Tuning and vertical dispersion

[shortine]

I am preparing to tune a new rifle. I have already tested 8 different types of ammunition...5-5 shot groups. Then tested the best 4...same method, then the best two...same method. So, 15 five shot groups of both Lapua X-act and Lapua Ctr-x.

Both lots are approximately the same age and speed. I tested both under the same conditions. There is very little horizontal dispersion between the two, with a slight edge going to the X-Act. The difference in group size between the Ctr-x and X-act is almost all due to vertical dispersion, with the X-act winning by about .08. The performance of the X-act would be competitive in an ARA Unlimited match with the proper operator (probably not me.): and that's with a naked barrel. I would obviously like to use Ctr-x (cost and availabilty of test lots). Should I tune with the Ctr-x? It will be much easier to measure any change in vertical dispersion. I should still be able to use the X-act with equal or possibly better results.

Does anyone but the test center offer actual test lots of X-act ? I mean in times of normal sanity. I use Good Shooting, but I don't believe they ever offered test lots of X-act.

Thanks,

Gerry

 

[grauhanen]

Tune with Center X. There's nothing wrong with using it when you have a good lot. Who can afford to shoot a lot of X-Act? Besides, there will be more lots of Center X now and in the future from which to choose when your current lot is gone.

 

[Hi-NV Shooter]

I am preparing to tune a new rifle. I have already tested 8 different types of ammunition...5-5 shot groups. Then tested the best 4...same method, then the best two...same method. So, 15 five shot groups of both Lapua X-act and Lapua Ctr-x.

Both lots are approximately the same age and speed. I tested both under the same conditions. There is very little horizontal dispersion between the two, with a slight edge going to the X-Act. The difference in group size between the Ctr-x and X-act is almost all due to vertical dispersion, with the X-act winning by about .08. The performance of the X-act would be competitive in an ARA Unlimited match with the proper operator (probably not me.): and that's with a naked barrel. I would obviously like to use Ctr-x (cost and availabilty of test lots). Should I tune with the Ctr-x? It will be much easier to measure any change in vertical dispersion. I should still be able to use the X-act with equal or possibly better results.

Does anyone but the test center offer actual test lots of X-act ? I mean in times of normal sanity. I use Good Shooting, but I don't believe they ever offered test lots of X-act.

Thanks,

Gerry

Use the most consistent ammo you have to find the setting for your setup. if this means the X-act then so be it. this is where a lot of shooters get confused, tune with lesser because better already shoots good, it will naturally shoot once I find the setting.
but how do you know you found the best possible setting if you use something that wasn't the most consistent and best lot. you already started off with second best, how could you achieve the best?

Lee

 

[grauhanen]

Something to consider. A box-and-a-half of each ammo shot outdoors is a small sample size. If there's a difference of 0.08" between the two, it's hardly conclusive evidence that one was superior to the other.

 

[shortine]

The difference between 15 five shot groups of .18 ctc and 15 five shot groups .26 ctc is pretty significant to me. I can't afford to test in brick quantity. Aren't most test lots sold in 2 box quantities? I was trying to keep my test quantities about the same as what I can buy. (hopefully... some time in the future). How many boxes do the rest of you use when testing?

Thanks,

Gerry

 

[VLNBYR]

You use as many boxes as it takes to satisfy your desires of where you want to be. If you're not ALL IN then you might as well not test and tune at all because you're never going to know how good you might have been.

 

[SGW Gunsmith]

The difference between 15 five shot groups of .18 ctc and 15 five shot groups .26 ctc is pretty significant to me. I can't afford to test in brick quantity. Aren't most test lots sold in 2 box quantities? I was trying to keep my test quantities about the same as what I can buy. (hopefully... some time in the future). How many boxes do the rest of you use when testing?

Thanks,

Gerry

And that's ALL that really matters, especially if you are wringing out a custom built, bench rest, rifle.
I am currently testing all sorts of, what some would consider, higher end rimfire .22 ammunition:

This testing is being done in a recently acquired CZ 457 MTR .22 bolt action rifle:

So far, this rifle, and how it shoots, has dismissed altogether, my faint desire to own an Anschutz 'anything' and that costs almost 3-times as much. I do all my initial ammunition test at 35 meters and then, if the 5-shot groups look acceptable, they're worthy of testing further out:

The group on the left is when using SK Rifle Match, the group on the right is with ELEY Target (yellow box). This CZ rifle has really made me happy with its purchase, and here's my "Tack-Driver Target" at 35 meters using RWS R100 .22 ammunition from the CZ 457 MTR:

I think your method of testing is just fine, and as long as it satisfies what you think it should, and does, it doesn't matter what others opinions entail. I also feel that 5 5-shot groups tell an early story concerning the ammunition involved and whether more should be purchased and tested, or not.

Two fifty round boxes (100) tells me whether to proceed with that ammunition of to try it in another rifle that may like it a lot better.

 

[shortine]

You use as many boxes as it takes to satisfy your desires of where you want to be. If you're not ALL IN then you might as well not test and tune at all because you're never going to know how good you might have been.

Winning the a-line in ARA is not on my bucket list. Shooting rimfire is my favorite long-time hobby...not an obsession. But I always appreciate your positive re-inforcement.

Gerry

 

[VLNBYR]

I agree 100%. What you have to deal with is the old "garbage in/garbage out" problem. You can't get or expect your results to be any better than the effort you put in. If you don't need top of the A-line results then your 15 5-shot groups are more than enough to tell you what you want to know. I would go with your Center-X and have a goal of getting it to shoot like the results you have with your X-act.

 

[grauhanen]

The difference between 15 five shot groups of .18 ctc and 15 five shot groups .26 ctc is pretty significant to me.

Having now indicated how small the group sizes are, .08" appears to be of significance. Most times, rifles without tuners don't shoot nearly as good.

Any time a shooter without a tuner has 15 five-shot groups are averaging .26" at 50 yards that's very good indeed, regardless of the ammo.

When he shoots 15 five-shot groups that average .18" at 50 yards without a tuner, that's incredible.

The performance of the X-act would be competitive in an ARA Unlimited match with the proper operator (probably not me.)

If I understand correctly, ammo that gives consistent .276" groups at 50 yards can do well in ARA. If the ammo performance described above is improved on with a tuner, it should be more than adequate.

 

[Hi-NV Shooter]

Having now indicated how small the group sizes are, .08" appears to be of significance. Most times, rifles without tuners don't shoot nearly as good.

Any time a shooter without a tuner has 15 five-shot groups are averaging .26" at 50 yards that's very good indeed, regardless of the ammo.

When he shoots 15 five-shot groups that average .18" at 50 yards without a tuner, that's incredible.



If I understand correctly, ammo that gives consistent .276" groups at 50 yards can do well in ARA. If the ammo performance described above is improved on with a tuner, it should be more than adequate.

Yes that is correct on the .276 but that is for a 25-shot group

Lee

 

[shortine]

Yes that is correct on the .276 but that is for a 25-shot group

Lee

Yes, and that single 25 shot group is a lot different than the average of five 5 shot groups. And I'm guessing that's for a "competitive" rifle.

The absolute top "winning" rifles/ammo probably shoot that group in the low 2's if not high teens. Is that the case?

Gerry

 

[grauhanen]

Yes that is correct on the .276 but that is for a 25-shot group

A 25-shot group that's .276" center-to-center would be an impressive group, indeed. A 25 shot group of that size is something near 12.61mm outside-to-outside. There can't be a lot of rifles/ammos that can achieve that even in a test tunnel or at the range. It should be able to produce a very, very good score.

I could be completely mistaken, but it seems that in order to do very well in theory, a single shot must hit within a center-to-center circle no greater than .276" around each individual dot. In other words, the center of each hit must be no further than .138" (half of .276") in any direction from the center of the dot, which is, I believe, about .143" in diameter.

Put another way, as a paper exercise, if an ammo and rifle is capable of producing consistent .276 groups -- even if they are fewer shots than 25 -- that pairing has the potential to do well on the ARA target.

The big problem, of course, is that maintaining consistent .276" equivalent results is very difficult. It must be repeated 25 times, with each shot involving moving to another target.

As noted above, repeatable and consistent .26" groups without a tuner at 50 is a very good achievement. Repeatable and consistent consistent .18" groups without a tuner at 50 is quite fantastic.

Is it possible that a tuner can improve on the .18" averaging groups OP says he gets with X-Act?

 

[VLNBYR]

My rifle and ammo shot 13.4mm out-to-out for a 30 shot composite group at the Lapua Test Center.

 

[grauhanen]

VLNBYR, was there a tuner on the rifle at the time?

 

[VLNBYR]

VLNBYR, was there a tuner on the rifle at the time?

Yes..In stock and ready to go. This combo is winning a lot for me. Hard to imagine anything better.

 

[shortine]

A 25-shot group that's .276" center-to-center would be an impressive group, indeed. A 25 shot group of that size is something near 12.61mm outside-to-outside. There can't be a lot of rifles/ammos that can achieve that even in a test tunnel or at the range. It should be able to produce a very, very good score.

I could be completely mistaken, but it seems that in order to do very well in theory, a single shot must hit within a center-to-center circle no greater than .276" around each individual dot. In other words, the center of each hit must be no further than .138" (half of .276") in any direction from the center of the dot, which is, I believe, about .143" in diameter.

Put another way, as a paper exercise, if an ammo and rifle is capable of producing consistent .276 groups -- even if they are fewer shots than 25 -- that pairing has the potential to do well on the ARA target.

The big problem, of course, is that maintaining consistent .276" equivalent results is very difficult. It must be repeated 25 times, with each shot involving moving to another target.

As noted above, repeatable and consistent .26" groups without a tuner at 50 is a very good achievement. Repeatable and consistent consistent .18" groups without a tuner at 50 is quite fantastic.

Is it possible that a tuner can improve on the .18" averaging groups OP says he gets with X-Act?

The key word here is average. One 5 shot group of .05 and one five shot group of .30 is avg.of .17. That's a great average, but if you stack them on top of each other....ten shot group... it's a .30 or worse. If I had stacked all 75 shots in one group, it would have been significantly larger. If I included the shots where I bumped the trigger, it would not have been good for a factory rifle, but I was testing ammunition, not my own incompetence.

I really like the idea of 25 and 30 shot groups to determine real accuracy.

Gerry

 

[shortine]

My rifle and ammo shot 13.4mm out-to-out for a 30 shot composite group at the Lapua Test Center.

Were you able to improve on that when you got it home?

Gerry

 

[grauhanen]

Yes..In stock and ready to go. This combo is winning a lot for me. Hard to imagine anything better.

That is indeed a great combination. I can only dream of something like that.

 

[grauhanen]

The key word here is average. One 5 shot group of .05 and one five shot group of .30 is avg.of .17. That's a great average, but if you stack them on top of each other....ten shot group... it's a .30 or worse.

That's the truth. A Center X average of .26" referred to above needs more than a few groups below average to ameliorate any groups that are larger. With the X-Act average of .18", there's not a lot of room for groups much larger as .18" is hard to improve on.