bullet runout

[cj mac]

maybe a dumb question what are some of the causes of bullet runout ? seating die , brass . it only happens once and a while

 

[Catskinner]

Runout is usally caused by jackets being thicker on one side, or dies wearing out. Also if core not seated completley.

 

[Hedge]

Cartridge necks not co-axial with the body, misaligned seating, bullet seated too far out to align with the neck come to mind.

 

[SS427]

To get rid of runout I bought better dies, both sizing and seating. Worked each time. Even with cheap brass, better dies improved runout, but it couldn't bring the runout in line with what I got with Lapua brass. So brass is a factor as well.

 

[bheadboy]

The question "bullet runout" has two possible answers,

if it is the actual bullet, the manufacturer has dies that do not hold the od of the finished product uniform. THis is true of all - however, some manufactures are worse than others, thus the matchking, specialty target bullets etc vs "factory" ammo bullets and some made for reloading

There is also the runout of the loaded ammo - hand loaded or factory-where the
seating of the bullet in the case results in a lack of centering and thus "runout"- lots of reasons stated above, dies, bullets, brass, press, operator error, etc.

Bob

 

[Catskinner]

I was not clear on my post by just talking about bullet runout, and not talking about case's that are not uniform in the necks. I found tha neck reaming makes a good start, my 2 cents.

 

[cj mac]

im using 165 nosler b-tip, i think its a good dual purpose bullet its very accurate in my gun, good for target & deer. i will see if i can barrow my friends redding dies to see if it helps. any thoughts on a light crimp?

 

[fdshuster]

cj mac: "it only happens once in a while", caught my eye. I can load a box of 20, using Lapua brass & will sometimes get 2 or 3 that will have excess loaded round neck runout, checked with the Sinclair gauge. Excess, for me will be .002" to .003" when the majority measure less than .002". Time and again I have marked these rounds with a black magic marker on the case head, fire, reload, & those same cases will again have the approx. same R/O, happens over and over again. That tells me those individual pieces of brass are defective, from the time they were formed. The other 17 or 18 in the box will continue to have minimal R/O. So, why not mark the rounds with R/O, reload & see if the problem continues. If it does, bad brass. If the R/O is changing from one case to another, then I would look at my loading procedures and tools used. Seems to me if it were a die problem, it would happen 100% of the time, with all rounds, not just a few. ps: Just saw your posting referring to crimping. Unless the bullet(s) you are using has a crimping cannalure groove, you will cause more problems than you will "fix". I can quote numerous sources very experienced in precision reloading/shooting who will backup that statement. It's not my opinion alone. ps: (again) You also did not identify the brand of brass you are using. I have measured loaded round runout of a very large, well-known firearm/ammunition manufacturer, using the Sinclair gauge & found as much as .012". Needless to say, I will never use their brass. A fair amount is outright junk! There's a reason why many of us use Lapua when possible.

 

[bozo699]

im using 165 nosler b-tip, i think its a good dual purpose bullet its very accurate in my gun, good for target & deer. i will see if i can barrow my friends redding dies to see if it helps. any thoughts on a light crimp?

cj mac,
The BT bullets don't have a cannelure or at least any of them I have seen you do not want to crimp a bullet with no cannelure. There are many things that can lead to loaded round runout, brass, dies, too much neck tension, sizing the neck to much at once, not chamfering inside necks, etc.

What is your fired neck diameter? What is it after you resize? and what is your loaded round neck measurement? to much sizing would be where I think your problem lays so if you turn your necks to much you may even create more of a runout issue.
I do agree with Frank the once in a while thing bothers me and he had a excellent idea of marking the cases with the runout, what kind of brass are you using and what do you call excessive runout?
Wayne.

 

[cj mac]

i dont have any brass at all right now. and excessive runout, about .007 {hornady brass}

 

[fdshuster]

O.K., you've identified the brass as Hornady. I've used very little Hornady, so can't comment, except for the experience I had when using 204 Ruger Hornady brass. I found it to be very good. Now, what is the cartridge? If Lapua is available for whatever it is, you might try a small amount as a test. Also do the marking test & see if it's the same brass with R/O over & over again. .007" is a lot, so you do have a problem. If I had a piece of brass that gave that R/O continually, it would go into the scrap bin. More questions: What kind of sizing die? Using the neck expander? If yes, what type, straight sided, taper, floating carbide button? Are you inside taper neck reaming the case mouths? Are you shaving bullet jackets when seating? What kind of bullet seater? Do you have neck R/O on the case after firing? After sizing? After seating? Have you used a tubing micrometer to measure case neck walls? All these questions ( and more) can indicate the source of your problem.

 

[MrMajestic]

Using a Necco gage and a quality indicator, I use a .0005"/graduation, you can check your runout a various stages of reloading and narrow down the cause or causes.