Bullet seating inconsistency

[ZLBubba]

I'm doing load development for my 308 right now. I'm using a Forster Co-Ax with Redding Competition Dies.

I'm having a helluva time getting the seating right on my loads. It seems like I have to adjust my micrometer for every single round. If I take five different rounds and seat five bullets in succession, I'll get anywhere from 2.804-2.813. That seems pretty bad to me. So what I've been doing is seating each bullet to 2.808-.810 and then backing the micrometer off a bit in preparation for the next round. The initial seating usually puts me around 2.815, then I gently adjust it down to the 2.808-.810 range that I'm working for. Shouldn't I be able to set my micrometer and just seat bullets at the same length like I do with pistol ammo? What am I doing wrong? Thanks for the help.

 

[jayd4wg]

Re: Bullet seating inconsistency

what bullets? have you used a comparator to ensure the correct ogive (or more correctly CONSISTENT ogive?)

if your seating die "grabs" the bullet at a point of known diameter (as most i've seen do) and this point of known diameter is at different places on different bullets, you could see significant changes in seating depth.

I have a similar problem with my loads but i'm using SP bullets and the problem is mostly in the lead nose being inconsistent. measuring to the cannelure is now consistent, but the OAL is not.

 

[Rookie]

Re: Bullet seating inconsistency

You didnt mention what type of bullets you are seating. However, bullets like SMKs, while very consistent on weight, have different meplate lengths. Your seater pushes on the ogive, not tip. So, the distance from ogive to lands in the barrel should be consistant even though COAL varies. I get about 15 thousants difference in COAL out of a batch of 50. Nothing to worry about.

 

[sniperdude]

Re: Bullet seating inconsistency

like everyone else said about the type of bullet and ogive. the press and die setup you have is a pretty good one , but check to see if the seating die is loose also. but I betcha its the bullets, get a good comparator if you dont have one

 

[ZLBubba]

Re: Bullet seating inconsistency

Just an update: I am using 175gr SMKs.

So the bullets themselves are what create the difference from OAL to OAL? If that's the case, then what strategies do people use to get uniformity? Backing the die off for each round seems to be the only way to get uniformity, it would seem.

 

[deadly0311]

Re: Bullet seating inconsistency

ZL, you are measuring the base of the brass to the tip of the bullet correct? You die is seating the bullet off of the OGIVE, the tips on the 175 SMK vary from one bullet to the next, but i would almost bet that if you got a bullet comparator you would see that all of your seating depths are the same from the Ogive. The tips from one SMK to the next arent uniform, thats why you are seeing the difference.

 

[desertHK]

Re: Bullet seating inconsistency

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ZLBubba</div><div class="ubbcode-body">Just an update: I am using 175gr SMKs.

<span style="text-decoration: underline"><span style="font-weight: bold">So the bullets themselves are what create the difference from OAL to OAL?</span></span> If that's the case, then what strategies do people use to get uniformity? Backing the die off for each round seems to be the only way to get uniformity, it would seem.

</div></div>

Absolutely. The SMKs are notorious for that. To make it more consistent it's best to measure the length using a bullet comparator (measure from the ogive), like mentioned above.

 

[ZLBubba]

Re: Bullet seating inconsistency

Ahh, I'm starting to understand now. This makes way more sense to me.

So which loads will fly more consistently: rounds loaded to OAL or to the ogive? Which part do you focus on for the best accuracy?

 

[doc76251]

Re: Bullet seating inconsistency

Ogive seated bullets will remove another variable from your reloading. The only time I use OAL is for rattle battle ammo, ammo for multiple guns and stuff that has to fit in a magazine that won't let me get to the lands. All else is measured to a specific ogive length and generally that is off the lands simply because I can't afford to have a chamber full of powder and a bullet stuck in the tube if someone calls "Cease Fire".

Cheers,

Doc

 

[dan46n2]

Re: Bullet seating inconsistency

You won't be able to seat the bullets to the exact same distance every time measuring form OAL or ogive. What I do is seat far enough to know most will be short enough to fit the mag. I measure each one and those that are a little longer go back and get seated again.