Maintaining the same OAL

S Mac

Sept. 10, 2021 Steve left us. You are missed.
Hello everyone. My first post, Question is when I am seating my cast bullets I am unable to have the same OAL unless I seat them long and adjust the seating stem every case. Is this a variation of the casting as far as diameter of the nose? It's not just one die, I have several different brands. I'm measuring Oal with my dial calipers.
 

Rick

Moderator
Staff member
Hi Steven, are you measuring the end of the bullet or on the ogive? Quite common for the tip of the bullet to have parting line marks. How much variation are you seeing?
 

S Mac

Sept. 10, 2021 Steve left us. You are missed.
Yes, I'm measuring at the tip. Many times .005, some times more than that. I don't think its just the parting line.
 

Brad

Benevolent Overlord and site owner
Staff member
Even with jacketed there is variation.
If you are within a reasonable amount I would just go with it. Anything under .005 is good to me.
 

yodogsandman

Well-Known Member
Just case neck cleaning with a brush will sometimes fix that. When seating a bullet, I like to do it in increments and spin the case at each increment some to help with any possible alignment problems.
 

JWFilips

Well-Known Member
I used to load a lot of Magtek .32 FMJ acp bullets for my WWI & WWII auto's This drove me nuts! Imagine a manufactured bullet doing this ( they were all over the place) then I put a goodEye & magnfier on the ogive...they were different! You could actually see it! Then I switched to cast...things got much better fast but every once in awhile bamm it happened again! Found out that it was TL build up on the seating die!
 

Winelover

North Central Arkansas
I find variation, even with cast and I always measure on the ogive. Probably the result of variation of multiple bullet mold cavities. I just quit worrying about it.
 

S Mac

Sept. 10, 2021 Steve left us. You are missed.
So, how do you measure on the ogive? Maybe my understanding of the definition of the term is lacking. Is this the widest point of the leading edge of the bullet?
 

Rick

Moderator
Staff member
Another thought Steven, are you certain that all primers are seated below flush? Slightly high primers will give the results your experiencing. I have a tool similar to the one brad posted but even with this if some of the primers are high you'll get the same results.
 

Ian

Notorious member
With spitzer and other "pointy" bullets that contact the seating stem somewhere on the "ogive", it is particularly important to insure that the noses of the bullets are round, or at least consistently elliptical in cross section. Often, through fluctuations in mould temperature or hand grip pressure on the mould handles or even tiny bits of trash getting in the blocks at some point in the casting session, roundness variances from one bullet to the next can result. Inconsistent castings will affect the uniformity of seating depth.

As the others have said, .005" variance is pretty good, I wouldn't worry about that too much.
 

yodogsandman

Well-Known Member
I had a problem with wildly different O.A.L.'s at one time. We're talking about say .050" length shifts. My cast bullet's nose would contact the die prior to the metplat reaching the seater stem's nose cup, causing the bullet to seat at that length, instead. The diameter was so close that any variation would cause one bullet to catch and the next would not, seating to the length where the nose cup was set at. On the sage advise of others, I had to buy a larger seater die (the next caliber up) and then still had to enlarge it with sandpaper on a split dowel held in a drill. This opened it up to prevent the bullets nose from making contact with the die first.
 

S Mac

Sept. 10, 2021 Steve left us. You are missed.
Now that makes sense to me, I do have a couple of different dies, maybe I need to modify one.
 

yodogsandman

Well-Known Member
If I had to do it again, I'd use a Lee seating die as a donor. Not a hard, heat treated premium set. I'd also gladly go up two calibers on the seating die first rather than honing another one out.