Reload OAL Inconsistent

[DadSmith]

If using mixed brass they can very in size even when trimmed. Say you set your trimmer at a certain length. You have a Federal 9mm case you used to set the trim length. However. You have 10 different manufacturered brass 9mm cases. You trim then all to what you set your Federal 9mm case length to.

Problem is every manufacturer may have a slightly longer or shorter case head. Some may have a thicker rim and wider extractor groove. Some may be thinner rim and slightly less wider extractor groove. It can have many variations with the different manufacturers. So when you set up and trim all the different cases According to one manufacturers case they will be all over the place after Trimming some shorter some longer.

Now you without thinking about that jump to loading. You take that Federal case or some other case and set up your seating die. Already every case that is different than the federal case trim length will be off slightly. Add to that the possibility of bullets being slightly longer or shorter then you start running into problems with COAL. Been there done that and found out what was causing the problem which I stated above. It works the same way for rifles as well.
I've found almost all cases differ slightly from one manufacturer to another.

Jump to 338 Lapua Magnum. Then all the above really matters.

 

[jason867]

Using regular pistol reloading dies, i don't see how variations in case lengths could appreciably effect the OAL of completed rounds.

The bullet seating dies set length from bullet tip or ogive to the base of the case. Variations in case length should show up in how far the case mouth extends up the sides of the projectile. All else being equal and consistent, OAL should be very consistent too.

 

[Leo]

I got out of the habit of loading by OAL, and focused on ogive to base

The relationship of the ogive to the lands can have impact on accuracy in a rifle. The OAL, as long as it does not interfere with feeding, really does not show as an much of an accuracy factor, even at 1000 yards.

In a pistol, except for 100-200 yards handgun Metallic silhouette ammo, I never saw much accuracy difference in any ammo that would feed, even from my Ransom rest system.

Get a box of something good, like Federal Gold medal match ammo. Carefully measure it up. Take a few apart and weigh everything. You will find that your ammo is probably already really good.

 

[XtremeVel]

Using regular pistol reloading dies, i don't see how variations in case lengths could appreciably effect the OAL of completed rounds.

You are right. Case length is totally independent in what the OAL of a completed cartridge measures.

varying case lengths can change how a consistent the crimp is. It can also change how consistent the case volumn within is, thus changing how consistent your pressure/velocity will be.

 

[Hawkeye7br]

I don't measure cartridge oal. I load mostly bottleneck calibers and rely entirely on ogive gauges that I got from Sinclair. About $20 for one that will work on 6 calibers.
OAL depends on the bullet tip being extruded exactly the same on tens of thousands of bullets. Far better to measure ogive. Added benefit is being able to keep the same distance of ogive to lands when changing bullet profile without a lot of trial & error crap.

 

[tsm]

I don't measure cartridge oal. I load mostly bottleneck calibers and rely entirely on ogive gauges that I got from Sinclair. About $20 for one that will work on 6 calibers.
OAL depends on the bullet tip being extruded exactly the same on tens of thousands of bullets. Far better to measure ogive. Added benefit is being able to keep the same distance of ogive to lands when changing bullet profile without a lot of trial & error crap.

Question about the above. When you measure a round with an ogive that’s too long, you can obviously reseat the bullet deeper. What corrective action do you take when it measures too short after the round’s been assembled?

 

[jason867]

Question about the above. When you measure a round with an ogive that’s too long, you can obviously reseat the bullet deeper. What corrective action do you take when it measures too short after the round’s been assembled?

Use a kinetic bullet puller, or a collet bullet puller, to pull the bullet out some. Then reseat to the proper depth.

 

[jason867]

Unless the difference is within your error tolerance.

 

[tackdriver]

Lot's of good points above! This used to drive me crazy. To make it worse, I was using a cheap caliper from HF to measure. I got more peace when I got a better tool to measure with. The next jump was measuring the ogive instead of the tips as mentioned above. I use the Hornady comparators because they were easy to get. I use .338 for my 9mm, but it's still better than the tip.

Once that was under control, I could focus on the real factors. For me, inconsistency got down to: 1. primer seating (getting lazy after a few hundred primers); 2. technique - getting sloppy with the arm sometimes; 3. the plate loosening up on my L-N-L progressive press; or 4. some bullets just aren't as consistent, and this really matters where the seating die meets the bullet. Now I know when it's me, my setup, or the components, and adjust accordingly. 9mm, 45ACP etc is now generally below +/- .003 on a progressive, +/- .006 with "bad" bullets (that shoot just fine).

Side note: after thousands of rounds and OCD tinkering and measuring, I've never seen any relationship between case length and COL in my ammo, but that's just me.

 

[tsm]

Congrats on getting it all sorted out! I always prime on either my RCBS progressive or Lyman turret press and once those are set properly, the primer depth doesn’t vary.

 

[armalitesheepdog]

Lot's of good points above! This used to drive me crazy. To make it worse, I was using a cheap caliper from HF to measure. I got more peace when I got a better tool to measure with. The next jump was measuring the ogive instead of the tips as mentioned above. I use the Hornady comparators because they were easy to get. I use .338 for my 9mm, but it's still better than the tip.

Once that was under control, I could focus on the real factors. For me, inconsistency got down to: 1. primer seating (getting lazy after a few hundred primers); 2. technique - getting sloppy with the arm sometimes; 3. the plate loosening up on my L-N-L progressive press; or 4. some bullets just aren't as consistent, and this really matters where the seating die meets the bullet. Now I know when it's me, my setup, or the components, and adjust accordingly. 9mm, 45ACP etc is now generally below +/- .003 on a progressive, +/- .006 with "bad" bullets (that shoot just fine).

Side note: after thousands of rounds and OCD tinkering and measuring, I've never seen any relationship between case length and COL in my ammo, but that's just me.

Just curious what brand of caliper did you get. Where and how much? I have a Cabellas branded set that was like 25 bucks.They seem to work but for that price I think they must be marginal at best. I think that may be my next upgrade

 

[jason867]

Just curious what brand of caliper did you get. Where and how much? I have a Cabellas branded set that was like 25 bucks.They seem to work but for that price I think they must be marginal at best. I think that may be my next upgrade

Mitituyo (probably incorrect spelling) seems to be well regarded. It's what i use.

 

[tackdriver]

Just curious what brand of caliper did you get. Where and how much? I have a Cabellas branded set that was like 25 bucks.They seem to work but for that price I think they must be marginal at best. I think that may be my next upgrade

Mitutoyo is the brand. I think 500-196 is the model, but not positive. I didn't think there would be a big difference, but I was wrong. These are extremely consistent, (even after turning off/on many times), and smooth. I'm definately glad I spent the money.

 

[warren5421]

Get a flat bullet seater.

see https://www.indianagunowners.com/threads/imr-sr-4756-in-10mm-ola-moves.507406/