C.Oa.L.

[MyDads38]

In a perfect world, all my reloads would be the same OAL. Well, they're not :-(
I use the Lee 4 die set on my Classic Turret press. The variance is +/- .02", seldom more than .04". My target COL is also 1.125" with Xtreme 165 gr FP plated bullets. From data on Hodgdons website, my load is right in the middle of min/max. Chasing perfection can drive you CRAZY! And that would be a short trip for me LOL.

 

[Rogeronimo]

Brass TRIM length has nothing to due with COL UNLESS you are setting to a specific point in a crimp groove or cannelure.


COL is not the sane as SET Back,

I completely agree; however, this cartridge headspaces on the case mouth, and if the loader doesn't mind a few thousandths tolerance here, why blueprint the cartridge at all. Just a generic statement, and the OP satisfied my curiosity.

 

[ggibson511960]

.40 S&W Headspace & Crimp

Straight wall auto pistol cartridges aren't really crimped. The case neck is swaged down to remove any bell mouth added for seating. It is simply re-formed in the seating die to a uniform diameter and never crimped lest the case lose its headspace index point. Crimping is for rimmed cases. All my auto pistol dies have a generous allowance in the "crimp" section of the seating die to accommodate differing case lengths, unlike rimmed case dies that roll the case mouth and are critically dependent on uniform case length for uniform crimping. Post #6 opined about COL varying if mixed length brass is used. That's a puzzler. The seating stem has no idea how long the case is.

 

[Nevada Ed]

Most Auto pistol loads set headspace on the length of the case for proper
OAL, for the action to close and the case to be in the correct position for the firing pin strike, which is followed by extraction, of the case.

Pistols use a taper crimp to remove the case belling that is made to accept the bullet and allow the finished load to fit into the chamber and also add a friction fit, to hold the bullet in place. This works in most loads but..............
If no sealer is used or the load is at maximum pressures, or loaded several times w/o being fired, the chance of bullet setback is increased in new ammo.

In revolvers, shooting bullets with a cannelure, set back is not possible if crimped correctly and if the crimp is at least medium in pressure and not too light.

 

[bigggbbruce]

I load on a turret press, so each step you feel the tension of the brass.

My brass is mixed headstamp and when seating a bullet I can feel the neck tension. If it feels weak, I check the round by pushing the round into the side of the press with the heal of my hand as hard as bearable. If measurements change after doing so I pull the bullet and ditch the brass.

 

[Rule3]

I completely agree; however, this cartridge headspaces on the case mouth, and if the loader doesn't mind a few thousandths tolerance here, why blueprint the cartridge at all. Just a generic statement, and the OP satisfied my curiosity.

Yes, very generic. Most all semi autos "head space" on the mouth not just "this one. and have never trimmed one yet.
Head space has nothing to do with what I wrote. Some folks think a shorter brass length changes COL.
The OP can get different COL depending on how hard he squeezes the calipers,or a variance in the bullet.

 

[Rogeronimo]

Yes, very generic. Most all semi autos "head space" on the mouth not just "this one. and have never trimmed one yet.
Head space has nothing to do with what I wrote. Some folks think a shorter brass length changes COL.
The OP can get different COL depending on how hard he squeezes the calipers,or a variance in the bullet.

Cartridges of uniform C.O.A.L. which headspace differently will throat their respective bullets differently, subsequently varying chamber pressure. If a loader isn't anal regarding case length, a few thousandths on seating depths is approaching pointless.

 

[rockquarry]

Straight wall auto pistol cartridges aren't really crimped. The case neck is swaged down to remove any bell mouth added for seating. It is simply re-formed in the seating die to a uniform diameter and never crimped lest the case lose its headspace index point. Crimping is for rimmed cases. All my auto pistol dies have a generous allowance in the "crimp" section of the seating die to accommodate differing case lengths, unlike rimmed case dies that roll the case mouth and are critically dependent on uniform case length for uniform crimping. Post #6 opined about COL varying if mixed length brass is used. That's a puzzler. The seating stem has no idea how long the case is.

I mentioned that in post #6 only because I've seen it happen. Another good reason to use like brass.

 

[Jwjarrett]

Homemade inertia tool... I'm picturing a 12 ga shell firing a chamber gauge holding the bullet into a block wall... bullet out!

No 12 gauge...16

I'll get a real puller soon enough, but in the meantime, necessity is the mother. When I wanted to pull a bullet the other day, I used my shell holder from my trim tool, taped it to a 16 in piece of pvc tube, put a piece of cardboard in the other end and then dropped it from eye level down a 1 inch diameter pvc on ro a paper on a concrete floor. Worked like a charm and saved me a trip to the store.

Now isn't that about as redneck as it gets?

 

[Jwjarrett]

No more OAL worries

All, I understand overall length, case mouth seating, proximaty to rifling much better. I am going to order the bullet seating plug from Lee. I am convinced that is the cause of the inconsistency. I checked the fit of the round in my EDC. Someday I will measure to the start of the rifling and determine my personal OAL for the round/gun combination. Someday.

In the meantime, I am going to adjust out to around 1.130 to 1.135 and rock on.

Thanks for all the input. It makes an interesting read!

 

[Rogeronimo]

All, I understand overall length, case mouth seating, proximaty to rifling much better. I am going to order the bullet seating plug from Lee. I am convinced that is the cause of the inconsistency. I checked the fit of the round in my EDC. Someday I will measure to the start of the rifling and determine my personal OAL for the round/gun combination. Someday.

In the meantime, I am going to adjust out to around 1.130 to 1.135 and rock on.

Thanks for all the input. It makes an interesting read!

I knew early on you knew your stuff. Shoot straight.

 

[Rule3]

For the 40 SW and all others it can all be found HERE


https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf


The case, not cartridge is .850 minus .010 = trim length of .840
Hornady is even more anal and uses .845

Handgun brass does not usually "grow" so if folks are anal enough to worry about .010 then they spend to much time trimming rather than shooting.


For the OP the chart also shows the MAX and MIN length of the CARTRIDGE with a FP Nose) bullet.

 

[Jwjarrett]

I'm picking at gnats a little with this question, but does rifle ammo "grow" or distort when fired?

 

[Rule3]

I'm picking at gnats a little with this question, but does rifle ammo "grow" or distort when fired?

The brass expands and then contracts but no back to original. Which is why you resize it. Rifle brass will "grow" in length which is why it needs to be trimmed after resizing. It stretches the brass due to the shoulder and neck.
I guess some necked hangun brass will stretch also but I do not load any of those.


Not gonna even try the FN 5.7. I priced it out and all dies, gauge, and projectile will cost more then factory ammo and it is a picky little cartridge.

 

[mikerjf]

I remember reading a post by someone who had decided to see just how many times a 45acp could be reloaded. Turned out to be a lot!

And in the end, the failure mode was stretching down above the rim... in between the rim end and where the case came back out to full diameter, it became too long to work right.