Whats up with the seating depth variation in 9mm?

jakfrost

jakfrost

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Hi all, been having a really hard time trying to figure out why I can't get consistent COAL's on my 9mm reloads with the Zero 125 JHP's. I'm loading using a Dillon 650 with the Dillon dies, tried using the Lee 'seating/crimping' die as well and the same results...variation between 1.158" and 1.164" and trying for 1.160" but never more than 2 out of 5 where I want them.

I measured the bullets and they are within less than 1 thousandth consistently. Tried measuring with the ogive adapter on the digital micrometer and the same variations as measuring base to tip.

I have adjusted the shell holder as snug as possible, checked the dies for play, checked the linkage on the press, all is good. The press is nearly new.

Any ideas? Am I chasing a lost cause? I'm loading for 9 Major and so want to try and keep the pressures as low as possible and still make 160+ for home and 165+ for USPSA. Seating the bullet deeper than necessary and the resulting compressed loads could, I believe, possibly spike the pressure and cause unnecessary wear on the gun components...

Cheers,
Jim
 
Are the dies new? Did you disassemble and clean them? I had the same issue a while back and found a nice big metal shaving left in there from the manufacturing process. Good luck.
 
Speed, depth and a host of other human error when using a Dillon will also make that tiny amount of change (.002-.005). I find my Dillon 550B throws powder the most consistent and gets the most exact bullet seating depth in the middle 92% of my reloading when I am most consistent as the user. The first 5% of a batch as I "get in the groove" and that last couple (when cases run out) somehow usually has a minute variation in powder throw (a .05gr +/-) and up to 0.002 +/- of bullet seating. Someone here will probably say it's bull-puckie, but I can't discount what I see with my eyes on the calipers and ogive adapter.

I am not looking for the exactness that you are. However, after in-depth checks other CGN members are giving, maybe say "f#ck it" and just try throwing together 50 practice rounds without worrying about it and see where there might be constancy. Of course, after checking the dies and the press set-up.

The anthology is like a friend of mine: when they tried for kids it didn't happen... and just when they said "f#ck it" and said let's live before we get Invitro... they had twins.
 
madcow said:
Check the seating insert in the die may have the wrong one for the type of bullet you are using.
Click to expand...

I hate it when someone beats me in posting a answer, so I will just be my normal graphical self. And ask the OP if his seated bullets have any circular marks on them. I have had the seater plug grab the bullet and cause variations in OAL.

DillonSDB45ACPSeaters1232011.jpg
 
Well I'm not quite ready for the 'f-ck it' method of reloading just yet, although after this mornings frustration I'm not far off...Spent a couple of wasted hours trying to get the Dillon Seating Die to give me something close to 1.160" and this is pretty much what I would have to settle for if there is no solution other than the above mentioned method...

Anyone got any suggestions? I have purchased a Redding Competition Seating Die, but doubt it will solve the problem, just make it easier to adjust.



 
Have you reloaded wax lubed bullets with that seater die? If so take it apart and look for lube buildup in the die. You might also check your brass for consistent length. That one that is measuring 1.157 looks funny to me. Are the casing getting all the way into the sizer die? the back end of that one looks wide. Maybe that's hanging up in the seating die and causing a shorter seat?
 
jakfrost said:
Well I'm not quite ready for the 'f-ck it' method of reloading just yet, although after this mornings frustration I'm not far off...Spent a couple of wasted hours trying to get the Dillon Seating Die to give me something close to 1.160" and this is pretty much what I would have to settle for if there is no solution other than the above mentioned method...

Anyone got any suggestions? I have purchased a Redding Competition Seating Die, but doubt it will solve the problem, just make it easier to adjust.
Click to expand...

You likely have already got the answer in earlier posts - the seating die isn't compatible with your bullet shape, and/or progressive presses have some range of variation or tolerance built in, or the turret wouldn't turn.
 
When I tried for consistent oal the variation is about as achievable as catching a unicorn. Could be the ogive is seating the bullet not the tip.
 
1) Try the round seating stem.
2) Make sure all the stations are occupied when looking for measurements/consistency.
3) Don't sweat small variations, however 0.01 is quite a bit more than usual.
4) Go to the Brian Enos forum. They got tons of information. (e.g. hxxp://forums.brianenos.com/index.php?/topic/240552-how-much-oal-variance-are-you-guys-seeing-in-9mm/#comment-2680107) *Change xx to tt.
 
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jethunter said:
hxxp://forums.brianenos.com/index.php?/topic/240552-how-much-oal-variance-are-you-guys-seeing-in-9mm/#comment-2680107)
Click to expand...


I didn't do that myself because it's on the fringe of rule 23.

No "hotlinking" email/website info or posting of phone numbers and/or contact information for businesses who do not support the operation of CGN.

The website also sells products so I played it safe.
 
Thanks for all the feedback guys...just had a 'eureka' moment. Even though this Dillon 650 has never seen anything except Zero 125 HP's, I decided to examine the interior of the seating die. When I pulled the pin to remove the centre of the die a black pin fell out onto my bench. I was wondering where the heck that came from, it looked a lot like the 'tool head' pins, when another part 'fell out' of the portion still in my hand. To my surprise, ( am I the only one who never knew this...?), that part is a reversible bullet seater. The conical end had been in use so I reversed it to use the 'flat' end, put it all back together and ran some bullets thru the press.

Eureka! The variation is now reduced to .002-.005. This is my first progressive press and my first Dillon, so live and learn. I learned something else after looking at the brass closely again, ( after another comment mentioned the 'bulge' at the bottom of one of the pieces of brass...), and then checked the re-sizing die. It was loose and wasn't even touching the shell holder. I adjusted it properly and tightened it down...again. Never thought it would work itself back up out of the tool head like that. Again, live and learn!

So now when I do my chrono testing for best OAL with a given powder charge the SD should be fairly consistent...all other things being equal!

Jim
 
All you have to do is post the link and click on the "Unlink" button. It's just to the left of the "insert image" button.
 
jakfrost said:
Well I'm not quite ready for the 'f-ck it' method of reloading just yet, although after this mornings frustration I'm not far off...Spent a couple of wasted hours trying to get the Dillon Seating Die to give me something close to 1.160" and this is pretty much what I would have to settle for if there is no solution other than the above mentioned method...

Anyone got any suggestions? I have purchased a Redding Competition Seating Die, but doubt it will solve the problem, just make it easier to adjust.



Click to expand...

Keep in mind with the redding competition seating die, you must precisely dial in your case expansion. The interior of this die only allows for a certain amount of expansion. Otherwise you are shaving brass.

https://youtu.be/fWkoDoFBH7I
 
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Lead hammer said:
That 1.157 brass looks terrible.
Click to expand...

I've seen many people complain online about this, and it appears to be common when using dillon dies. 9mm is naturally a tapered cartridge, so some coke bottle effect is going to be a common thing. As long as it chambers and functions normally, appearence is not a huge deal.
 
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