Seating depth tuning question

[SDDasher]

When tuning a load with great ES, SD and decent vertical spread, how many shots at each different seating depth do you take until a satisfactory group is achieved? Recent threads have discussed two shot groups vs three and five shot groups and that got me thinking about the question. Are two shot groups sufficient to establish accurate verticle groups by adjusting seating depths?

 

[Lapua40X]

When tuning a load with great ES, SD and decent vertical spread, how many shots at each different seating depth do you take until a satisfactory group is achieved? Recent threads have discussed two shot groups vs three and five shot groups and that got me thinking about the question. Are two shot groups sufficient to establish accurate verticle groups by adjusting seating depths?

IMO, absolutely not. A two shot "group" depends on 50/50 odds that everything is perfectly correct with both the shooter and the load with every shot. That's ludicrous, IMO. I used to try working with three rounds but found that it actually took longer (and more ammo) to be certain of the outcomes in each test. I was testing on top of tests to be certain that my data was clean. I still use three shots to find what I believe to be a range of worthy loads, but I do my final testing with five shot test groups. Build the load, fix the seating depth, and walk away.

 

[SDDasher]

George
I too use three shot groups for most tuning decisions that "go forward" to more indepth testing where at least ten shot groups at three hundred are used to verify what the three shot group told me at two hundred.
The reason I am interested to hear thoughts on the usefulness of two shot groups is I have a limited number of pricey custom bullets to test seating depth on and wanted opinions on how useful two vs three shot test groups would be.

 

[dcali]

Two and three shot groups are horribly inefficient, statistically speaking. Waste of good ammo.

 

[SDDasher]

Two and three shot groups are horribly inefficient, statistically speaking. Waste of good ammo.

Soooooo, are you advocating more or less to prevent waste or inefficiency? Accuracy of the tuned load is the goal focusing on reducing verticle dispersion via seating depth on the bullet in relation to the lands and case.
I would like to hear how the experts go about establishing the optimum seating depth of their ammo to achieve that goal?

 

[CaptainMal]

You shoot two shots to see if there is a group. If they are hideous, stop and do something else.

Two-shot groups are a start. If good, then two more and two more etc.

Two is a start. If they are bad, why continue?

 

[dcali]

If you know what the rifle is capable of and three shots is materially worse than that, then we can use some common sense and stop. Even then, though, I'd be careful, as you have a lot riding on those three shots. They had better have been perfect.

If you don't know how good the rifle is and your'e trying to find out, you need to shoot more than 2-3 shots. And if you're going to shoot 10, you are better off shooting 2 5-round groups than 5 2-round groups. Not that 10 shots will give you a high level of confidence, but it is quite a bit better than two.

 

[Corey Schwanz]

Lot of people will say 3 shots tests the load/equipment, 5 shots tests the shooter. One thing is for certain. A group will never get smaller with the 4th and 5th shots so it can only go downhill. I've started shooting 3 shot groups to do initial testing then when I think I'm on to something I will repeat that load with 5 shot groups. When shooting 3, you have to be very honest with yourself on shot calling and knowing when it was a good shot or if you pulled it somehow.

 

[SDDasher]

You shoot two shots to see if there is a group. If they are hideous, stop and do something else.

Two-shot groups are a start. If good, then two more and two more etc.

Two is a start. If they are bad, why continue?

I am leaning towards this train of thought for initial identification of potential success.
* The ten shot group at 300 is for verification of what I already know. Final verification comes at Blakely, Ga using electronic targets that allows for a snap shot of the twenty shot relay upon completion with your personal IPhone.

 

[Joe Salt]

Even at 200 or 300 yards 2-3 shots would only tell me that my hunting rifle was good enough. But my 1000 yard gun the least I would test is 5 shots! And for those who thinks they are just wearing the barrel out? what are you saving it for if it won't put 2-3 shots in the same hole at 100 yards. Sometimes they need some rounds through them. Just helped my buddy with his new L.G. Rifle didn't have 30 rounds of break-in and he shot a 1000 yard match this weekend and shot 8.5" with a 96 score. Thats 10 shots. Don't baby the rifle.

Joe Salt

 

[savagedasher]

Yes two shots work . 5 -2 shot will give you the same results as 2 - 5 shots. 2 shots will also show Vertical or horizontal . With 2 shots you measure each then add them together and divide by the number of 2 shots. The answer will be the same .
I find powder charge is vertical . Seating depth for horrizontal Larry

 

[SDDasher]

Yes two shots work . 5 -2 shot will give you the same results as 2 - 5 shots. 2 shots will also show Vertical or horizontal . With 2 shots you measure each then add them together and divide by the number of 2 shots. The answer will be the same .
I find powder charge is vertical . Seating depth for horrizontal Larry

Larry
That is interesting as I have always been told seating depth will Tune verticle and powder charge horizontal. Not being contrary but for the sake of discussion do you think the barrel tuner could be the wild card? ( Al kicked my butt again Sunday with his at Blakely, only dropping one point in the 3/600)

 

[Canadian bushman]

I do 3 when im just getting going on load development and deciding which way i wanna go.

Once i get onto a good load i shoot 5. When i get a load i may pursue ill run a 10-15 shot string with it and compare it to other loads i may be interested in. The longer strings seem to always show me something.

 

[SDDasher]

I do 3 when im just getting going on load development and deciding which way i wanna go.

Once i get onto a good load i shoot 5. When i get a load i may pursue ill run a 10-15 shot string with it and compare it to other loads i may be interested in. The longer strings seem to always show me something.

Sounds close to my load development practice. I am wondering how many use the same or different practice when fine tuning the load for powder/seating depth.
I know this another whole discussion but personally I like to test first at 200 and if promising (all touching or very close) and fine tune at 300 (max distance at our local range).

 

[TC260]

That is interesting as I have always been told seating depth will Tune verticle and powder charge horizontal.

Every ladder test I've ever done, the impact pattern moves vertically not horizontally. So I'm not sure how much horizontal can be corrected with powder charge.

 

[savagedasher]

Yes two shots work . 5 -2 shot will give you the same results as 2 - 5 shots. 2 shots will also show Vertical or horizontal . With 2 shots you measure each then add them together and divide by the number of 2 shots. The answer will be the same .
I find powder charge is vertical . Seating depth for horrizontal Larry

Larry
That is interesting as I have always been told seating depth will Tune verticle and powder charge horizontal. Not being contrary but for the sake of discussion do you think the barrel tuner could be the wild card? ( Al kicked my butt again Sunday with his at Blakely, only dropping one point in the 3/600)

Here is my thought . Why do we check the speed of a bullet it is for vertical. what changes the speed of a bullet. powder charge. That is why I said what I did.
Seating depth can do the same. Depending if your seating the bullet near or in the lands. because of the pressure spike you get at first start. Neck tension has effect when your touching the lands or in . Because of the pressure spike at start.
Tuning a bullet to the barrel is finding where the barrel is pointed when the bullet leaves the barrel in the exact same spot every time. This is why I do 2 shots. 2 -2 shot will tell you your load is trending in which direction.
I know a tuner is a wild card. But AL is a very good shot also. Larry

 

[SDDasher]

[/quote] Here is my thought . Why do we check the speed of a bullet it is for vertical. what changes the speed of a bullet. powder charge. That is why I said what I did.
Seating depth can do the same. Depending if your seating the bullet near or in the lands. because of the pressure spike you get at first start. Neck tension has effect when your touching the lands or in . Because of the pressure spike at start.
Tuning a bullet to the barrel is finding where the barrel is pointed when the bullet leaves the barrel in the exact same spot every time. This is why I do 2 shots. 2 -2 shot will tell you your load is trending in which direction.
I know a tuner is a wild card. But AL is a very good shot also. Larry
[/quote]
I see the logic and you are dead on about Al's skills.

 

[nastynatesfish]

I've never been able to tell anything from 2 shots? Il use two sight era then work on 3 shot strings to look for charge weight. I've got a good majority of my target that If I only use 2 shots, they are more less same hole. To me it's like plotting a chart. Ya you can see your start and finish but not the neighborhoods you have to go through. Here's mine from today I'm looking for help on in another post also...

 

[savagedasher]

I've never been able to tell anything from 2 shots? Il use two sight era then work on 3 shot strings to look for charge weight. I've got a good majority of my target that If I only use 2 shots, they are more less same hole. To me it's like plotting a chart. Ya you can see your start and finish but not the neighborhoods you have to go through. Here's mine from today I'm looking for help on in another post also...

Where was the first shot and the second and third. If the bullet that is out was that wind mirage or the shooter?. I wouldn't be happy with any. Many show good but the one out Was that conditions or you.
Larry

 

[SDDasher]

I sure would be looking closer at 4&9 to see if that could be further developed.