ShotMarker or SilverMountain/SOLO are pretty common now in NRA F-class matches and gives us those readings at distance, just curious if they are "correct"? They seem pretty consistent from one mfr to another.
Range Report How accurate are Electronic target's terminal velocity readings?
- Thread starter smoothy8500
- Start date
I have shot over downstream acoustic, optical, and doppler; but never a shotMarker, so I have no idea. Still, would have to assume that it is as accurate as any optical or acoustic chronograph that we use near the muzzle.
If your calls/POI are lined up with your solver using a muzzle velocity, try running the chart and see if the two agree. Either way, there seems to be some fudging at the muzzle to make things work. As an example, after I test my MV it might say 3030, but it hit a hair high at 500, so I need to adjust it to 3050. Now my 100-500 are good, go to 1K, and I am a tiny bit high. The downstream velocity, my calculator, thinks I have is 1589fps. But I tweak my BC from .534 to .540, so my 6.9mil 1K call is centered. The 1K predicted velocity now says 1602fps. If I tuned correctly on paper in the first place, the downstream devices I've used seem every bit as close to the muzzle end, maybe closer.
In FFS, we used to create a chrono profile so that when you entered the chrono data, the solver auto-adjusted it. I guess you could do much the same if the shotMarker were not much in agreement with your solver.
You'll have to test and report back for us
Jim
If your calls/POI are lined up with your solver using a muzzle velocity, try running the chart and see if the two agree. Either way, there seems to be some fudging at the muzzle to make things work. As an example, after I test my MV it might say 3030, but it hit a hair high at 500, so I need to adjust it to 3050. Now my 100-500 are good, go to 1K, and I am a tiny bit high. The downstream velocity, my calculator, thinks I have is 1589fps. But I tweak my BC from .534 to .540, so my 6.9mil 1K call is centered. The 1K predicted velocity now says 1602fps. If I tuned correctly on paper in the first place, the downstream devices I've used seem every bit as close to the muzzle end, maybe closer.
In FFS, we used to create a chrono profile so that when you entered the chrono data, the solver auto-adjusted it. I guess you could do much the same if the shotMarker were not much in agreement with your solver.
You'll have to test and report back for us
Jim
Manly, F-class and Bnechrest guys are using these types of target systems.
With the above in mind, It is important to note these shooters also do not use predictive solvers the way we do as the distances tend to be always the same, even more relevant is that the sighter process (sighter shots before each record) works much better for their needs than trying to tune a solver to the POI. So for them the only value might be looking at BC variance if one goes down that rabbit hole. Most the good shooters have their loading process so refined, it would be no surprise if they did not find value in that part of the system.
For the field shooter, having an accurate downstream MV, could be used to quickly verify your solver. Not everyone is going to get a chance to play at Yuma, but it would be interesting to see if the makers of the systems did, or would validate their tech.
Last edited:
Reviewing the screenshot of my last match at 1K, Shotmarker shows the average velocity of 20 round string is 1,389fps SD of 35.6 which I compared to Strelok Pro:
My 308 loads: Nosler 175gr CC chrono'd at 2699 with SD of 10. Strelok truing/validation puts it at 2,707fps to work with my Leupold Mk4 16X M1 knobs, which I have not verified with a tall target. Strelok calculations correlate with my scope from 800 thru 1K using MOA not "shooter's MOA" (1/4" at 100yds).
Strelok calculation right now/current condition says the velocity at 1K is 1,236fps with 34.1 MOA elevation. My notes in the scorebook show I had 34-1/2MOA elevation on the scope, range conditions were sunny but mild temps.
The Shotmarker presents a 150fps discrepancy from Strelok. However, the validation (truing) was based on an assumed scope value. Despite that, the Strelok "velocity" is pretty close to my chrono muzzle velocity.
Considering some undefined variables, I guess 150 fps is not necessarily close enough for gov't work. I will take some time to verify the scope elevation accuracy and input that to Strelok for further evaluation.
My 308 loads: Nosler 175gr CC chrono'd at 2699 with SD of 10. Strelok truing/validation puts it at 2,707fps to work with my Leupold Mk4 16X M1 knobs, which I have not verified with a tall target. Strelok calculations correlate with my scope from 800 thru 1K using MOA not "shooter's MOA" (1/4" at 100yds).
Strelok calculation right now/current condition says the velocity at 1K is 1,236fps with 34.1 MOA elevation. My notes in the scorebook show I had 34-1/2MOA elevation on the scope, range conditions were sunny but mild temps.
The Shotmarker presents a 150fps discrepancy from Strelok. However, the validation (truing) was based on an assumed scope value. Despite that, the Strelok "velocity" is pretty close to my chrono muzzle velocity.
Considering some undefined variables, I guess 150 fps is not necessarily close enough for gov't work. I will take some time to verify the scope elevation accuracy and input that to Strelok for further evaluation.
Last edited:
To start with, 34.5MOA to 1K with a .530 G1 at your MV is suspect at 2700fps. to get 34.5 (I am not a MOA guy) - I think you'd need to be about 70fps-50fps slower than your reported MV 85F 29.9inhg/70F 2650fps.
Something is off in your base unless I am assuming the wrong bullet. I would suspect scope if your MV is really correct. but that is a guess at best.
Last edited:
Garbage-in, garbage-out I guess. The only number I "know" is the muzzle velocity averages the chrony gave me. Everything else was just picked from the drop-down menu in Strelok. M1 knob "says" 1/4 MOA but I haven't verified. I'm assuming Strelok is using what Nosler "says" is the BC, I've never even looked it up. I seem to recall that when I compared the initial calculations at 800yds they were close and I did the validation/truing.
Verifying Leupold's M1 knob with a tall target will bring things closer to reality.
Verifying Leupold's M1 knob with a tall target will bring things closer to reality.
this right here^^^^
we have a shot marker and its an awesome tool for load development but as far as actually using the numbers from one i would not....i watched my smith shoot a 1.5" group at 600yds that showed a 69.9fps es and a 27.7SD and at 600yds that is plenty far enough for those kind of numbers to show up.
personally i do not care what a chrony says anymore only what the target says at distance...ive seen way to many high number loads shoot consistent small groups...i use the numbers as a starting point.
same af ^^
Dave,
At your DA, it is plausible for something like a 6mm to shot well under 1.5" with an SD of 28 - Although, not sure how to reconcile the ES.
I think the main question was accurate is the velocity numbers. I think that is a relative question and it depends on how the answer is given. People love the Magnetospeed and swear by it accuracy that can easily end up at *99.5% (depending on the mounting). 99.5% sounds great. But is 15fps as accurate as I thought on my 6mm? So 99% sounds great, off by 30fps doesn't sound as good.; yet both are the same.
If we put Dave's numbers into content, they seem relatively good/usable. Let assume Berger does an excellent job on BC uniformity and manages 1%. That is about 5fps at 600 on my rifle, so I would expect a bit of an increase in the SDs.
I look at this like we have a 7SD at the rifle plus, BC variance from engraving and manufacturing. Let's say a combined total of 12fps at 600 just to be extremely optimistic. If we assume our Muzzle or optical chrono is mounted dead perfectly every time, and we are getting *99.7% accurate MV reading; that's almost over 9fps. . We are now around 21fps variance at the target. Now let's assume the ShotMarker (I have zero idea) is 98% accurate, and my bullet is predicted to be about 2178fps at 600; the make-believe 2% variance of the Shotmarker, is about 44FPS. Add this all together, and compare to the results you reported, it seems to add up.
So, the point is that the downstream velocity reading of the ShotMarker might be off a small percentage, but other error stacking is sure to create a surprising result. It seems like a good tool, In Smoothy's case, it obviously helped show he has a tiny bit of upstream data corruption
Anyway- again, I know NOTHING about the product. Just jumping in to make sure we think about the error stacking that is happening even before we attempt to validate on target velocity.
*My Labradar clams to be 99.9% accurate, but I can get less accurate depending on several user factors, Magneto speeds 99.5% and mounting angle does matter
At your DA, it is plausible for something like a 6mm to shot well under 1.5" with an SD of 28 - Although, not sure how to reconcile the ES.
I think the main question was accurate is the velocity numbers. I think that is a relative question and it depends on how the answer is given. People love the Magnetospeed and swear by it accuracy that can easily end up at *99.5% (depending on the mounting). 99.5% sounds great. But is 15fps as accurate as I thought on my 6mm? So 99% sounds great, off by 30fps doesn't sound as good.; yet both are the same.
If we put Dave's numbers into content, they seem relatively good/usable. Let assume Berger does an excellent job on BC uniformity and manages 1%. That is about 5fps at 600 on my rifle, so I would expect a bit of an increase in the SDs.
I look at this like we have a 7SD at the rifle plus, BC variance from engraving and manufacturing. Let's say a combined total of 12fps at 600 just to be extremely optimistic. If we assume our Muzzle or optical chrono is mounted dead perfectly every time, and we are getting *99.7% accurate MV reading; that's almost over 9fps. . We are now around 21fps variance at the target. Now let's assume the ShotMarker (I have zero idea) is 98% accurate, and my bullet is predicted to be about 2178fps at 600; the make-believe 2% variance of the Shotmarker, is about 44FPS. Add this all together, and compare to the results you reported, it seems to add up.
So, the point is that the downstream velocity reading of the ShotMarker might be off a small percentage, but other error stacking is sure to create a surprising result. It seems like a good tool, In Smoothy's case, it obviously helped show he has a tiny bit of upstream data corruption
Anyway- again, I know NOTHING about the product. Just jumping in to make sure we think about the error stacking that is happening even before we attempt to validate on target velocity.
*My Labradar clams to be 99.9% accurate, but I can get less accurate depending on several user factors, Magneto speeds 99.5% and mounting angle does matter
Last edited:
I have been using the shotmarker a fair amount for the last couple of months and comparing MV at barrel with recorded velocity at the target. Unfortunately I have been limited to 547 yards for the shotmarker. At first I was skeptical of the Shotmarker velocities but the more I used it and analyzed the data the more I started to believe the numbers were accurate. I also went into JBM and calculated the BCs based on the 2 velocities at known distances. I did a lot of testing with different brands of bullets as well as pointing vs not pointing on different days and finally concluded that the velocity readings are pretty accurate.
What I found was that as per Berger's NoBSBC, some bullets have more variation in BC than others. When I pointed bullets I only saw a slight increase in BC but I saw much less BC variation. One of my most eye opening experiments was to take a lot of good shooting bullets with low muzzle ES/SD and mangle with meplat with pliers. To my surprise the groups stayed good at 545 yards despite the fact that they were traveling about 100 feet per second slower at the target. My takeaway was that it confirmed that BC not a huge factor at shorter distances. As many have said it is possible to shoot great groups at shorter distances even with poor ES/SDs
Need to get the target out further and do more testing.
This was one set of data with pointed 105 Hybrids. It should say 547 not 500 in 2nd row of velocities
What I found was that as per Berger's NoBSBC, some bullets have more variation in BC than others. When I pointed bullets I only saw a slight increase in BC but I saw much less BC variation. One of my most eye opening experiments was to take a lot of good shooting bullets with low muzzle ES/SD and mangle with meplat with pliers. To my surprise the groups stayed good at 545 yards despite the fact that they were traveling about 100 feet per second slower at the target. My takeaway was that it confirmed that BC not a huge factor at shorter distances. As many have said it is possible to shoot great groups at shorter distances even with poor ES/SDs
Need to get the target out further and do more testing.
This was one set of data with pointed 105 Hybrids. It should say 547 not 500 in 2nd row of velocities
This is why we love you Jim lol!
And this is another reason I stopped worrying about numbers....if my gun is shooting 1”-2” groups at 600yds I do not care what the numbers are because the gun shoots better than my capabilities....numbers are just a mind fuck.
the difference between your example and mine is that ive seen to many high ESs and SDs to believe the numbers are that far off on both magneto speeds and our shot marker...dont get me wrong i love the shot marker i just use the numbers as a starting point then shoot at distance and get actual dopes.
Well, I’ve seen you shoot. As they say it is the Indian not the arrow... you’re one hell of an Indian
jim
If you don't trust your magneto speed you should check it against another chrono to verify. Just because they have high ES/SD doesn't mean they aren't true. Have seen many shooters tell me they don't believe their magneto because the numbers don't line up with "what they see". I put a labradar next to it and shoot them together and eveytime I have done it the numbers have been VERY close. Truth be told the reason I bought the Labradar was that I didn't believe my magneto
If the ES/SD is big at the muzzle it will be as big or bigger at the target. So if you are not measuring ES/SD at muzzle it is really hard to make judgments on velocities at the target.
When I had good ES/SD at the muzzle but big SD/ES at target I initially thought the target numbers had to be off. Then I noticed over time certain bullets always had large ES/SD at targets and others didn't. That is when I starting recording both MV and target velocity and putting all the numbers in JBM to see what BC would need to be to have that velocity at target. You can get some pretty wide velocity swings at the target if the bullet has significant BC variation (all while still shooting good groups). Next time you shoot at shotmarker record your MV and all enviromentals and then plug into JBM to calculate BCs. You might be surprised what you find.
Last edited:
Example: at 600 yard if you have a MV of 2850 and BC variation of 5% (and yes some bullets have that much BC variation) that would produce an ES of 40 ft/sec at 600 yards. Now if you are starting with an ES of 30 at the muzzle you will now see an ES of ~ 70 ft/sec at target. If you accidentally dinged up your bullet meplat you could easily see an ES of 100 ft/sec or greater
BC variation is the number one reason for “I always do load development at 300 or 500.”
If you have good sd/es with acceptable accuracy at 100yds, the only two things left are the shooter and the bullet. If groups fall apart at distance, those are the only things it can be.
Well, I’ve seen you shoot. As they say it is the Indian not the arrow... you’re one hell of an Indian
jim
now your just making me blush
If you don't trust your magneto speed you should check it against another chrono to verify. Just because they have high ES/SD doesn't mean they aren't true. Have seen many shooters tell me they don't believe their magneto because the numbers don't line up with "what they see". I put a labradar next to it and shoot them together and eveytime I have done it the numbers have been VERY close. Truth be told the reason I bought the Labradar was that I didn't believe my magneto
If the ES/SD is big at the muzzle it will be as big or bigger at the target. So if you are not measuring ES/SD at muzzle it is really hard to make judgments on velocities at the target.
When I had good ES/SD at the muzzle but big SD/ES at target I initially thought the target numbers had to be off. Then I noticed over time certain bullets always had large ES/SD at targets and others didn't. That is when I starting recording both MV and target velocity and putting all the numbers in JBM to see what BC would need to be to have that velocity at target. You can get some pretty wide velocity swings at the target if the bullet has significant BC variation (all while still shooting good groups). Next time you shoot at shotmarker record your MV and all enviromentals and then plug into JBM to calculate BCs. You might be surprised what you find.
i get what your saying and i myself was a big numbers guys for years but after some of the stuff ive seen over the last year or 18mons or so i just dont worry about the numbers anymore...or as much as i did...unless theres a problem that comes up more than once....because at the end of the day the only thing that really matters it whats happening on target at what ever distance/distances we are shooting...most of my shooting is done from 175yds out to 1100yds with an occasional shot or two past that.
ive shot groups over my magneto speed that showed 0 and 1FPS ESs then shoot a match that i just tanked in come home and have a high ES and start tweaking the load when in fact the problem was me not the load so again FOR ME running numbers and checking chronys all the time is just a giant mind fuck that makes me go into full re-loaders tweak mode LOL!!
i was going to post some pics with a story but im to lazy LOL!
Last edited:
Agree that it is easy to get sucked into the numbers and lose sight of the real goal, getting shots on target. The current craziness left me with some extra time so I played with numbers and spreadsheets for shits and giggles and in the process learned a few things including:
- I believe the shotmarker numbers are accurate in most instances (if windy and target is moving all bets are off).
- I need to stop chasing the highest BC bullet for the ranges I usually shoot, accuracy and precision much more important
- Pointing did not significantly increase my BC but did seem to make BC more consistent
- BC variation/consistency varies amongst different bullets and will come into play at long distance
I been sayin this for 5 yrs now...glad Berger finally getting on board so everyone will agree now lol
Crazy talk!!!! That extra 0.01 of G7 BC will make all the difference in the world. Especially when I bump up my powder charge and get another 25 ft/sec!!!!!
you see ive already done all the tweaking you can think of or should i say all the case and bullet prep...ive said before that all that stuff turned reloading into a full time job that made me hate reloading so much i quit shooting for almost 2mons.
i sold ALL of my tweak tools i like to call them and have not done any brass prep sense and the last key to stopping the insanity was leaving the magneto speed at home when i go shoot.
Willing to bet everyone who has the “groups fall apart at distance” could instantly fix that with either A) sucking less or B) bullet sorting and/or tipping.
yep ive noticed these slowly starting to show up...i think their compensating for something LOL!
I’ve basically replaced seating depth tests on my prs rifle with tuner. Does the same thing without having to load different depths and such.
what tuner are you using?
Erik Cortina’s.
But I predict with mpa and Alamo advertising tuners, we are going to see a ton of “I can’t get my tuner to work” posts soon.
I just shot a match with a barrel I could no longer make any seating depth adjustments. It was a solid 2-1/2 MOA before I put a tuner on. Dthomas texted me through questions and the gun then shot 1+MOA. I would not have believed this could do anything on a smoked barrel and I know that’s not the intent of these but it was a fun to see it somehow help.
I only tried this after I saw a magneto speed do the same. @Jabot and @Swoodhouse19 w
I only tried this after I saw a magneto speed do the same. @Jabot and @Swoodhouse19 w
what tuner?
This is true his groups tightened up with a magneto speed attached. Pretty damn funny, we told him just to shoot the match with magneto speed attached to rifle .
@Dthomas3523 knows the one. It’s the one you just spin your break off and then spin on the tuner followed by your break.
I think it’s called Kinetic something.
Bad cell right now up it in the Mountains
@Jabot - just texted you the Elk tag info- 3rd rifle
