High $ ammo

[jerber]

Got to try the Tenex
Grouping was pretty good but then again maybe I was having a good session!
I did have a small glitch
On my second magazine load
The first round would not feed?!?
I took the mag out,reinstalled it and could not get it to feed
I forced it a little and went in
Everything was fine after that
First time anything like that happened
Got good results but I think I need to shoot more than a box to really make a comparison
Will I buy Tenex again? Well maybe not now
I'm going to stick with the target or the CCI for now

[morten]

Here's a 22Lr ammo test done by a Swedish gun magazine in 2009

They placed an Hammerli SP20, Pardini SP and Feinwerkbau AW93 in a ransom rest, shooting at 25 meters (27 Yd,) center fire target.

At least it should give you some indication on how the different ammo performs.


http://hem.bredband.net/nfdt/22lr/09/index.html

If you place your cursor over one of the targets, you will see some numbers.

First number is grouping size in milimeters
The second number is average speed in Meters per Second
Third number is standard deviation (?? what ever that meens, measured in milimeters)



There's also a test from 2005 where they used a Sako TriAce, Unique DES 69, and a Walther GSP

http://hem.bredband.net/nfdt/22lr/index.html

[jenrick]

Standard deviation is basically how big the range of variance is. A lower standard deviation means a lower variation. For example if the average velocity is 320 m/s, and the standard deviation is 5 m/s, then approximately 70% of that ammo will be withing 5 m/s of the average. A large S/D means that you'll get wild variances. For example an average 300 m/s velocity with 100 m/s S/D means one round can be 200 m/s and the other can be 400 m/s. This of course will make it incredibly difficult to get any accuracy out of that round. Conversely a 300 m/s average with a 1 m/s S/D is probably going to be pretty accurate everything else being equal.

Thanks for the links.

-Jenrick

[Rover]

You would think it does, but a wide SD is not necessarily reflective of the ammo's accuracy.

[rigwhanson]

My philosophy is to use the best gun that I can buy and ammo that will at least shoot a small 10 ring group. I have found that less expensive ammos will shoot x ring in many guns, depends on your barrel. I don't think that using a ammo that does not group well because you cannot hold that small is a bad philosophy. If you have correct trigger pull habits and let your subconscious control the shot release you will shoot groups that are tighter than you can hold even though you may be moving a fair bit. By saying this I am not suggesting that it is not better to have a smaller steadier hold because it certainly is. However you can shoot some really small groups at 50 yds with the correct technique in running the trigger and your mind.

[Zipp0]

Hey Morten, great link - the pictures give me flashbacks.

Although not an expert in these matters - I recently spent some quality time with a Ransom Rest and a bunch of ammo - including 4-5 lots of Tenex Pistol, Practice, Rifle, SK Standard Plus, RWS and a few odds and sods run separately through Pardini SPs. I had expected Tenex Pistol (the most expensive ammo we had) to shoot the pants off the rest (so to speak). However, not the case. My earned advice would be to test as many types you can find (by lot number) and when you find a great shooting lot - buy it.

A variable we did not test (or plan to) is the consistency of a lot over several boxes. A couple of lots of SK Standard Plus out performed the Tenex Pistol (which runs at over three times the price) and one thought was that maybe the cheaper ammo had a higher frequency of 'outliers' within the lot, ie a 1-in-100 outlier or a 1-in-200 so that maybe the value of the primo ammo (and the (wallet-emptying) mental health that goes with it) is the consistency over 100s of rounds that tests and comparisons of sample sizes of 10-20 rounds do not uncover. To do that we would have to acquire $200 worth Tenex (maybe using two lots of 200 rounds each), similar quantities of other ammo and design a robust statistical test employing excellent method (maybe double blind requiring division of duty). Not for the faint hearted.

As a side note - we (independently) noticed that the first shot of a string (from our SPs) appeared to generate outliers (mostly high). I am aware of the 'more boys get born during a full moon' statements but we all mentioned that 'something was going on with the first shot'. I realise that we need a robust test to determine if the observations have statistical merit but it encouraged us to 'double down' on our shot-preparation method for consistency and one factor I tried to eliminate was 'chambering velocity' by inserting the magazine of the next string when the last shot of the current string was chambered so that the round would be 'auto-loaded' as opposed to a manual release of the slide (which is an obvious difference in the way we were shooting strings). It seemed to smooth out the results but we need a robust test to determine if the conclusions from our observations have significance.

Anyone else noticed this? - see the attached photo.

thanks

~zip

[jenrick]

The issue of minute differences in barrel lock up and seating was always one of the arguments of why theoretically revolvers were more accurate then semi-autos. Same for bolt action rifles over semi-auto rifles.

Does the Pardini use a buffer system at all? That I can see would definitely give a different slide velocity depending on if the gun was hand cycled or not. Recoil spring weight and wear could also be a factor. I'd replace the recoil spring and buffer if so equipped and see what happens.

If the spring was very heavy I can see it causing issues as well. If the recoil of the cartridge normally doesn't fully compress the spring, the energy the spring supplies to action is specific to the amount of energy each cartridge supplied it with under recoil. Manually working the action is highly unlikely to get it tot he same spot as firing a cartridge is, so you'll have a different amount of energy seating the cartridge. I can't imagine an Olympic style pistol being that heavily sprung though.

-Jenrick

[Ricardo]

Allow me to nerd out. The 9-ring is about 42% greater in area than the 10 "ring", which is really a circle. So if you always shoot within the 9-ring (randomly) you would hit the 9-ring 42% more often than the 10. For a 60-shot AP or FP match this translates into a score of about 565. At this level, a defective round that misses by one scoring ring will help you about as often as hurt you. If this is true, then ammo that groups within a circle no wider than the width of a scoring ring should be acceptable. For FP this means that ammo grouping within 25 mm at 50 m is dandy for a shooter with an average score of 565. For AP, a grouping of 8mm should be good enough. Why do I care (I shoot way below that)? I'm just trying to figure out how the numbers compare to y'alls opinions. For my competence level I can probably do swell with ammo that groups within 2 inches for rimfire, 16 mm for pellets. Unless my math is wrong.

[deadeyedick]

Your maths are not wrong Ricardo.

[jenrick]

What you're looking for is the Circular Error Probability (CEP), with a given round. Basically it's the statistical calculation of the shot variance from the point of aim, and gives a result of the radius of a circle that 50% of the rounds would fit inside (n). Doubling that distance (2n) would statistically put 93% of all fired rounds into a circle with that radius, tripling the CEP (3n) will statistically include approximately 99.7% of all rounds fired of that ammo.

The following math presumes that the group is centered on the Point of Aim.

A 10 shot group that puts all it's round into say a 50mm group would have a CEP of about 16.66 mm if it had a "normal distribution" (there's a technical term for when you're dealing with variances in a circle, but normal distribution will suffice for this). With a CEP of 16mm that means the 5 shots closest to center (50% of a 10 shot group) should be in group 16mm or less. If the whole 10 shot group is say 17mm across that means the CEP is about 5mm, or group of 5 rounds barely bigger then bullet diameter (ie almost all 5 through the same hole). A group that is 25mm (a scoring ring) in size, will have a CEP of approximately 8.33mm. So approximately 93% of the rounds will shoot into a 16.66mm group, still holding the X basically.

Ammo which shoots under 75mm (approximately 3") in an average group, will put 93% of it's fired rounds statistically into the 10 ring assuming a dead on hold and nothing other then ammo variance's effect the shot location. That's 55.8 10's or X's, with statistically the other 4-5 shots landing in the 9 ring. So basically a you'd be looking at shooting a 595 or 596. Real world if you can vice/bench your gun and put your rounds into a group under 75mm, the only thing keeping you from setting a world record and winning a gold medal is simply your ability to aim and hold. Using the 565 score threshold, we'd need a group of approximately 90mm (approximately 3.5") in a viced gun to statically come in somewhere around that score.

For 10m air pistol, a 17mm group of pellets should shoot dang close to a perfect score viced/benched. If they group into about 20.625mm (approx .81 inches) it should shoot about a 565 assuming you shoot perfectly (or use a vice).

The more rounds you can fire in a given group the better the data is to generate statistics and predict things. Ideally you could fire all but the 60 rounds you need for you next match from a given factory lot of ammo (however many thousands of rounds of ammo that is), this would give you the best indicator. Real world that's not feasible. I'd recommend no less then 10 rounds, and ideally 60 out of every 500 round brick of .22 ammo. It's highly unlikely you'd see an outlier that's off far enough to clear the expected scoring ring for a given CEP. For air pistol the rings are so small, you'd really have to bump up your sample size to have the same assurance, to 125 pellets roughly out of every tin of 500.

So in short, if it groups better then 75mm in .22 or 17mm in pellets when shot out of a vice, the shooters ability is what's keeping them from a world record or gold medal. If you goal is to shoot at least a 565, then your ammo had better group better then 90mm/20.625mm out of a vice, or due solely to ammo variance you can do everything right and still not shot a 565.

It's been well over 15 years since I took a stats class, but from the best I recall the math above should be correct.

-Jenrick

[Ricardo]

Jenrick, that was very cool. I knew that either stats or calculus would be needed to do this analysis properly, and I'm guessing that calculus was involved in figuring out the statistical rules. Bottom line then, as many agree: if your ammo doesn't actually suck, more rounds at the range beats more dollars. And for outstanding shooters the thing to watch for is the number of outliers rather than group size. I think it's good to have some numbers to back up an opinion.

[deadeyedick]

These calculations have been done before, however many people still want to believe that a "magic bullett" has to be an expensive one.

The "magic" is gained from contacting a coach to identify faults in a shooters technique then practising to eliminate them.

[jenrick]

Thanks, glad I can put some of my minor to use every once in a while.

-Jenrick