Bullet seating depth/COL giving me fits!

Hillbilly77 · Jan 5, 2015

I have a problem that I could use some help with.

When I am working up a load, when seating the first bullet, I adjust the seating die a bit at a time until I get the right depth/COL.
Then, the very next bullet seats a few 1/1000'ths too deep.

This has happened to me with different calibers, both rifle and pistol loads.

Right now, I am working up some .44 Magnum loads.
As per my loading manual, I set the COL to 1.60". The second bullet I seated went to 1.5970. This has happened multiple times.

I find myself backing the adjustment out on the die and slowly working to the correct seating depth on each round, which seems like a waste of time.

My question is, am I doing something wrong, or does this "just happen"? Is .003" enough to worry about, or am I being too finicky?

Measuring the difference:

Close-up of the cannelures.
The deeper one on the right:

SMSgt · Jan 5, 2015

Don't sweat it. You are wasting your time trying to get perfectly identical COLs. Measure a box of factory ammo and it will vary also. Bullets and cases are not all perfectly uniform. The only ones who might need to be concerned are ultra match shooters or snipers.

fredj338 · Jan 5, 2015

You realize 0.003" is less than a sheet of paper in thickness. It means nothing. The bullet nose profile probably varies that much. If your variation gets to 0.010", then start looking for something wrong in your gear or technique.

scooter123 · Jan 5, 2015

You are being WAY too picky, With the case volume of the 44 Magnum you could probably have +/- 1/16 inch of variation without causing any excessive spikes in pressure, especially if you are loading below the maximum charge.

RussellD · Jan 5, 2015

Question_even if you are using carbide dies, are you using case lube? Using case lube like Hornady One Shot will help with more consistent COAL. Try ten cases with lube and ten without and measure them.

Agree with others-if you can equal the variance in a box of factory ammo, you are doing well.

Moe Mentum · Jan 5, 2015

The brass casing might be a tad to long/short, or the bullet itself may be off, don't sweat it, your in range....

Symmetry · Jan 5, 2015

If you are using a progressive press, the upward pressure of the sizing, flaring, and crimping stations will change your seating depth a tad. Usually it will increase my COAL by as much as .005". When you are making your seating die adjustments, generally you are working on one cartridge at a time and the other stations are empty. So you get a little upward pressure on the toolhead in the press. When the other stations are assembling cartridges the seating depth will change with that toolhead play, but usually it goes in a very predictable direction. Usually it increases COAL, but depending on what machine design you are using it could decrease it. Either way, it is a fairly predictable change.

Hillbilly77 · Jan 5, 2015

I forgot to mention, I am using a single stage press and I seat and crimp in two different steps.

It sounds like I'm doing ok?

gboling · Jan 5, 2015

Several months ago I measured a box of Federal premium, 45 acp and found no deviation in oal. This was the only time I have measured factory ammo so I have no idea of consistency. But I assumed it would be quite good.

I strive for .003 and settle for no less than .005 but I do not to claim to be an expert on the matter.

arjay · Jan 5, 2015

Sounds about right.I think what you're running into is that the stem doesn't really fit the nose and hits on the ogive of the bullet and those tend to vary.Id say your rounds are good enough.

ChiefStealth · Jan 5, 2015

IME, I get a slightly different result when seating in small increments, than when seating all in one stroke. I've seen this with many different types of bullets. The seating in one stroke almost always results in a slightly shorter OAL. When I'm doing the small increments, I stop when I think it's just a tad longer than what I want. So, when I do the one stroke seating, it seats exactly where I want it. Like others wrote, a couple-few thousandths is no big deal.

kbm6893 · Jan 5, 2015

Hillbilly77 said:
I have a problem that I could use some help with.

When I am working up a load, when seating the first bullet, I adjust the seating die a bit at a time until I get the right depth/COL.
Then, the very next bullet seats a few 1/1000'ths too deep.

This has happened to me with different calibers, both rifle and pistol loads.

Right now, I am working up some .44 Magnum loads.
As per my loading manual, I set the COL to 1.60". The second bullet I seated went to 1.5970. This has happened multiple times.

I find myself backing the adjustment out on the die and slowly working to the correct seating depth on each round, which seems like a waste of time.

My question is, am I doing something wrong, or does this "just happen"? Is .003" enough to worry about, or am I being too finicky?

Measuring the difference:

Close-up of the cannelures.
The deeper one on the right:

I just went through this with 9MM, and I got the same response. Factory ammo also varies. I checked all the factory ammo I had and none of it was exact.

I set my COL to just hit the cannelure on revolver rounds and don't even measure. For the 9MM when COL is important for proper chambering, I settled on about 10% longer than minimum COL and the rounds chambered, fired, and extracted fine.

fredj338 · Jan 5, 2015

Moe Mentum said:
The brass casing might be a tad to long/short, or the bullet itself may be off, don't sweat it, your in range....

Case length would have little to do with OAL, but it would look diff at the cannelure. Really, actually look at say 0.005" on your calipers, it's nothing. In tests over the chrono, I've not seen any appreciable vel increase, all things being equal, pressure = vel, until I get to 0.150" & that is in the tiny 9mm case with a med burner like Unique. When you get to 0.030", things start getting interesting but still nothing to worry about. At 0.060", vel increase is very noticeable, so 0.050" is where I start getting concerned, as in bullet setback.

Twoboxer · Jan 6, 2015

You're having the same reaction many AWAKE AND AWARE new reloaders have. But don't worry, your results are to be expected, and are fine.

A quality single stage press might be able to hold OAL variation to +/-0.0005" . . . IF all bullets had exactly the same shape and profile. Since bullets are not identical and they are not (necessarily) pushed down from the very tip, they will be contacted by the bullet seater at slightly different points. That leads to different OALs, and it is especially true with hollow points like the ones you are using.

[For future reference, progressive presses have more ways to produce differing OALs lol.]

As someone already mentioned, case lengths could be different but that would have no effect on OAL; however, the end of case might fall at a different point vs the cannelure.

Those rounds you made look fine

Engineer1911 · Jan 6, 2015

You are doing a good job, attending to details. This is a case of "close enough" , not "all exactly the same". Carry on.

venomballistics · Jan 6, 2015

since you have some calipers .. measure a hair on your head.
That'll give you some perspective on what your dealing with.

Your right to ask when you have doubts .. but your doubts are within the thickness of a human hair.
not bad at all once you measure the runout of a box of factory loads.

Hillbilly77 · Jan 8, 2015

Thanks to everybody for your time and input.

It's nice to hear that I was worrying about not much.

I guess the perfectionist in me might have to come to terms with the limitations of the tools and components.

Thanks again.

smokindog · Jan 8, 2015

Au Contraire!!!

You OBVIOUSLY are a danger to yourself and all around. Pack up all your powder, primers, bullets, cases, and equipment. I'll PM you the address for shipping. You'll thank me some day.

Really, you will!

Hillbilly77 said:
Thanks to everybody for your time and input.
It's nice to hear that I was worrying about not much.

I guess the perfectionist in me might have to come to terms with the limitations of the tools and components.

Thanks again.

H Richard · Jan 9, 2015

The little differences will have no bearing on your shooting. Once you get to rifle loading, and are competing in Benchrest, they you may need to pay this close of attention.

chief38 · Jan 11, 2015

I have been reloading for quite some time now (around 36 years) and have a plethora of all different brands and ages of cases in the calibers I shoot. There are slight variations in the cases and brass does stretch as it gets shot more & more. I no longer separate different brands or segregate cases by how many times they have been reloaded.

In a Revolver like your .44 Mag. unless you are many thousandths off, the few thousandths that make up the variation mean nothing. In an Auto Loader where tolerances are more critical (head spaces on face of brass cartridge) there are also slight variations that won't mean a lot to most shooters. I have seen some really tight guns (Ed Browns for instance) that are VERY finicky about reloaded cartridge tolerances, but for instance in my Colt .45 acp's - they never even have a hic-cup when I reload my mixed bag of .45 acp cases.

If you can keep your variation to + or - a couple of thousandths you are doing fine!

Bullet seating depth/COL giving me fits!

Member

Member

Member

Member

Member

Member

Member

Member

Member

US Veteran

Member

Member

Member

US Veteran

Member

Member

Member

US Veteran

Similar threads