boatdoc173 Posted December 14, 2023 Share Posted December 14, 2023 (edited) Hello My 550c for 9mm reloading has been consistent for years. I have noticed lately that the solidly locked-in bullet seating die is moving just enough to change my O.A.L. by -0.001--0.003 every so often(. Often enough that I find my self taking time out away from reloading the verify OAL every 500-1000 rounds.) I only use my Dillon dies and their lock rings. , I am baffled as to how the OAL can change when the lock ring is locked down tight and the die has zero play anyone else had this happen? any ideas on how to stop this? the first 50,000 rounds were loaded @ 1.140" to fit into a fussy CZ A01. NO issues were noted when I made them. it was set it--forget it 2020-2022 the new need to check OAL way too often is more than annoying. thanks in advance for any insight ad help offered Edited December 14, 2023 by boatdoc173 Link to comment Share on other sites More sharing options...
GrumpyOne Posted December 14, 2023 Share Posted December 14, 2023 Clean the die. Stuff gets built up in them and causes some of these issues, but .001 isn't anything to worry over. Link to comment Share on other sites More sharing options...
Maximis228 Posted December 14, 2023 Share Posted December 14, 2023 (edited) Brass and projectiles can have larger variances alone than what you mentioned above. Depending on your projectile of choice, you may see a larger variation. Are you continually drifting in one direction? That could show that a die is moving on you. I would witness mark your dies and lock rings with the toolhead with a paint pen. My current 9 major ammo I'm loading has an OAL range of 1.164 - 1.170. No issues at all with that spread. Edited December 14, 2023 by Maximis228 Link to comment Share on other sites More sharing options...
ddc Posted December 14, 2023 Share Posted December 14, 2023 The only time I see an OAL variation of 0.001" is when I compare a maximum of two cartridges; then I might get lucky. For any reasonable sample size I'm happy if the variation is around 0.005". For example my target OAL for current 9mm load is 1.125" to 1.130" and even at that I might see a few that exceed that spread. Link to comment Share on other sites More sharing options...
Nickb45 Posted December 14, 2023 Share Posted December 14, 2023 I don’t worry about anything unless it’s more than +-.005. if you’re shooting for less than .001 variance calipers are not the correct tool for that measurement. Link to comment Share on other sites More sharing options...
Farmer Posted December 14, 2023 Share Posted December 14, 2023 Are you saying .001-.003 Longer? If the die is tight I would check shell plate or tool head. If it’s shorter check for die crud or bullet mash. Have seen up to .005 from a tight fit and mashing the bullet nose especially on HP’s. Like the others have said under .005 is gtg unless you’re OCD. Link to comment Share on other sites More sharing options...
Sarge Posted December 15, 2023 Share Posted December 15, 2023 Mixed brass will vary wildly. If you are sorting then I’d guess maybe not enough lube to even distribution. Link to comment Share on other sites More sharing options...
shred Posted December 15, 2023 Share Posted December 15, 2023 Most likely bullet profile, especially if you have a round-nose seating stem in there. Link to comment Share on other sites More sharing options...
boatdoc173 Posted December 15, 2023 Author Share Posted December 15, 2023 (edited) great answers. thoughtful and to the point guys. THANK YOU. I was baffled. thought about it all night too I will address some of the ? in my post below I think the brass length varying is part of the issue. I clean my dies regularly. I do NOT sort brass by name brand though. I sorted out all of the brass that caused issues when priming in the past. I use hornady one shot regularly. that said , using a plastic baggie to spread the one shot around might leave some cases lacking in enough lube. I am very glad that you guys have posted that such small variances do not make reloading or shooting dangerous( pressure increases). my variance is 0.001-0.003 shorter than the desired OAL. I use RMR .355" 124 gr FMJ round nosed bullets and my die has the round nose tip installed. again, much thanks for the thoughtful replies Edited December 15, 2023 by boatdoc173 Link to comment Share on other sites More sharing options...
boatdoc173 Posted December 15, 2023 Author Share Posted December 15, 2023 (edited) @Nickb45--what would you use for the best measurement outcome? I have noticed that my calipers ( digital from dillon when I bought my initial reloading supplies) has to be zeroed every time . After reading the replies so far, I am guessing that the calibers might contribute to my issue.. exact measurement depends on consistent placement of the cartridge in the calipers when measuring. a more reliable way to measure OAL would make a difference Edited December 15, 2023 by boatdoc173 Link to comment Share on other sites More sharing options...
Nickb45 Posted December 15, 2023 Share Posted December 15, 2023 I have a set of Brown and Sharpe dial calipers on my reloading bench. For most tolerances calipers are fine, a micrometer that goes to 4 decimal places will be better… but totally unnecessary for reloading pistol ammo. Link to comment Share on other sites More sharing options...
HOGRIDER Posted December 15, 2023 Share Posted December 15, 2023 10 hours ago, boatdoc173 said: @Nickb45--what would you use for the best measurement outcome? I have noticed that my calipers ( digital from dillon when I bought my initial reloading supplies) has to be zeroed every time . After reading the replies so far, I am guessing that the calibers might contribute to my issue.. exact measurement depends on consistent placement of the cartridge in the calipers when measuring. a more reliable way to measure OAL would make a difference @boatdoc173 I have also found when loading my standard PD 124g JHP, that I can rotate the finished round and get different OALs! This is using a Mitutoyo 0.0005" Resolution digital caliper. I attribute this to the slight variances in the hollow point forming of the bullet; plus my Redding micrometer seating die is seating off the ogive. But I can still get a "standard" variation of +/-.002" once the press has filled the shell plate. Just have to make sure the round is in the "sweet spot" when measuring....... Link to comment Share on other sites More sharing options...
boatdoc173 Posted December 16, 2023 Author Share Posted December 16, 2023 (edited) @Nickb45--thanks for the info @HOGRIDER--I agree. that is one cause for variation. brass and bullet size and shape being others . My concern was the potential for an increase in pressure when a cartridge would shorten down to 1.137, 1.136, 1.135" even. I did shoot a couple of the 1.136" rounds yesterday and as predicted by our members, the ammo shot fine. Edited December 16, 2023 by boatdoc173 Link to comment Share on other sites More sharing options...
Farmer Posted December 16, 2023 Share Posted December 16, 2023 @boatdoc173 If you’re shooting minor loads you would have to seat the bullet about .025” deeper to bump the pressure and at that it isn’t going to get you necessarily into a danger zone. Maybe a bit hotter but generally nothing to worry about. Now if you’re at major that’s a little different story. Link to comment Share on other sites More sharing options...
boatdoc173 Posted December 17, 2023 Author Share Posted December 17, 2023 @Farmer--just plinking loads. not loaded too hot. however with titegroup, the powder charge range is very tight. thanks for the reply.it is reassuring Link to comment Share on other sites More sharing options...
IVC Posted January 1 Share Posted January 1 I wish my variance was as little as 0.001 - 0.003. Coated bullets and mixed brass even in principle won't produce that level of consistency - the bullet is seated by pressing off-center, towards the ogive, so the tip of the bullet is not touched and any deposit (coating or lead below) will change the OAL. Look at the bullets before you load them and you can see with naked eye that the tips are a bit off. Also, it's easy to measure the length of each bullet and you'll see variability. Note that this doesn't even mean that the base of the bullet is seated at different depth, the depth could be anything. But it will be close enough... Brass is another issue. I'm pretty sure that the press won't hold the brass within 0.001 at the seating die. Maybe at the sizing die, if overcammed, but not at other stations. You don't have a problem Link to comment Share on other sites More sharing options...
boatdoc173 Posted January 2 Author Share Posted January 2 thanks @IVC Link to comment Share on other sites More sharing options...
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