How Do You Configure/adjust Oal?

[Radical Precision Designs]

Normally you take a measurement instrument: micrometer, caliper, gage, etc. and take a reading from bottom of case (rim) to tip of the bullet and determine the OAL.

The question I'd like to pose is: Do you consider the "inside" lenght of the space occupied by the powder after seating the bullet to be just as important, or more/less important than the external measurement we refer to as OAL????

For me the external dimensions of my handloads are determined by the clearance space inside my magzine, and what my barrel feeds better with. I would say is fair to assume that most shooters use similar criteria?

My latest "pet peeve" came after realizing how may variants we get in bullet lengths in the same bullet weight, often even between batches of the same manufacturer, and lately especially within the same box. This is more noticeable with "pointy" full metal jackets (FMJ) bullets. It can be annoying to set your bullet seater to a specific OAL, and later on see the various +- actual lengths you ended up in your loading session, because of the individual bullets nose shape above the "ogive" area contacted by your seating stem. When you look and gauge your ogive it seems very consistent and it seems to fall in the same place when measured from the bullet base. But not the nose, and yet that is what we use to determine OAL. The point here is that when you adjust the OAL to match your "ideal", you also change the internal position of the bullet in relation to your inside volume which can affect your consistency in pressures from cartridge to cartridge, possibly affecting your performance from shot to shot. Taking into consideration that the seating stem contacts the bullet at the same "dimensionally stable" spot this should create a similarly stable inside dimension with that brand of bullet regardless of the final OAL. It will also clear the rifling and establish a "leade" consistenly for even, consistent pressures and performance. But should you continually adjust the OAL to satisfy your "likes" you would be also adjusting your potentail performance.

This is my opinion/finding. How about yours? Does it really matters enough to care?

[Matt Cheely]

I'm not loading a "high performance" load close to the edge of sanity, so all I'm looking for is reliable feeding and length to fit in the mag.

[XRe]

The question I'd like to pose is: Do you consider the "inside" lenght of the space occupied by the powder after seating the bullet to be just as important, or more/less important than the external measurement we refer to as OAL????

I think both matter - but I'm beginning to think that in the context of racegun loads using slow powders, it doesn't seem to make a huge impact on the amount of powder I need to make a given PF. I don't have pressure testing gear, but I don't notice any differences in the primers, etc, so....

I would still be careful, of course, about working up loads with a longer bullet seated to the same OAL. And, obviously, it matters more and more the faster your powder burn rate becomes, as the tolerances for changes in initial case volume seem to matter more due to the more rapid rise in the pressure curve, etc.

For me the external dimensions of my handloads are determined by the clearance space inside my magzine, and what my barrel feeds better with. I would say is fair to assume that most shooters use similar criteria?

For me, this is true. I load to the length that feeds best in my gun, and work the load up from there.

My latest "pet peeve" came after realizing how may variants we get in bullet lengths in the same bullet weight, often even between batches of the same manufacturer, and lately especially within the same box.

I noticed the same thing in the latest box of 2K FMJs that I shot through. Different lengths, different nose shapes, different ogive shapes. It did seem to result in inconsistencies down range, but not so much that the rounds were unusable. I just could shoot as tight a group with them as I could with a HAP. With high quality options available at reasonable prices (Zero and Hornady), why shoot a lower quality bullet that exhibits these problems?? (at least, that's my thinking on it... ).

Does it really matters enough to care?

Yes and no... I don't really think it matters enough downrange to get upset about it (well, at least it doesn't in my gun with my loads). But, if you want to end up with the best possible ammo with the highest possible consistency, stick to higher quality bullets (and, note, quality is not determined by price, but instead by measurement of a good sized sample, and by empirical performance in your gun).

[dillon]

I noticed this more than twenty years ago, when a customer called complaining that our equipment was causing OAL variation. I had him send in his machine, brass and bullets for examination. I found .026" variation in the location of the diameter where the bullet seat stem contacted that diameter on the height of the bullet, out of 100 projectiles. If you modify a bullet seat stem to seat on the nose of the projectile, you can reduce this. In limited accuracy testing, it really didn't make much difference out to 25 yards. At 50 yards, it was significant.

For FMJ projectiles, try this: Fill in any lube bleed holes with clay. Select the projectile with the contact surface closest to the tip of the bullet. Coat the nose of the bullet with vaseline. Partially fill the bullet seat stem with epoxy, and insert the bullet into it. Be sure the bullet is straight up and down. Let the epoxy cure overnight. Tap the bullet to remove it. You now have a bullet seat stem specifically for that bullet profile, designed to seat off

the tip of the bullet.

You will still find that FMJ bullets in particular vary in length from nose to tip, especially bulk bullets, but this will significantly reduce OAL variation, which will still help reduce internal capacity variations.

Lead bullets, especially if out of the same mold, are more consistant, as are plated bullets such as Rainier. Hope this helps

[Radical Precision Designs]

I noticed this more than twenty years ago, when a customer called complaining that our equipment was causing OAL variation. I had him send in his machine, brass and bullets for examination. I found .026" variation in the location of the diameter where the bullet seat stem contacted that diameter on the height of the bullet, out of 100 projectiles. If you modify a bullet seat stem to seat on the nose of the projectile, you can reduce this. In limited accuracy testing, it really didn't make much difference out to 25 yards. At 50 yards, it was significant.

For FMJ projectiles, try this: Fill in any lube bleed holes with clay. Select the projectile with the contact surface closest to the tip of the bullet. Coat the nose of the bullet with vaseline. Partially fill the bullet seat stem with epoxy, and insert the bullet into it. Be sure the bullet is straight up and down. Let the epoxy cure overnight. Tap the bullet to remove it. You now have a bullet seat stem specifically for that bullet profile, designed to seat off

the tip of the bullet.

You will still find that FMJ bullets in particular vary in length from nose to tip, especially bulk bullets, but this will significantly reduce OAL variation, which will still help reduce internal capacity variations.

Lead bullets, especially if out of the same mold, are more consistant, as are plated bullets such as Rainier. Hope this helps

Thank you, Dillon.

That was very usefull info.

[tightloop]

Good stuff for pistol ammo, but I prefer my Wilson straight line dies and my arbor press for quality, low production rifle ammo...

[shred]

A somewhat less accurate, but speedier method of doing the custom seater trick is to wedge a ball of aluminum foil in the tip of the seater, then seat some bullets, which will form the foil into the needed shape.

but..

I find the Redding micrometer seating die to be amazingly consistent with good bullets and so easy to use you can make up a little table for all of your bullets and quickly and toollessly set it where you want it. I forgot how good I had it until last night when I adjusted a 'normal' seater. Bleh.

[AZ38super]

I had the same problem with one of the named brands in this post on FMJ bullets.

So much so after I used the lot I purchased I went back to my old plated ones mentioned as well out of frustration.

Now I shoot HP rounds in my open gun with the Redding comp seat die and still get a bit of variance showing up.

The truth is the variance is very minor and for fast action shooting like USPSA it really doesn't matter.

For high precision shooting at long distance then yes it can make enough of a difference.

[Jaxshooter]

I would have to believe this could be a real problem with a real hot on the edge 9mm or 38 SC major load. We are already tetering on the brink of disaster, how much pressure increase can be incured by reducing the internal volume of the case by the amount you mentioned?