I bought some of the new Lapua Rapid Pistol to try out. It's supposed to be a slower velocity round for Rapid Fire (275 m/s), but still comfortably above the legal minimum. However, when I took it to the range and tried it out it felt rather inconsistant from shot to shot. I decided to dig out the chronograph, and tested it along with Wolf Match Target, SK Standard Plus, and Aguila Super Extra (SE). My impression of the Rapid Pistol was accurate- the ammo is extremely inconsistant in velocity, ranging from 885 feet per second (270 m/s) to 978 fps (298 m/s). It was far more variable than any of the other brands that I tested. I shot four five-shot strings of each except for the Lapua, which I shot eight five-shot strings. The reason for that is that I shot four strings of the Lapua first, then did four strings of the three other brands. I then decided to do another four strings of the Lapua at the end to make sure it was consistant with my results from the beginning, which it was.
I've attached two graphs- one showing the high/low spread for each string, and one showing the standard deviation for each. I've also pasted the spreadsheet with the data as a picture file for quick viewing, and attached the excel document for anyone who wants to play with the numbers in more detail. All the ammo was shot with a Pardini SP1 Rapid Fire. The chrono was set about 30" from the muzzle (after I finished testing the ammo I tried moving the chrono about a foot closer and then about a foot farther with no noticeable impact on the measured velocities).
I'd be interested in anyone's thoughts on these results.
Thanks a bunch for posting this info. You obviously put a lot of work into it. A couple of thoughts about your results:
1. The legal minimum, 250 meters/second, converts to 820.25 feet/second. Looking at the average velocities you found, it appears that none of the manufacturers are even close to the minimum. I'm a little surprised that the Lapua Rapid Pistol ammo isn't slower than it is. It makes me wonder if they put more emphasis on functional reliability than on minimizing recoil.
2. IMHO, standard deviation means little. Why do I say this? Many years ago, I tested my Toz FP with multiple brands (and batches) of ammo, and at the time, Eley Tenex clearly had the best SD. However, the best 50 meter groups came from one lot of RWS-R50 which had a SD a good bit larger than the Tenex. Did I care the the SD was larger? Heck no. The *only* thing I cared about was what ammo shot the best group out of that pistol.
3. With all that being said, your data is very meaningful for velocity. However, under the current RF rules, the ammo selected needs to meet three criteria for the shooter:
a) Is it reliable?
b) Does it group acceptably well?
c) Does is meet the required minimum velocity?
Were you able to record group sizes as you tested this ammo? Did any of the ammo used prove to be functionally unreliable?
This is excellent work Ted, we don’t have access to this form of test equipment and often rely upon secondary information; you clearly went to a lot of effort to test, collate and report!
Given 275 meter per second approximates 902.23 feet per second, the Lapua ORF in the Pardini looks a high risk and the SK Standard Plus confirmed our observations.
We would be interested to know if the are any velocity variance between the SP1 and the SP1 Rapid Fire models as we use the SP1 electronic for the rapid fire event as well as standard pistol.
I have seen the Signum brand used in video clips at some of the ISSF matches. I wondered if anybody had Pardini experience of this brand? I did shoot a few rounds and it felt very smooth but the owner had not measured velocity and his pistol was a longer barrelled pistol than our Pardini units. We use Pistol King for standard and some of us for training 50m pistol. Again, would be very interested to know velocities of this brand in the Pardini.
BTW Many thanks to the feedback on the balance point of the Pardini from muzzle. My custom LP50 short barrel arrives mid next week. Will feed back after we have shot it a few times. A few will try their LP5 grips on this LP50, I think our excellent UK Steyr dealer may have a few rush Xmas orders!
You raise a good point about the accuracy being more of a concern than velocity and standard deviation, but I think that in rapid fire, compared to a precision discipline, "accuracy" is more of a combination of both grouping and consistant velocity/recoil. Inconsistant velocity/recoil makes it difficult, if not impossible, to maintain the rhythm necessary for a successful series, especially in the four second series. Thus, while the Lapua could be the best grouping ammo of the four in a precision scenario, I would not use it for rapid fire. (I haven't actually tried to shoot any groups with it yet- just ran a couple of quick rapid fire strings and then did the chrono testing.) However, with regards to reliability I had no reliability issues with any of the ammo I tested, including the Lapua. (Gotta love that Pardini!)
Paul T-
I might order 50 rounds of Signum to test out just for curiosity's sake. Eley Pistol Match is another one that was recommended to try.
One thing to watch out for when doing ammunition test like this is that switching between ammos without cleaning or "re-conditioning" can produce odd results. I don't know what is going on, but I've definitely seen situations where things don't settle down until I've fired at least 15 to 20 rounds of the new ammo. I think it may be some sort of interaction with the different lubes. It's been a while since I did this, but my recollection was that I would get large groups (like many inches across at 50 feet) and even keyholing from my Benelli MP90S until things settled down. My recollection was that Wincester T22 either acted the worst or caused other ammo to act poorly.
I hate to throw water on all of your efforts, but you might want to do a few more tests either with a good cleaning between ammo changes, or a good number of shots to let things settle down. It's hard to tell from the data if there was any sign that things might be settling down as the testing progressed.
Seems like a minor quibble to many folks, but GWhite makes a good point about experimental design. In order to measure the velocities "fairly" you have to rule out other possible contributors to variance (like temperature, bore condition, angle of sun against skyscreens,etc.).
One good way to protect against "exogenous variables" like that is to simply *not* shoot your subjects in "groups" but ot randomize- or at least interleave- your subjects.
For example, in order to test 5-shot strings of three brands of ammo (A, B, and C) you could follow the protocol of
- clean
- A, B, C fouling shots
- dry patch
- A
- B
- C
- A
- B
- C
- etc.
or something similar. I know this is critical for sandbag accuracy testing, as "tiredness" of the tester is a huge factor and if you don't do this, you will see first batch and last few batches will invariably look worse than they really are.
