I am considering starting yet another "step" to case preparation, "neck reaming".. I have been doing some research on it and find that virtually ALL the "serious" benchrest competitors do both outside neck turning and inside neck reaming. I then went to Sinclair's catalogue and noticed that the reamers themselves are ground for FIRED, UNSIZED case sizes... That part puzzles me as the necks, at that point, are not "round / concentric" but slightly distorted from the firing. That would mean that if you inside reamed the case neck at that point, it would be cut heavier on one side than the other, rendering the case worse than the start! Presently, I outside turn the necks, however, just enough to remove the "high spots" and on nearly every case, there is a small portion of that case where the neck turning tool does not reach ALL the way down to the "lowest" point on the case neck wall. I know I would need a smaller bushing after both inside and outside turning, however, I have bushing dies so that is not a problem. My question is, "at what point, in the case prep process, is the actual inside reaming done AND how would you determine the correct size reamer, assuming you are BARELY taking off hardly any brass on the inside of the neck"? Any help on "the best procedure(s) to inside ream AND at what point does this take place" would be greatly appreciated. Thanks for any and all suggestions!
Inside neck reaming
- Thread starter ShootDots
- Start date
If you turn necks inside and outside, you will lose bullet tension. Your expander ball is all you need on the inside. With bushings, you are compressing the exterior neck down by several thous. Some competitors may turn inside, but I know none of them.
Years ago I bought an entire set of inside reamers for my Forster trimmer/turner. After a short time, I became very unhappy with the radical differences in seating and gave up. Have not used them in many years.
Years ago I bought an entire set of inside reamers for my Forster trimmer/turner. After a short time, I became very unhappy with the radical differences in seating and gave up. Have not used them in many years.
timeout
Silver $$ Contributor
I have dabbled with neck reamers for two reasons. The first was for donut removal. K&M neck turn mandrels have that built in, at least the one I had did. I also had some new brass that was terribly uneven when measuring neck thickness. I spent a good deal of time and money trying to correct that with inside neck reaming and outside neck turning. I never did obtain the results I desired. If you must inside ream, the easiest way for me has been using my LE Wilson case trimmer and their reamers. You can mess with different size neck bushings and order reamers of any size from McMaster Carr, don't ask me how I know. I gave up on that brand/batch of brass and bought Lapua. Problem solved. One of the better known gunsmiths told me and I quote, "none of the competition shooters inside neck ream, at least none of the winners do". It seemed like such a great idea at the time. 
BoydAllen
Gold $$ Contributor
I think that most reaming by benchrest competitors is done by those who compete at longer (600 & 1,000 yd.) distances, to remove doughnuts at the neck shoulder junction. As far as short range benchrest goes, I am not aware of any who do, since bullets are not seated that deep in the neck.
Years ago, I went to the trouble to pick up a neck reaming die, that was set up to true up the inside of necks s that they were better aligned (supposedly) with their case body centerlines. This was done for brass that was destined for us in a .222 chamber that had a .244 neck, and did not take necks to their finished thickness. There was enough left so that the final neck thickness was produced by turning the outsides of the necks, with a Sinclair tool. After all of that trouble, I was not able to see any advantage( at the target) to reaming before turning, and the insides of the necks were roughened noticeably by the reaming, so that it took a couple of firings for seating force to be normalized. The brass was Lapua. To add a little more related detail, I believe that a few successful long range competitors have, and continue to use no turn chambers for rifles that use Lapua 6BR brass.
Years ago, I went to the trouble to pick up a neck reaming die, that was set up to true up the inside of necks s that they were better aligned (supposedly) with their case body centerlines. This was done for brass that was destined for us in a .222 chamber that had a .244 neck, and did not take necks to their finished thickness. There was enough left so that the final neck thickness was produced by turning the outsides of the necks, with a Sinclair tool. After all of that trouble, I was not able to see any advantage( at the target) to reaming before turning, and the insides of the necks were roughened noticeably by the reaming, so that it took a couple of firings for seating force to be normalized. The brass was Lapua. To add a little more related detail, I believe that a few successful long range competitors have, and continue to use no turn chambers for rifles that use Lapua 6BR brass.
Inside reaming does not work well. A reamer will follow a crooked hole. Many years ago I built tooling and would bore the inside of necks. This was because I could not buy brass for a 7mm BR so I made it from std 308 win, later the 308 BR brass became available and that helped. You can remove material from the doughnut but it will not be very precise.
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