Got a question about over all length

[jwbanks]

I've got a Lee breach lock press and just started loading. While seating bullets and checking oal, I noticed the length was pretty erratic. Seemed the more I loaded the shorter they got, started at 1.130 and saw 1.128, 1.125, 1.127 , ect. Any ideas

Thanks

 

[jwrowland77]

Actually, perfectly normal to see that amount of variation.

Load'em and shoot'em.

 

[jwbanks]

Thanks, I'm pretty new and worry about every little thing

 

[jwrowland77]

I completely understand. I was there a few years ago myself. The bullets themselves have that much variation.

I started with 9mm, and measured everyone in a box of WWB. Those things are all over the place. Lol

 

[pretzelxx]

Same question I had, just loaded up 5 dummies last night had similar variations. Then I measured the bullets without the case. I figured that much difference in the bullet size shouldn't be too big a deal. I plan to get powder and primers this weekend and load up some live rounds and shoot them all next weekend! Good luck on your loading!

 

[FROGO207]

The punch of the seating die pushes on a part of the bullet called the ogive. It is a ways down on the shank of the point end. All bullets will be seated to the same depth with respect to the ogive but the end point will not always be the same length. As a rule the more expensive the bullets the more identical they will be with respect to sameness in all measurements. As long as the punch is not filled with wax and dirt the bullets should be the same depth at the ogive and not change. If you want to find the spot to make them all equal get a bullet comparator and then the measurements will mean something when you make them.

 

[tightgroup tiger]

The punch of the seating die pushes on a part of the bullet called the ogive. It is a ways down on the shank of the point end. All bullets will be seated to the same depth with respect to the ogive but the end point will not always be the same length.

That holds true with pointed rifle bullets but with an OAL of 1.130 I suspect JW Banks is loading 9mm or similar, which would have either a flat seating profile or a round nose profile where both push on the tip of the bullet.

Being that they do push on the end of the bullet the OAL should be the same regardless of the variances in the bullets themselves, the base of the bullet would change depth, not the tip as long as your using the correct seating stem.

.002" of variance is usually as good as it gets with the best loading presses.
.003" is no problem either. Actually, usually better than normal

Just for the heck of it look up in the seating die and you will see what I'm talking about. Make sure the profile on the seating stem matches the profile of the bullet your using. If it doesn't your bullets won't seat straight. Also, if you don't flare the cases enough the bullets could seat crooked which again will affect the OAL.

 

[Walkalong]

A .005 spread is nothing to worry about. Nothing unusual about it. Some bullet/seater stem combinations will do better, but I have several pistol loads with a .005 spread.

 

[ky8]

I agree you will very some. On the auto cases I worried like you.
Get yourself a case gauge or OAL gauge. I won't say it is 100% but
it can take a lot of the worry out. So far I have not had a round pass the
gauge that failed in use.
JMO.

 

[gamestalker]

The one aspect regarding oal that is of particular importance, is if your OAL's get shorter after being cycled through an AL firearm, this is referred to as set back. This is where things can get dicey, in regard to pressure spikes. Even .010" of set back can have a noticeable effect on pressures. And not to under mine the significance it represents for any AL cartridge, but high pressure cartridges such as 9mm and .40 display an obvious need for heightened concern when set back issues occur.

I take my loaded rounds and measure before and after cycling to check for significant changes. You can expect some variance, but anything that indicates .010" or more is an indication of lacking neck tension.

GS

 

[788Ham]

Tiger,
Your mentioning "matching the bullet stem to the bullet profile", I had this trouble with my older RCBS seating die, it mashed the Hornady V-Max bullets when seating. I took my coldness drill, drilled out a smidgen of the bullet seat stem, inside, quit mashing the tips, perfect bullets then. Thanks for adding this to your comments.

 

[spitballer]

I'll be the first to admit I'm a perfectionist and when I get variation in OAL I want to know WHY. If my bullets are the same length, then why am I getting a different OAL when I star seating them?

In my case I have found that neck tension (hard brass) is usually the culprit. When my brass starts to get hard, the OAL length starts to vary. I can compensate to some degree with good press technique, but when I get more than .001" OAL variance with a .001 press fit, I am not happy and will not load any more until the problem is solved, either by annealing the necks or switching to a slightly looser neck sizer.

Take note that cheaper brass is sold without regard to neck thickness, and when it starts to get hard, the cases with thicker neck walls will not seat as easily as will the cases with thinner necks. When the brass is new and soft, you will not notice the difference.

 

[gamestalker]

Another fun fact is olgive consistency on bullets in my experience can vary significantly, especially noticeable with high powered rifle bullets, this is due to the long slender profile. Even match grade bullets will exhibit some degree of olgive inconsistency.

If I ever got .001" oal consistency with high powered rifle bullets, I would be feeling like I won the lottery, and I use competition seating dies, and customized stems for certain bullet profiles. This helps reduce some of the inconsistency often incurred where the bullet contacts the stem.

GS

 

[noylj]

COL: Cartridge Overall Length
There is enough variation in a box of bullets to get that little bit of variation. You buy a box of bullets and, not only do you have variance from bullet to bullet due to variations in jacket/lead/pressure/etc. but you will also have bullets being mixed from several swage dies. For plated bullets, you have plating inconsistencies along with swaging inconsistencies. Thus, you will find length, ogive, and meplat variations.
Then, you have your own press variations and the speed that you moved the ram. This is followed by a seating stem that doesn't exactly fit the bullet, presses mostly on the meplat, and may not be pushing the bullet exactly straight.
One needs to be very concerned about bullet set-back--generally about 0.100" or more, so you should applying thumb/finger pressure to each bullet to see if you can easily push the bullet deeper--which is a FAIL. Didn't your loading manuals give you some idea about COL variation? Do loading manuals even talk about COL anymore?
Every reloader should look at 0.2gn of powder and 0.005" of space to see the insignificance of each. They can have an effect (for very small case or very small charge weights), but it won't be a dangerous one--not even a +P effect.
For comfort, try measuring the COL of factory rounds.
Factory rifle rounds easily have weight variations of +/- 0.5gn, and often more.

 

[dagger dog]

Are you shooting cast, jacketed, or plated ?

If shooting cast or swaged , you need to make sure the seating die doesn't get clogged with lube, that will cause the COL to get shorter with every batch. The lube is shaved off the bullet and accumulates in the nose area that pushes the bullet deeper in the case.

With your breech lock it's simple to remove the die and clean the lube off the seating stem.