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Topic: Seating depths... (Read 163 times) previous topic - next topic

Seating depths...

Where do you start? And what increments do you follow?
Rick

Re: Seating depths...

Reply #1
I believe bullet ogive to the lands must be determined before anything.
Then if a magazine is used the magazine may determine how close you can get to the lands.  Often a loaded round at full magazine length does not reach the lands and testing may begin there and move away in preset increments.
The Berger method of finding "optimal" distance to the lands is a good place to start.  It can work no matter where you are starting.  An internet search will find you that method and it will work with all bullets.   However I have found their starting increments may be too large and a person might miss a seating node by passing right by.
Narrowing down after finding nodes can be done in as small of increments as you have time for.
Others will chime in here with more experience.
11X Grandfather
Part time Savagesmith

Re: Seating depths...

Reply #2
Randy pretty much nailed it. If I were looking for a seating depth on a rifle without magazine length restrictions. I would start at .010" off shooting 3 shot groups seating .003" deeper until it rolled into something.

There is more accuracy to be found in seating depth than charge weight. It pays to put in the work here!

Dave

Re: Seating depths...

Reply #3
Dave....I saw where you posted that picture before...I was impressed and hence the reason behind my question!
Rick

Re: Seating depths...

Reply #4
Dave....I saw where you posted that picture before...I was impressed and hence the reason behind my question!

I post it frequently because it clearly shows the seating node come in settle and go back out. The other thing it clearly shows is if a person is taking big jumps you can miss these nodes completely.  Then lastly it shows how a .5 MOA load can be brought into the .2s with a little tuning.

 
Dave

Re: Seating depths...

Reply #5
agree with randy about finding the lands first thing... gives you a base line.... and also with dave about moving it in .003 increments... i go about things a little different than alot of guys about this.... alot of times i will seat my bullets to where the boat tail and bearing surface junction is just above the neck and shoulder junction... not really caring what the jump to the lands are as long as its not just touching the lands... i want to take advantage of all the neck and bearing surface contact their is...   then i test powder and get it tuned with powder the best i can.... i find in doing this this way  sometimes i dont have to move my seating depth at all... even though i will test seating in .003  increments on both sides of what i started with out to .009 from my starting point.. so 3 sets on both sides... one side or the other it will get better unless you got the powder and jump combination right on with your powder tuning... but seating still needs tested to verify that...thats how i go about it any way... im no expert at this by no means and dont claim to be... i just know what works for me and my needs....i also believe you can get a powder charge close to the node and fix it with alot of seating depth testing... meaning you may have to go 40 , 60 maybe even 100 thousandths to get it lined out and i think that is what bergers seating depth testing is designed for... start at .015 off the lands and test it then . 030 off then .045 off then .060 off and one of them will be better than the rest then you can fine tune around which ever was the better one...
Grant

Re: Seating depths...

Reply #6
I usually start at .020" off the lands. Never usually go closer for my match rifles as I want reliability and don't want anything jammed near lands. I will usually move back away from lands .005-.010" if needed to adjust.

Depending on the bullets you can get great accuracy farther off too. I have factory loads that are jumping .090" and shoot great.

As mentioned mag length may play into it also so you might have to seat farther off the lands to fit in some mags.

Re: Seating depths...

Reply #7
Seating depth is where you find it. This is why I generally start a little closer to the lands coming off .003" at a time until I find what I'm looking for.
It can be at .005 off or over .100 off and it can be a workout finding it in .003s but very rarely have I not found something that pretty good by the time i got to .030 off so thats 10 sets of 3 or 30 rounds to find it and know where it comes in settles, centers and goes out.
I find it easier for me to just test it out early on and know where it is because it makes powder tuning more productive.
Dave