Simple tip for cartridge concentricity

[Jim Hardy]

How can you have very well prepped brass and necks out of very straight dies and still get loaded round run out that does not fit your standards? Here is a tip that can, on occasion, turn that lack of loaded round concentricity to dead nuts straight.

Always keep in mind that you need to give your case necks the same respect as you give your barrel crown. The neck is the last place the bullet lives before it enters the bore and the crown is the last place the bullet lives before it travels to the target. Both require exact precision at the point of departure if extreme accuracy is to be had.

Whether you load a 30 cal with 187 BIB flat base bullets, or a 200 + grain BT offering by Berger or Sierra -- or a custom made bullet, that bullet must "marry" up with case mouth. That starts with a precise chamfer your bullet likes. Most bullets have a preference for a 14*, 28*, 30* or a 45*. You might just be shocked at the difference that can make on your loaded round run out. it might just be worth a little time checking this out in your precision loading process. Food for thought.

Jim Hardy

 

[22BRGUY]

Thanks Jim

 

[luckyshot52]

Good point Jim. Trust ur health is good

 

[Gr8Horses2003]

Mr. Hardy,
Thanks for the information. Can you provide us a list of where one might obtain the proper chamfer tools and what bullets seem to like what degree of chamfer, if you will please.

Thanks.
Harry

 

[Jim Hardy]

Mr. Hardy,
Thanks for the information. Can you provide us a list of where one might obtain the proper chamfer tools and what bullets seem to like what degree of chamfer, if you will please.

Thanks.
Harry

Harry:

The old reliable RCBS and Wilson tools will give you the 45*. The K&M will give you the 14*. Sinclair also carries carbide tools in 30* and 45* that work with the Wilson trimmer. I "think" the 28* is provided by Holland. As to which works best with each bullet, that is an issue that is best addressed by each individual shooter. BTW, you can burnish the case mouth inside and out with a fast spin in 0000 steel wool (a Richard Franklin tip) without any real chamfering -- you screw up nothing and sometimes this works great with individual bullets. I often use the Franklin technique until the brass is fire formed so the necks are absolutely true with the chamber -- it just makes it easier to get a perfect cut. I also believe there are some old articles/reviews on chamfering tools listed on the index (or whatever it is called) -- worth finding for a quick review.

Jim Hardy

 

[perry42]

Thanks for the information. I have used a VLD/ steep angle type chamfering tool in the belief that all bullets flat based or BT would benefit from a gradual entrance to the cartridge.


perry42

 

[Gr8Horses2003]

Mr. Hardy,
Thank you for the information. I appreciate the help.
Harry

 

[nmkid]

I've always wondered, can we really hold a small chamfer/deburring tool straight enough to make a good chamfer cut. Or hand hold a case against a whirling chamfer tool and get a straight cut. I recently bought the new Redding chamfering tool with a pilot that comes out through the primer hole. Seems to be what I've have been looking for. I pay as much attention to chamfering as any of the case preparation steps.

 

[Gr8Horses2003]

Mr. Hardy,
Again, thank you for taking your time to throw us some pearls. I would like to ask you a couple of more questions, if you will. First, I am shooting a 123gr. Scenar out of Lapua brass from a .260 Rem AI. Any thoughts on chamfer angle for that bullet? Second, concerning neck tension and seating pressure, do you lube your necks before seating and with what? Do you use 0000 steel wool after chamfering and before seating or no?

Thanks, again.
Harry

 

[Mozella]

Dang, just when I was getting comfortable weight-sorting my primers, now I gotta' do load work-up testing based on chamfer angle. And not just two; there are four different common ones and I suppose I could order a chamfering tool with a custom angle if need be.

What's next, length-sorting my extruded stick powder? The kernel lengths are different you know;.............. long, medium, and short.

 

[rardoin]

What's next, length-sorting my extruded stick powder? The kernel lengths are different you know;.............. long, medium, and short.

Don't be ridiculous......it is common knowledge that you should be weight sorting ball powder granules...throw away that stick crap!

 

[Brians356]

Dang, just when I was getting comfortable weight-sorting my primers, now I gotta' do load work-up testing based on chamfer angle. And not just two; there are four different common ones and I suppose I could order a chamfering tool with a custom angle if need be.

You only know the half of it. There's the angle, but you also have to control depth of cut. Taken to the extreme depth, you finish up with a sharp leather hole punch tool. (Don't laugh, I've actually used a scrap 270 case for a hole punch, after using the standard L.E. Wilson chamfering tool, spinning the case on a drill, to produce a nice sharp case mouth. Works great on leather, soft plastic, etc. The brass doesn't hold an edge long, but it's easy enough to touch it up again! The 270 Win neck is plenty long, so it takes a few iterations to run out of neck. )

Ok, gang, fun's over. You can all go back to cleaning and tumbling cases to jewelry-like sparkle. What price, accuracy?
-

 

[wapiti25]

I bought the RCBS VLD tool, it is a piece of SXXX. It does not cut, just rubs the neck.

 

[pressedRat]

Dang, just when I was getting comfortable weight-sorting my primers, now I gotta' do load work-up testing based on chamfer angle. And not just two; there are four different common ones and I suppose I could order a chamfering tool with a custom angle if need be.

What's next, length-sorting my extruded stick powder? The kernel lengths are different you know;.............. long, medium, and short.

thats what i do. because its so tedious, i buy cases of 1 lb bottles and do one bottle at a time. i have a very long piece of precision cut glass. i stand each granule on end and once the entire 1 lb bottle of powder has all of the granules standing on end, i then move then around putting the shortest granules on the left and working to the right with increasing height of each granule. if a granule has an uneven end, i put it in a special holding jar to be used only for fowlers.

im still trying to figure out how to stack all of the granules length-wise so that they are parallel with the case stacking one layer at a time until the case is stacked with the correct weight of powder.

 

[zipollini]

I like the K&M which offers the steepest cutting angle I have ever seen at 7deg. plus it has adjustable depth control also.

http://kmshooting.com/tools/case-neck-tools/case-neck-chamfer/large-6mm-338-reamer.html

 

[Steve Ladino]

Dang, just when I was getting comfortable weight-sorting my primers, now I gotta' do load work-up testing based on chamfer angle. And not just two; there are four different common ones and I suppose I could order a chamfering tool with a custom angle if need be.

What's next, length-sorting my extruded stick powder? The kernel lengths are different you know;.............. long, medium, and short.

Maybe....like everything else we conjure up about case prep and loading....it all seems to help with getting consistent and better accuracy. I know that the more care and ( work ) steps etc. are tedious and time consuming, they seem to be worth the effort in the long run even if in so doing it's only the confidence of knowing we have done our best.

 

[bigstick6017555]

from the time you turn the lights on in the shop to start reloading, till the time that bullet hits the target we are trying to control all the variables we can to put bullets in one hole. now i have no scientific figures, but i would say these variables are in the millions, if not more. controlling these variables costs money and time, lots of it. so the question is, "just how accurate do you want to shoot." i think some people get too tied up on variables that cannot be controlled to any consistent degree to be proven effective. i think one of the biggest variables is mental confidence, if you sit down at the bench feeling good it will go good. if you feel what you are doing is worth it, it will show in your confidence. we all have our different ways searching for that magical .000. if you think it is working for you it can not be all wrong.

 

[Brians356]

No wonder the general population refers to us as "gun nuts". I wonder how many of the current world records, or any of the previous ones, were scored using weight-sorted primers, or tuned chamfer angle?

Read this article.

http://www.angelfire.com/ma3/max357/houston.html

Here was a guy who could put all bullets through the same hole tiny, every time, for months on end. And he didn't weigh primers, in fact he said powder charges only "bracketed within a couple of grains" were sufficient. He never found the type of primer made any difference but used 205M because everybody else did, seated them with the cheap Lee hand tool, and was unable to detect any accuracy variance resulting from seating pressure. Read the whole article to glean what he did find was critical (you might just be surprised, if not a little skeptical.)

However, I'm not saying there's only one formula (his) for ultimate accuracy. Why was this mythical chap King, with such a consistently accurate rifle and load, never able to produce results in competition? (He walked away after a relatively short campaign, in disgust.) Answer: He could never get the hang of wind doping. Period. Indoors, he might well have been unbeatable. Outdoors, he discovered he was just another "nut behind the butt", and not nearly the most capable. There's a lesson in there, somewhere.
-

 

[nakneker]

I think all the little details are fun to think about. I don't shoot competition but I do use many of the procedures and tricks to help me with accuracy for varmints and long range shooting.

However, as I watch all of tips and tricks being discussed it causes me to wonder how many bench rest shooters or competition shooters are in the looney house or put aside ample funds for Therapy. I'm sure some are just perfectionists to the point that the rabbit hole never ends. Fun!

 

[savagedasher]

I use the RCBS 3 way trimming tool .
The inside chamfer I had a tool shop grind it to the VlD angle . Every 3 loadings I anneal and trim . Larry