So tomorrow I am going to go shoot my first batch of reloads, I'm nervous as hell and gotta ask. I am measuring my COL for a 9mm 115gr LRN, using 4.0gr Hodgdon Universal on a Lee 4-hole turret press. COL on their manual states 1.100....my cases vary (I don't know why) from 1.095-1.105....am I being paranoid here or should I just toss this batch? Help!
Why is my 9mm COL varying so much?
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RidgwayCO
Member
Your COL is only varying +- .005, which is acceptable.
243winxb
Member
For a progressive type press, .010" is ok from what we see on this forum. Single stage presses run about .005" http://www.leeprecision.com/cgi/faq/index.cgiSeating depth variations
There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.
Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.
The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.
There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.
Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.
The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.
Assuming that 115gr your bullet is .539" long (Hornady 35557 115gr), Quickload calculates that your 1.100" load develops 29.5K PSI pressure, which is 84% of the SAAMI max. The 1.095" load is hotter. It develops 30.1K PSI, which is 86% of the max.
Either of your loads is perfectly safe. The noted variance is on par with OAL differences for factory handgun rounds.
Either of your loads is perfectly safe. The noted variance is on par with OAL differences for factory handgun rounds.
.010 varience is more than it should be. You should be able to keep it to .005 or even less with some bullets.
It's not enough to be alarmed about, especially if you are not running max, but you should be able to do better.
You may need a seater plug that fits the bullet better. Also check for lube builed up in the seater die.
It's not enough to be alarmed about, especially if you are not running max, but you should be able to do better.
You may need a seater plug that fits the bullet better. Also check for lube builed up in the seater die.
1SOW
Member
Take a batch of your bullets and measure them. I'll bet they vary more than your load OAL. Some of your OAL variance is due to the ogive not being exactly the same on every bullet.
With my LEE turret press, a change in handle pull will make small variances in the seating depth. A steady consistent pull speed and force gives best results.
This is just my opinion, but I truly believe it to be fact: the diifferences in various range brass thicknesses/hardness affects the bullet seating depth on my turret press. If I'm loading Win cases and I slip in an F.C. case, it will load to an OAL at least .003 shorter than the Wins, sometimes more. I sort brass and have accidently slipped in an F.C. case several times. On the bullet seating die, the handle pull is "a lot less" to seat the bullet in an F.C. case, so it goes deeper.
There is nothing wrong with the F.C./Speer/ Blazer/*-* cases. They just load differently on my press, so I group them together when I load. Win, PPU and R&P will load the same, so I can load them together and have more consistent oals..
With my LEE turret press, a change in handle pull will make small variances in the seating depth. A steady consistent pull speed and force gives best results.
This is just my opinion, but I truly believe it to be fact: the diifferences in various range brass thicknesses/hardness affects the bullet seating depth on my turret press. If I'm loading Win cases and I slip in an F.C. case, it will load to an OAL at least .003 shorter than the Wins, sometimes more. I sort brass and have accidently slipped in an F.C. case several times. On the bullet seating die, the handle pull is "a lot less" to seat the bullet in an F.C. case, so it goes deeper.
There is nothing wrong with the F.C./Speer/ Blazer/*-* cases. They just load differently on my press, so I group them together when I load. Win, PPU and R&P will load the same, so I can load them together and have more consistent oals..
Alabama2010
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That used to bug the heck out of me too- until I measured the variance on factory rounds...
ranger335v
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"I think my rounds have a tad too tight of crimp, which is probably leading to this"
If you over do crimps on rimless cartridges that can cause more problems than your small OAL variation due to headspace difficulties; fail to fire or hang fire.
Many people today are agonizing over a specific OAL and that need not be. When I started this stuff many manuals and other sources didn't bother to suggest an OAL. We lived!
If you over do crimps on rimless cartridges that can cause more problems than your small OAL variation due to headspace difficulties; fail to fire or hang fire.
Many people today are agonizing over a specific OAL and that need not be. When I started this stuff many manuals and other sources didn't bother to suggest an OAL. We lived!
1SOW
Member
IMHO: For handgun: With a little care you can get +/- a few thousandths with fairly consistent bullets.
As was said, with A LOT of hassle, you can get right on, but it isn't worth all that trouble.
amlevin
Member
Unless you are seating your bullets with a seater plug designed specifically for YOUR bullet you will have variations. Most seating dies seat by contacting the bullet on the ogive and pressing it into the case. Bullets can vary in measurement from the ogive to the meplat (tip) by sometimes many thousandths. The OAL as measured to the tip matters when feeding from a magazine or in a cylinder of a revolver as too long will jam the weapon. The OAL as measured by the ogive will matter if you care about how much "jump" there is to the lands of the rifling. Usually only considered in precision rifle loading, not for semi-auto pistol loading. OAL is shown as a minimum because you don't want to squeeze the powder charge too much for any given load. Too short can cause high pressures.
Don't sweat the .010". It's not bad at all.
Don't sweat the .010". It's not bad at all.
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