Aol of a 9mm load

[Eusebio Lyle]

What happens when on a load that calls for a oal of 1130 you go to 1100?Or the other way around you make them 1160?

 

[Mainer]

Changing the length of the cartridge can affect the feeding and pressure. If the cartridge is too long it may not cycle through your gun. If the projectile is set too far into the case it can raise pressure. I am not sure either of these will happen in your situation, but that is the general principle.

 

[Gustav7]

What happens when on a load that calls for a oal of 1130 you go to 1100?Or the other way around you make them 1160?

1.) Please use decimal points
2.) To understand what a given load may or may not do, please list more information. An OAL change could do nothing, or it could do something, hard to say without your load/gun info.
3.) For regular 9mm loads, generally the concern is going to be feeding issues if it's too long. The bullet should never be seated deep enough to where the case mouth is not touching the side of the bullet.

 

[perttime]

Feeding.
The shape of the bullet matters too. A bullet that is the same weight but different shape might need to be seated to different length, for feeding.

Seating depth can also affect pressures.

 

[Molon]

What happens when on a load that calls for a oal of 1130 you go to 1100?Or the other way around you make them 1160?

There's a lot of interactive variables involved. Such as exactly what style of bullet and bullet weight is being used:

full metal jacket?
full metal jacket with concave base?
hollow point?
tuncated cone/flat point?


What specific powder are you using? Where is the powder charge that you are using positioned between the minimum and maximum loads?

How much does your COAL length vary from the reloading manual's stated COAL? How far is the ogive of the seated bullet from the lands?

To give just one specific example. The Hornady manual states that the COAL for the 115 grain HAP was 1.075". I load that bullet to a COAL of 1.100" with a medium burning powder with a mid-range powder charge and get no ill effects and excellent accuracy. The 10-group pictured below was fired from a distance of 25 yards. The group has an extreme spread of 0.62".

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