Seating Depth Variation

[Genghis]

I'm a fairly new reloader, reloading .38 Super for USPSA. Looking for Major PF with 124 grain Zero bullets, using 9.2 grains of 4756 powder. I'm trying to seat the bullets so I have 1.230 OAL.

I'm seeing huge variations in seating depth. I called Dillon and they told me to tighten the set screw on the main Allen bolt, and to turn the seating die so the side with the flat opening was facing the bullet. With both of those things done, I'm still seeing a lot of variation. Every fourth or fifth bullet sticks way out, as much as 78 thousandths variation in OAL. It's very noticeable.

The powder fills most of the case, so there's a chance some of the bullets just don't have enough room to seat properly. But the guy who sold me the gun used this load successfully.

These are jacketed bullets without lube, so there is no gunk building up in the seating die.

I've tried holding the handle down for a second or so, but I'm still getting some long rounds. I've tried running them through the seating die again, which helps some but still leaves them longer than 1.230.

I'm afraid this will make the velocity vary significantly. I am also seeing some differences in powder charges, which must account for some of the variation, but velocities on the chrono varied from about 1250 fps to over 1450.

I need to KNOW I'm going to make major PF at the upcoming matches. Suggestions?

Edited March 13, 2006 by Genghis

[al503]

How much are you belling the case? If you're belling it too much in the powder drop station, you might not have enough tension between the bullet and case to keep the OAL from changing before it gets crimped.

While a compressed load certainly doesn't help in regards to consistent OAL's, it shouldn't cause that much of a variation. I'm usually +-.002 when loading 38 SC with 4756.

Edited March 13, 2006 by al503

[Flexmoney]

If it is every 5th round, you might have an issue with one of the stations on the shell plate. Worth checking out.

[galt11]

Are you using a redding competition die? I ran into a problem like this once with a rifle die. The reddings won't do a compressed load because of the spring inside. Hope this may help.

Adam

[Chris Keen]

I am also seeing some differences in powder charges

How much of a variation in powder ?

[Ray_Z]

Are all the cases if the same manufacturer? Case volume will change with manufacturer.

[ihatepickles]

If it is every 5th round, you might have an issue with one of the stations on the shell plate. Worth checking out.

This is exactly what I thought of when I read "every fourth or fifth round..."

Aside from double checking the shellplate, stay in touch with Dillion. Don't suffer in silence.

[Genghis]

al503: I believe the cases are belled a little wide.

Flex: I took the shell plate off, along with the main allen bolt, and removed and cleaned the indexing bearing and spring. I think the plate is okay, unless I missed something. I don't think the pattern is consistent, but I'll look for it next time I reload.

galt11: I'm using stock Dillon dies.

C.Keen: Powder charges seem to vary from 8.9 to 9.4 grains. Once in a while the powder spills over the casing, so I can't weigh them, but when I weight what's in the casing it's usually light (8.9 or so).

Ray Z: Casings are mixed.

[al503]

al503: I believe the cases are belled a little wide.

I'm a cheap a$$ so I want to get as many loadings out of my SC cases as possible. My goal is to have the primer pockets get loose before the cases split. Regardless, I bell the case so little that I have to keep the bullet on top of the case with my fingers as the seating die comes down. The added benefit is that there should be enough tension created between the bullet and the case to keep the OAL from changing before the crimp die can get to it.

If you're powder drops are varying that much, I don't think you're powder measure is working correctly. I'd check it out and see if everything is tightened down and there isn't a foreign object in there messing things up.

[RogerT]

Variations in powder drop may be related to a weak mounting of the press, it is not as steady as it should be.

Strong, sturdy bench top is vital to consistent powder charges from a Dillon type of powder meter.

[galt11]

If I remember correctly, a while ago I came across some information that the Dillon powder drop insert would not work real well with 38 super brass. I sent my insert to Starline and the re-milled it and it has always worked for me. I will look to see if I still have any of the info.

Adam

[shred]

Personally I don't think "New loader", "9.2gr of 4756" and "OAL variations" belong in the same county together, but I digress.

new reloader, reloading .38 Super for USPSA. Looking for Major PF with 124 grain Zero bullets, using 9.2 grains of 4756 powder

Tried a load that isn't compressed to see if that helps? 6.6gr of 4756 makes a nice steel load and won't be trying to shove your bullets back out of the cases when the shellplate cycles.

[TxD]

Genghis.

Try backing the seating die out a 1/4 turn or so and then re-adjust the seating stem.

This die should not touch the brass on the seating stroke.

If the die is down to far it tends to start a crimp on slightly longer brass and cause

LOA variations.

Another thing: pull the bullets on the longer seated rounds and measure the length

of this brass against the length of brass with properly seated bullets.

This will confirm the problem.

Hope this is clear and hope it helps.

Edited March 14, 2006 by TxD

[Genghis]

Thanks for the suggestions, including Shred's, which I interpret as, "Are you out of your mind!?!"

[al503]

Thanks for the suggestions, including Shred's, which I interpret as, "Are you out of your mind!?!"

Shred and many, many others here have probably forgotten more than I know about this sport and reloading but there shouldn't be any reason you shouldn't be able to work with compressed loads. Are they more difficult to get consistent, sure. Will it be impossible? Absolutely not.

If you can get yourself a lb or two of the powders that aren't compressed, by all means, give it a try and see what happens. However, at what point does someone 'graduate' to compressed loads? I say jump in with both feet. Since it seems you're erring on the long side, you don't have to worry too much about anything besides your gun feeding the longer OAL's. 4756 is a good powder with good pressure characteristics.

Edited March 14, 2006 by al503

[shred]

Thanks for the suggestions, including Shred's, which I interpret as, "Are you out of your mind!?!"

Shred and many, many others here have probably forgotten more than I know about this sport and reloading but there shouldn't be any reason you shouldn't be able to work with compressed loads. Are they more difficult to get consistent, sure. Will it be impossible? Absolutely not.

If you can get yourself a lb or two of the powders that aren't compressed, by all means, give it a try and see what happens. However, at what point does someone 'graduate' to compressed loads? I say jump in with both feet. Since it seems you're erring on the long side, you don't have to worry too much about anything besides your gun feeding the longer OAL's. 4756 is a good powder with good pressure characteristics.

Well, I just remember when I started loading... my output had some variability for a while that I would now call 'scary'.

Compressed loads add one more variable to the loading process. With care, no problem, but it is more complexity to worry about. IME, most novice loaders, like novice shooters are pretty far up the task-loading curve as it is. Thus my suggestion to load some minor/steel loads using the same powder, bullet and all-- you can make sure everything else is working correctly before taking the jump to rifle pressures.

I'd also say 1.250+" is the "long side" of 38 Super, rather than 1.230". I aim for 1.245" most of the time with a JHP.

[Genghis]

UPDATE: Last night I pulled my press and took it to my friend Harold's place to see if he could diagnose the problem.

We noticed that some of the bullets were loose enough in the casing that you could turn the bullets in the casing by hand and pull some of them out of the casing. This is after the bullet was seated and the casing crimped.

To make a long story short, we still had the seating problem after Harold went over the entire press and adjusted every station. We started sorting the problem cartridges into a separate pile. ALL of the problem rounds turned out to be American Ammunition brass, and ALL of the good rounds were other brands. I bought some of this ammo to get me by while I was getting set up to reload.

It appears that for some reason, this once-fired A-Merc brass will not hold a bullet properly.

I found some discussion of A-Merc brass and ammo on the net, not complimentary (and some other favorable discussion), but I only had one FTF in 500 rounds.

We loaded a bunch of rounds with new Remington brass and had nary a problem.

[dfwmiket]

Cool deal. Glad it was something that easy.

Mike

[virginiascout]

The only thing I do with A-Merc is trow it in the trash. It does not load well at all.

[roby]

ive been having lots of oal variations too. ive been using win brass and trying to seat to 1.235 but some are getting seated at 1.240...its driving me nuts. i also have nickel cbc brass and it will have a different oal from the winchester brass. argggh! never had this problem when loading 40sw.

[dillon]

Roby,

You are worrying about about the shooters' equivalent of how many angels can dance on the head of a pin. .005" OAL variation is very minimal, especially on handgun ammunition. If you adjust your bullet seating die( and a good idea for all dies) with a fired case in station 1, then you will maintain consistant upward toolhead pressure. Beyond that, your variation is due to the manufacturing tolerances from one projectile to the next. Jacketed projectiles, especially round nose style, can typically vary up to .025" in where along the projectile the bullet seating stem makes contact. The seat stem then pushes the projectile down a fixed distance. Measure some factory ammunition sometime, you'll be very suprised!

[Bronson7]

Roby,

You are worrying about about the shooters' equivalent of how many angels can dance on the head of a pin. .005" OAL variation is very minimal, especially on handgun ammunition. If you adjust your bullet seating die( and a good idea for all dies) with a fired case in station 1, then you will maintain consistant upward toolhead pressure. Beyond that, your variation is due to the manufacturing tolerances from one projectile to the next. Jacketed projectiles, especially round nose style, can typically vary up to .025" in where along the projectile the bullet seating stem makes contact. The seat stem then pushes the projectile down a fixed distance. Measure some factory ammunition sometime, you'll be very suprised!

About a year ago, I performed an experiment that proves bullet style (or ogive) effects oal.

I removed the seating stem from my die and measured the total length of the stem and bullet (with the stem sitting on the bullet).. I measured just the bullet length beforehand and subtracted it from the total length to compensated for bullet length variance. I did this on twenty rounds, using two styles of bullets. The results surprised me. I was accurately able to predict what my variance would be using the two styles. One style had much less variance in oal. This was born out by the finished round. So, if your machine is properly set up and you're using a steady cadence, the style (ogive) is the deciding factor.

Bronson7

[Flexmoney]

I am with Shred. if you are new enough to reloading that you are just learning that A-merc brass sucks, then you ought not to be loading compressed Super to Major yet.

Back off to well into Minor and learn a thing or two before dancing on the edge.

Better safe than sorry.

[virginiascout]

One think I learned after having oal bounce was the seating stem. I was trying to load ranier 200 FP's in 45. It was driving me nuts. But in perspective the nuts was .004 to .006 variance, really did not matter except I like things consistent.

I ended up taking a seating stem round and putting a slight undercut in it. I then coated a ranier with release agent like used in a bedding job, mixed up a small amount of acraglas gell put it in the seating stem and then put the bullet in the acraglass. This allowed me to make a seating stem that was the exact shape of the ranier FR.

This simple custom stem eliminated the variation.