Concentric ammo

[maliveline]

I’ve noticed some issues with my reloads when the bullet is not quite concentric
Inside of the brass case. If I roll the cartridge across the table I can see movement in the bullet tip. Anyone have any tips on how to improve this?
I don’t know why I put this in the picture section

[JonB_in_Glencoe]

I moved your thread to this section, because my experience has been that the major cause of Runout, for loading Rifle ammo, is the seating die. For me, it has happened with standard dies seating cast boolits due to them being designed for j-words. After I acquired a benchrest seating die, I could see how the Standard seating dies could cause runout, especially Lee dies with their nose guide insert being loosely fitted. I don't mean to disparage Lee, Most of my Dies are made by Lee, and I like many of Lee's innovations...but their Rifle Seating dies are suited for J-words and are generally a poor option for seating cast boolits, especially it they have a large meplat.

[country gent]

Check your brass for concentricity. measure wall thickness at neck and possible a set point near base. This can cause a banana effect on the case when sizing. What press are you using? Check the presses alignment between ram and die hole. check other tools Shell holder ram plat dies for same and square. Sometimes a thin o ring under the lock ring allows for some give to center every thing up and shift. Seating stem fit can be an issue as can the thread and lock nut. A concentricity gage can help a lot trouble shooting this problem. a tight expander ball can pull necks out of square also.

If you have or can borrow a different die set and test it in your press it might give an idea where the problem lies same with shell holders.

[smoked turkey]

Another area affecting boolit concentricity (run-out) can result from too much neck tension when seating the boolit. The press puts lots of compression on the case neck resulting in a skewed neck as a result of the boolit seating process. This can be helped by using the proper size neck expander die such as the Lee or Lyman. I have found that opening the neck up so as to be about .001 smaller than the sized boolit gives adequate neck tension and gives the boolit an easier ride down the case neck. It is also necessary to put just a very small amount of belling on the end of the case in order to not have the boolit shave lead as it is seated. I imagine you have already discovered that. I have also found that the neck expander spud in most decapping dies is too small for most of our sized cast boolits.

[Bazoo]

Sizing cast bullets can cause misalignment if the top punch is not an exact fit. It might not be out enough that you'd notice until the bullet is seated.

[jmorris]

I would suggest buying or building a runout fixture so you can measure fired cases to see what you are starting with and then measure at each step after.

If the case has little runout formed to the chamber and it gets worse at some point of your process, you will be able to find the operation that needs to be fixed.

If it’s at the size die, might also try it without the expander/decap pin installed in the die and see if that fixes it.

If it’s at the bullet seating die, you might try different bullets (shape).

[jcren]

For max precision in my cheap lee dies, I rotate the cartridge 180 about halfway through seating the bullet then finish seating. Also, using the factory collet crimp, i rotate it 1/3 twice and bump the crimp on each 1/3. No visible run out on lead or jacketed using this method.

[lightman]

I'm a big believer in concentric ammo. My test have shown that a crooked bullet results in a flyer. I use the fixture from Sinclair but there are several others. JMorris is a very skilled fabricator and I think I have seen pictures of his fixture. Maybe he will post them again.

[kaiser]

All great suggestions! I purchased a Hornady Concentric tool a couple of years ago, similar to RCBS and Sinclair brands, that you can adjust "run-out" to almost zero. It's easy to set up, change cartridges, and produces excellent range results.

[jmorris]

I made two different styles. One can only measure a finished round.



The other lets you measure just the case or a completed round.



And you can adjust the bearing points as well as far as what is the reference.

[Shopdog]

A couple things here.....

As posted above,the nice thing about a gage is you can "sort of" isolate where problems are being initiated.... annealing plays a roll in producing deadnuts straight ammo. It "can" be a big problem, but can also not. Which is why there isn't an "absolute" concerning it's practice. But,yes... checking your progress during the loading steps will usually uncover where the culprit is.

Understand that die manufacturers have a "big picture" as the largest criterion. So,don't hold them too hostage when checking their work. Having said that..... the seating op is going to be hit and miss with over the counter equipment.

One thing to try on the cheaper side of things is a few shell holders. And also try "clocking" them differently in your press. Really look at how the shell holder functions... it has adjustment during the process in the direction that the case enters/exits... more so than at a 90* to that position.

Once you have established a working protocol, and hopefully discovered where the bad juju is being introduced.... your coencentricity gage is going to be gathering dust,for that specific cartridge and die set. Which is a great reason to fabricate one yourself. The D.I. can be repurposed,and you aren't out that much $$.

[jmorris]

One thing to try on the cheaper side of things is a few shell holders. And also try "clocking" them differently in your press. Really look at how the shell holder functions... it has adjustment during the process in the direction that the case enters/exits... more so than at a 90* to that position.

One thing co-ax owners don’t get to play with.

[HangFireW8]

Good info in this thread. I can add that sizing balls often pull case necks out of alignment, after which all the careful seating in the world won't make a straight cartridge.

I have an RCBS Case Master, which I feel is the best value in a case tool, because it can be used for so many different measurements and tests. I use it on both necks after sizing, and boolits after loading.

Besides indexing your shell holders... Try indexing your sizing die. You may find several have a real bias towards one side. Mark that side. Measure case runout before sizing, size with the high side oriented towards (or away) from the index mark.

You can also use the eccentricity tool to discover which rifle chambers straighten out the brass... and which bend it.

[MT Chambers]

Neck turning, in-line bullet seating dies, quality sizing dies (Redding, Forster), Forster Co-ax press.

[jsizemore]

Neck turning, in-line bullet seating dies, quality sizing dies (Redding, Forster), Forster Co-ax press.

Amen!