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KYregular

KYregular

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Ok guys, I think I know the answer to this but want some input. I was testing some loads today with various different previously fired case. The two in the pic were easily the best. All cases and bullets were weighed to match. Load was Hornady XTP 124 over 5.7 grains Power Pistol. Image on the left was FC case at 1128 fps with an SD of 11. The right was RP case with 1134 fps with an SD of 7. O can see where each could be better, but I am thinking the TO case on the lest is better. Bench shot with a CZ P09 at 7 yards, pretty good wind though I don't think it mattered much. What ya think? 20181006_174106.jpg
 
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And . . . never heard of TO cases. A new manufacturer? Or are they RP cases, like what the writing appears to be on your target?
 
You have vertical in both groups which is likely you, and the fact that it is all vertical in one group is not a difference in cases. IMHO.

If I had just shot them, I would have more hope for the one on the right and figure if I did a better job of consistent recoil control it could be a tight group indeed.

Either way, it isn't the case.
 
Walkalong said:
You have vertical in both groups which is likely you, and the fact that it is all vertical in one group is not a difference in cases. IMHO.

If I had just shot them, I would have more hope for the one on the right and figure if I did a better job of consistent recoil control it could be a tight group indeed.

Either way, it isn't the case.
Click to expand...

I agree that I do not believe the case is of any difference. All shots however were slow and methodical from a bag rest on the bench, so recoil should not play into it. And, with that low of SD it shouldnt either apply to fps differences. Oddly, at that distance I actually shoot better standing. I just wonder if total round weight difference play into it.
 
fxvr5 said:
What does this mean?
Click to expand...

All bullets, cases, and of course powders were weighed individually. But, may have varied by a half a grain or more when completed because the cases would very rarely weight the same.
 
It amazes me what people think is an adequate sample size for comparing two relatively close loads. There is no freakin' way to tell whether a group that is 10% tighter than another group is that way because of random chance or something repeatable based on a single pair of five shot groups. It is perhaps possible to conclude that a load is total garbage based on a single 5 shot group. Perhaps.

Trying to tell the difference between a 2 MOA load and a 2.5 MOA load based on a five shot group of each is like trying to eyeball the difference between a .270 hitter and a .300 hitter based on watching a single baseball game. No possible way to do any better than a random guess with that sample size.
 
KYregular said:
All shots however were slow and methodical from a bag rest on the bench, so recoil should not play into it.
Click to expand...
Then it is jerking the trigger down. Or both. And it is recoil control, not differences in recoil.

Shoot multiple groups of both loads if you want some idea of which one is better.
 
The vertical string is probably due to changing grip pressure as you pull the trigger, not your load. I had a problem with that when I started shooting handguns. Your tightening your grip as you squeezed the trigger. At 7 yrds your not going to see a lot of difference in loads unless one is really really bad.
 
ATLDave said:
It amazes me what people think is an adequate sample size for comparing two relatively close loads. There is no freakin' way to tell whether a group that is 10% tighter than another group is that way because of random chance or something repeatable based on a single pair of five shot groups. It is perhaps possible to conclude that a load is total garbage based on a single 5 shot group. Perhaps.

Trying to tell the difference between a 2 MOA load and a 2.5 MOA load based on a five shot group of each is like trying to eyeball the difference between a .270 hitter and a .300 hitter based on watching a single baseball game. No possible way to do any better than a random guess with that sample size.
Click to expand...
Really
ATLDave said:
It amazes me what people think is an adequate sample size for comparing two relatively close loads. There is no freakin' way to tell whether a group that is 10% tighter than another group is that way because of random chance or something repeatable based on a single pair of five shot groups. It is perhaps possible to conclude that a load is total garbage based on a single 5 shot group. Perhaps.

Trying to tell the difference between a 2 MOA load and a 2.5 MOA load based on a five shot group of each is like trying to eyeball the difference between a .270 hitter and a .300 hitter based on watching a single baseball game. No possible way to do any better than a random guess with that sample size.
Click to expand...
Really, I've been doing this for a while and ya think I don't know that? So, I guess of the six test loads I made I should have made a thousand rounds each? I have developed several accurate loads starting off with 5, then taking the best 2 or 3 groups and developing 20 or so each, then narrowing it down from there. Just trying something a little different and asking opinions and drawing criticism because someone else has a better way than You? "Amazing"
 
Blue68f100 said:
The vertical string is probably due to changing grip pressure as you pull the trigger, not your load. I had a problem with that when I started shooting handguns. Your tightening your grip as you squeezed the trigger. At 7 yrds your not going to see a lot of difference in loads unless one is really really bad.
Click to expand...

Good call, but I was shooting off a rest and making sure proper fundamentals were applied. That is why I thought that group was strange in the first place.
 
Still can, but I assure you I'm not. After 40 plus years of this I have kicked that habit, not saying I can't occasionally but not consistently.
 
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KYregular said:
Really
Click to expand...

Yes, really. With two groups of generally similar sizes, 5 shots isn't a large enough sample size. When you are trying to detect small differences, sample sizes have to get pretty big. That's not special to shooting. That's for anything where there is some level of uncertainty.
 
I see vertical stringing and horizontal stringing of the first handful of shots, and later that pattern disappears as more shots are added. And that's from a Ransom Rest. I repeat, what you can conclude from this data is: Nothing.

People need to wake up to the fact that there are rigorous methods for testing things for a reason - to rule out chance - because things happens by chance. If you can't understand that, then you'll never understand the real world.
 
ATLDave said:
Yes, really. With two groups of generally similar sizes, 5 shots isn't a large enough sample size. When you are trying to detect small differences, sample sizes have to get pretty big. That's not special to shooting. That's for anything where there is some level of uncertainty.
Click to expand...

Like i said I understand that 5 shot groups are not deciding factors, but it is often big enough to weed out the really bad stuff, such as loads that wont even cycle your gun. I get your point, mine was that I have never seen two groups that different just because of case headstamp.
 
fxvr5 said:
I see vertical stringing and horizontal stringing of the first handful of shots, and later that pattern disappears as more shots are added. And that's from a Ransom Rest. I repeat, what you can conclude from this data is: Nothing.

People need to wake up to the fact that there are rigorous methods for testing things for a reason - to rule out chance - because things happens by chance. If you can't understand that, then you'll never understand the real world.
Click to expand...
Thank you, that's the kinda info im looking for, never used a ransom rest, just a bag.
 
??? Those groups are not "that different." They appear to be very similar in size. They are shaped differently, but 5 rounds really gives you no reliable basis for assessing whether that difference in shape is just random chance or something repeatable. I feel like you're kind of missing the basic concept here.
 
Here's a lesson in group size: even with many more shots (15) in your group, the groups can vary by a factor of 2.8. That is, the largest group is 2.8 times larger than the smallest group. And that's with the Same Ammo from the Same Gun tested at the Same Time, and also from a Ransom Rest! The actual data can be seen at this link: https://americanhandgunner.com/exclusive-consistent-velocity-accuracy/ Look for the data for the 115 grain Zero JHP and 6.5 grains of Power Pistol.
 
Walkalong said:
Shoot multiple groups of both loads if you want some idea of which one is better.
Click to expand...

Actually, you're better off shooting lots of rounds into one group. Multiple, small groups increase the chance of missing how all the shots align with each other. You get around that by shooting all the shots in one group.
 
KYregular said:
I agree that I do not believe the case is of any difference. All shots however were slow and methodical from a bag rest on the bench, so recoil should not play into it. And, with that low of SD it shouldnt either apply to fps differences. Oddly, at that distance I actually shoot better standing. I just wonder if total round weight difference play into it.
Click to expand...
then your "bench" procedure is flawed. better to shoot standing and take walkalong's suggestion about using the same grip with each shot. it doesn't take much grip variation to show a vertical string in a shot group.

luck,

murf
 
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