Check Your Seating Depth Carefully

[cmh2007]

I am posting this cuase I am a fairly experienced reloader and want people to learn from my experience. I shoot two loads with my .308 one uses the a-max and the other uses the scenar. I made up a batch of loads two days ago and forgot to verify the seated depth of my load prior to going on. the load is a very minimal compression but with the difference of ogive on the bullet it turned into a very compressed load (verified by measuring loaded shells). so long story short, got 15 rounds off, and none showed any signs of pressure on shot 16, there was a gross overpressure situation resulting in a complete case head separation.

I got home, knocked the shell out and checked the rest of the loads, none were over charged, but all were seated .050" too deep the load called for 2.875" OAL and mine were seated to 2.825" OAL.

So learn from this experience, and check carefully your seating of your bullets

 

[JohnSH]

Re: Check Your Seating Depth Carefully

Unless maglength is at issue, wouldn't where the ogive sits with respect to the lands be a more important bit of information to determine bullet seating depth into the brass, rather than cartridge OAL? At least that's been my experience in finding seating depth testing loads using 175 SMKs, 190 SMKs and 208 AMAXs.

 

[cmh2007]

Re: Check Your Seating Depth Carefully

well, these loads will not fit my magazine no matter how i look at it. the basic gist of it is that the bullets were seated way too deep creating pressure to start out with, which created a gross overpressure once the shell ignited. that is why they give you a minimum OAL for the particular bullet and load in the recipe

 

[bohem]

Re: Check Your Seating Depth Carefully

One way or another, the farther you stuff that bullet into the case has a profound effect on the pressure curve for a particular load.

However you track the position of the ogive to the lands is your call, but seaggie's comments are very important.

 

[hntbambi]

Re: Check Your Seating Depth Carefully

Yall need a chronograph. I have not seen where seating deeper increased pressure. In fact Berger recommends gonig from touching the lands to a .120" jump and velocity is reduced the farther the jump is. Less velocity = lower pressure. Sorry but I don't buy that .050" jump created a case head seperation. Too many loads, too many hot loads, excessively working the brass, excesive headspace, etc are reasons for case head seperation, not bullet seating depth.

 

[Munson]

Re: Check Your Seating Depth Carefully

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hntbambi</div><div class="ubbcode-body">Yall need a chronograph. I have not seen where seating deeper increased pressure. In fact Berger recommends gonig from touching the lands to a .120" jump and velocity is reduced the farther the jump is. Less velocity = lower pressure. Sorry but I don't buy that .050" jump created a case head seperation. Too many loads, too many hot loads, excessively working the brass, excesive headspace, etc are reasons for case head seperation, not bullet seating depth. </div></div>

I hope your right. I dont check alot of that stuff very deep when I am making up large batches to shoot through the auto's. I'll take it out to the 2nd decimal place and move on. If being that little amount off would create enough pressure for case seperation...well lets just say i've been real lucky

 

[cmh2007]

Re: Check Your Seating Depth Carefully

when it goes from a compressed load to seriously compressed load it has a very good chance to do it

 

[LawnMM]

Re: Check Your Seating Depth Carefully

Do you weigh each charge? Pressure should drop as you back away from the lands. Not rise. It would have to be super hot to begin with for that little difference to create a separation.

I'd check the rest of your brass. If the case head separated it didn't 'just happen' with that load, its been on the verge for the last load or few...