One flier in every group 308 load developement

Harvey_NW

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So is no one gonna mention seating depth, or am I missing something here? 3-5 shots may not be a sufficient "group" for some, but it's definitely an indicator of whether or not you're in or around node. I use the same method as many of the best shooters in the PRS circuit, because it is the fastest and most efficient way I've found to develop a solid load. Do a seating depth test to find an accuracy node, shoot a powder ladder to find a velocity node, tune your powder charge, load and shoot. Also, contradictory to popular belief, don't worry about staying close to the lands. There is tons of data from highly accredited shooters that shows the most forgiving accuracy windows are generally .050"+ from the lands in many calibers.

 

Rob5589

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So is no one gonna mention seating depth, or am I missing something here? 3-5 shots may not be a sufficient "group" for some, but it's definitely an indicator of whether or not you're in or around node. I use the same method as many of the best shooters in the PRS circuit, because it is the fastest and most efficient way I've found to develop a solid load. Do a seating depth test to find an accuracy node, shoot a powder ladder to find a velocity node, tune your powder charge, load and shoot. Also, contradictory to popular belief, don't worry about staying close to the lands. There is tons of data from highly accredited shooters that shows the most forgiving accuracy windows are generally .050"+ from the lands in many calibers.

For a hunting load in a factory chamber, I don't worry about it. In my Tikka for example, the load recommended from Barnes puts the round at mag length. I have never even measured the chamber because for that gun, it really wouldn't matter. On my past PRS style guns, that did matter. But I was shooting a custom chamber, vld style bullet, much further distance, etc.
 

bsnedeker

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For a hunting load in a factory chamber, I don't worry about it. In my Tikka for example, the load recommended from Barnes puts the round at mag length. I have never even measured the chamber because for that gun, it really wouldn't matter. On my past PRS style guns, that did matter. But I was shooting a custom chamber, vld style bullet, much further distance, etc.
I measured the chamber on my 300 WM Tikka just for the hell of it (and in case I decided to ever upgrade to a different bottom metal that would allow cartridges longer than SAAMI spec. With a 3.340" CBTO (which is all the tikka mag will accept) I'm .250" off the lands!!! The guns a shooter regardless, right around 1 MOA even with factory loads.
 

Marble

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I measured the chamber on my 300 WM Tikka just for the hell of it (and in case I decided to ever upgrade to a different bottom metal that would allow cartridges longer than SAAMI spec. With a 3.340" CBTO (which is all the tikka mag will accept) I'm .250" off the lands!!! The guns a shooter regardless, right around 1 MOA even with factory loads.

.250 or .0250?

Sent from my SM-G986U using Tapatalk
 

DJL2

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May 22, 2020
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My M70 in .30-06 jumps anything of the ELD/TMK variety around 100 to 200 thou depending on the specific bullet and seating depth based on mag limitations. My KRG SOTIC in 6.5 CM does 100 thou or so for ELD/TMK. I found some old, old, old Accubonds that actually hit the lands at around 2.84, so that's my smallest jump currently @ ~30-40 thou. My T3x just got a bottom metal upgrade, but that's still coming together... might be possible to jam, but that's just daft...so, probably a smaller jump there than some.

That being said, my SOTIC was sensitive to seating depth. I think it just prefers 140 grain bullets generally (and shoots everything I've tried well in factory form). The 130 TMK was more finicky. I need more time at the range and less at the bench, so I'm gonna hold what I've got and load what I need until I run out of primers. I've never loaded anything with even a remotely brag worthy ES/SD. Won't see it at the ranges I normally shoot, though.

To the OP - measure your deviation on each shot from point of aim. You want the radial (aka: straight line) magnitude as well as the X and Y component thereof. Take that, put it into Excel. Plot your shots onto a chart. You can color code different strings if you prefer. If you've run a bunch of 3 shot groups, you should have a goodly number of shots. If what you get looks like a fairly typical normal distribution, you'll have a wonderful graphic example of what @Formidilosus mentioned. You can also calculate your mean point of impact and adjust your optic accordingly.

You can also cheat the above by tracing the shots from all the groups onto a single piece of paper using the POA as the reference for the overlay. Then you can use any number of apps to give you mean point of impact, aggregate group size, etc.
 
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This is a 10 shot velocity ladder in a 6.5 CTR barrel. It was a clean barrel when I started. Those fliers might be foulers, me, or the fact that the group spans almost 2 grains of powder and 150 FPS. I’m inclined to believe it’s one of the former. I don’t remember. I was really just blasting to get velocity numbers.

Moral of the story is that 10 shot groups will tell you a lot about your rifle and that powder charge matters a lot less than the internet will lead you to believe. If anything, seating depth is the knob worth turning. An egregiously large group points to something else wrong with the system and it’s unlikely to be powder charge.

bb2777c07bbc5015876f7670969df220.jpg
 
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The endless “load development” is the silly part. Load 5 rounds at book max or just under. Shoot them. If they shoot remotely decent, load 20. Shoot ten to zero, and ten to velocity true. Load development is done. .1, .2, .5 grain changes in powder isn’t going to make an actual real difference. Either it shoots, or you need to make a major change in components- change powder and/or bullet.

Incremental reductions in group size do not, and will not increase hit rates on animals in the field- group size isn’t why people miss.
I think you just changed my whole outlook for load development for my hunting rifles.
 

DJL2

Lil-Rokslider
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May 22, 2020
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This is a 10 shot velocity ladder in a 6.5 CTR barrel. It was a clean barrel when I started. Those fliers might be foulers, me, or the fact that the group spans almost 2 grains of powder and 150 FPS. I’m inclined to believe it’s one of the former. I don’t remember. I was really just blasting to get velocity numbers.

Moral of the story is that 10 shot groups will tell you a lot about your rifle and that powder charge matters a lot less than the internet will lead you to believe. If anything, seating depth is the knob worth turning. An egregiously large group points to something else wrong with the system and it’s unlikely to be powder charge.

Doing the same sort of ladder test in my 7mm RM yielded much the same sort of result. Just above 1 MOA (out to 300 yards) shooting 10 different charge weights into a group that had more wind/horizontal than vertical due to powder (which was essentially non-existent at this range). Pretty sure I posted that group on here somewhere (probably in the Tikka 10 shot group thread, come to think of it).

I had 9-shots that ended up looking a lot less like a series of 2 and 1 than a mostly circular blob today as well. That group is inclusive of the cold bore shot and it started clean. That's factory ammo...now I just need to get something comparable out of my hand loads and I'll call it good.
 

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OP
razorsharptokill
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Feb 12, 2014
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Oklahoma
After bedding the rifle the accuracy is about the same with my two hunting loads 1.5" ish with max loads. 400 would probably be my max range in field. Factory federal power shoks in 150 grain yielded about the same. Below is a group with 168 gr AMAX. Not planning on hunting with tje AMAX.Seems like in most of my groups with various loads the groups spread out laterally.
 
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