Acceptable OAL Variance

[chb119]

I am getting inconsistent bullet depths. I am trying to load to a max of 1.120, but keep getting between 1.115 and 1.125 so +/- .005, is that acceptable or is something going wrong? Thanks in advance.

[TreblePlink]

When loading Precision moly (coated) round nose 185s in .40, I try for 1.185 and see about plus or minus 0.002 typically - on a 550. The bullet seater fit can affect this, or there might be lube or lead on it. Or something could be a bit loose and is moving. The variation you're seeing should not cause a problem as long as the mean length isn't close to the max or min length acceptable to your gun.

I am getting inconsistent bullet depths. I am trying to load to a max of 1.120, but keep getting between 1.115 and 1.125 so +/- .005, is that acceptable or is something going wrong? Thanks in advance.

[two shoes]

I am getting inconsistent bullet depths. I am trying to load to a max of 1.120, but keep getting between 1.115 and 1.125 so +/- .005, is that acceptable or is something going wrong? Thanks in advance.

FWIW, I was having similar issues with my Hornady LnL Progressive. Turned out my shell plate was loosening up. Once tightened (and a drop of blue loc-tite) all has been well since.

[drysideshooter]

Also remember that it's the distance from the ogive of the bullet to the base that really matters.

I do quite a bit of precision rifle reloading and measure the round length from the base of the case to the ogive of the bullet, and strive to keep that measurement the same on loaded rounds. You will no doubt have some variance in bullets, but your accuracy will be less effected by OAL variances than by ogive to base variances. Of course you need to stay within the limits for your gun.

If you want to see how your rounds are varying from ogive to base you can get an attachment for your caliper that will let you measure from the bullet ogive.

Take your seating die apart and clean it really well and make sure nothing is sticking too.

[SlowShooter]

Maybe mine has a problem, or this is normal?

I am loading on a Hornady LnL (the style that has the EZ-eject).

When press is empty (just starting-up) I get approx 10/1000" shorter than when all stations are full (progressive loading).

After I get running in full-progressive (all stations full) it settles-out, and the most variation I see is +/- 3/1000".

I am loading 9mm 147 grain Moly with a separate bullet-seater die followed by a Lee FCD which does the crimp.

I have experimented with running the seater/crimp die only (no Lee FCD) but didn't get any significant difference in OAL variations, and still had the large variation from single-loading vs full progressive.

(all measurements in inches, eg. 5/1000" means "five thousandths of an inch")

Edited January 25, 2012 by SlowShooter

[GregJ]

SlowShooter, From everything I've read, it is farily normal, mine does this as well. Seems like when the other stations have a working load due to a case in that station, it reduces the flex in the ram base plate. this is why I set my seating die for the desired OAL when the stations are full. The first and last rounds will be a little short, but not enough to make any difference.

OP, I also have variations in the OAL on my LNL press. For example, loading 45ACP SWC using the flat stem. Logically, since variations in bullet nose profile should not be an issue using the flat stem, there should be no reason for OAL variations. However, there is enough flex in the ram that depending on how hard you bump the handle at the bottom of the stroke (ram is raised) will affect the OAL.

I've read that single stages can vary by .003" and progressives by .009 or more. I know for a fact I can change the OAL on .223 rounds as much as 10 thou depending on how hard I bump the handle.

Try this, raise the ram up, then with the handle down and watching the top of the primer tube, see how much it moves as you bump the handle. You'll probably be surprised by the amount of movement. I know I was.

EDIT: Another tip for consistent OALs, tighten the seating die bushing in the press. Take a pair of pliers or a wrench, and make sure it is very tight in the press. If it's just hand tight, there will be enough give to cause fluxuations in the OAL.

Edited January 25, 2012 by GregJ

[drysideshooter]

Some of the variances you are seeing could be variances in the bullet's. Depending on the seating die that you are using the ogive to base measurement may be more consistent.

[noexcuses]

I am also getting around 10thou variance with my LNL AP, my shell plate and dies are tight. I will have to get the adaptor for measuring the ogive, I have one but I just need the correct size as my kit only goes up to .338.

[Scoobb]

on my LNL I'm honestly getting +/-.001 meaning 1.122-1.124

I do notice though when its not full I get one round that comes out a little shorter.

[Joe139]

My 550 with a Unique Tek clamped tool head and a Redding micrometer seating die loading 38 super comps I get + - .002 on 90% of 100 shells and + - .003 on the other 10% and I am happy with that. With the factory dillon head and seating die I got + - .006 and sometimes a little more.So these upgrades on my press helped and I feel were worth the extra money.Just my 2 cents I didn't think + - .006 was acceptable

Edited January 31, 2012 by Joe139

[JD45]

I think a huge factor is mixed brass, if you mix it. When loading about 5 mixed brands in .45 I expect .010" variation. But if I measure all of the Win., then Fed. together, they will all measure nearly the same. I believe it has to do with neck tension between brands.