Why do OAL Sources differ?

[Rustynuts]

Seems like every source I read gives a different OAL? Some just state the max for 45 ACP of 1.275, while others give 1.20 for the same components and powder charge. Is OAL somewhat flexible between the extremes?

For example, the Hodgden site gives 1.20 as the COL for 45 230 FNJ FP, 4.3 to 5.3 gns Win 231, while Midway has 1.275" for ALL 45 230 rounds. Lyman only has 230 TMJ also at 1.275". Lee has min OAL listed as 1.19", 4.8 to 5.1 gns (tight range!). Loadbooks also has 1.275" with 4.9 to 5.7 gns.

What gives? Very confusing for a newbie.

 

[Jim Watson]

1.275" is the SAAMI maximum OAL for .45 ACP.

You can load a hardball type roundnose that long and get it in the magazine and chamber, as did Lyman and apparently the source for Loadbooks.

The reason you see other numbers is that the components are NOT the same.

Hodgdon for some reason uses the Hornady truncated cone bullet which seats a good deal deeper than a standard roundnose.
Lee does not actually test ammo, they get their data from the powder companies who use whatever bullet is convenient, like Hodgdon above.

Midway, on the other hand, tested in a single shot fixture and could load all shapes to the maximum because they did not have to deal with magazine length or automatic feeding.

That is what the fine print about "starting loads" and "working up" is about, and the application of judgement on such stuff is the start of the road from recipe hunting reloader to Handloader.

 

[Rustynuts]

Guess I'm not getting why bullets should seat differently in the case (at least of same types, lead vs lead and copper vs copper). I can see why OAL could differ due to bullet length, but why would seating depth into the brass change on like diameters, like jackets, same weight?

How do you then come up with a recipe for specific components when no one has data for it? I thought you were supposed to use powder co. data a gospel, but when they don't supply it for your bullet? Does each bullet maker publish data too?

 

[Canuck-IL]

Some makers have data available. Basically you use common sense and match similar components in the load books with the rounds you're trying to load ... and, start low, test and work-up. Even with something as apparently simple as 230gr RN 45ACP, there are different ogives among the various makers. Rainier's 45cal 230 TMJ is very 'pointy' as compared to a traditional ball bullet. With that extra nose length, it can't seat as deeply as a blunter, shorter round, yet both are sold as 230 RN.

No substitute for experience and commonsense ... the load books are a place to start for safe loads using those exact components.
/Bryan

 

[Rustynuts]

Seems like the extra nose length would make it seat DEEPER in the brass to stay under max OAL? Unless the nose eats up mass and then the overall bullet length is less?

I've got a RN round and a Horn XTP that are essentially the same bullet length. Weird since it seems most JHP would be shorter. If I press them in the same max OAL or 1.275, the XTP looks silly since the shoulder of the bullet is way higher than the edge of the brass.

 

[Bullet]

Part of what your seeing could be that the different companies that give reloading data do their own testing and can be or is different from the other companies. They usually list the OAL they used in their testing. As long as their within SAAMI specs they’re ok, but different. Most of the bullet velocities listed won’t be the same as you get either because some use test barrels (which can be different lengths) or different firearms from each other or yours.

 

[345 DeSoto]

What Canuck-IL said about ogive. Bullets are seated on the ogive, not by forcing them into the case by the tip if the nose...the ogive (curve) being farther down the side of the bullet. Thus, different bullet shapes determine where the seater contacts the bullet to seat it...farther up on some, farther down on others...

 

[Jim Watson]

If I press them in the same max OAL or 1.275, the XTP looks silly since the shoulder of the bullet is way higher than the edge of the brass.

It probably wouldn't chamber, either. The .45 ACP chamber has a short to no leade into the rifling and the shoulder into the bearing surface of the bullet cannot be more than about .030" above the case mouth for most.
Which is why different bullets load to different OALs for use in real guns, not single shot pressure testers.