I'm in the middle of doing up 1000, 223 rounds. all the casings,mixed military were run through my press and Dillon power trimmer. all were trimmed exactly the same length after resizing.
Ive noticed now when seating bullets some are crimping rite on the grooved bullet seat and some are deeper and the grooves are almost all in under the lip of the caseing. all are 55 gr winchester fmj bts? i would think they would all seat in exactly the same place? any incite?

Interesting....

Perhaps an inconsistency in bullet length leads to an inconsistency in the groove placement?

Not being conversant with Dixon power trimmers do they register on the shoulder? If so you might be getting some spring in the case after sizing.

Be interested to see what others have to say.

im sorry i ment dillon trimmer.

https://www.dillonprecision.co...m_1200B_Case_Trimmer

now that ive read yoru post it makes perfect sence though, seeings this outfit is actualy sizing the neck at the same time the thicker casings would flex less and could very well be whats happening. when im seating more im gonna take note if thats the case, some are lc and some are the zs.

I have found significant inconsistencies in the placement of cannelures on some mass-produced bullets. The lot I had problems with in the past were Remington 55 SP, however any bullet made with worn dies can exhibit this problem. Considering the shortage of bullets over the last year or so and the rate at which the ammunition companies have been cranking out components, I would not be at all surprised to see Winchester producing bullets on machinery/dies which should have been replaced many thousands of strokes ago.

You can verify whether the problem is in the bullets of with your trimming simply by measuring the length of two cases which show disparate cannelure locations. My bet is on bad bullets.

The mislocation of the cannelure can be either from the cannelure itself being at varying points on the bullets, or from the ogive being slightly different shapes, thus the seating stem pushing the bullet to different depths. Either way it is a frustrating circumstance and can only be abated by using a more carefully manufactured lot of bullets.

BTW, in my experience, when you are having this cannelure placement problem you will also experience a significant degradation in accuracy (regardless of whether you crimp or not).

thank you stone creek i will try and measure the caseing. it wasent the diffrent make of brass doing it i checked that today. what you are saying makes a lot of sence. glad this batch is only for fun plinking with my m4 and the boys target rancher.
if it is the ogive being the problem there should be an overall lenght diffrence i would think, am i thinking rite?

With the lot of bullets with the "bad" cannelures I had you could set four or five bullets up on their bases on a table top side-by-side and see the varying location of the cannelure visually. If the problem is with the ogive it would make sense that the bullets will vary slightly in over all length.

If you have varying overall lenght it may be caused by your bullet seating die. I just went through that probelm with a Lee 223 die.

The bullets would hang up on sharp edges on the cup that holds the bullet in place as the case is raised. This caused horrible differences in seting depth.

I took the die apart and put a little lapping compound on a bullet tip then "ground" the edges sharp edges down and made the seater cup "fit" the bullet better. My variations in over all lenght went from .01 to .001"

Big difference.



Different brand cases with different thicnesses and hardnesses can also cause varing amount of grip on the bullet. A "tight" neck will result in a longer OAL. If this is the problem run the ram up and down a few times to get the bullet pushed all the way down.

2 things, The Dillon thing that holds the dies, moves, this can make a .005" to .010" difference. 2. The bullets are not all made on the same machine. From Lee's website, could apply here also. Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

Uniquetek's toolhead clamps Link

It's called tolerance stacking.
You take the variance in the overall length of the bullets, and the variance of the location of the ogive, canulure, case length, and press slop. and it's easy to see that you could have a variance of .020" quite easily

The shell plate can cause different COL if the slots in the plate are not all the same. If the bottle neck type FLRS die is adjusted touching the smaller measuring slot, the larger slot will keep the ram from making its full travel up. From Dillon- 550 plate dimensions should be .250? thick top to bottom, .132” +/- .005” from underside of the shellplate to top recess where the die contacts. This shell plate is undersize, causes cartridge headspace & COL problems.