Why different primers

[RichCoyle]

What specific result are you looking for??? In other words are you looking for group size, ES/SD, vertical or something else???
I've usually picked a primer based on feedback for that particular cartridge and powder BUT that is not the best way. Thanks in advance

I heard some times a regular primer will produce higher velocity than a magnum primer does. This test was to check that. Perhaps you noticed the Winchester primer produced more than 70 feet per second variation in only three shots, while the others were about 20 feet per second difference. There's no way I would pursue the Winchester primer with this load.

What is the "best way"?

 

[biednick]

You don't have enough data to draw any conclusions here. If you're chasing the tiny bit of precision you can find by changing primers you need way more rounds on target. Shoot 25-30 rounds for each, not 3. If you repeat the same test with 3 shot groups a few times you'll likely get completely different results each time.

 

[Mark37082]

I haven't evolved my reloading process to include primer crush measurements yet. Maybe one day. I'm also primer poor with regard to an adequate supply of different primers brands for full on testing. I did notice a difference between Fed 210 and CCI BR2 in some test loads. Now I'm out of 210's and have a couple thousand BR2's. So I'm interested in learning, but forced to develop loads with what I have. Interesting topic.

 

[RichCoyle]

You don't have enough data to draw any conclusions here. If you're chasing the tiny bit of precision you can find by changing primers you need way more rounds on target. Shoot 25-30 rounds for each, not 3. If you repeat the same test with 3 shot groups a few times you'll likely get completely different results each time.

Now a days, it cost about two and a half bucks every time I fire the rifle. I certainly don't have enough money to fire 25-30 rounds of each.

I have fired the same three shot groups on two different days and get the same results. That "proves" to me some are acceptable and some are not.

I haven't evolved my reloading process to include primer crush measurements yet. Maybe one day. I'm also primer poor with regard to an adequate supply of different primers brands for full on testing. I did notice a difference between Fed 210 and CCI BR2 in some test loads. Now I'm out of 210's and have a couple thousand BR2's. So I'm interested in learning, but forced to develop loads with what I have. Interesting topic.

Same here. I can size a few cases on the press and get a couple thousandths difference in head space. How in the world would I be able to duplicate primer crush with currently available home reloading equipment?

 

[biednick]

Now a days, it cost about two and a half bucks every time I fire the rifle. I certainly don't have enough money to fire 25-30 rounds of each.

I understand. I can't afford to truly optimize most of my hunting loads either. At $2 for just the bullet I'd probably be $1000 in the hole if I was chasing the best possible precision. Unfortunately there's no free lunch. You can spend a lot of money collecting good data, make decisions based on inadequate data, or not worry about it. The last two options give you roughly equal odds of lucking into the best load, so I choose not to worry about it.

Over many groups you'll find group size is normally distributed. With enough groups you can predict the range your group size will fall in. With a couple of 3 shot groups your results are essentially random.

Unless your group are truly identical- same size, distance/position from center to POA, and mean distance to center- your results didn't repeat.

In the end you'll do about as well with low round count groups as random guessing, so you're not hurting anything but your wallet. If it makes you feel more confident in your load there's an argument the psychological benefit is worth it.

 

[Rich Coyle]

Based on what you're saying at least 90% maybe even more are not shooting he best load. Is that correct?

 

[biednick]

Based on what you're saying at least 90% maybe even more are not shooting he best load. Is that correct?

I won't put a percentage on it, but most shooters do make decisions based on inadequate sample sizes and thus can't know if they're shooting the best possible load or not. For things that make a minor difference, like primer selection and depth, most shooters would do just as well with random guessing.

For things that have a significant impact on precision like bullet and powder selection it doesn't take as many rounds to eliminate bad options, so inadequate testing is better than random guessing.

Many shooters don't even know how well the load they settle on shoots. You need a lot of rounds on target to get a true measure of precision.

 

[Sierra6]

I heard some times a regular primer will produce higher velocity than a magnum primer does. This test was to check that. Perhaps you noticed the Winchester primer produced more than 70 feet per second variation in only three shots, while the others were about 20 feet per second difference. There's no way I would pursue the Winchester primer with this load.

What is the "best way"?

I don't claim to know the best way on any aspect of this sport. I was acknowledging that my way of picking a primer and just running with it is probably flawed. Maybe you noticed me being thankful for this thread.

 

[MagnumManiac]

I have said this here many times and have been poo-pooed by many, to verify a load, especially shooting F-class or other forms of comp, you NEED to shoot 3 10 shot groups to get an average group size.
You can determine your loads at 100, but then verify at 600 as I described. One 3 shot group will tell you what groups closely together at 100, but it won't be the same at 300, 600 or 1,000.
Barrel life to me is not a consideration for NOT shooting verifying groups, even in a non comp gun.

Different strokes for different folks, I guess.

Cheers.

 

[Mark37082]

I completely agree with "different strokes for different folks". Some have decades of experience and have accumulated the tools over time to take loading to a level beyond most shooters expectations. I really enjoy reading about their efforts to get the ultimate precision. I file some of it away in my brain and determine what is practical for me. Off to reloading bench I go. I just prepped, neck-sized, and primed 50 new Peterson cases last night.

 

[Mikecr]

The statistically minded think that validating what they have is more important than improving what they have..
They'll nit-pick about inadequacies of small sample size, while generalizing that little things (as speculated) would make no difference anyway.

Don't let them talk you over the side of a high bridge, so that you could join the apparent 13.5% that survive it, only to climb back up to the highway, and try to move forward (as you were to begin with).
You can always go back and jump later,, if you just wonder about that.

 

[biednick]

The statistically minded think that validating what they have is more important than improving what they have..

You can't make improvements without validating your starting point and the result of each change you make.

EDIT: Actually you can, as any change could be an improvement. You just won't know if it improved, stayed the same, or got worse without validation. Putting time, effort, and money into something equivalent to random guessing isn't my first choice for making decisions, but you do you.

 

[DoneNOut]

I have said this here many times and have been poo-pooed by many, to verify a load, especially shooting F-class or other forms of comp, you NEED to shoot 3 10 shot groups to get an average group size.
You can determine your loads at 100, but then verify at 600 as I described. One 3 shot group will tell you what groups closely together at 100, but it won't be the same at 300, 600 or 1,000.
Barrel life to me is not a consideration for NOT shooting verifying groups, even in a non comp gun.

Different strokes for different folks, I guess.

Cheers.

I get the giddies when I superimpose all my 5-10 shot groups over the course of a couple months! Really, a 1MOA 30-50 shot superimposed group is quite impressive!

 

[asd9055]

I can tell you where best crush is: 5thou for CCIs, 2thou for everything else.
This, I set directly with an indicated K&M.

The testing, especially striking optimizing, goes better from the git-go with that crush standard in-place.
Otherwise, it's more concealing of what you're after.

Mike can you explain the "2thou" measurement? What do you measure exactly