Love To Hear Your Thoughts.. OAL Creep Up

[PFISTO]

Good Morning,

Well I have been using my 550b for about 3 months now and I have made some obsevations and would like to hear your thoughts.

When I start a reloading session as I am still in the load devolpement stage I pick my bullet and charge and after I get my charge correct I move on to the bullett OAL. Now I raise the seater as to not overseating the bullett and continue to lower the die until I get my desired OAL. Once this is complete I'm ready to start reloading. Now the problem, it seems that after a few round have been loaded the OAL starts to creep up from lets say 1.244 to 1.250 then I have to adjust the OAL again which doesn't make any sence to me why this happens. Any thoughts would be appreciated.

Thanks Mike

[Vlad]

Quick question .. what crimp die are you using? I use a Lee FCD and it makes the rounds longer by .005 to .010 depending on the brass. I think the extra squeezing just makes the round longer. I have to take that extra length into account when I set my sitting die.

[ima45dv8]

Other than the obvious (a loose lockring on your seating die?), are you adjusting the dies with a case in every station?

These machines are built like a tank but many have found that the press operates differently with a case in every station. If you adjusted with just one case in the machine, and then when in full production saw the need for a .006" adjustment, no worries. Reset the depth with a full load of cases in the shell plate, lock it down, and check every now and then.

[kevin c]

I agree w/ ima45dv8, although it's also possible that you are changing the AOL by changing the amount of pressure on the handle as you hit the downstroke. If you pulled down the handle one way when making your initial adjustments, and use another way when you are in "production mode", you will alter the AOL by a few thousandths easily.

It's the same difference as carefully actuating the handle to dump charges into the case for weighing, and forgetting that the vibration and force of the charge bar hitting the measure is different with a full and fast stroke of the handle using extra force to size the case and seat the primer. +/- a tenth or more from what you were expecting.

[old john]

The seating die(dillon) has a inside cup for either flat noise or round noise bullets. are you using the correct one with your bullet of choice? old john

[iweiny]

I don't know if this is right or not but I have found that +/- 0.005 is not a big deal. I get things close and go with it. Also I think if you are using mixed brass you will find some changes. I try and set the die so that with the brass that I have I get a pretty good average right where I want it. I am sure that my chrono numbers are not at tight as they could be but...

Ira

[standles]

+1 ima45dv8

I had the same problem. Once I started setting dies with full stations it worked itself out.

[eric nielsen]

That always happens with my SDB presses too - it's the difference in how much the shellplate tilts with one round vs with every station filled.

I allow for it one of these ways: either crank another 1/8th turn CW on the seating die after checking the first round [assuming it's the right OAL]

OR

Leave the setting from the previous loading session. Seat the first [solo] round extremely slowly & barely hit the stop at the end of the press stroke. This usually makes that first round no more than .005" short, which I can live with. I measure it in any case & if it's more than 5-thousands short, I throw that round in the trash.

[PFISTO]

Other than the obvious (a loose lockring on your seating die?), are you adjusting the dies with a case in every station?

These machines are built like a tank but many have found that the press operates differently with a case in every station. If you adjusted with just one case in the machine, and then when in full production saw the need for a .006" adjustment, no worries. Reset the depth with a full load of cases in the shell plate, lock it down, and check every now and then.

Yes there is no doubt that things react differently with all the stations filled. I guess it's just the nature of the beast during the setup. I have also noticed that the charge weight goes up after the initial setup. It's just a bit of a pain when your doing small lots of different loads.

[dillon]

There are two things that primarily affect OAL variation: die adjustment and variation among projectiles themselves. Regarding die adjustment, we suggest that you tighten your die lock rings with cases/cartridges in all stations. This both centers the dies in the toolhead and puts consistant upward pressure on the toolhead. Doing this will give consistant die settings except for the last 2 or 3 rounds, depending on the machine model being used. Toolhead play only amounts to .003-.006", and as long as there is a fired case in station one, the toolhead is always lifted upwards completely.

Variation among projectiles is far more common than most loaders suspect. The bullet seat stem seldom seats on the tip of the bullet, especially with jacketed projectiles. The seat stem contacts the bullet on the ogive, or curved part, at a given diameter, and pushes the projectile from there down a given distance. With how projectiles are manufactured, where this diameter is located varies from one projectile to the next. I have personally measured up to .026" variation among a box of 100 9mm 115 grain FMJ projectiles. In general, any variation under .020" isn't worth worrying about. Just keep in mind this is only ammunition, and it does not have .000" tolerance in any dimension. Look at the SAAMI specs for ammunition sometime, and you will wonder why we aren't still using rocks and pointy sticks