6mm Seating Depth Sensitivity/Nodes.

[Curious]

Guys,

What are your experiences on seating depth sensitivity?

Once you have found your optimum seating depth for the bullet you are using how tolerant are they either side of optimum?

My 6BRA is shooting 105 JLKs very well with a 0.005" jam but 0.002" either side the groups open up. At 0.005" jam Im getting 3 shot groups consistently in the 0.1s at 100yds, either side they quickly go into the 0.2s & 0.3s. This has happened with two different powders in favourable conditions recently.

Are your favourite 6mm bullets any more or less forgiving than these?

 

[JFrank]

Guys,

What are your experiences on seating depth sensitivity?

Once you have found your optimum seating depth for the bullet you are using how tolerant are they either side of optimum?

My 6BRA is shooting 105 JLKs very well with a 0.005" jam but 0.002" either side the groups open up. At 0.005" jam Im getting 3 shot groups consistently in the 0.1s at 100yds, either side they quickly go into the 0.2s & 0.3s. This has happened with two different powders in favourable conditions recently.

Are your favourite 6mm bullets any more or less forgiving than these?

Seems as though a couple thousand on each side is about my max window as well.
I will say that I've recently started working with the Berger 108 target, (I have zero scientific proof so please don't flame me) however during load development using a .005 increment one group will be totally vertical the next 5-10 o'clock then totally flat followed by slight erratic. After seeing this example I went back through some targets from a 107 SMK and found that the window was also small just not as difinitive as the Berger.
SPJ

 

[HTSmith]

The 105 Berger VLD-H's I've been shooting out of my 6BR are the same deal. It is surprising how much difference 2 or 3 thousandths can make.

 

[Link]

Are you guys shooting at a jam? If so maybe a jump would give more window? Just asking.

 

[JFrank]

Are you guys shooting at a jam? If so maybe a jump would give more window? Just asking.

I can only speak for myself starting from a solid lands CBTO Datum (and yes I said Datum)
I work out in .005 increments noting about the same window with each setting.
I'm just a country boy not smart like them city fellas " however it may have to do with the 6 mm Bullets running at high volocities ,
My 308 seems more forgiving.

SPJ

 

[Curious]

Are you guys shooting at a jam? If so maybe a jump would give more window? Just asking.

In my case with these JLKs a .005" jam shot the smallest, .002" either side and they started opening up in a predictable way.

During my test I covered from .020" jump to .020" jam in .005" increments and again groups either grew or shrank in a predictable way until I was happy I had found the optimum, this included repeating different seating depth to check they were not false readings on the target - as I said in my OP conditions were very good on my test day so I felt my data was trustworthy, the rifle is a LR BR gun shot from a good rest and bags with a scope I trust.

Ive ran VLD bullets like Berger at much bigger jumps in the past with great accuracy but in this case I had only enough rounds to cover the range I did, I seem to be influenced recently to initially look in this .020" jam to jump range based on lots Ive read here.

Maybe doing a much coarser test like Berger recommend might find me a place jumping that then has a bigger leeway either side. Like so many things I could test this barrel to death so rather than do that Im trying to gauge other peoples experiences.

Thanks so far to the guys who have shared theirs.

 

[Curious]

Surely there must be more guys on this forum with experience of this question?

 

[eric n]

I see the same thing. Load to the long side of it and shoot away.
You are shooting in the 1’s, why change it?

 

[Curious]

I see the same thing. Load to the long side of it and shoot away.
You are shooting in the 1’s, why change it?

Thanks for your thoughts Eric.

I dont need to change it, I just want to know if other people are finding the same with other 103-110 class bullets or if there are others out there more forgiving?

 

[dfry]

Well I can say for years I chased the lands, usually staying at .020ish off. With my current 6BRX I started at .015 off with the barrel new and found my node. I kept my loads in That node and did not chase the lands. Right now a 107 SMK does not touch the lands with the bullet falling out of the case. I am actually at about .085-.090 from the lands and the rifle is still just hammering. I have stayed at my original seating depth.

So for now,I’m sold on the node and have forgotten about chasing the lands, but I am just a sling shooter so YMMV,

Dave

 

[JFrank]

^^^Interesting that you could stay in tune so well, do you feel as in some way this is related to the tolerance of Sierras or the rifle?
Curious

 

[dfry]

Well, I have the same results with Hybrids and Berger 108's so far. I know several people doing the same thing with the same results, but, of course every rifle is different and this may not work. I will say the the 107 is very forgiving, and since they are a little cheaper and shoot great, I have just been shooting them most of the time for the last year.

I can say i am doing the same thing now with my palma rifle and 155.5s and having the same results. Time will tell in The long run if this works with that rifle also.

 

[Keefe300]

My experience with 105 Berger Hybrid bullets has been favorable. I started shooting them 0.010 jammed and 1000 rounds later I am now shooting 0.028 jump. The gun is shooting as good now as it ever did. Last 5 shot 300 yard group shot in a match was 0.642.

 

[Willow]

I'm more inclined to choose a bullet that is less fussy on seating depth which is why I like the Berger 108gr BT and the Lapua Scenar L 105gr. They don't seem fussy on seating depth, not based on my experience. I find the VLDs easy to get working provided I jam them. Might try jumping VLDs in the future, but I've got the Lapua's running fine so I don't see a need to change what's currently working.

 

[Nature Boy]

I'm more inclined to choose a bullet that is less fussy on seating depth which is why I like the Berger 108gr BT

That's what I found too