Trying to figure out OAL

09outlander

09outlander

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Ok, bear with me, I'm not great at putting thoughts into words.

I have 2 lots of bullets, some plated, the others are FMJ, all are 230gr.

The Campro plated bullets are listed as a round nose but are actually flat nose.

The 2 types of bullets, measure to different lengths with calipers.

The plated bullets are .583 in length and the FMJ are .666 in length, with a difference of .083

My Lyman manual say to set OAL to 1.275 for a 230gr RN FMJ, but if I seat the plated bullet to that length it's not in the case very far, so I figured I would subtract the difference in bullet length from the OAL, which is 1.275 -.083 = 1.192 OAL

This leaves the same amount of bullet seating into the case.

I'm just trying to figure out if I'm getting this right or not???

Left is 230gr plated and right is 230gr RN FMJ

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If you have a bullet comparator set (Hornady, Sinclair and others make them...), you can measure the length to the land diameter.

You could also measure the length of the bullets before you load them, and adjust your OAL so the bullet is inserted the same amount into the case.

As long as they feed okay (Check this with some dummy rounds - no primer or powder), and you've started low in the acceptable load range you should be okay.
BTW, the dummy rounds can be useful when setting up your seating die. Just back out the seating plug, insert the dummy, and adjust the seater plug to the dummy round.
 
Just use the OAL from the manual for the specific bullet, that way you won't decrease the internal capacity and raise pressures too high. Next, plunk test them in your barrel to make sure they chamber nicely. If the bullets passes the test, you're good to go!
 
Simple way to make sure they will fit and your slide will go into full battery,
Take your barrel out of firearm, drop an empty piece of sized brass into barrel, listen to the sound it makes and visually note the head of the brass and the back of the barrel. Now load a projectile into an empty primerless case. Drop into barrel. Listen for the thunk, and look at case head and barrel. If there is no thunk or brass does not sit right, you need to seat lower. You can also use sharpie on the projectile and look for rifiling marks.
 
OAL is the length that does not allow the bullet to engage the rifling (as described above) AND is short enough to fit YOUR magazine. The book is just a guide. I tend to ignore the book and start by finding what OAL clears the rifling in my pistols. Some pistols have very shallow throats and require the bullet seated quite deep. Norc and CZ come to mind.

For pistols I start long and seat deeper until I have met both critera with some extra clearance as a fudge factor. If there are feeding issues, I then try deeper seatings. Once I have the OAL set, I can then run a test in 0.3 gr increments, starting with the START load in the book, to see what groups best.
 
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