Seating depth nodes

[moe africa]

Hi all
I've been handloading for about a year now and I want to choose seating depths that gives me room as the thoat erodes
I test 142 gr SMK with N555 (43.3gr) at a few seating depths (6.5 creed)
I have a few of the pics and a graph to show the groups vs cbto
Im leaning toward the cbto of 2.211
All shots are unmarked (3 shot groups)

 

[G Liles]

200 yards?

 

[moe africa]

200 yards?

100m

 

[G Liles]

How deep into the lands are you seating them?

 

[moe africa]

How deep into the lands are you seating them?

0.090 from the lands is 2.202

 

[G Liles]

If you’re not seating to fit a magazine I would move in closer. I always start with a 5 thou jam and work out.

 

[moe africa]

How deep into the lands are you seating them?

0.090 from the lands is 2.202

If you’re not seating to fit a magazine I would move in closer. I always start with a 5 thou jam and work out.

Unfortunately I am stuck with 2.86" mag

 

[Jeff Porter]

Don’t be afraid to jump a bullet if it does not impact your case capacity to push it in. I have had a couple of 223 rifles that liked Berger hybrids jumped 0.130” ( not a typo). 75 Amax was tightest at .090”. Berger has a routine for jump testing to see what your rifle /load combination groups best with. Once you find that you tweak small increments either side to establish the window of jump or CBTO in your case. Load to the shorter jump ( longer CBTO) and don’t worry about chasing the lands until it doesn’t group well anymore

 

[Sandstorm]

Unfortunately I am stuck with 2.86" mag

Then I suggest you start there and go shorter by .003 and keep going till you find a happy place.
Dont go too fast and test with 3 shot groups....you will find a good spot im thinking.
Disclaimer: Once you find a powder charge that works )

 

[bks22345]

My 6.5 likes the 142 SMKs at 0.025 off. Your vertical was getting better every group so I would keep going.

 

[Beiruty]

2.211

 

[JMayo]

Some just automatically move out .002 every 800 rounds.....

I rarely have but... lately i have accepted & adapter the measurement that was longer. My scores have proven this method !

 

[big5ifty]

Your pictures are inconclusive, IMO.

Shoot at least three groups per load.

If all three groups of the same load print differently, that will tell you that you need to focus on your shooting technique or platform.

If you manage to get three very similar looking groups from the same load, your technique and platform are consistent enough to show seating depth variation on the target.

It's not possible to identify a good group before you can shoot consistently good groups.

 

[moe africa]

Your pictures are inconclusive, IMO.

Shoot at least three groups per load.

If all three groups of the same load print differently, that will tell you that you need to focus on your shooting technique or platform.

If you manage to get three very similar looking groups from the same load, your technique and platform are consistent enough to show seating depth variation on the target.

It's not possible to identify a good group before you can shoot consistently good groups.

Im not the greatest shot out there , but 3 x 3 groups are a waste of components IMO

 

[Zero333]

If they don't shoot 0.020" in the land or 0.020" jump, I change powders and/or primers.
A benchrest rifle is a different story.

 

[big5ifty]

A

Im not the greatest shot out there , but 3 x 3 groups are a waste of components IMO

It's only a waste of components when you keep doing the same thing over and over with no improvement.

 

[Webster]

Hi all
I've been handloading for about a year now and I want to choose seating depths that gives me room as the thoat erodes
I test 142 gr SMK with N555 (43.3gr) at a few seating depths (6.5 creed)
I have a few of the pics and a graph to show the groups vs cbto
Im leaning toward the cbto of 2.211
All shots are unmarked (3 shot groups)

Based on group size I assume it's a hunting rifle. I would pick the best load you can shoot now and if the groups get bigger after 500-1000 shots, then worry about it. I would think the powder type and bullet are the big things to determine group size in your rifle. I don't think the groups are small enough or consistent enough to evaluate seating depth. My varmint rifles shoot under ½” groups and I cannot see obvious differences from seating depth. I would think you would need to consistently shoot groups around 1/4" to have a chance at seeing seating depth changes. How much of your group appearance is due to bench manners and shooting skill? It’s a mistake to think the group is just determined just by the load. Many of us are not exceptional shooters with great rifles. I see a lot of guys testing loads at the range with no flags.

 

[davidjoe]

Ok, I’ll just ask, what kind of rifle are you shooting? Can we see a picture of it and the support you are using front and rear?

Those SMK bullets are capable of shooting much tighter than that, but they are long and need stabilization. It’s a big picture issue affecting your group size.

 

[davidjoe]

Im not the greatest shot out there , but 3 x 3 groups are a waste of components IMO

Moe, your groups are much smaller than 3x3. The small square are .5 inch. Your groups are actually at the 1.5” accuracy guarantee of sone very good, and expensive factory rifles. But those 142’s, a go-to in the early days of Fclass, could easily all touch or overlap on a .284 case (+ ~5 grains)) with a fast twist barrel and a heavy gun, which is the reason for the question.

 

[moe africa]

Moe, your groups are much smaller than 3x3. The small square are .5 inch. Your groups are actually at the 1.5” accuracy guarantee of sone very good, and expensive factory rifles. But those 142’s, a go-to in the early days of Fclass, could easily all touch or overlap on a .284 case (+ ~5 grains)) with a fast twist barrel and a heavy gun, which is the reason for the question.

The 2.211 group is 0.7"
The 2.220 group is 0.6"
The picture attached is a 5 shot group at a cbto of 2.202"