Range Report Crono necessary?

[TimActual]

First let me qualify my uncertainty, by declaring that I am a beginner to technical long range shooting, although I am some weeks into studying, book rather than practical application.

On to it... Regarding ballistic software; Do you feel that a cronograph is necessary for entering your muzzle velocity into ballistic software? Or for a starting point could one simply use the mv per the spec of the ammo?

Considering that a crono may have a margin of error, compounded by (generally?) having to tweak the mv in the software anyway to fine tune it? Would a crono just be an unnecessary added expense?

Lastly, other than using a crono for that purpose, is it a tool that I should have available irrespective of the above purpose?

Thanks, and I hope that's not a bone question.

T.

 

[normbal]

I use a chronograph while doing load testing. Or I did for quite a while. I've also done OCW testing alone and taken the most accurate load closest to maximum charge (short of high pressure signs) out to a 1275 yard range and just shot 20-30 rounds of unknown velocity, dialing on MILs until I'm getting hits. I then plug the data obtained (mils at known distances) into the Ballistics AE app on my iphone and estimate the velocities until I get the best fit curve for my data, using the rest of the data from the app to dial on to the next target.

I have been very surprised several times that data from my chronograph (Millennium CE2 AND a Chrony Beta Master at one time) could be off by as much as 100 fps, meaning, what I get at a 100 yd range at, say, 72 degrees F and 60% humidity at 300 ft ASL is off a LOT at another range with similar, very close atmospheric data.

In other words, don't fully rely on your chronograph data.

 

[TimActual]

Thanks for your reply NB. I can see the need for a crono when reloading ammo, which at this point I'm not doing. Although perhaps in the future I may, especially considering the cost of ammo these days. I do save my brass though.

Oh, and thanks for mentioning OCW. I have to admit that I had to look that one up, but I found that concept to be very interesting, (you learn something new every day). The effect the charge going off has on creating an oscillation up and down the barrel where the timing of which affects the projectile, especially upon exiting the barrel, -if I have that correct. That's heady stuff and very cool indeed.

Thanks also for your insight on how you use your software. Those are my thoughts as well on how to dial the software, that is once I get to that point. That point which I feel is coming soon, after a couple more purchases I want to make to ready myself.

Much appreciated,

T.

 

[Fried Chicken Blowout]

I've run into the same thing... I'll develop a load based on accuracy knowing that I'm near the top end of safe pressure and call it good. Shoot it at range and get my data and call it good. I'd be interested to know what people are actually using chronos for and how they help load development beyond what I'm doing. I would assume they can give you some sign if temp sensitivity without having to shoot at long range to find out. They could ID some changes in velocity from shot to shot, but if that was happening significantly, I'm not sure I could ID the problem if I already knew my power changes was on the money and neck tension was good. I may be looking at this out from my small box of thinking and I need to be educated. But all I used a chrono for is pistol loads to make sure I make Power Factor. I don't use them for rifle loads.

If I'm missing something I'd be happy to get an education. Hopefully this is not hijacking the OP thread, but I've been thinking the same thing as the OP so I figured I'd jump in and ask.

 

[TimActual]

Not a problem at all FCB. Let it roll.

 

[turbo54]

I have probably worked up 20+ long range loads for various rifles in varying cartridges, mostly with the "common" well known bullets like 175smk, 142smk etc etc. I mention the bullets, because the BC of them is common knowledge.

Anyway, I've NEVER had it just "work out" that I could chrono, plug the MV, BC and atmospherics into ANY calculator, and have good dope.

I ALWAYS have to finagle the MV to reconcile calculated dope and actual observed dope. Oftentimes, there's a 100fps or more disagreement.

I've no need for a chrono for trajectory calculations.

I've seen the argument it's helpful to minimize MV variations, and maybe that's true, but I've been able to tune ammo that will usually hit a clay bird @ 1000 yards without using one.

It would be good to have one if you compete in a shooting sport that has rules based on velocity.

EDIT TO ADD: I should have mentioned that I use quality optics (Premier) that have been collimated and tracking was confirmed good.

 

[Rob01]

I must be lucky as I use my chrono numbers, plug them and all the data needed into JBM and do just fine with it at matches. Never been off more than .2 mils at longer ranges and usually it's right on or maybe .1.

If you are going to do the whole shoot data and reverse engineer then you better make sure that your scope tracks on 100%. If not then you are getting bad data. That's where I believe people see the shot data not matching the muzzle velocity on a chronograph. Also there are other factors effecting the bullet.

If you have a decent chrono you will get good numbers. Chrono brand cheap chronos aren't what I would recommend. Spend some money and get a good chrono. I have an Oehler, after having a Chrono, and it's night and day. There are others out on the market now that work very well.

 

[Name Enough]

If you reload you should get a chromo. My first one was El Cheapo. Don't get one of those. Get a good one.

 

[rduckwor]

Chronos give you another piece of data to help build the big picture. There isn't any absolute requirement to use one, but I think they help you reach the end point a bit more quickly. External ballistics isn't an absolute; 2X2 don't always equal 4, many factors impact the final "answer". Expecting solid dope based upon chrono data isn't realistic. Too many other factors influence POI.

 

[TimActual]

Guys, thank you very much for taking the time to reply to my post. I've read each and every one of your replys and they are all very helpful and points taken. Since I am not currently reloading I will spend my money on stuff that has moved higher on the list now. The next decision I have to make is LRF or spotting scope. Or damn the torpedoes and buy them both at the same time. I've been saving my penneys, hea, so I'm about ready for the next buy. I picked up a Kestrel 2500 last week, and have been geekin on that for a few days. (Set altitude to zero so it resolves to station pressure), where my software has a setting for "absolute" for the barometric pressure, which I believe is the preferred method. Learn, learn, learn, but having fun at it.

Thanks again and feel free to chuck any other knowledge my way if you think of anything. I'm really fng at this right now so I'll be happy to sponge up anything you care to throw my way.

Thanks again,

T.

 

[tnichols]

I must be lucky as I use my chrono numbers, plug them and all the data needed into JBM and do just fine with it at matches. Never been off more than .2 mils at longer ranges and usually it's right on or maybe .1.

If you are going to do the whole shoot data and reverse engineer then you better make sure that your scope tracks on 100%. If not then you are getting bad data. That's where I believe people see the shot data not matching the muzzle velocity on a chronograph. Also there are other factors effecting the bullet.

If you have a decent chrono you will get good numbers. Chrono brand cheap chronos aren't what I would recommend. Spend some money and get a good chrono. I have an Oehler, after having a Chrono, and it's night and day. There are others out on the market now that work very well.

Very similar experience as Rob01. Now that I'm running a CED M2 over IR screens in a coffin, it's pretty dang close to plug and play. Chrono, put the data in the ballistic calc (I still use Exbal) and shoot to verify. It's extremely close for the ranges we shoot at, which is 900 yards on in.

 

[TimActual]

Thanks Rob01 and TNichols. I must say that I'm a little surprised. TN, I did some light reading about your equipment and I did not realize that you are talking about such a computerized system. I was thinking of it being way more analog. I would like to know how it is leveraged into your firing solution. More specifically is it something that you use for a finite amount of time to dial in your ballistic software and then you are good? Or, is it more like you just keep fine tuning more and more as day's go on? I would like to think that one could get to a place where the software can provide a good enough firing solution where it pretty much comes down to the shooter, and the shooter's ability to utilize the software/hardware to its fullest potential. I'm not sure that what I'm getting from you two is that you feel that using that equipment gets you more accurate then the other guy, or gets you "as" accurate as the other guy, only faster?

 

[TimActual]

One more thing before I go to sleep here as I should already be. Regarding the comment above about being off due to scope tracking. I have good equipment, scope, rail system, rings, torque, and took a lot of care mounting it all. Is there a difinitive method to determine that a scope is tracking bad? Or would that just become apparent over time provided you are thinking about it and looking for it in your printing? Thanks guys.

 

[Capt Academy]

I agree with some of the above posts, I use my Beta Chrono to build my dope out past 600 yards. It works usually spot on from 600 yards and in, but after that, I usually need to adjust my fps to get accurate hits past that distance. Picking up a new V-2 soon from Mile High, will see how well it works.

 

[turbo54]

Is there a difinitive method to determine that a scope is tracking bad? Or would that just become apparent over time provided you are thinking about it and looking for it in your printing?

You can set up a tall target (needs to be about 4 ft tall) at 50 yards, and put a SINGLE small target spot at the bottom. Fire 2-3 rounds at the spot, then dial several mils up. Fire another 2-3 rounds AT THE SPOT. Dial a few more mils and fire more rounds AT THE SPOT. Once you've gone through the full elevation range of your scope, fetch your target and measure from group to group and see if the distance between centers corresponds to the number of mils between each group.

Trouble with this method is shooter, rifle and ammo inconsistencies are also included, and they can really make it much harder to determine results. We all would like to think our 1/2 moa rifles will "single hole" at 50 yards, but you'd be surprised what you end up with after doing this test.

The better method (in my opinion), is to fashion a fixture you can clamp down to something rigid, onto which you in turn clamp your scope. Set up a yardstick (which you should put a level on to ensure it is vertical) at 50 yards, and then run the scope up and down along the yardstick. This is called collimation.

I made one of these out of a scrap hunk of steel. I bolted a chunk of picatinny rail to it so I could mount a scope. I just clamp the fixture down onto the concrete shooting benches at the gunclub and get to it.

 

[tnichols]

Thanks Rob01 and TNichols. I must say that I'm a little surprised. TN, I did some light reading about your equipment and I did not realize that you are talking about such a computerized system. I was thinking of it being way more analog. I would like to know how it is leveraged into your firing solution. More specifically is it something that you use for a finite amount of time to dial in your ballistic software and then you are good? Or, is it more like you just keep fine tuning more and more as day's go on? I would like to think that one could get to a place where the software can provide a good enough firing solution where it pretty much comes down to the shooter, and the shooter's ability to utilize the software/hardware to its fullest potential. I'm not sure that what I'm getting from you two is that you feel that using that equipment gets you more accurate then the other guy, or gets you "as" accurate as the other guy, only faster?

Don't want to get in over my head as I'm no expert and there are fellas here with far more experience than I, but I chrono at least 5 rounds (more is better) and average the velocity. I chrono everytime it's a new lot of ammo (when I'm purchasing ammo) or if there is a lot or component change (for my handloads). The average velocity of those rounds fired gets fed into the ballistic solver. Simple as that. The solver uses the velocity along with a lot of other information that you provide (BC, atmospherics, etc...) to provide you with a firing solution. I chrono each rifle/load combo maybe a 2-3 times a year on average.

It isn't more "accurate" so to speak than shooting at distance to determine velocity, but it can be done for those that maybe only have access to a short range at home to give you data prior to going to a comp, or a hunt, etc...

Don't know that I answered your question directed to me, hope that I clarified it perhaps. There is a ton of great info on this site from guys with ALOT of experience.

 

[bogeybrown]

I don't reload yet, but bought the Magneto Speed on the Group Buy for the reason TN stated, in that I am RARELY home, and when I am I have easy access to 100yd range, so I can chrono my setups and have good beginning data for my calculator before I make the trip to the nearest long range facility. I'll still have to "true" my data, but it'll save me a ton of time, and as a guest wherever I shoot I know the range staff is going to be skeptical of someone they don't know wanting to shoot to the farthest ranges, so the closer my misses the less I look like an idiot and the more slack I get.
Plus, shooting solely factory match ammo, I'm at the mercy of the lot number, so it'll allow me to adjust my dope if necessary before I attempt farther ranges.

 

[TimActual]

Guys, thanks again for just a bunch of great information.

Capt., thanks for describing your usage. Im filing all this stuff away as valuable information and I appreciate your response.

Turbo54 those are very intersting tests, especially the second one, as you mentioned. The scope on my long range rifle is a Nightforce Benchrest 8x32 56. I bought NF rings as well. I suppose that even though that is more towards a higher end product, that there can always be lemons to be found. I have no idea how they do their QC. I must say that second test equipment idea is brilliant!

TN, thank you once again, I did find it helpful to learn not only how you use the crono, but the frequency of how often as well. As for you saying that your not an expert, look at it this way, it's a certainty that you know more about this subject than 99% of all the people on earth!

Btw, I like your slogans, they make me think of one I heard many years ago... "If it jams, force it. If it breaks it needed replacing anyway".


BB, thank you sir. That is very sound advice and I can totally relate. There is a membership range I would like to join, where a bunch of old timers, probably ex mil, are doing long range shooting, having competitions, etc. hea, my plan is to build up to some degree of expertise at another range, and out in the desert, before I go out to the one I really want to shoot at and meet those guys, just so I don't look like some kind of dork. So I indeed appreciate your suggestion.

You all know that the equipment is pretty darn expensive. My philosophy has always been that it's better to wait and purchase the best you can afford. I want to make this my sport and hobby. I think I have a knack for it, champion? Nah, but I can shoot pretty well. I figure I need to accumulate a certain amount of equipment to do this right. Then it's just ammo and barrels. I'm trying to get what I need as fast as I can, but being smart about what I buy.

I recently read something that kind of stuck in my head, "Don't get too caught up on equipment, rather focus on your shooting". I think we all realize we need tools to do this well, but the fun is in the man behind the machine. That said, I'm really having lots of fun learning the theory, buying the toys, and sometimes even hitting a target.

 

[TimActual]

I got to thinking some more about how to prepare for using software without a crono. If I was to visit the range without a crono, find that I'm hitting low, what am I going to do? Just start throwing random numbers into my ballistic software's mv field and hope for the best? So what I came up with (I know, sort if a no-brainer but I'm kind of slow), is to create some dope on tweaking the software ahead of time so that I will have some numbers to go by for raising or lowering my poi via editing the software's mv field. Here's what I came up with as a starter for the ammo I'll be using, which is .308 Federal Gold Match 168gr. I'll continue to build upon that until I get enough dope to provide solutions to get me where I need to be. That dope in theory could be used whenever I may need to tweak the software as time goes on.

I used a mv of 2630 as that provided a solution of 100 clicks U to hit dead on at 500yds. (My scope is in 1/8 moa).

500yds = U100 clicks to hit dead on (in theory before tweaking).

So now let's say I shoot and my grouping is 1moa low or high at 500yds. I would need to tweak the software's mv setting as follows, based on the testing I did with the software ahead of time at home:

To raise poi 1 moa -85 mv to 2545
To lower poi 1 moa +85 mv to 2715

So I figure that if I spend some time building a little dope on this at home before I go out and actually shoot, it should save me some significant time out on the range getting the software nicely dialed in to where I need it to be.