my .313" Hart chamber. It is a complete turn with no unturned surfaces left and is consistant from mouth to shoulder with a tight fitting mandrel.

The pin gauge in the pic above slides in with the same consistancy until it hits the do-nut at the shoulder and my micrometer says that the neck brass has a consistant thickness. There is a small ridge at the shoulder/neck junction that is not there on the new cases. The OD is also very consistant and the powder blow back line is a consistant distance from the case mouth all the way around which is an indication of a consistant neck thickness all the way around.

No other explanation than the firing caused brass flow along the shoulder and formed the do-nut.

IMO

As far as reaming, I use the Forster reamer. It is .003" over caliber so I outside neck turn to a thickness that will give me .003" clearance around the neck in the chamber. After firing, the .003" transfers to inside clearance for the reamer.

The reamer shaft is the same as the outside turning mandrel shaft so it will fit in my hand held turner

that way I can trap the brass between the reamer and the outside turning blade, ream the inside and clean up the outside for a very consistant neck thickness after the first firing

usually reduces the neck thickness ~.0005"

IMO I get a better product with the full length reamer blades that will work on the full length of the neck at the same time than I did with the K & M cutter mandrel which has a cutter on the very end of the mandrel.

YMMV

It may be the photos but it does not look as if you are turning beyond the neck shoulder junction by 1/32". Stopping short will invite donuts nearly every time.

 

[woods]

The photos show the clean up turning after the first firing of the cases

This is what my turning normally looks like on new cases

I admit it's kinda skeery to turn into a shoulder and maybe I don't go far enough but I do it

 

[Ackley Man]

The photos show the clean up turning after the first firing of the cases

This is what my turning normally looks like on new cases

I admit it's kinda skeery to turn into a shoulder and maybe I don't go far enough but I do it

Looks like they are perfect!

 

[paphil]

There is definately a learning curve on neck turning and even with good tools , you can easily seperate an occasional neck. An easy guage to use on fired brass is to use a bullet of the same caliber. It will slide all the way in unless it hits the donut. I drilled a small hole in the tip of the bullet and use a thin wire to prevent the bullet from falling into the case. It won't fix the donut but it will let you know that it is there.

 

[sp6x6]

I searched this thread and confirmed, I have donuts. How do I avoid and fix, saw the neck turning,remening inside. My situation,338 nm, 15 cases, took a few up to pressure signs. I had no shoulder bump gauge, do now. with .420 bushing, case lengths new brass 4.068-.070.Fired 5x- 4.076 some hot. I was sizing to 4.072, this seemed like what I HAD TO DO to close bolt, pulled spring. I was trying to shot 285 hornady and noticed that when I used a .375 coparator bushing, my length grew .005. This was checking right at neck and shoulder. The hornady seated past this point, where the long berger boattail missed this junction. N ow the berger bottoms on the donut of the just fired cases. At 4.072 I could load berger but not hornady without tight bolt i also have been seeing pressure, which I should be under load. 86.5 gr retumbo 2670 vel.300 hyb. fed215.took it to 90 retumbo2790 vel.help please

 

[MontanaRifleman]

I searched this thread and confirmed, I have donuts. How do I avoid and fix, saw the neck turning,remening inside. My situation,338 nm, 15 cases, took a few up to pressure signs. I had no shoulder bump gauge, do now. with .420 bushing, case lengths new brass 4.068-.070.Fired 5x- 4.076 some hot. I was sizing to 4.072, this seemed like what I HAD TO DO to close bolt, pulled spring. I was trying to shot 285 hornady and noticed that when I used a .375 coparator bushing, my length grew .005. This was checking right at neck and shoulder. The hornady seated past this point, where the long berger boattail missed this junction. N ow the berger bottoms on the donut of the just fired cases. At 4.072 I could load berger but not hornady without tight bolt i also have been seeing pressure, which I should be under load. 86.5 gr retumbo 2670 vel.300 hyb. fed215.took it to 90 retumbo2790 vel.help please

A couple of ways that I can of... I use an RCBS Power Pro to trim and turn necks, (switching to Wilson trimmer and Sinclair turner) the RCBS system uses reamers that will eliminate any do-nuts. The Sinclair system uses expanding mandrels that should also eliminate any do-nuts. This is done using a press. Also, sizing with an expander should eliminate do-nuts but might cause some runout, for that matter, using the RCBS turner and reamer could also cause some runout. Not sure about the Sinclair expanding mandrels, but it sounds like it would keep the necks concentric or close to it.

 

[rscott5028]

K&M makes a mandrel with a fluted end for their neck turner that'll remove the donut.

 

[MontanaRifleman]

Question.... wouldn't partial neck sizing alleviate the concern about do-nuts?

 

[sp6x6]

When I first started shooting cartridge, the cases where about 6-7 thousand. loose, did not Know this at the time. Had to size very little, later had to keep turning sizer down.Then I wanted to try the Hornady 285, I had to bump shoulder back .005-006. to get to close bolt on hornady because I had to seat farther to stay out of lands, but a berger would seat and no bolt close problem. Well on last size the berger bullet stops on donut in fired case, have not sized yet and believe I should anneal at this point also, advise, and I WOULD LIKE TO TRY hORNADY. . I quit the Hornady because it seemed like I had to take shoulder back so far, but it was mainly issue right at neck shoulder junction.

 

[woods]

Hey sp6x6, I'm having a little disconnect with associating the amount you are pushing the shoulder back having a bearing on how deep you are seating the bullet and subsequent difficulty chambering. Pushing the shoulder back .005" to .006" is way too far and will lead to a case head separation in a very short time.

If you are saying that seating the bullet past the do-nut is causing difficulty chambering then I am at a loss there also. IOW with the do-nut that I had, I could seat a 160 gr Accubond well past the do-nut into the powder and have no difficulty chambering and all while only pushing the shoulder back .001" to alleviate the crush fit.

I'm confused.

 

[sp6x6]

That is exactly what I am saying,I thought I was minimum on sizing at first adjusting die so bolt just closed easy. This seemed at 4.072. Then at 4x sized I wanted to try 285 hornady.Had checked all brass for easy fit in chamber.Loaded some 285 and started messing with seating.After loading 6 I tried one in chamber, closed very tight. Confused I looked at my seating, first for this bullet. I got coal w/hornady oal gauge. Somewhere in here I DISCOVERED that my brass for gauge jig is 5-6 thousand short of what I THINK chamber to be, these are generic brass .I was using a bushing for a 338 lapua on my comparator. I had my brass that I USED FOR MY min. size,same as just loaded and thought I WOULD MAKE A dumby 300 hyb. to have for seat bullet for later. This fit my chamber fine. Lapu bushing read low on shoulder and is tapered for shoulder. I went to a .375 hornady straight bushing on comparator, and when I SEATED THE hornady the case grew by close to .005, this bushing reads close to neck,read very little 1-2 thousand on shoulder. I used same brass and had to size .005 . past for this bullet to close.When the berger fit original sizing, the berger boatail looked to be above neck junction, hornady below.So I gave up on Hornady. Came home from range and was going to make a new oal brass gauge out of the ,closer fit to chamber fired 4-5 time brass for the hornady coal. Went to drop a bullet down neck and that is when bullet stoped at previous seating depth, which was close to .005 off, but this was before I noticed that the generic brass gauge was .005 short of chamber, checked other gauges and a friend was over with a 300wsm gauge and 2x ired brass and gauge was same deal, inheirant discrepancy . When I SEATED a hornady,past neck case grew .005, with .375 bushing, would have done same with berger, jsut wasnt seating that low.

 

[rscott5028]

I got coal w/hornady oal gauge. Somewhere in here I DISCOVERED that my brass for gauge jig is 5-6 thousand short of what I THINK chamber to be, these are generic brass.

That is a major flaw in the Hornady COAL gauge. I pondered that for a long time and just kept loading (thinking I was seating .010" off the lands) because they didn't point that flaw out in their instructions.

Finally, I took some other measurements and cross-checked and compared and convinced myself that the gauge was reading ~.015" short of what it should.

The bottom line is that the Hornady "modified case" is short by some amount. But, not all of them by the same amount. So, you get a good reading from the front shoulder to where the ogive meets the lands. But, the distance from the shoulder to the case head+headspace+bolt face varies.

This may not always be true. But, it sounds like you ran into the same problem.

-- richard

 

[sp6x6]

Another ? on fix. I only have a sinclair mag.Would the Forester neck reamer fit my Redding trimmer?Pilots have a .187 shaft, or fit the sinclair nt-155 neck turn tool mandrel spot.