my second precision/long range rig..6.5x55

rpollock said:
Respectfully, we will have to disagree on this point. I will still contend a 2 shot group can't tell you anything.
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Respectful is great, and I don't mind if we end up disagreeing, but I *think* I can try to convince you:

- A 2-shot group can be considered to be the first two shots of a (say) fifteen shot group.

- Say that those two shots are too far apart, i.e. "bad" in the context of the rifle and shooting setup at hand (for example, a good well-built varmint rifle, shot off the bench by a competent shooter under decent firing conditions, places two shots 1.5" apart at 100 yards)

- Firing the rest of the shots, to form a fifteen shot group, can't make the group smaller. It may well make it bigger, but the fifteen shot group can never be smaller than the group size formed by its first two shots. If all of the rest of the shots land inside the first two, you still have a 1.5" group - which (in the context stated) says, "bad".

Basically what I am saying is that once a group shows itself to be "bad" enough to cast a negative vote on a particular load combination, there's no need to fire more shots into that particular group. It's already done its job, and delivered the bad news to you. Maybe you might want to start another group, perhaps to rule out shooter error.


Cheers,
 
rnbra-shooter said:
Respectful is great, and I don't mind if we end up disagreeing, but I *think* I can try to convince you:

- A 2-shot group can be considered to be the first two shots of a (say) fifteen shot group.

- Say that those two shots are too far apart, i.e. "bad" in the context of the rifle and shooting setup at hand (for example, a good well-built varmint rifle, shot off the bench by a competent shooter under decent firing conditions, places two shots 1.5" apart at 100 yards)

- Firing the rest of the shots, to form a fifteen shot group, can't make the group smaller. It may well make it bigger, but the fifteen shot group can never be smaller than the group size formed by its first two shots. If all of the rest of the shots land inside the first two, you still have a 1.5" group - which (in the context stated) says, "bad".

Basically what I am saying is that once a group shows itself to be "bad" enough to cast a negative vote on a particular load combination, there's no need to fire more shots into that particular group. It's already done its job, and delivered the bad news to you. Maybe you might want to start another group, perhaps to rule out shooter error.


Cheers,
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I suppose I would quit if the first 2 shots are 1.5" apart, but in the context of this thread that doesn't really happen. I am thinking that the first 2 shots are .5 apart, I would carry on and see what the rest of the group looks like, since it well tell me a lot about the load. In your example what if I ended up with a 1+14 group? Mind you I don't shoot 15 shot groups in load development, as the time required to complete the group virtually guarantees multiple conditions will be shot. I would shoot 3 (5) shot groups instead.

I certainly appreciate what you are saying. ie you can't improve a group with more shots. I am not trying to improve it. By firing a few more shots, I would be trying to figure out why the shots landed so far apart.
 
One more kick at the cat, with a different foot!

In your 15 shot group lets consider if the group played out in reverse order. ie; you get a nice 14+1 group with the 15th shot out of the group. Most would consider this a killer load and blame the flyer on the wind, bad bullet, brass, colour of socks, or whatever. I know I would!

How are the results for this load any different if the flyer came on the first shot, ie you get a nice 1+14 group, with the first shot being the flyer. It is the same load, therefore it is still a killer load isn't it?

The problem is you don't know when it is a flyer until you finish the group.
 
rpollock said:
2 rd group (pair?) won't tell you anything. Flyers can go in or out of a group. ie a 1 moa rifle will occasionally produce a 1/4 moa 3 shot group. It happens all the time. What if the first shot is a flyer? (wind, gun handling, loading error, bad bullet, bad brass etc etc)Then the rifle proceeds to stack 9 more in the same hole? You will never know under your methodology if a killer load was discarded due to the first 2 shots not touching.

Many a barrel has been burnt out chasing a lucky 3 shot group in load development. In your case a lucky 2 shot group.

Flame suit on.
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If your way off, 2 shots shows a lot. if you are close then it begs further testing. It is an incremental game, the shots usually get closer and then farther apart. Why waste ammo when a 25gr shot doesn't even get within a 2" group or 1" and then a 28gr group gets you down to 3/4"? why would you sit there and test 25gr with extra rounds just to know it doesn't work.

It comes down to experience. There are enough arm chair bench rest boys out there, but Mysticplayer (from his posts and his reputation around the okanagan) is a heavy duty customer, I'd listen to him before I listened to half the "wise men" on this board who have no "actual" practical experience.
 
aninchlow said:
If your way off, 2 shots shows a lot. if you are close then it begs further testing. It is an incremental game, the shots usually get closer and then farther apart. Why waste ammo when a 25gr shot doesn't even get within a 2" group or 1" and then a 28gr group gets you down to 3/4"? why would you sit there and test 25gr with extra rounds just to know it doesn't work.

It comes down to experience. There are enough arm chair bench rest boys out there, but Mysticplayer (from his posts and his reputation around the okanagan) is a heavy duty customer, I'd listen to him before I listened to half the "wise men" on this board who have no "actual" practical experience.
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Did you even read the rest of the thread before you posted this? Seriously, why the personal attack?
 
Appreciate the kind words of support but let's keep this from getting personal.

I agree with both rpollock and rnbra-shooter. By combining both ways of looking at your groups, my test method tries to reduce the number of shots fired and narrow down where serious testing should begin.

In a nut shell, working up a load in small increments will start with large groups, then shrinking to some small groups but at low/moderate pressure, expanding again, then back down with velocities at desired levels, expanding quickly with obvious pressure signs.

Each time the groups shrink, I call a node. Have yet to shoot a barrel that didn't have two and a few have three but that third one is definitely a hot load and should be used with care (watch ambient temp change too).

If the goal is for the lowest ES/SD and vertical stringing, I will gravitate to the second node. This load is definitely warm. You might see slight primer flattening but there will be no issue with extraction or case bulging. Primer pockets stay tight after several loads. The usually stuff.

So let's say my 2 shot ladder test showed a second node around 44.5gr (let's use a 308 type case as an example) 44.8gr, some pretty obvious pressure signs at 45.1gr with groups starting to open up, then 45.4gr where groups definitely opening up maybe even being vertical and the fired case showing strong pressures signs.

Of course, you could keep going up but for my uses, I wouldn't bother as I don't like using really hot loads.

So I would go back to 44.3gr then work up in 0.2gr increments. I may shoot 2 or 3rds in a group and maybe 2 groups just to make sure I don't have a shooter induced error wasting a test level.

The groups show that 44.3gr and 44.5gr again are not bad but there is some vertical and not as tight as desired. At 44.7gr things really start to snug up. 44.9gr is also really good. At 45.1gr, groups open up as expected.

We started by doing to 2 shot ladder test and fired say 20rds to go from starting load to max pressure. Found a couple of interesting nodes on the way.

Retest uses up another 30rds cause I want to shoot 2 3rds groups. I have now narrowed my testing to 2 potential loads.

I can now go back and retest 44.6 to 44.9gr if I really want to be picky to see which one has the tightest group but also the lowest amount of vertical dispersion. For some rifles, this amount of powder change will not show up on target. For others, there can be a tangible difference especially when testing at 200yds.

So you retest with a larger sample size and more groups at each powder increment but now going up in 0.1gr. Maybe you want to do 2 5rds groups.

Voila, you find 44.8gr to be the best compromise with both accuracy and lack of vertical.

At this point, you have shot less then 100rds and have a great load. some would argue that the number of groups are not statistically adequate. for them, they can now shoot as many 5 or whatever sized groups they need to satisfy their concerns.

For me, I would retest again with a couple more groups then go practise and have some fun. I no longer want to spend alot of time working up and retesting a load. I would rather pound small targets at LR.

Key points is testing at 200yds, using fireformed brass that has been prepped as well as possible, a very accurate scale, ammo with little to no runout, great rest/bench and stock set up, quality optics that let you see at least 1/8" at 200yds (smaller better) and most importantly - shoot with as little wind as possible and use flags.

Pretty simple process really and has worked on all the rifles I have worked on over the last 5yrs. Saves a whole bunch of shooting. If you note, I don't play with seating depths as I don't like working with a moving target. I prefer to use very small powder increments to do the same thing. You must use a scale with accuracy UNDER 0.1gr. The usual balance beam scale and most digital scales are only good to +/- 0.1gr

Using proven components, this process gets me dialed in quickly. Hope it works for you.

Jerry
 
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Rick's point about the potential for an errant first shot is certainly valid. In BR shooting, as in other disciplines, errant shots do happen; in competition and in testing. One of the Forslund brothers told me something to the effect that if the first shot didn't hit where expected, and if he didn't see a reason for it, he would always chase the shot (this for group shooting of course). Like Rick said, really widely spaced shots don't happen with a good rifle and components. Now, it is possible that a load will produce a group double what it should be and that group will be apparent within three shots. Probably a reason to pass on that load.
Another bit of Forslund advice was to the effect that if a rifle shooting a reasonable load, using good components, and shot in good conditions, didn't produce a group which at least showed promise (on the order of 3/8 moa or better at that time), there was something wrong with the rifle and there was no point in dicking around with the load. I still follow this thinking. If I put a new barrel on my 6.5 and it doesn't shoot with my usual bullet and powder charge, I will try another powder but I'll go over the rifle pretty carefully first. Regards, Bill
 
Hi Bill, what is meant by the terminology "...chase the shot"? Does it mean to try to make the next four shots in the group land where that one did? Or something else?
 
In all group shooting the first shot is , in reality, a gimme. One just has to hit the same spot four times. If the first shot lands away from the expected point of impact the shooter has to decide whether the shot hit there due to some unrecognized condition or hit there due to some other factor. It was their contention that if they didn't see a condition change, it didn't exist. This being the case, they would adjust their point of aim to hit what they assumed to be an errant shot for unknown reasons. Chasing the shot.
Today, most shooters will go back to the sighter in an attempt to confirm or refute the suspected cause of the errant shot before deciding whether to chase or not. For whatever reason, we seldom did so. I think todays shooter's techniques work better for the most part. I know that, on the rare occasions when I attend a short range BR match, I don't win anymore! Regards, Bill
 
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