Thoughts on seating depth

wdchuckhuntr

wdchuckhuntr

New member
I've been doing some load development for a long range varmint rifle in 6.5x55 for the past month or so. So far I've put 200- 142gr Seirra matchkings down the barrel as well as 100- 140gr Hornady A-maxs. My results with both bullets have been less accurate than my initial hopes/expectations. Within the past week I picked up a couple hundred Berger VLD target 140gr'ers and have been searching the web getting a feel for what has worked well for other VLD shooters. In my internet travels I came across this article,

http://accurateshooter.wordpress.com/2009/03/14/berger-tips-for-loading-vld-bullets/

I've always followed a loading routine which includes a seating depth of .020" jam to .020" jump depending on my intended use. This would include the Sierra and Hornady's I had loaded in the .01"-.02" jump range of which neither shot that well. So now I read this article which suggests a jump of .130"! Blasphemy I say! No one in the reloading community has suggested this much jump with a match grade barrel (that I'm aware of) and I'm starting to think Eric Stecker has fallen of his rocker. But then I realize what I've been doing isn't working with this 6.5 so why not give his recommendation a try. So I load up some of the new VLDs with 48grs Reloader 22 @ .01 jump, shorter @ .05 jump, even shorter @ .09 jump and a starting to wonder if the bullets going to bottom out in the case .130 jump. So off to the range I go to test this new found theory that seating depth may not be the low man on the accuracy totem pole. The end result 5 shot groups:

.01" jump .629"
.05" jump 1.09"
.09" jump .404"
.130" jump .230"

It would appear, with the VLD's at least, that my rifle likes alot more jump than I expected. Now I'm starting to wonder if I had applied this method of looking for a seating depth first with the Sierra's and the Hornady's would I have seen better results? How many powder and bullet combinations have I discarded in other rifles as "bad" when it may have not liked the seating depth? With the ability to match bullets to barrel twists, a large amount of available data for caliber/powder combinations and the availability of quality components maybe one of the bigger variables these days is seating depth. Maybe not.

Just thinking out loud.
 
Don't know what twist you have in your rifle. My 6.5x06 has a 1-9 and aI asked Hornady about stabilizing the 140gr A-Max, they said no. I talked to Sierra about the 140gr SMK and they said it would but not the 142gr SMK. Go figure! The 140gr match king's shoot very very well. Haven't tried the others. The Shilen site, I have a Shilen barrel, say's you need a 1-8 twist to stabilize 140gr bullet's. I think Sierra makes a 123gr MK. I just looked. They make a 120gr and a 123gr MK. You might try them.
 
I am pretty much a rookie reloader and after admitting that,here is something I think is worth sharing FWIW? according to my Lee factory crimp die literature (I hear people scoffing allready),"..handloaders had to obtain uniform start pressure by seating the bullet so that it would touch or nearly touch the rifleing."I reduced the expander portion of my resizing die by .001" (greater tension)and I also use a very light crimp with the Lee factory Crimp Die, and have had pretty good results with my .223 and .243 the .243 likes .070" jump with a 58g VMax.
 
now take that 1/8" jump and experiment with charge grs or even powder / primer..and ask for for forgiveness...
 
I've been loading for a number of years for various calibers but have never looked at seating depth as a first stage to load development. It always been 1.bullet 2.powder 3.primers(std vs. mag) 4.seating depth and I have plenty of rifles that shoot very good (.5moa-.75moa) using that order of importance with very little effort on my part.

I built this 6.5x55 with the intent of it being a .25moa-.5moa rifle and up to this point it has only been a high .5moa reliably. Unfortunately as my initial test results with Bergers recommendations suggest I may have been missing the boat when it comes to my reloading methodoligy.
 
I usually start working up loads for a rifle in the same order that you do...

I initially set my seating depth to fit the magazine on the rifle and only if I can't get a really nice group out from one of my test loads, will I start adjusting the seating depth within the published load ranges...

To save running back and forth from the house to the range, I've put together a portable loading press that allows me to take it to the range and play with the seating depth there...

It is usually on of those 'all day' projects, since I use the carrying box for a wind break to trickle charge the cases... Our shooting club has a nice club house that I can take it inside if needed, but I'd rather do it right there, at the bench..

I only load .204 and .223 rounds and will run a series of test loads in .2gr increments and if I get a group that shows promise, I'll make up some more, using .1gr on either side of it to check them...

It is then that I start playing with the seating depth to get the best that I can... If nothing pops up, then I'll start over again...(Different powder, primer, etc.)
 
My initial findings with the VLD's suggest that my Swede likes quite a bit of jump. So I'm just thinking to myself that starting out with the MK's and A-Max's near the lands may have been 300 "wasted" rounds. Maybe Berger has a viable suggestion in finding the rough seating depth before starting to much load development then tweaking from there.
 
I struggled to get a good round made in my Browning A-Bolt in a 300 WSM. I tried 6 different bullets, then 6 different powders. I was discourged all the time. Rifle range is 1 hour drive and I can only go on the weekends. So it was a long time in developing. I read in the bullet books about the COAL and did all that was printed. Powder lite powder heavy all the stuff written. Finally I goofed some bullets in making and jammed them in the rifling. Too long, hard time closing the bolt. Mind you I'm not new to reloading, 40 + years of this. Finally I realized the length of bullet was making a difference. I played with that and the fog lifted suddenly the jump did make a difference. Boy I felt dumb. Now I test all reloading COAL in the bullets and twik them all.
 


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