Seating depth tolerances

[ArcticFun]

Edit: Its late and the Nyquil hasn't kicked in yet, I apologize for my grammar and spelling.

So I just got done with my first batch of reloads, around 70-80 rounds total for the .308 Winchester. I'm using once fired brass from FGMM with an RCBS Rockchucker press and RCBS FL dies (neck sizing for the next reloads). I'm also using an RCBS seater die. The question I have is this: What is an acceptable tolerance for bullet seating depth? My COAL (cartridge overall length just so all the damn acornmyns are right) varies by +/- .005". As in when trying to achieve a 2.800" COAL I have anywhere between 2.795" and 2.805". This is measured with a digital calipher.

As a side note that is most likely very important, I have not been culling or altering any of the bullets I have been using in my reloads. The bullets in question are the 168gr SMK and 175gr VLD. I have noticed that with both the VLDs and the SMKs that the tips of the bullets are almost NEVER paralel to the base of the bullet. Is this a design intention or should I use a small flat file and try to get it to as paralel as possible?

Last but not least all my reloading is done with the intent to make my reloads as precise as humanly possible. I realize this takes grade A compenants and experience that can't be gleamed from the Internet. I will be getting competetion dies as soon as funds allow and doing my best to make sure my reloads are as good as possible.

 

[xringdb]

Re: Seating depth tolerances

The important OAL measurement is to the ogive, not COAL. The Hornady Lock-N-Load Bullet comparator tool will give you an accurate measurement of this. You can buy the comparator body with a .308 insert for $15.

Measuring to the bullet tip will be frustrating regardless of the seater used.

I would not file to try to uniform the tips. If you get your seating depth adjusted to the proper jump/jam to the length to lands in your throat, your consistency and subsequent accuracy should increase.

Hope this helps.

 

[Fuzzball]

Re: Seating depth tolerances

The "precision" needed for OAL accuracy is significantly less than many conclude from reading or seeing tools for it in catalogs. Few non-BR rifles shoot best seated at or into the lands, most seem to do better from 20 thou or much more off, sometimes out to 80 thou.

Next thing is that the "best" seating depth is a window, or range, it's NOT a specific point plus/minus nothing. Anything inside that range the rifle doesn't care. Every factory rifle I've tested have windows from 10 to 15 thou wide. No bullet meplat or length will change that much, none I've seen anyway. So, if we find the best OAL range and seat in the middle of it, small variations in the bullets won't matter nor will how we measure it matter.

 

[ArcticFun]

Re: Seating depth tolerances

I'll have to pick up one of those comparator tools then and see how things turn out. Thanks guys.