OAL repeatability - Dillon SDB

[sperman]

I just started reloading, and I'm currious how consistent my overall length should be. I have a new Dillon Square Deal in .45 ACP. I am loading Magnus 200 Gr SWC. Most of my brass is once fired.

I was trying for 1.247 because of the inconsistency. I have loads anywhere from 1.243 to 1.252, with about half of them being either 1.247 or 1.248. Here is a chart of the distribution.

I feel like I should be able to do better than that, but I have no idea what I am doing wrong.

[HoMiE]

Watch the lead build up, clean frequently and it should be a little bit more consistent.

[kevin c]

Somehow, I'm remembering a range of 0.005" as typical.

Make sure the shell plate bolt is snugged down tight - if too loose it may rock and cause some variability.

The amount of pressure you apply on the down stroke needs to be repeatable - I can get 2 or 3 thousandths variation between just kissing the shellplate up against the dies versus hitting home hard enough to make things shake.

A clean seating stem is important for any bullet that might allow build up of lube or shaved lead or plating. The bullet profile also has to match the seating stem you're using.

Really important is the consistency of the bullets you're using. What with mold lines, surface irregularities, lube and other variables, I find cast to be a little less uniform. Best, I think, is a JHP, which gets a lot of dimensional consistency from a hard jacket worked from both ends. Pick a good brand, but be aware that even with the best bullets, there will be lot to lot variation, so don't mix bullet lots together, or, if making a mid run change, at least recheck OAL with the new batch.

The worst variability I ever got out of my SDB happened with mechanical failure of the press - broken link arm, handle and the frame itself have all happened to me, but a call to the good folks at Dillon took care of that.

ETA more verbiage and correct decimal...

Edited July 29, 2008 by kevin c

[G-ManBart]

Are you measuring with a bullet comparitor (sp?) or a caliper? Are you using the same headstamp brass or mixed? Lead bullets tend to have a little variation in them to start with (all bullets really), so take that into account.

If you're using mixed brass, that will change things. Measuring with a caliper will add some error into that and then when you add the bullet variation, a couple thousands either way isn't a big deal at all. R,

[Nik Habicht]

I just started reloading, and I'm currious how consistent my overall length should be. I have a new Dillon Square Deal in .45 ACP. I am loading Magnus 200 Gr SWC. Most of my brass is once fired.

I was trying for 1.247 because of the inconsistency. I have loads anywhere from 1.243 to 1.252, with about half of them being either 1.247 or 1.248. Here is a chart of the distribution.

I feel like I should be able to do better than that, but I have no idea what I am doing wrong.

I think that's right in the consistency ball park I get out of a 650 and a 1050 using mixed brass. A variation of 5/1000 either way wouldn't worry me with pith pistol ammo.....

[sperman]

Are you measuring with a bullet comparitor (sp?) or a caliper? Are you using the same headstamp brass or mixed? Lead bullets tend to have a little variation in them to start with (all bullets really), so take that into account.

If you're using mixed brass, that will change things. Measuring with a caliper will add some error into that and then when you add the bullet variation, a couple thousands either way isn't a big deal at all. R,

Calipers and Mixed Brass.

Thanks for all of the advice. I felt like variation in the bullet casting was part of the equation. I guess if you stack that on top of the other factors it all adds up. I'm glad to know its not going to affect things too much.

[ghawk249]

Sperman I do not have a SDB but have the 550b and was having the same problem. After making a call to dillon they suggested when adjusting the seating die to make sure all the stations are full. After trying this my OAL is well within the variation mentioned by the other folks.

[Edubya]

Are you measuring with a bullet comparitor (sp?) or a caliper? Are you using the same headstamp brass or mixed? Lead bullets tend to have a little variation in them to start with (all bullets really), so take that into account.

If you're using mixed brass, that will change things. Measuring with a caliper will add some error into that and then when you add the bullet variation, a couple thousands either way isn't a big deal at all. R,

With emphasis on same headstamp brass or mixed!

This caused me a lot of worry. I took my 550 and dies apart, just trying to figure out how the variations could happen. I cleaned the dies and parts, put it back together and got the same kind of results. I shimmed the tool head so that there was no play; same results. It wasn't until a friend was looking over my shoulder and asked, "Do you think that the make of brass would have anything to do with it?" I checked out the 50 already loaded bullets and sure enough, that's the way it measures out- .012 difference on the extreme. I now load by headstamp!

[UW Mitch]

The other question that may matter more than being precisely on the numbers is does all your ammo feed in your guns and make the power factor you want? If yes, I wouldn't worry about 0.010" variation.

~Mitch

[Edubya]

The other question that may matter more than being precisely on the numbers is does all your ammo feed in your guns and make the power factor you want? If yes, I wouldn't worry about 0.010" variation.

~Mitch

I got into reloading for more than economics. I want to learn. I want to learn why some bullets tend to run better (more accurately) and how velocity affects a bullet's accuracy and effective power. Assuming that the brass has done its job of holding things together, the primer has done its job of igniting the powder completely, the bullet will obdurate filling the barrel riffling substantially enough to build speed from that pressure and to create a rotational velocity to equate the speed and weight of bullet to suitable harmonics and gyrotational torque, thus producing a flat, straight trajectory with enough power to put a living animal down for a long, long time (or to, predictably, make a hole in a paper target).

The powder companies have tested and retested their loads, they have given us a min/max powder load and the C.O.L. (no min/max) that produces a safe and predictable trajectory. I guess that the powder manufacturer's recommendations should be sufficient, since I don't have the means of testing the pressure.

I am beginning to understand more, but by no means all!

[GW45ACP]

You didn't mention if you are using Hornady OneShot on the cases before loading. If not, I would recommend it, especially with the SDB.

[High Lord Gomer]

I had inconsistencies when I had the seating stem upside down in the seating die on my 550. I was using the wadcutter stem on round nose bullets.

[Irishlad]

When I used the cheap, pocket slide rule caliper, I just marked the 1.25" line and all my ACP loaded on the SDB were "spot on"...and worked great in my gun.

When I bought a digital caliper, I had the same "large" variances as you have...and they worked great in my gun.

So, instead of working on the machine, I just switced back to the slide rule caliper...and they are "spot on" again.

[Triggerbender]

Same load, same machine, 20,000 rounds or so no issues with 1.250 O.A.L. +/- .005 .

Be sure you have the right bullet nose insert in your seating die (best contour for your bullet tip) and watch for wax build up from the bullet lube in your dies.

[Edubya]

Same load, same machine, 20,000 rounds or so no issues with 1.250 O.A.L. +/- .005 .

Be sure you have the right bullet nose insert in your seating die (best contour for your bullet tip) and watch for wax build up from the bullet lube in your dies.

Trigger, I wish that you were somewhere within 100-miles of me, I'd like to bring my press and have you set it up correctly for me. It's my first progressive and I've only got the basic mechanical skills of a retired certified aircraft and powerplant mechanic. I'm use to things being +/- .001 and have found this simple press very daunting.

[Triggerbender]

Same load, same machine, 20,000 rounds or so no issues with 1.250 O.A.L. +/- .005 .

Be sure you have the right bullet nose insert in your seating die (best contour for your bullet tip) and watch for wax build up from the bullet lube in your dies.

Trigger, I wish that you were somewhere within 100-miles of me, I'd like to bring my press and have you set it up correctly for me. It's my first progressive and I've only got the basic mechanical skills of a retired certified aircraft and powerplant mechanic. I'm use to things being +/- .001 and have found this simple press very daunting.

Target 1.250 o.a.l. ranging 1.245 to 1.255 to be clear on what I get.

I struggled for a while until I found out most of the problem for me was the variation in the bullets themselves and found the same thing and worse with bulk .223 when I started to reload for rifle.

I had a good local caster for my pistol but he just gave it up so I will be back to square 1 when I use up what I have.

You can forget about that +/- .001, I could not get there spent 25yrs as wrench myself and I know how you think.

Edited September 2, 2008 by Triggerbender