Progressive press OAL variations

[Sandman799]

Hello and good day to all, I’m new to reloading, I learned the basics on my neighbors RCBS Rockchucker press that he’s had for 20 plus years and he loves them so much he has two of them, so of course he wanted me to get one too but I wanted progressive, so I bought a Lee Loadmaster to further learn on then moved up to a Dillon XL-650 after two months, so now I am loading on the Dillon XL-650 press, one thing I notice all the time is there is constantly variations in Overall length even though it’s only a few thousandths, it’s still all over the place.

Like last night I wanted to run a batch of 40 rounds of 45 ACP using Win brass and 185 grain XTP bullets, I set up my dies and adjusted my powder measure and crimp station and set the bullet seating die to a seat depth to 1.245” and ran a round through and it was dead on so I ran another round through and it’s rght there, so I fill the case feed tube and start loading, I loaded my 40 rounds and pull the bullet catch bin and start inspecting the rounds, I always re-measure and triple check everything every time I load, so when I get my calipers I start measuring and instead of 1.245 they are all in the 1.250-1.257” range??? I know I am not short stroking the press because it bottoms out every stroke, so I re feed each bullet through the seat station and crimp station and each is good but if again I start to process all them again the OAL is off again, it’s like when a finished bullet is in the crimp station and the seat station it effects the OAL in the seat station? But if I adjust based off that then the first two bullets will have to be seated too deep, like by 5 to 10 thousandths? And can’t that be dangerous? I have lots of questions and concerns and don’t want to blow up my expensive guns so any help would be appreciated

Bill

[Jim Watson]

You will have to make a final adjustment to seating and maybe crimp with all stations loaded.

When I change bullets, the ones I use to get a rough adjustment with will be a bit off spec. I just put them in the plinking box. A few thou in OAL will not overpressure you if you are not already into +P.

A seating plug made to fit your exact bullet will help uniformity after you are set up. But I am not after that degree of precision, bulk bullets aren't that uniform anyhow.

[RC20]

You also need to be aware that bullet tips vary a LOT.

What you are after is an average, measure a sample of 20 bullets and that will give you a good idea of the mid point to set.

If you want to see what really is going on get a Hornady Bullet compare setup and measure the OGIVE (curve of the bullet) that is more accurate.

its not spot on.

As long as your bullets average out where they fit the magazine, (barrel of a semi auto is a good tool to check) cylinder or do not stick in the lands (ri9fle) you are fine.

note: you want to be .020 off the lands in load development and if you move to the lands, you want to do carefully so as not to overpressure with hotter rounds.

[Nick_C_S]

Welcome to TFL Sandman799.

There's no quick n dirty answer. On progressives, OAL's tend to float about a little. Some variance is to be expected.

it’s like when a finished bullet is in the crimp station and the seat station it effects the OAL in the seat station?

It probably is. We're dealing with a mechanical device and it shifts n flexes, etc. It's not a truly "fixed" system. When I first set my OAL and then start loading "normal production," I notice that the OAL's can be a little longer than originally set. I just cinch down the seater a bit and continue loading, and that usually puts my OAL's in the correct range. (I have a Dillon 550 - Dillon's are the best and should have been your first purchase - but that's neither here nor there now.)

Another thing that is likely happening is that when you go to re-seat the already seated/crimped bullets, you're distorting the nose of the bullet (particularly pronounced with hollow points) and effecting the OAL. Now I know in theory that the OAL shouldn't so smaller than the original setting, but sometimes it does. Like I said, it's not a truly fixed system.

If your OAL's are short because of bullet tip distortion, it's highly unlikely to be dangerous. If your OAL's are short because the bullets are actually seated deeper, that has the potential to be dangerous because the smaller internal case volume may cause the propellant burn rate to increase; and thus, a corresponding increase in peak pressure. Will 10-thousandths cause an unsafe condition? Not likely. But if you're loading to the very top of the pressure scale to begin with, then you have little margin for error. Makes sense?

Try to get your final setting of OAL while in production; i.e., when your ammo is going through all the stations. If some OAL's are too far off while you're doing this final setting, reserve those rounds and fix them after you've completed your production.

Last thing: Try not to get too deep in the weeds here. It's not a perfect system. Some variance is to be expected (10-thousands is possible - and I've seen plenty of hot factory ammo with even more); so don't make absolute perfection your standard.

Load safe.

You will have to make a final adjustment to seating and maybe crimp with all stations loaded.

Yeah, what Jim Watson said while I was composing this .

[RC20]

I will also add, I do not like to do the crimp with any other function, separate step.

I am not sure if you can do that on a progressive, I never have had one.

If not possible, then I would do the crimp on a single stage press.

[Nick_C_S]

I do not like to do the crimp with any other function, separate step.
I am not sure if you can do that on a progressive

You can. But there's some minor practicality issues associated with doing so; and defeats the purpose of the progressive.

With my progressive, I actually do up to three crimps . . .

When seating, I have the die body take out most of the flair (contrary to common practice, I flair generously).

The next die applies a taper crimp (semi-auto or revolver).

The die after that applies a roll crimp (if applicable - about 50% of my revolver rounds).

[RC20]

I started out doing the crimps and seating on my single stage.

I could do it but it took so much fiddling I finally figure out I was a lot better off time and accuracy wise to get a second die and do it that way.

[jmorris]

one thing I notice all the time is there is constantly variations in Overall length even though it’s only a few thousandths, it’s still all over the place.

Depends on what you are feeding it.

Measure the components you are feeding the presses and see if they are “all over the place”.

From all the machines I have used from single stage to the most expensive progressives, the components and dies have made the largest difference in consistency in the final product.

Quantify what you are talking about, .0015” +/- would be a few thousandths and be outstanding with the best press and dies with some bullets.

[kmw1954]

From your description I have to go along with the 1st statement in post #2 as the biggest influence and then the variations in bullet shape.

I use both a Lee Turret press and a Lee Pro1000 progressive. With the Lee turret in the progressive it, the turret, needs to be loaded before it will give consistent results. When I get to the end of a run and am on the last case in the press it is also been shorter than the rest. As a whole I see variations of about .003" and I attribute that to the bullets and not the press. BTW this is also with using stock Lee dies.

[Zacf16]

I found that my variations in OAL really went down when I started sorting my mixed brass by headstamp. I also found that I needed to tweak the seating stem after all stations were populated (like Nick and Jim mentioned above).

[Stats Shooter]

I switched to a progressive press a while back. I load match, plinking, and hunting ammo on progressive and single stage presses. I have Dillon, Redding, RCBS and herters presses.

Listen to jmorris regarding presses....dude is the press whisperer

But here are my own observations and bits of unsolicited advice.
1: measure base to ogive for length. Only worry about COAL for feeding from magazines. Why? Because bullet tips are not uniform. They can vary by over 0.01" even on match grade rifle bullets. The ogive shouldn't vary by more than a few thousandths. To convince yourself, measure several bullet lengths. Tip variance isn't a big deal regarding accuracy.

2: even though I just said ogive is more consistent, check bullet base to ogive ogive on a few bullets if you are having inconsistent seating issues. I wrote a thread a while back showing how a box of 500 sierra match kings had 3 different ogive measurements.

3: use good seating dies with a proper seating insert for the chosen bullet. I use Forster BR or ultimate micrometer seating dies in all my presses now (except pistols and lever guns).

4: highly compressed loads can cause seating depth issues

5: on my Dillons, I get the seating die close, then adjust it once all the stations are full. It can change a few thousandths if all the stations are full vs empty.

I load AR-10/15 match ammo, on a Dillon 550 C. Toolheads have RCBS size die with Lyman carbide expander ball, Forster BR seating dies, Lee Factory Crimp Die. Cartridge base to ogive measurements +/- 0.001. And even with the dispenser shy IMR4064, in my ar-10 the powder drops are +/- 0.002. Which is more consistent than federal GMM factory ammo. And varget in my 223 drops 0.001+/-.