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Lapua Center X ES
- Thread starter Dawhit
- Start date
Typical lot variations.
There is no find the brand y'er rifle likes.
There is only find well made cartridges with tight mv's.
There is no find the brand y'er rifle likes.
There is only find well made cartridges with tight mv's.
I've not seen that many 5 shot ES's like that. It makes me wonder if there might be some issue with your particular chrono???
I use a MagnetoSpeed, which is very consistent, and while I might get an outlier that expands an ES, you can see what I get and the data I've collected in the pic below:
20 shots for each lot#. Chrony could be off but every group that had a flyer, I would get a hot or cold reading on the flyer. I have a V-3 also but only use it with verified repeatable accurate loads. Had issues running Saterlee ladders on one centerfire gun.
In my limited experience in shooting and observing others, what you got out of your Center-X is not typical.
Thats very big ES with just 10 shots.
Center-X should be better but I have also gotten bad lot of Polar
Why not collate the numbers together?
You get very meaningful statistical information from a larger sample of >30.
I agree. I'm in a habit of always running groups of 5 or 10. But wouldn't many smaller groups of data be more representative of the performance of the 5 or 10 shot strings that most are used to shooting? I usually don't measure how many total rounds fired hit a target, rather the string size which usually is a magazine. I suppose it depends on which numbers mean most to you.
I get what you are going after but in reality, the more data the more robust it is.
If you were to shoot 5 or 10 shots during the whole range trip, why not.
But you have to be as "cruel" in your math as possible to weed out possible bad lots and see the weaknesses.
I use my own decision power with the larger sample. If the SD is awesome but ES is thrown off by 1 shot like from cold bore, I might discount it but I just change it to text format by adding ' to the front. In the end it does not matter really, but it is good to plot the numbers also and see what is in there.
After I am done with the whole string and I suspect that the ammo warmed up or cooled during the session I just select the last 15 or 20 rows in the excel. It will show the min/max/avg in the info bar and compare the avg against the overall average. Or I make a line graph and see if it trends upwards or downwards.
If the avg is clearly off and temp was the likely reason to that I cut them into 2 data groups. With good planning I seldomly do this but I sometimes chrono all ammo from start to finish.
To give an idea how the sample size matters check out this graph.
You see that the only rounds in the extreme regions are quite alone there? You do not need to ditch the lot if it has them but just acknowledge what is the chance of it.
That's interesting. That's what I guess I mean. It seems like it would just show the very few extreme shots in such a large group. But if you really combed over your data like you do, then you could get a good look at what's going on. It seems like it is more manageable for me to interpret the many smaller groups.
Anyway, that's a good method you have. I may do that when I have more match ammo to spare.
Yes, it is. And even higher when I combine the 10 shot data.
Yeah. I didn't get very good results with it either. And because I didn't shoot it in very cool weather, I wondered if that might have been a contributing factor.
That's what I often do with my 10 shot groups to get a more "meaningful" idea of how the lot performs. Then there is also some data I have from some people who've done 50 shots.
Did you say what your settings were on V3? I get a lot of bad readings with it on 22 match ammo so curious. Thanks,
I set the sensitivity to 8. I've never had a bad reading (so far) and have used it with just about everything from slow subsonic ammo with MV's below 600 fps to hyperspeeds likeAguilla Interceptors at over 1600 fps, and . . . from a number of different guns.
And of course, I've set the height so that the Bayonet Sensor is under the bottom of the bore by the Alignment Rod as instructed.
BTW: For the primary gun I use most (an RPRR), I don't have it mounted to the barrel. Since a picture is worth a thousand words . . .
Here's some notes from a range session back in February when I was shooting 300 and 400 with Lapua Center X. Kept the Magnetospeed on the chassis the entire time.
Shots: 99
Avg: 1094
Min: 1065
Max: 1123
SD: 11
ES: 58
Shots: 99
Avg: 1094
Min: 1065
Max: 1123
SD: 11
ES: 58
For some Center -X of the same lot, here some of my numbers to compare:
Shots: 60 through factory 18" barrel
Avg: 1057
Min: 1027
Max: 1094
SD: 11.8
ES: 67
Shots: 130 through a Shaw 18" SS barrel
Avg: 1100
Min: 1080
Max: 1121
SD: 8.3
ES: 41
Last edited:
Are you sure about the SD?
Statistically it should be 6 times less than ES.
SD of 36 would mean approximate ES of 216.
You're right!
Don't know how that number came about, but it's definitely wrong. I've got all 130 velocities recorded and upon calculating the SD, it's 8.3 instead. So, I've edited that post accordingly.
Thanks for the catch.
I agree on the sensitivity. It doesn't need to be anywhere near max for rimfire. If anything, I found more errors when the sensitivity is too high.
As as mentioned by straighshooter1, making sure the bayonet is correctly gapped to the bore using the alignment tool is also critical.
