Testing was done in 2010 using a Swiss made Bleiker rifle which is well above average, and I'd guess the ammunition manufacturing components and equipment have changed to some degree.
- Thread starter Eoddave27
- Start date
Appears SK's stated velocity is out of a 4-6" barrel.
200 yards, SK Pistol Match Special...impressive eh?
CZ 455 Varmint, Lilja EPS chambered barrel, set trigger, Mueller 8-32x44 target reticle, Sinclair bipod
That's a small sample. Nothing I would rely on for a verification of ammo quality.
Total disclosure, 50 shots, provides much more useful information.
How does this 50 round group rank in your 200yd testing?
Base on the monthly 100/200 match I shoot, considering wind and direction those results should deliver a Top 3-4 position.
Were you shooting using wind flags?
I often shoot 60 round prone training sessions at the Olympic Training Center in Colorado Springs. We shoot on electronic targets that show all 60 shots. The small circles are just the center point of the bullet impact. The last shot actually shows the OD of the bullet. The latest software upgrade corrected this annoyance.
This is 60 shots, aiming center of mass on a rubber 10 inch black bull with no scoring rings or other markings at 50 meters. Just over a 1/2 inch (maybe a touch less) vertical spread and a touch more for windage. For no small aimpoint, I will take it.
Can't argue with those results, all the information is available.
Comparisons between results obtained with large samples allow more accurate conclusions.
Using the ballistic calculator on the SK PMS results at 200 yards,
1064 low, 1104 high should produce right at 4 inches of vertical spread.
Measuring off the image shows 4.5 inches of vertical.
Accuracy limited by the ES, not the wind.
Comparisons between results obtained with large samples allow more accurate conclusions.
Using the ballistic calculator on the SK PMS results at 200 yards,
1064 low, 1104 high should produce right at 4 inches of vertical spread.
Measuring off the image shows 4.5 inches of vertical.
Accuracy limited by the ES, not the wind.
Something I see happening is that temperature plays a big part in how well a 22 rimfire shoots. I can go out one morning and shoot groups, rounds all touching, one after the other at 50Y, with my Lapua PB in my 1827F.
Go out the next day and I cannot produce the same results.
Or in the same day, checking my zero before the match, I will put 5 into low .2's at 50Y, then on the 50Y stage later in the morning, shooting at progressively smaller dots in low winds, and the shotgun pattern displayed is dismaying, even though I'm concentrating on my form as I did while checking zero.
So what I did a few months ago was glass bed my rifle. Two days later I shot two 5 shots groups at 50Y and they were awesome. Went to the match the next weekend, 3 shots into .1" checking zero. Later during the 50Y paper stage, no joy.
I really am thinking of having a tuner installed because there has to be enough fluctuation in velocity to affect the barrel harmonics.
Go out the next day and I cannot produce the same results.
Or in the same day, checking my zero before the match, I will put 5 into low .2's at 50Y, then on the 50Y stage later in the morning, shooting at progressively smaller dots in low winds, and the shotgun pattern displayed is dismaying, even though I'm concentrating on my form as I did while checking zero.
So what I did a few months ago was glass bed my rifle. Two days later I shot two 5 shots groups at 50Y and they were awesome. Went to the match the next weekend, 3 shots into .1" checking zero. Later during the 50Y paper stage, no joy.
I really am thinking of having a tuner installed because there has to be enough fluctuation in velocity to affect the barrel harmonics.
Yeah, not doubt that temperature can play a big part is one's results. I was curious about how much difference and wanted to see some numbers, so I ran a little experiment and posted my results here:
https://www.snipershide.com/shootin...recision-rimfire-barrel.6901759/#post-7248339
Note that I found that different brands didn't act the same. Where one will have a decrease in velocity, another brand will have an increase in velocity as well as a similar difference in SD's and ES's. So, what you shoot well in the summer may not shoot so well for you in the winter.
To which I offer this question:
How do you know if it's temperature related?
Variations in muzzle velocities can be blamed on multiple cartridge problems.
Rimfire quality is not a constant. What is produced on the line at 9:42 am
will not be the same as what is produced on the line at 12:07 pm the same day.
Did the tolerances slip on the case crimp due to wear on the machine?
Was there clumping of the primer compound causing too much in this case, too little in the next?
Were the bullets used from a carefully inspected supply or were they the leftovers from the bottom
of the bin with the weight of the bins topped off load pressing down and crushing them out of shape?
Did the brass come from a machine freshly calibrated?
Or one that was due for an overhaul after a week of continuous operation?
Did powder supply change mid run from one drum to another?
Chemistry of powder and primer varies mix to mix. Burn rates/pressures will change.
It's rimfire...the rated muzzle velocity is only the design average, not a guarantee.
Anyone who has run a ballistic chronograph while shooting rimfire, will attest to that.
How do you know if it's temperature related?
Variations in muzzle velocities can be blamed on multiple cartridge problems.
Rimfire quality is not a constant. What is produced on the line at 9:42 am
will not be the same as what is produced on the line at 12:07 pm the same day.
Did the tolerances slip on the case crimp due to wear on the machine?
Was there clumping of the primer compound causing too much in this case, too little in the next?
Were the bullets used from a carefully inspected supply or were they the leftovers from the bottom
of the bin with the weight of the bins topped off load pressing down and crushing them out of shape?
Did the brass come from a machine freshly calibrated?
Or one that was due for an overhaul after a week of continuous operation?
Did powder supply change mid run from one drum to another?
Chemistry of powder and primer varies mix to mix. Burn rates/pressures will change.
It's rimfire...the rated muzzle velocity is only the design average, not a guarantee.
Anyone who has run a ballistic chronograph while shooting rimfire, will attest to that.
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If you are referring to me, I bought 5000 rounds of the same lot# which were found to be the most accurate in my rifle at the Lapua test center.
Justin, have you looked into the phenomenon called "positive compensation" yet? Many of those guys adhering to this theory are record setting long range benchrest shooters. Who are shooting tighter groups at 600Y and 1000Y than their loads ES should allow for. A lot of those same guys are using tuners to keep the barrel tuning optimal throughout the day as temps change or as tune goes out.
The other thing is the transition from sonic or supersonic to subsonic that can happen with 22's, we're right in the stupid zone half the time. I know the Silhouette shooters were using different 22 ammo's for different distances and we have seen the same thing.
Which is why in that other 22 thread I mentioned it'd be interesting to experiment with 45-50 grain 900 fps match ammo's at different distances. I don't think such a thing exists right now but I could be wrong???
But I certainly agree the ES of 22 ammo is poor as well as the other variants you mentioned. We have no control over them, but that barrel tuning/timing we can control.
Also at matches I see all kinds of 22's malfunctioning and the first thing I think of is - Take the miss, take the miss, ah man dude, don't pick up that dirty and bent up bullet and fire it, lol!!! Or, if a magazine problem exists and it's not feeding well. My point is a damaged cartridge isn't going to do anybody any favors.
Just for conversations sake.
Justin, have you looked into the phenomenon called "positive compensation" yet? Many of those guys adhering to this theory are record setting long range benchrest shooters. Who are shooting tighter groups at 600Y and 1000Y than their loads ES should allow for. A lot of those same guys are using tuners to keep the barrel tuning optimal throughout the day as temps change or as tune goes out.
The other thing is the transition from sonic or supersonic to subsonic that can happen with 22's, we're right in the stupid zone half the time. I know the Silhouette shooters were using different 22 ammo's for different distances and we have seen the same thing.
Which is why in that other 22 thread I mentioned it'd be interesting to experiment with 45-50 grain 900 fps match ammo's at different distances. I don't think such a thing exists right now but I could be wrong???
But I certainly agree the ES of 22 ammo is poor as well as the other variants you mentioned. We have no control over them, but that barrel tuning/timing we can control.
Also at matches I see all kinds of 22's malfunctioning and the first thing I think of is - Take the miss, take the miss, ah man dude, don't pick up that dirty and bent up bullet and fire it, lol!!! Or, if a magazine problem exists and it's not feeding well. My point is a damaged cartridge isn't going to do anybody any favors.
Just for conversations sake.
Steve, I'll take useful information from anyone willing to pass it on.
I've reached the level of informed amateur, but certainly not an authority on firearms or ballistics.
I keep asking questions in hopes of obtaining answers from those who compete at the upper levels.
Supersonic transition is one of those subjects that fascinates me.
I keep reading reports of loss of accuracy with the 22lr and 22wmr due to the transition,
yet the article they relate to the problem, deals with the SMK bthp.
A stubby round nose 22lr/22wmr is not a long, slender, tail heavy bthp.
The physics are not the same. My results on target show no yaw or tumbling,
no real variations in trajectory not attributable to wind/cartridge defects.
Group sizes match the numbers predicted by the ballistic calculator.
If the transition is causing serious accuracy problems with the 22lr/22wmr
then why does the time of flight/gravity/vertical spread match so well?
I noticed this a few weeks back while testing Eley 42 grain 22lr at 200 yards.
One box of subsonic, one of supersonic, group sizes matched the ES.
If the transition was going to show up, here was the perfect opportunity.
The hi-v ammo goes transonic at about 35 to 40 yards and continues down range the remaining 160-165 yards.
Plenty of time for a trajectory shift to be amplified to a visible amount. Didn't happen.
I've reached the level of informed amateur, but certainly not an authority on firearms or ballistics.
I keep asking questions in hopes of obtaining answers from those who compete at the upper levels.
Supersonic transition is one of those subjects that fascinates me.
I keep reading reports of loss of accuracy with the 22lr and 22wmr due to the transition,
yet the article they relate to the problem, deals with the SMK bthp.
A stubby round nose 22lr/22wmr is not a long, slender, tail heavy bthp.
The physics are not the same. My results on target show no yaw or tumbling,
no real variations in trajectory not attributable to wind/cartridge defects.
Group sizes match the numbers predicted by the ballistic calculator.
If the transition is causing serious accuracy problems with the 22lr/22wmr
then why does the time of flight/gravity/vertical spread match so well?
I noticed this a few weeks back while testing Eley 42 grain 22lr at 200 yards.
One box of subsonic, one of supersonic, group sizes matched the ES.
If the transition was going to show up, here was the perfect opportunity.
The hi-v ammo goes transonic at about 35 to 40 yards and continues down range the remaining 160-165 yards.
Plenty of time for a trajectory shift to be amplified to a visible amount. Didn't happen.
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I have settled on Eley Force for PRS style 22 matches. It is cheap for Eley ammo and uses the same lube as Eley CMP so I have even cheaper practice ammo.
Did you go to the link and read how the experiment was conducted and look at the data?
True, the more data points one has the clearer the picture can be. As you've pointed out, there are many variables at play and with this experiment, I tried to keep them to a minimum and keep as many things constant as possible. There was some significant difference in the comparison of that day and could also see the difference from my larger collection of data that I've accumulated (currently having collected 758 lines of data for a variety of 22LR brands and types). I feel the experiment did show that there is a significant different with some LR ammo. But that's all it did as I don't think anyone can take those numbers and rely on them in any way as useful shooting dope.
But, hey . . . I do appreciate your skepticism.
I've been skeptical ever since I found out "find the brand y'er rifle likes" was not true.
Since then I read, then try, then try again until the BS ratio has been determined.
I did look at your numbers.
I didn't see anything in the pdf that couldn't be explained by variations in ammo quality.
Maybe I opened the wrong pdf?
I'm sure not saying y'er wrong either.
It does look like I have another range test to attempt.
What you've done makes sense as heat increases the rate of a chemical reaction.
Cold should slow it down. Another project to keep an amateur busy.
Now I have to figure out how to keep a hot chamber from heating a cold cartridge.
This could be a long, long project. 100 cold bore shots.
That way barrel temp won't affect ignition rates.
Ice pack on the barrel?
Since then I read, then try, then try again until the BS ratio has been determined.
I did look at your numbers.
I didn't see anything in the pdf that couldn't be explained by variations in ammo quality.
Maybe I opened the wrong pdf?
I'm sure not saying y'er wrong either.
It does look like I have another range test to attempt.
What you've done makes sense as heat increases the rate of a chemical reaction.
Cold should slow it down. Another project to keep an amateur busy.
Now I have to figure out how to keep a hot chamber from heating a cold cartridge.
This could be a long, long project. 100 cold bore shots.
That way barrel temp won't affect ignition rates.
Ice pack on the barrel?
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I think all the negative detractors you've already pointed out make the transition lost in the noise, so to speak.
Some 22 bullet shapes could behave differently during transition. Say we shot a not so optimistically shaped bullet that was subsonic to begin with, then shot a supersonic bullet more suited to transition well, both for groups at different distances, it might be that they could still group similarly???
I don't pretend to be anything but less amateur than you are. I often see things while living here on earth that don't add up. The professional explainers have to get their grant money so any plausible theory will do, right???, even if it's off, but that's not to be questioned. Half the time I'm thinking to myself, yeah right, those stories they're giving us are facts, sure, because the smart guys were actually there back then. Me - no it's theory, and they can't say otherwise, it can't be proven one way or the other, but it's right there in the text books stated as absolutely 100% true. That is until they change their mind, then that new theory is not to be questioned either.
I wonder how the part of the 22rf bullet that is in the case, that round part, affects bullet flight at the longer distances, compared to a normal bullet, at the same speeds??? Maybe there is something to it that upsets the bullet???
I don't know, again, I'm just taking a stab at other possibilities.
Now I have to figure out how to keep a hot chamber from heating a cold cartridge.
This could be a long, long project. 100 cold bore shots.
That way barrel temp won't affect ignition rates.
Ice pack on the barrel?
This was an issue that had concerned me and why I proceeded with the method that I did. I decided to I fire each cartridge before the chamber has a chance for transferring much heat to the cartridges. To do that, I would hand load the cartridges by hand and fire it as soon as the chamber was locked down . . . NO AIMING. So, there was very, very little time for the chamber to transfer its heat to the inside of the cartridge. The experiment wasn't about accuracy, and I just wanted chrono data to look at for evaluation. As for the effects of barrel heat on the ignition event as the bullet travels through the barrel, I don't think there was enough variation in barrel heat that can provide anything measurable (plenty of time between firings to keep it somewhat constant).
As expected the average MVs were way low and at the slowest end of the data I have for Sv's and Ultra Match, but interestingly to me . . . not so for Center X, which maybe a little lower but not discernibly. The stand out surprise to me was the numbers showed SV's improving substantially and Ultra Match getting substantially worse in terms of ES and SD when they were cold. For Center X's it didn't seem to matter (at least for the temp differences I used). BTW, I chose these three makes of cartridges since they are among the most consistent that I have.
Ice pack on the barrel for cold bore shooting experiment might indeed be interesting . . . where it might help some in quantifying how different lubes might affect those first shots particularly???
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Wolf match used to be the gold standard for inexpensive target ammo. I guess SK has taken it's place. Supposed to be the same stuff.
@willicd76- wolf used to be repackaged SK, now it is not....
Wolf MT and ME are now manufactured by Eley.
Decent MV's/ES in the few boxes I've tried.
Decent MV's/ES in the few boxes I've tried.
I
I presume this is indoors? Did you use a sling?
All ISSF positional rifle shooting is done supported with a sling while in the prone and kneeling positions. No slings are allowed during the standing stage of a 3 position match. No bipods or other artificial support is allowed, ever.
50 meter matches are shot both indoors and out. I believe World Cup and Olympic finals are always indoors to remove one variable that the shooter can't control. Hoser will have to say where he shot his target.
No measuring instrument has perfect precision or accuracy. Precision is related to resolution and accuracy to calibration. How accurate are the muzzle velocities?
Theoretical predictions also have imprecision, not from the mathematics per se but from the applicability of the equations or uncertainty in the value of the input variables. A graphical comparison of theory and experiment should contain two sets of error bars, one from observation and one from prediction. The degree of overlap provides a measure of confidence in any conclusions. If there is no overlap, back to the drawing board.
Theoretical predictions also have imprecision, not from the mathematics per se but from the applicability of the equations or uncertainty in the value of the input variables. A graphical comparison of theory and experiment should contain two sets of error bars, one from observation and one from prediction. The degree of overlap provides a measure of confidence in any conclusions. If there is no overlap, back to the drawing board.
Maybe you should shoot more and theorize less? I haven't seen you do much shooting at all in the shooting thread you started.
Thanks for the intel.
Dry fire in the Late Fall and Winter. Live fire in the Spring and Summer. If that range at the Olympic Training Center is indoors and public could use it, would shoot all year round. And to be with superb positional shooters, that is heaven on earth.
Most people do not have formal education in physics so perhaps I can bring something to the table that might interest some people. Not interested do not read my posts. Also does not appear most people do positional shooting. Not surprising as this is Snipers Hide so people do sniper shooting. Will start a thread in the Spring using a competition rimfire benchrest. This is as close as I can come to using a rail gun support. Rail gun support and standing offhand, the two ends of the support spectrum.
I learn a lot reading posts since no little about the practical aspects of firearms. By the way in the Winter I pursue my intellectual hobbies, advanced mathematics and physics. Good stuff.
Merry Christmas and All the Best in 2019.
Rick
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How does that prevent you from participating in your own thread? I enjoy traditional positional shooting and that's why I participated in your thread.
I couldn't give a rat's ass if no one else here likes that kind of shooting. Isn't going to stop me from doing it.
At 50 yards out of my rifle, the difference between CCI sv and Lapua center x is pretty hard to tell. But, at 200 yards, the center x really shines. And, if you are shooting 1/4” targets at 50, center x may be better for that as well. I can say that with cci sv through my Kidd super grade, i hit 50 of 74 targets at my first 22lr match. Everything over 100 was a crap shoot. Changing to center x for my second match, I hit 72 of 74. That’s 5th place to 1st place. I’ll buy the cci to practice and shoot with the kids, but shoot the center x at matches...
@rick137
Theoretical Physics, pretty graphs and statistical predictions have little to do with your stated interest of Positional Rimfire shooting. If you want to get good at 3P you need to learn-
1. How to build stable positions to include body mechanics, adjusting your Natural Point of Aim, adjusting the rifle to you, and adjusting the sling
2. Burn a couple cases of small bore ammo practicing the shooting fundamentals with the above in mind
3. Actually read the rule-book @308pirate keeps referring you to
4. Go to the Oregon State Shooting Association web page lookup the Small bore and Air Rifle Schedule and reach out to the match directors to see if there is a competitor in your are who could coach you a little, the learning curve will be much steeper
5. Go shoot the small bore matches on the schedule, this will teach you far more than internet interactions or pseudo-science theorizing, talking with real small bore competitors and shooting the matches, learning will occur.
Theoretical Physics, pretty graphs and statistical predictions have little to do with your stated interest of Positional Rimfire shooting. If you want to get good at 3P you need to learn-
1. How to build stable positions to include body mechanics, adjusting your Natural Point of Aim, adjusting the rifle to you, and adjusting the sling
2. Burn a couple cases of small bore ammo practicing the shooting fundamentals with the above in mind
3. Actually read the rule-book @308pirate keeps referring you to
4. Go to the Oregon State Shooting Association web page lookup the Small bore and Air Rifle Schedule and reach out to the match directors to see if there is a competitor in your are who could coach you a little, the learning curve will be much steeper
5. Go shoot the small bore matches on the schedule, this will teach you far more than internet interactions or pseudo-science theorizing, talking with real small bore competitors and shooting the matches, learning will occur.
I'm sure he'll have a reason to refute every one of your five excellent suggestions.
Kinda of a long commute from Eugene, OR to Colorado Springs ain't it?
Prone, Atlas bi-pod, S&B 12-50, TBAC Ultra 7 and a magical lot of Eley (Blue) Team. Just having fun at the Olympic Training Center. Not everything has to be coat and sling. But the ISSF target is very unforgiving as far as the 10 ring goes. Even more-so holding center of mass on a big black blob of a target.
Every one excellent.
I'd not had a bolt repeater that would feed any of the flatnose match ammo up until I bought the Kukri & Ranch bbl'd actions from VGW. I'd tried Eley Match EPS & Tenex in my Anschutz 2011, but had been disappointed with the accuracy compared to that of SK & Lapua ammo, so pretty much set aside the lot samples I'd purchased 9-10yrs ago & forgot about them.
Then last weekend, while a friend I'd sold a Bartlein Kukri bbl'd V-22 action to was out here to do some 600-1000yd shooting with his 6x47Lap on Saturday, we had favorable conditions on Sunday for 22RF shooting, so did some 200yd shooting with our V-22s, I tried a couple of lots of the 10yr old Match EPS, as well as a lot of Match that I'd bought from Brownells a year ago. Up until now, the only ammo I'd had any real confidence in at 200-300yds was Lapua Polar Biathlon, but at least at 200, one lot of the Eley EPS & newer Match shot a couple of 10rd groups that beat anything I'd shot before. Sooo....now I'm wishing I had a full case of the lot of Eley Match I bought last year - have three boxes of it, so will be saving that little dab for use at 200-300yds next spring. Will be looking into trying more samples of Eley Match this winter, as well as doing some shooting today with some SK Flatnose Basic that came in yesterday. I also bought some Eley Edge last year, so some of that needs to be run through the Bartlein Kukri V-22....off on another turd hunt for better LR 22RF ammo.... Should mention that both the Eley EPS lots I shot last weekend hit at least .2 mil higher on steel at 200 than any of the SK, and perhaps a little higher than even Polar Biathlon, which is usually .2 - .3 mill higher than Center-X or SK. Either the Eley's MV is considerably higher than SK/Lapua, or that dimpled flatnose bullet has a higher BC, or perhaps it's a little of both factors. One short range session raises a lot more questions than it answers.
Then last weekend, while a friend I'd sold a Bartlein Kukri bbl'd V-22 action to was out here to do some 600-1000yd shooting with his 6x47Lap on Saturday, we had favorable conditions on Sunday for 22RF shooting, so did some 200yd shooting with our V-22s, I tried a couple of lots of the 10yr old Match EPS, as well as a lot of Match that I'd bought from Brownells a year ago. Up until now, the only ammo I'd had any real confidence in at 200-300yds was Lapua Polar Biathlon, but at least at 200, one lot of the Eley EPS & newer Match shot a couple of 10rd groups that beat anything I'd shot before. Sooo....now I'm wishing I had a full case of the lot of Eley Match I bought last year - have three boxes of it, so will be saving that little dab for use at 200-300yds next spring. Will be looking into trying more samples of Eley Match this winter, as well as doing some shooting today with some SK Flatnose Basic that came in yesterday. I also bought some Eley Edge last year, so some of that needs to be run through the Bartlein Kukri V-22....off on another turd hunt for better LR 22RF ammo.... Should mention that both the Eley EPS lots I shot last weekend hit at least .2 mil higher on steel at 200 than any of the SK, and perhaps a little higher than even Polar Biathlon, which is usually .2 - .3 mill higher than Center-X or SK. Either the Eley's MV is considerably higher than SK/Lapua, or that dimpled flatnose bullet has a higher BC, or perhaps it's a little of both factors. One short range session raises a lot more questions than it answers.
the Eley's MV is considerably higher than SK/Lapua
Don't trust the labeling on the box.
Quite often there are major differences.
The label is the design average or the factory lot tested average.
I've found the label mv and the measured mv to be two totally different things.
I was setting up my 455 Varmint Lilja a while back, when one of the 50 yard benchrest competitors walked up.
The locals know I always shoot across a chronograph at the range.
Test these for me, would you? Something isn't right. New order of Tenex and they are all over the target.
Partial box of Tenex and a brand new one labeled 1058 fps to test, lucky me.
200 yards and 50 shots at a single aimpoint.
Sent 20 to season the freshly cleaned Lilja, then sent 50 at the sight point.
Chrony kept track, not bad, but a higher mv than the Annie likes with it's tuner.
1111 fps hi, 1093 avg, 1081 low...only 30 fps ES
This batch of Tenex was shooting like cold weather biathlon ammo...mislabeled box maybe?
The muzzle velocities didn't fit the annie's harmonics and were showing undesired vertical spread.
With my bedded barrel the differences in mv average have minimal effect on the results.
With a bench rifle and tuner set for a specific range of velocities, problems can occur.
Don't trust the labeling on the box.
Quite often there are major differences.
The label is the design average or the factory lot tested average.
I've found the label mv and the measured mv to be two totally different things.
I was setting up my 455 Varmint Lilja a while back, when one of the 50 yard benchrest competitors walked up.
The locals know I always shoot across a chronograph at the range.
Test these for me, would you? Something isn't right. New order of Tenex and they are all over the target.
Partial box of Tenex and a brand new one labeled 1058 fps to test, lucky me.
200 yards and 50 shots at a single aimpoint.
Sent 20 to season the freshly cleaned Lilja, then sent 50 at the sight point.
Chrony kept track, not bad, but a higher mv than the Annie likes with it's tuner.
1111 fps hi, 1093 avg, 1081 low...only 30 fps ES
This batch of Tenex was shooting like cold weather biathlon ammo...mislabeled box maybe?
The muzzle velocities didn't fit the annie's harmonics and were showing undesired vertical spread.
With my bedded barrel the differences in mv average have minimal effect on the results.
With a bench rifle and tuner set for a specific range of velocities, problems can occur.
You're absolutely right.
The published MV's on or for any box of ammo does nothing more than serve as a loose guideline. MV's are affected by many different factors (e.g. barrel length, barrel material, barrel design, chamber configuration, etc, etc.). For example, I swapped out my target barrel for a match barrel and with my match barrel I was getting 40-45 fps more using Center-X and similar differences with other ammo.
You can't even test someone else's ammo in your gun and give them what they can expect out of their own gun (even as much as the guns seem identical). The best you can do is take a good measured samplings out of the lot(s) of ammo you have and go by the MV you've measured (and hopefully, you're using a chrono that somewhat accurate and consistent).
I'd never chrono'd any of the Eley stuff I mentioned in the above post, but had run my current stock of SK & Lapua lots over the screens. The Polar Biathlon ran a tad faster than any of the other SK or Lapua, but I believe the different bullet shape's higher BC contributes as much as the slight velocity difference at 200 & 300yds. I've seen it listed at .162, while SK Rifle Match & Lapua Center-X were both listed at .154~.155 from the same source. Haven't taken the time to go looking for the BC of the Eley EPS, nor the newer SK Flatnose yet.
I got out today and had a chance to test the ammo I picked up out to 300 yards. The SK Pistol Match Special was the winner. Some of the other ammo I had shot just as good but was about twice the price. I started out at a fairly sheltered 100 yard range and then moved to an open range where we were getting wind from 10-15 mph which made shooting pretty interesting.
