Load development.....opinions??

[Clark]

I did a number of accuracy work ups in 2000, 2001, and 2002.
I found none of them repeatable on return trips to the range.

This reminds me of my cousin stating in 1976 that all beer tastes the same. We had a taste test, and I could identify all the beers and he could identify none.

I am just not good enough that ladders make any difference.
I have shot 36 big game animals since 2008, and only two were beyond 600 yards.
I just hope I don't get kicked off long range hunting forum for being a putz

 

[Mikecr]

Wish I could identify every beer right now!
I'll just remind that SEATING is vital to this endeavor. For accuracy, seating is the coarse adjustment while powder is merely the fine.
So if you first find best seating, and then go to an OCW, then final tweak seating for group shaping, and your results are good enough right there, it could make sense to stop right there. If not, there are a lot of other potentials, and shooting a ladder at distance should be considered for sure.

 

[User4302021]

Wish I could identify every beer right now!
I'll just remind that SEATING is vital to this endeavor. For accuracy, seating is the coarse adjustment while powder is merely the fine.
So if you first find best seating, and then go to an OCW, then final tweak seating for group shaping, and your results are good enough right there, it could make sense to stop right there. If not, there are a lot of other potentials, and shooting a ladder at distance should be considered for sure.

If you do the math on velocity gain per 0.1g of powder and how it affects barrel time, then do the math on the effect of different seating depths on barrel time...you see that it is, in fact, quite the opposite.

 

[willyqbc]

You do enough reading, and its interesting to see how many differing opinions there are on how best to go about load development. Some feel powder charge is most important, others feel seating depth is key, some looking for no vertical, others a common poi or common velocity. If anyone could come up with a way to combine all of the above without burning up 200 rounds, id have to buy him/her a beer!!

Mikecr...id be interested to hear your load development procedure focusing on seating depth.

Chris

 

[User4302021]

You do enough reading, and its interesting to see how many differing opinions there are on how best to go about load development. Some feel powder charge is most important, others feel seating depth is key, some looking for no vertical, others a common poi or common velocity. If anyone could come up with a way to combine all of the above without burning up 200 rounds, id have to buy him/her a beer!!

Mikecr...id be interested to hear your load development procedure focusing on seating depth.

Chris

Basically, a 0.1g change in charge weight will get you an average change of 5-7fps. With something like a 308win, that is an average of about 0.002% change in velocity and therefore barrel time.

To get an equivalent change in barrel time from seating depth in a 24 inch barrel. You would need a 0.050" change in seating depth.

 

[Mikecr]

I do not know what seating depth is doing, but I do know it's not velocity and not barrel time. If it were, anyone could more easily dial in MV/barrel time using powder, as we have to single kernels of resolution there.
I'm telling you and you can test it (Berger's recommended), with a hunting capacity cartridge, no amount of powder tweaking makes up for the differences between best & worst seating. I can open a 1/4moa load to near 1moa results with 25thou seating change and see zero change across a chronograph with this.

If you just pull a seating condition out of your butt, and powder develop with it, you're very unlikely to have hit on best overall from that combination. It happens, but there is no rational reason to see it as any more than luck. That is, unless pretty much all is already known up front about the combination. Something like a barrel change with same chamber (actual, not just within SAAMI).

 

[User4302021]

I do not know what seating depth is doing, but I do know it's not velocity and not barrel time. If it were, anyone could more easily dial in MV/barrel time using powder, as we have to single kernels of resolution there.
I'm telling you and you can test it (Berger's recommended), with a hunting capacity cartridge, no amount of powder tweaking makes up for the differences between best & worst seating. I can open a 1/4moa load to near 1moa results with 25thou seating change and see zero change across a chronograph with this.

If you just pull a seating condition out of your butt, and powder develop with it, you're very unlikely to have hit on best overall from that combination. It happens, but there is no rational reason to see it as any more than luck. That is, unless pretty much all is already known up front about the combination. Something like a barrel change with same chamber (actual, not just within SAAMI).

A couple of things...firstly, we agree on the importance of seating depth, just from differing perspectives.

Secondly, small velocity changes due to seating depth would be an order of magnitude below a chronographs resolution capabilty.

Thirdly, if what you propose is true...to the extent you indicate, then a proper seating depth would make any reasonable powder charge shoot well, so why even work up the load?

 

[Mikecr]

What I'm suggesting is that seating is the coarse adjustment, powder is fine.
Coarse in itself is too broad to calibrate, and fine in itself is too limited.

To find best you would logically adjust both.
Start with coarse and finish with fine.

 

[User4302021]

What I'm suggesting is that seating is the coarse adjustment, powder is fine.

Well, we are just going to have to respectfully agree to disagree on that. But, that is what hashing it out is about sometimes, right?

Good shooting.

 

[Barrelnut]

I did 6.5 Creedmoor workup this summer with 48 rounds. Shot 4 round groups throughout. Found these to be a good compromise between 3 and 5 shots groups.

First shot for seating depth with .10 thru .50 jumps.
Second used the .30 jump with charges in .3 Gr increments ti find the final load.

This load does well at maintaining low SD with accuracy and low vertical out to 700 yards. And lines up well with the drops calculated in my ballistic app. I really have no need adjust the load more. Though, playing around with a .50 jump and powder loads on either side of 42.6 might yield something. But I have only 100 more of these bullets and don't want to waste them on more development!

Noticed that the sweet spot for the final load is just 1.17% off of the max load. Not far off from Rocket Dog's 2% method above...

I have done workups with ladders and OCW before. If done here I think I would have used more bullets and the results would have been about the same.

DATA:

H4350 Jump Group Average SD
41.3 .10 1.36 2618 7 (For fouling)
41.3 .10 1.26 2628 11
41.3 .20 .99 2630 17
41.3 .30 .74 2639 4 (Chose .30 for final Jump)
41.3 .40 1.2 2630 14
41.3 .50 .65 2624 4

H4350 Jump Group Average SD
41.7 .30 .58 2666 6
42 .30 .95 2692 9
42.3 .30 .78 2717 5
42.6 .30 .39 2735 4 (Choice for final load)
42.9 .30 1.6 2755 6
43.1 .30 .89 2764 6 (Hit pressure)

 

[User4302021]

I did 6.5 Creedmoor workup this summer with 48 rounds. Shot 4 round groups throughout. Found these to be a good compromise between 3 and 5 shots groups.

First shot for seating depth with .10 thru .50 jumps.
Second used the .30 jump with charges in .3 Gr increments ti find the final load.

This load does well at maintaining low SD with accuracy and low vertical out to 700 yards. And lines up well with the drops calculated in my ballistic app. I really have no need adjust the load more. Though, playing around with a .50 jump and powder loads on either side of 42.6 might yield something. But I have only 100 more of these bullets and don't want to waste them on more development!

Noticed that the sweet spot for the final load is just 1.17% off of the max load. Not far off from Rocket Dog's 2% method above...

I have done workups with ladders and OCW before. If done here I think I would have used more bullets and the results would have been about the same.

DATA:

H4350 Jump Group Average SD
41.3 .10 1.36 2618 7 (For fouling)
41.3 .10 1.26 2628 11
41.3 .20 .99 2630 17
41.3 .30 .74 2639 4 (Chose .30 for final Jump)
41.3 .40 1.2 2630 14
41.3 .50 .65 2624 4

H4350 Jump Group Average SD
41.7 .30 .58 2666 6
42 .30 .95 2692 9
42.3 .30 .78 2717 5
42.6 .30 .39 2735 4 (Choice for final load)
42.9 .30 1.6 2755 6
43.1 .30 .89 2764 6 (Hit pressure)

When I do initial pressure testing, I use the maximum OAL I can stand. I then back off 2% from there. So with the longer OAL, the pressures have a bit more room to build. So, where I would have ended up and where you ended up are probably even closer than your numbers indicate.

 

[willyqbc]

continued with load development today with 2 priorities in mind.

First, I wanted to see how high I could go before my POI shifted, so loaded up 45.0, 45.1, 45.2, and 45.3 and shot 5 shot groups at 200yds. 45.1 and .2 grouped with the original 45.0 loads and 45.3 showed a 2" jump up in point of impact. So looking back to earlier testing, I can see that i have a range of 44.5 - 45.2 where my POI does not shift. In that range, 45.0 showed the tightest groups....considering that gives me some "wiggle room" for temperature fluctuations, reloading variation etc....i'm pretty happy with that charge.

Secondly, I wanted to see if I could tighten up the group with seating depth so loaded 5 each at .010 off the lands to .050 off using the 45.0 charge....group size was as follows at 200 yds

.010 - 1.172" .559 moa
.020 - 1.505" .718 moa *this was the original seating depth
.030 - 2.104" 1.004 moa
.040 - 2.485" 1.186 moa
.050 - 2.162" 1.032 moa

So, while testing charges from 42.5 to 45.5 we saw a difference of 1.217 moa at 110 yds from worst group to best, and while testing 44.4 - 45.0 at 220 yd we see a difference of .904 moa from worst to best group.

while testing seating depth from .010 off to .050 off at 200 yds we see a difference of .627 moa from worst group to best

Obviously would need many more rounds to be statistically significant....but, on the surface it seems that the powder charge has the potential for bigger variation in group size than does seating depth.

That being said, my suspicion is had I done seating depth first and charge second, I would have probably ended up at the same place. Not sure I believe either one is more important that the other, but rather that the specific combination is what works....and very well may not be the only one. I suspect i could load anywhere from 44.4 up to 45.2 and find a different corresponding seating depth that would perform as well as 45.0 @ .010" off.

Chris

 

[User4302021]

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[willyqbc]

you seem to have had a posting malfunction at the junction Dog Rocket!! Haha!

ain't technology wonderful!