Few seating depth questions

[Lonewolf74]

I've done a bit of testing with seating depth and usually I always go in .010 increments back from touching lands. However after reading the Berger seating depth test I see they use about .040 increments.

So my first question is do any of you find this to be too much and end up passing over the sweet spot?

Have you found the sweet spot to stay consistent with a particular bullet regardless of powder?

 

[mobenzowner]

I have only tried their method once with vld's. Guess what, it turned out to be where best seating depth for that rifle was .008 to .011 off the lands. Same spot it usually ends up for me on most other rifles. I know every case is different, but what I would really love to see is a poll on their VLD's and what % of folks actually find the best depth way back off the lands. I know I have seen several posting about the .040-.050 range being good, but it has never happened for me.

To answer your question, yes you may end up passing over your best sweet spot. In my mind however the test is to find your general sweet spot and then test a bit above and below that area to find the "maximum" sweet spot. The purpose is to find your general area and tweak in small increments from that area. Hope this helps.

 

[Rich Coyle]

By using the .040" system I found the accuracy node on one rifle at .120".

 

[Lonewolf74]

Yes opinions and experiences are what I'm looking for hear to see what ppl gave come up with and how they got there.

In my own experience with one rifle and load I loaded 3 rounds at .010 off .020 off .030 off and .040 off. In my test .030 seems to be the sweet spot but all shot well. I was just thinking if i followed the Berger system I may have passed up this sweet spot. On the other hand I may find a point that it's even better going further off the lands.

 

[dok7mm]

I recently was checking seating depth on a 6.5 w/140 HVLDs that was shooting well @ .015" jump. I ran the Berger test, but used .020" increments, and found it would shoot 1 hole at .050" jump @ 100 and 1/4 moa @ 400 yd.

 

[BHC]

I developed a load for a client once with a Berger 210 vld for his 300shortmag. .60 off the lands shot 3 rounds I could easily cover with a dime. In his case this was extremely advantageous as the deeper seating allowed a COAL that would actually fit inside his magazine, which was a big concern for such a heavy for caliber bullet. I love the VLDs and hunt with them every time.
Good luck.

 

[Rem6br]

Berger VLD bullets always seem to like to be jumped in every rifle i've shot them in

 

[Mikecr]

Wasn't long ago that experts insisted VLDs had to be jammed to shoot!
This, leading to many efforts in finding land relationships.
What a bunch of hogwash...

Berger's seating testing will quickly remove poor areas from the table. With this you can do more meaningful powder development. After powder, go back and tweak in finer increments to define your best seating window and shape your grouping.

As far as any land relationship in this? Most of the time it doesn't matter.
If your best load is not relying on high starting pressure provided by an in the land(ITL) condition, then it never will. The throat can erode inches down the bore and your best CBTO will still hold right where you initially found it.
There is enough advantage right there to seek OTL seating, and not even mess with ITL.

 

[Lonewolf74]

Mike always like to hear your input!

Just to clarify what you are saying. If you find a sweet spot at say .020 off lands which for that cartridge is say 2.910 base to ogive that COL will stay the sweet spot regardless of throat erosion? To put it another way 2.910 will continue to be the sweet spot even if after about 500 rounds 2.910 is closer to .040 or .050 off lands due to throat erosion?

 

[Lonewolf74]

To add to that it is the theory and reason I started at .010 off in my seating depth test. I would like to find a stable sweet spot where I don't have to chase the lands much if any to compensate for throat erosion

 

[Mikecr]

To put it another way 2.910 will continue to be the sweet spot even if after about 500 rounds 2.910 is closer to .040 or .050 off lands due to throat erosion?

That's correct.
Let's say your 'accurate barrel life' is 1500rnds. If 2.910/.020 OTL was found as best initially, you can expect this to hold as true to 1500. Beyond this, seating tweaks will shape grouping as always, and with this & powder adjustments you might extend accurate barrel life another ~200.
But of course, barrel life itself is another discussion. You may not get 1500 great shots from it, or extend life another 500 with a barrel setback..
Either way your optimum seating window should hold.

For those that 'chase the lands'?
It better be a **** good load before I would put myself there, as erosion is not linear. And it really takes off later in life.
If I were shooting an underbore, like a 6PPC or 30BR, where barrel life is completely known and I had a solid plan to reach it every time, then I wouldn't be concerned about ITL relationships. For a hunting cartridge (way more powder per bore), no way I'd bother with it.

 

[Lonewolf74]

Mike that is what I'm striving to find. I like load development but I don't want to have to tinker with it once I've found a load.

The other question I posted is how often do guy's find the seating depth sweet spot to remain constant regardless of powder used in that load?

 

[Methow Packer]

Mike that is what I'm striving to find. I like load development but I don't want to have to tinker with it once I've found a load.

The other question I posted is how often do guy's find the seating depth sweet spot to remain constant regardless of powder used in that load?

I've heard once you've found your seating depth, powder charge or powder brand/type makes no difference. I too am curious if this is true

 

[mobenzowner]

I've heard once you've found your seating depth, powder charge or powder brand/type makes no difference. I too am curious if this is true

That's what Berger tells you.