Obsessing over 0.001" ?

[awptickes]

When reloading .40 S&W, should I be obsessing about getting 1.125" every single time?

Should I be concerned when I get a few rounds that have a COAL of 1.126 or 1.127?

Does one to two thou really make that much of a difference with a pistol?

I've worked up to a load of 4.4 gr of titegroup that works well in everything. I'm using FC brass (years 8, 9, and 10) and it functions flawlessly in both my pistol and pistol calibre carbine. No signs of overpressure, and it stays under the sound barrier every time.

 

[sgt23preston]

Sgt Preston here...

I load on Dillon 550 using Dillon Dies...

I was always able to control 99% of the process perfectly...

However I was never able to control the Overall Length much closer than + or - .002 on all my calibers...

I know the equipment didn't move or change...

So I assumed the shape of the bullet heads varied slightly...

My paper targets could never see or tell the difference anyway...

As long as I made good shots, they'd all go in the X ring..?

 

[amoebicmagician]

I agree, honestly as long as there's no NOTICEable setback, you're gtg. You're much more concerned with overpressure than having one slightly longer in OAL, all that will really do at worst is throw off your accuracy a little bit.

just as a rule of thumb +/- .004 is acceptable

not OPTIMAL mind you, but acceptable

 

[sgt23preston]

I agree, honestly as long as there's no NOTICEable setback, you're gtg. You're much more concerned with overpressure than having one slightly longer in OAL, all that will really do at worst is throw off your accuracy a little bit.

just as a rule of thumb +/- .004 is acceptable

not OPTIMAL mind you, but acceptable

I agree with you...

I always tried to hold it closer, but never seemed to matter...

 

[amoebicmagician]

yeah, I've found if I work REAL hard to try to make things perfect the best you'll end up with is +/- .001

But I gave that up when I realized I could make about five times as much ammo on a progressive press if I would accept .004

Call me crazy, but a five gallon bucket quarter full of nine mils or .45 acp ready to shoot...

gives me shivers, makes you proud.

Plus this way I can shoot as much as I want without having to worry too much about how much time it's going to take to reload back up to where I like to have my ammo numbers at.

 

[Hotrod Diesel]

Seems you've gotten an answer already, but if your calipers were less than $100, and have never been calibrated, there is no reason to obsess over .001.

 

[frdfandc]

Seems you've gotten an answer already, but if your calipers were less than $100, and have never been calibrated, there is no reason to obsess over .001.

This is the correct answer. Calipers need to be calibrated at intervals depending on amount of use.

Used to finish O-rings for Dupont ( for the Space Shuttle, rockets, etc) and had to make sure they were within a certain specification.

We used Brown & Sharpe or Starrett calipers. The "cheap" ones start at around $150 bux. The ones we used were roughly $250/each. They had to be sent out every 2 months to check calibration.

To calibrate your $25 calipers, it would cost more than the value of your calipers.

Don't worry about .001

 

[kalister1]

Don't forget the average piece of copy paper is .003 - .004"

 

[ALBY]

You will be fine. That kind of variance is normal given your gear.

Measure some factory ammo and you will be surprised how good yours look.

 

[Deep Creek Rock]

Deep Creek Rock here

Some of your variance in COL, could be primer extruding from the bottom
of the case.

They dont always seat to the same depth, and will effect your COL reading.

Next time you go to load your rounds, measure a few cases that are primed, (no powder or bullet and sized) and see if there is a variation. If there is -the COL will never be the same as all the others.

This might be hard to do, if the cases are not the same length (untrimmed).

I would not lose sleep over .001" variance

Hope This Helps​

 

[spanokopita]

So just sayin'

Have you picked up some factory match ammo and compared it to your handloads? Caliper technique (cocking the cartridge slightly in the jaws vs getting a perfectly aligned reading) can account for your measurement error. If you're measuring without a jig, using a caliper by hand, expect some variation.

Also Deep, if you've got centerfire primers sticking out enough to affect OAL, you're gonna have bigger problems than inaccurate ammunition...

 

[Deep Creek Rock]

So just sayin'

Have you picked up some factory match ammo and compared it to your handloads? Caliper technique (cocking the cartridge slightly in the jaws vs getting a perfectly aligned reading) can account for your measurement error. If you're measuring without a jig, using a caliper by hand, expect some variation.

Also Deep, if you've got centerfire primers sticking out enough to affect OAL, you're gonna have bigger problems than inaccurate ammunition...

Im well aware of slam fires - but they do protrude slightly sometimes enough to change your readings.

 

[spanokopita]

Deep Creek, your primers should never protrude. If they do, someone screwed up. You didn't swage correctly, or clean the pockets, or use the tool correctly, or something. And it's not just about slam-fires, it's about drop-safety, or loss of the casehead-primer seal during fire, or other safety issues.

I would suggest if you have primers sticking out of the casehead, disassemble that ammunition, and figure out why.

 

[awptickes]

It's not the primers sticking out, they're always slightly recessed, and within spec. They all sit flat on the scale when I'm done. I inspect each one on a scale to determine weight, and if it's over-weight for the given casing (I sort and weigh all before loading the press) it gets set aside, pulled, and reloaded one at a time.

My calipers are Mitutoyo 500 series, so it's not a lack of accuracy, although they've never been calibrated.

The rounds are actually about .001 to .002 over size each time, rarely are they under-length, which means they're still safe.

I did find a way to reduce the over-length issue down to either 0 or 0.001: Bring the press down about 1/8 of an inch, then back up seating the bullet twice. I think it may have to do with the fact that it's a progressive and is doing two other things at once.


Thanks for the help. And I did measure a box of Federal factory ammunition... I feel a lot better now, lol.

EDIT: I just measured a primer, and it's recessed 0.002 on all of my sample (about 10 rounds.)

 

[awptickes]

So, I couldn't help myself, and I measured some match ammo, and it had as much as 0.004 variance, but average variance of 0.003 across 15 rounds.

Interestingly enough, the Russian made 7.62x54r I just pulled and measured ranges from 3.009 to 3.021, and the Yugoslavian made 7.62x39 is 2.182 to 2.193. Both are regarded as accurate surplus.

 

[kalister1]

If you seat the bullet with one die and then crimp with another, that COULD increase you precision? But, +/- .002" is nothing to worry about, as you said.

 

[IndispensableDestiny]

So, I couldn't help myself, and I measured some match ammo, and it had as much as 0.004 variance, but average variance of 0.003 across 15 rounds.

Did you measure COAL to the bullet tip, or OAL using a bullet comparator?

 

[awptickes]

Did you measure COAL to the bullet tip, or OAL using a bullet comparator?

To the bullet tip, but these are flat point bullets.

 

[sgt23preston]

Sgt Preston back again...

I've measured & weighed the bullet heads many times...

In general I have found small variations in bullet weight = + or minus 1/2 a grain...

I'm convinced that the shape of the tapered nose of the bullets were also not all identical...

And that there may have been a slight variation of the angle of the taper and that variation affected the OAL...

However without using a comparator, it's impossible to measure accurately...

Being anal by nature, I always tried my best to make every round identical...

But in the end, these are man made products & tools...

Plus or minus something is simply a reality...

 

[guthook]

You're fine.

Sometimes bullets are very slightly mis-shaped.
Sometimes points are flatter or longer.
Sometimes case rims are slightly bent from extraction or have burrs.
Sometimes the calipers have a bit of carbon dust on them or OOS.
And sometimes you're just chasing your tail trying to strive for absolute perfection with imperfect components.

Don't sweat it, the target doesn't care how long you've tumbled your shiny cases or if you've even cleaned out the primer pocket this time.
Chasing flawlessness on a .40 caliber pistol round is an futile excercise in overachievement. In the short distance the round travels, .001" isn't going to make a bit of difference.

Just for curiosity's sake, what kind of bullets are you using?

.