Lot Testing Theory

[BAJ]

Hi everyone,

I would like to start by divulging the fact that by discipline I am a smallbore position and prone shooter. I do not compete in benchrest competition, but I try to stay on top of the current developments in benchrest.

Anyway, whether it be in position shooting or benchrest shooting, everyone I know tests different lots of ammo to find which one shoots better. I have done, my fair share of ammo testing over the years, from the bench, in position etc and fully understand that certain ammo shoots better in my rifle then others. Accepting this as fact, the question arises, what makes that particular ammo shoot better in my rifle than others? Often times the obvious answer lies in the grade of ammo being used. Certainly I would not expect SK Standard plus to shoot better than my Eley Tenex, simply from a tolerance in manufacturing standpoint. Now when you take the manufacturing tolerance differences out of the equation what is it really that makes two different lots of the same grade ammo shoot differently?

Personally, I believe that if you are shooting a quality grade ammo, like Eley EPS, there is no superior difference in lots. This goes on the assumption that the ammo has been made to the same exacting tolerances. Basically you aren't going to have two lots of Eley EPS with one shooting 0.265" groups and the other shooting 1.5" groups. If you do then you are just extremely unlucky or something is broken. Now you might have two different lots with one shooting 0.265" groups and another shooting 0.305" groups. Since the one lot had groups 0.040" larger than the other, does that mean the ammo is crap? Personally, I don't think so. With quality ammo, I think the only difference seen in lots is that one lot by chance more closely matches the ideal harmonics of your rifle than another. With tuners and torque settings, however, the harmonics of the rifle can altered. So by changing the torque around on my bedding screws or my tuner settings, I can completely reverse the above test making the lot that shot bad the first time shoot the best out of the two. With this in mind what is the point in testing lots? If you are using quality ammo, with a little bit of experimentation and tweaking, you can change the way the ammo shoots in your rifle to better suit your needs.

Maybe this doesn't apply to benchrest the same as it does position shooting, but I have never had a quality ammo that I could not at least get groups out of, which I could stuff inside the 10 ring. I don't know how big of a 10 ring ya'll have, but in international smallbore rifle at 50 meters it is 10mm.

I probably made to many assumptions, so tell me what ya'll think.

Brian

 

[Tom C.]

prepare for incoming rounds.
we just lot test for something to do and to have
something to complain about. thanks for setting
us straight.

 

[Peter Armstrong]

Brian,
I’ll think you’ll find that BR shooters test lots for the same reason that the better smallbore shooters go to the ammo factories and test lots. Same lots are better than others and you need to find the lot that works in your barrel. I take it you’ve never seen a printout of a smallbore rifle tested at the Eley factory, if you had you wouldn’t think all tenex is the same.

As for SK, you can find good lots in that too but you do need to test, in July I was at the Lapua factory in Germany (I live in Australia) and I found a lot of SK match that shot on par with all the X-Act I tested there.

Peter

 

[Bill Wynne]

Brian,

Watch out! Here is a round incoming.

First, I would like to say that I have to tip my hat to a position shooter. Most of us rimfire benchrest shooters could not come close to your skill and we know it.

That being said, we rimfire benchrest shooters are reaching for the ultimate in accuracy. Our game is even more a test of equipment and ammo than your game. With our great one piece rests and 36 power scopes and four to six wind-flags we can out shoot your discipline. (It 's not braggin' if you can do it.)

In 50/50 our ten ring is about 6 mm compared to your 10 mm. We could shoot a lot more 250s if our 10 ring were 66% larger but it would not be as challenging . In our game the best shooters do lot test. It makes a difference. I really don't know if it would be worth the effort in your game to lot test. It would not help me very much.

Concho Bill

 

[tim]

Well most I know in BR test ammo which boils down to the fact that barrels have distinct preferences, and I swap lots of ammo and info with a nationally ranked prone shooter who does the exact same thing.

 

[Joe Haller]

Incoming rounds ain't much fun when it's artillery or mortars!

Finding a lot of ammo your rifle likes is real FUN! But the fun can depend on the temperature.

UP here on the Canadian Border, many of our club matches are shot at temperatures below 55 degrees. When that happens, we shoot the faster speeds of Eley Black Box and Biathlon. I still have some Federal 1000A (1140 FPS) I use when it's below freezing UP here. A few of our shooters test by lot number, but tuner setting, temperature and ammo speed are more popular at our club.

I was a prone/position shooter before I got OLD, fat and lazy. Benchrest is a good option for anyone who lives long enough to experience 2 out of 3 of those symptoms.

Joe Haller (Mr. Frosty)

 

[Pete Wass]

On RF Tuning:

Could you please explain what you are saying about making ammo shoot in a rifle by adjusting bedding screws? Does this apply to BR rifles that are Pillar Bedded?

Thanks,

Pete

 

[1813benny]

Could you please explain what you are saying about making ammo shoot in a rifle by adjusting bedding screws? Does this apply to BR rifles that are Pillar Bedded?

Thanks,

Pete

By changing the torque on the action screws, you can change the performance of a rifle. Essentially, you are changing the harmonics of the action.

Every rifle is different, and the change varies from one rifle to the next. In some, the change is significant while others it is marginal at best.

 

[pacecil]

I think what BAJ somewhat may be trying to say is that good ammo is VERY VERY good. The variation within a lot and the variation between lots is so small that it's just kinda hard to believe a shooter might accurately be able to measure this difference. Maybe if he carefully fires enough rounds he could find it but by this time the lot is probably all shot up! Most shooters want to believe their rifles are capable of reacting in some way to the little variation but again, it's so hard to accurately measure the very small difference, I think the normal shooter will, after a lot of shots, come to some point at which he believes he's found the best lot and he'll just go from there. Or.....what is more likely to happen, he will only shoot a few shots and simply take the results to indicate one, or the other, lot is better and thus go with it. Bottom line is....the very good ammo is so good you will get good results no matter which lot you shoot!

 

[martin hammond]

Brian,
I’ll think you’ll find that BR shooters test lots for the same reason that the better smallbore shooters go to the ammo factories and test lots. Same lots are better than others and you need to find the lot that works in your barrel. I take it you’ve never seen a printout of a smallbore rifle tested at the Eley factory, if you had you wouldn’t think all tenex is the same.

As for SK, you can find good lots in that too but you do need to test, in July I was at the Lapua factory in Germany (I live in Australia) and I found a lot of SK match that shot on par with all the X-Act I tested there.

Peter

what is gained testing sending a rifle to eley or lapua, shooting at 54.68 yards. coming home and shooting lots that were tested by the manufacturers at 54.68 yards tested in a rifle at 54.68 yards that was tuned at 42 yards and the goal all along is shooting 50 yards. I don't get it.

 

[Peter Armstrong]

what is gained testing sending a rifle to eley or lapua, shooting at 54.68 yards. coming home and shooting lots that were tested by the manufacturers at 54.68 yards tested in a rifle at 54.68 yards that was tuned at 42 yards and the goal all along is shooting 50 yards. I don't get it.

Martin,
It might be hard to understand, but international rimfire BR matches are shoot at 50m not 50 yards.

Peter

 

[martin hammond]

Peter, thank you. that's exactly my point. other than getting tenex before the chinese get it, what is the point or advantage of an american testing in any eruopean facility?

 

[martin hammond]

Peter, let me phrase this differently. as a international bench shooter what advantage is it to: purchase a rifle shot and tuned at 38.4 meters then, purchase ammo shot and tested at 50 meters, compete at 50 meters return to the states and shoot at 50 yards? or is their no advantage of any of this? thank you. martin hammond

 

[tonykharper]

Peter, thank you. that's exactly my point. other than getting tenex before the chinese get it, what is the point or advantage of an american testing in any eruopean facility?

Martin, I'll take a shot at your question. If it don't shoot in your rifle at the factory, no matter where that might be, it probably won't shoot here. But if it does, you at least have a chance it will shoot here. I would love to be able to test all the ammo available in my rifles before commiting funds.

 

[HuskerP7M8]

I’ll take a shot (pun intended) at this also.

Earlier this year over about a 3 month time frame, I fired approximately 1,000 shots in my tunnel across dual calibrated chronographs with four different Bench rifles and 25 various lots of Lapua/Eley ammo. The rifles were fired both with and without muzzle weighting, but no attempt was made to find an exact tuner setting.

Every shot fired was plotted to a location on target accurate to about 0.005” with its matching velocity. I’ve provided an example taken at random of a 25 shot group that visually illustrates what some of that data looks like with the color coded data points having a minimum of 40 ft/sec in ES:

Don’t try to read anything special into this sample specific testing result or draw any conclusions about velocity/vertical dispersion because it didn’t always repeat and this particular ammo is some of the most inaccurate I’ve ever tested. But, it was useful for some of my testing because it also has the most variation in speed I’ve ever encountered with match ammunition. I had to acquire the data from several hundred shots before I thought I could see some trends I had much confidence in.

The point I’m trying to make is that there will be both vertical and horizontal dispersion not attributable to velocity variation or muzzle weighting and lot testing a large enough sample is effective for picking the best ammo regardless of distance or tuning. Even if you totally disagree with the tuning aspect for dispersion in the y plane and whether it’s distance specific....the x-axis dispersion is equally important and just might be the best indicator of ammo quality.

Landy

 

[Peter Armstrong]

Peter, let me phrase this differently. as a international bench shooter what advantage is it to: purchase a rifle shot and tuned at 38.4 meters then, purchase ammo shot and tested at 50 meters, compete at 50 meters return to the states and shoot at 50 yards? or is their no advantage of any of this? thank you. martin hammond

Martin,
Testing at the factory is good fun, I took a few new barrels, tested about 70 lots of ammo and selected what I wanted and when that runs out I’ll go back and do it again.

Why go to trouble, first doing it this way is cheaper than buying lot after lot to test plus the odds of finding a killer lot are better. People have asked how many lots I needed to test to find a good one, in my case it was about 1 in 40.

I don’t understand what you are going on about tuning at 42 yards etc, I tune, test and shot matches at 50m and sometimes 100m. Once I get dialled in I don’t play with the tuner any more and I’ll shot 50 yards to 100m at the same settings and still win.

Everyone has there own ideas on what works and what doesn’t and that is a good thing, but I think matches results are the best way of working out whose theories are really working best. How is the match part working out for you???

Peter

 

[martin hammond]

Peter, thank you. everything has a new perspective. I now realize I had a good year and could have been considerably worse if, my rifle was tuned for 50 and 100 meters. thank you.

 

[Joe Friedrich]

Peter, there is no nice way of saying this the matches this year sucked! when the other shooters walked by my station they commented about my ammo sitting in the sun, how else was i to loosen the lube on ammo mfg. in 2005 or the 2 bricks of USA ammo? that's how some of us competed this year after eley threw the screws to us. all year one brick of eley mfg in 2009. about your tuning and such being able to shoot at 50 meters and 100 meters without touching the tuner? it's not suprising to me you went thru 70 lots to find what you wanted. do you honestly think eley produced that much ammo that was not conducive to your rifle? is it the science and engineering that wins in the end or the money? if it's the money it keeps going and going.

Martin,

First off I commend you in your application of how to tune your rifle, BUT your lack of getting new ammo, because Eley put the screws to us is just not so. The shipment that came in before this one is some of the best I tested in awhile. You can't complain about not getting ammo it's there, there is a new shipment that just came in, my advise is to give Dan Killough a call and put yourself on his mailing list, the only other thing i can assume is you like getting the old stuff to work in your rifles. If you really want to test your theories on tuning, the ammo is there if your willing to make the calls.
I state this with all due respect. The choice is yours to make.

Joe

 

[Joe Friedrich]

Peter, there is no nice way of saying this the matches this year sucked! when the other shooters walked by my station they commented about my ammo sitting in the sun, how else was i to loosen the lube on ammo mfg. in 2005 or the 2 bricks of USA ammo? that's how some of us competed this year after eley threw the screws to us. all year one brick of eley mfg in 2009. about your tuning and such being able to shoot at 50 meters and 100 meters without touching the tuner? it's not suprising to me you went thru 70 lots to find what you wanted. do you honestly think eley produced that much ammo that was not conducive to your rifle? is it the science and engineering that wins in the end or the money? if it's the money it keeps going and going.

Martin,

First off I commend you in your application of how to tune your rifle, BUT your "lack of" getting new ammo, because Eley put the screws to us is just not so. The shipment that came in before this one is some of the best I tested in awhile. You can't complain about not getting ammo it's there, there is a new shipment that just came in, my advise is to give Dan Killough a call and put yourself on his mailing list, the only other thing i can assume is you like getting the old stuff to work in your rifles. If you really want to test your theories on tuning, the ammo is there if your willing to make the calls.
I state this with all due respect. The choice is yours to make.

Joe

 

[Slick Willy]

Martin, I bought ammo on each of the four previous shipments in 2010,the 5th is now here and will be distributed to all ,next week. There has not been many chances for test lots,if that is the problem,but I`ve gotten ammo from Dan and BOB. The speed at which one has to react is very critical to getting it. Most shooters bought blind with no test lots and the Black box is gone in the blink of a eye. Act now ,or your chances will gone by the end of next week or sooner! Don`t get mad, buy now!