Question regarding consistency in muzzle velocities....

I just got a Tikka T3x TAC AI in 6.5 Creedmoor, 24" barrel. I'll be reloading at some point (once I collect enough brass), and can find components/ powder). So I went shooting today and chronographed the factory ammo to get a baseline.

Factory ammo is Hornady ELD-M 140 grain, a match-grade round.

I chrono'd 17 rounds. Mean is 2687fps. SD is 18fps. Spread is from 2643 to 2717, so a spread of 74fps. Chrono is an older Shooting Chrony F1, circa ~2005. I'm the only owner, and have taken good care of it.

With match grade ammo, I would have expected much tighter results. So, is it possible I'm seeing this spread due to my measuring instrument? Or is this as good as it gets for factory ammo?

The corollary here is if it's my chrono, what would you recommend to replace it with?

You are getting good results. I have seen VERY accurate shooting from loads with much larger SD. The TARGET tells the tail, not SD.
18/2687 = 0.7% SD from mean.
Take an exterior ballistic calculator and determine POI for the slowest and fastest load at various distances and see if it is at all significant.

quote:

Originally posted by IntrepidTraveler:
Question regarding consistency in muzzle velocities....

I just got a Tikka T3x TAC AI in 6.5 Creedmoor, 24" barrel. I'll be reloading at some point (once I collect enough brass), and can find components/ powder). So I went shooting today and chronographed the factory ammo to get a baseline.

Factory ammo is Hornady ELD-M 140 grain, a match-grade round.

I chrono'd 17 rounds. Mean is 2687fps. SD is 18fps. Spread is from 2643 to 2717, so a spread of 74fps. Chrono is an older Shooting Chrony F1, circa ~2005. I'm the only owner, and have taken good care of it.

With match grade ammo, I would have expected much tighter results. So, is it possible I'm seeing this spread due to my measuring instrument? Or is this as good as it gets for factory ammo?

The corollary here is if it's my chrono, what would you recommend to replace it with?

The target may tell the tale (not tail) but at long range, that tale will have a long chapter about velocity consistency. It actually goes even beyond just a very low SD, but there is such a thing as BC consistency that match shooters bring into the mix. This is why people will trim the meplats or at the very least point them.

This sort of stuff starts making a difference beyond 500 yards and since you didn't mention a distance, I suspect you were talking about 100 yards of something like that.

The Chrony is ok, but the two most accurate devices that are easy to use and somewhat foolproof are the Magnetospeed (what I use) and the Lab Radar. Any optical chronograph is a pain to set up and must be done the exact same way every time and set up very properly to be accurate and dependable.

NikonUser, you're right, I'm only at 100 yards right now, so it's not likely to affect me significantly.

It's more of an engineering thing with me. I plan on reloading for this round, and I want my reloads to be as good as possible. Which means my tools - both measurement and reloading - need to be as good as possible (practical). I'm striving for excellence, all the while knowing that it's not really attainable, and even if it is, I'm not capable of shooting that well anyway.

I'll probably put a MagnetoSpeed on my Christmas list. Because, at this rate, components aren't going to be available until then anyway. (Fotunately, I do have a stock of primers; it's the powder that's going to be the limiting factor.)

Same rifle and ammunition, velocity measured with LabRadar chronograph.
Station pressure 21.34 inches Hg, 12 rounds.
Mean velocity - 2668 fps
Standard deviation - 21.7 fps
Extreme spread - 71 fps

Hornady 147 grain ELD Match, LabRadar.
Different day, SP = 20.90", 19 rounds.
Mean velocity - 2522
Standard deviation - 21.0 fps
ES - 80 fps

Velocities are supposed to be at the muzzle, so station pressure and other atmospheric conditions shouldn’t make any difference.

The 147 grain load has been very precise for me. I have had many consecutive five shot groups typically measure <0.5 - <0.7 inch at 100 yards. The 140 grain load hasn’t been as consistent for me, but that may be inconsistent shooter skill.

I am satisfied thus far with the LabRadar chronograph, but I also have a couple of much older Oehler 35-P units that I used for years. At one time Bryan Litz, the ballistician who has authored many books, preferred that model, but in recent times has switched to the LabRadar himself. The LabRadar is a little tricky to get set up properly, but all in all is significantly more convenient that the Oehler units. I decided on a recoil trigger that attaches a sensor to the rifle itself because of the problems I read about with the muzzle blast trigger option. That permits mounting the unit on the bench with the rifle, but on the other hand just running the bolt manually can sometimes trigger the unit and result in a “no reading” display. That’s easy enough to ignore and delete, but is a little annoying.

I gave some consideration to the MagnetoSpeed when looking at more convenient options than my old Oehler units, but a couple of things turned me off it. The first was the effect on accuracy and possibly precision by clamping something to the barrel. The second was that it can’t be used with pistols (AFAIK). It’s probably more convenient than even the LabRadar, but those factors made it unacceptable to me.

With the Magnaspeed V3 model, they make a Pic rail adapter that is supposed to be compatible with pistol rails (not sure if that's a recent development). But that doesn't solve the rifle clamping to barrel issues. My Tikka does have a Pic rail, but the bipod lives there. I sent them an email to see if it would work at 90° rotation to use on one of the side rails.

Somewhat related; there was an article in Handloader magazine years ago where they tested powder position in the case to speed differences.

They chrono’d the loads with the powder forward compared to rearward in the case. This was with a handgun, of course extra room in the case, 38 spcl I think.

The speeds were markedly different, higher FPS with the powder against the primer. They were so different, a casual observer would think they were different charges of powder.

This may or may not apply in the above instance, but powder position itself can have a bearing. That can be one benefit to a load where the powder just about completely fills the case, or is mildly compressed.

quote:

Originally posted by IntrepidTraveler:
NikonUser, you're right, I'm only at 100 yards right now, so it's not likely to affect me significantly.

It's more of an engineering thing with me. I plan on reloading for this round, and I want my reloads to be as good as possible. Which means my tools - both measurement and reloading - need to be as good as possible (practical). I'm striving for excellence, all the while knowing that it's not really attainable, and even if it is, I'm not capable of shooting that well anyway.

I'll probably put a MagnetoSpeed on my Christmas list. Because, at this rate, components aren't going to be available until then anyway. (Fotunately, I do have a stock of primers; it's the powder that's going to be the limiting factor.)

I use the Magnetospeed to get an idea of the velocity for ballistics purposes and of course, to make sure I'm not developing a load that's too over-pressure. The velocity of a load is the most important pressure sign; when you're piercing primers and have sticky bolts, you are already way over pressure, a bad way to monitor your load development.

Once I have may velocity parameters, I play with my loads (minute changes, seating depth, etc.) until the target shows me the proper results at 100 yards and then I do a final velocity check for ballistics.

The items sigfreund listed are all very valid and the Labradar is a great device. But it's spendy and as I say, I don't check my velocity all the time. The MS 3 has been in my arsenal for years and that's all I needed.

If you want to develop for competition, I would point you to my stickied thread here for ideas on that. Hornady makes great ammo, and thinking you can do better when just starting into handloading is a little far fetched. You can, but it will take time.

Yesterday at the 1000 yard match, I captured the results of my efforts from the Shotmarker and one of its data points is the velocity at the target. I was pleased to note that the SD of my bullets at 1000 yards downrange was in the single digit range.

quote:

Originally posted by IntrepidTraveler:
Factory ammo is Hornady ELD-M 140 grain

I chrono'd 17 rounds. Mean is 2687fps. SD is 18fps. Spread is from 2643 to 2717, so a spread of 74fps. Chrono is an older Shooting Chrony F1, circa ~2005.

Your Chrony F1 isn't helping. I had one for awhile, and found the data could be inconsistent. I now use a MagnetoSpeed V3, which is really consistent. The V3 can affect POI and accuracy, but I find the effects to be minimal with large profile barrels. The V3 does noticeably change the POI with a couple of my smaller profile AR15 barrels. I'm clamping the V3 to a suppressor, which means the V3 is hanging a long ways out in front.

I use the MagnetoSpeed to attain MV, then it's off the gun. I change targets and shooting positions enough to make the Labradar a challenge to use. Using good suppressors makes the Labradar a challenge.

Hornday's ELD-M ammo is one of the better match-grade factory ammos on the market. It's not perfect however. It's plenty good enough for the steel matches I shoot in, given a few caveats. I shot ELD-M 140 in Nightforce's Wyoming ELR match this summer. I hit targets that were from 800 to 1800 yards, when the crosswinds were under 20 mph. The 25-35 mph crosswind stages weren't so good for me. I missed the long-bomb 2100 yarder, but that's beyond the capabilities of my 6.5 Creedmoor anyway. Our steel matches generally have targets ranging from 1 MOA to 2.5 MOA. Most of the better competitors have rifle systems capable of at least 1/2 MOA accuracy. We miss targets due to judgement calls, wind calls, unstable shooting positions, and mental errors.

Hornady's ELD 140 tends to be reasonably consistent within a given manufacturing batch number. Unfortunately, the variation in MV between batches can be really irritating. I had a batch which turned out to be about 100 fps slower than expected. Being a total sheepdip, I took that batch to a long distance match without testing MV in advance. I just assumed the MV would be about the same as another batch from the same manufacturing year. Yeah, that match didn't go so well for me.

SDs of 18 aren't all that unusual with ELD 140. Most of the time I see SDs in the high single digits to the low teens. The batches with SDs in the single digits shoot really well in my rifle. But I also won a regional steel match with ammo that had an SD of 24 -- and targets out to 800 yards. The batch with the SD of 24 produced .3" groups at 100 yards, and was manufactured in 2016. Honestly, I'd buy another couple thousand rounds from that batch if I could.

Use factory match ammo as a performance guideline for your future handloads. As your handloading skills develop, your loads will show less MV variation. Your rifle system's accuracy potential will improve at all distances. Nevertheless, the skills of the nut behind the buttstock need the greatest attention.

fritz, I had to laugh at your "nut behind the buttstock" comment. In my biz, we often talk about the "nut that holds the keyboard down".

How many shots do you chrony to get your stats? I know statistically, the more the better, but how many is good enough? my above mentioned SD and ES are based on a 15 shot sample size.

I'd qualify my reloading skills as "OK but a little rusty".

I use groups of 5 shots. I've also tried groups of 10, but I don't see significant differences in average MV, ES, or SD with quality ammo.

With factory ammo I am more concerned about variation between manufacturing lots, which might be similar to a hand loader's testing of powder lots. Anyway, I prefer to do 3 different 5-round MV tests for any given lot, using ammo from different boxes within the same lot. So far, this works for me. I haven't seen significant swings (yet) between different boxes within the same lot.

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Putting things into perspective with 6.5CM Hornady 140 ELD-M ammo. Records show that I currently have about 2200 rounds on hand, in 6 lots. I used to buy in 6.5CM ammo in groups of 200 or 400 rounds, but now it's in groups of 800 or 1000 rounds. This helps to minimize potential MV variations during a big match. Most of my ammo lots have MVs in the 2800-2810 fps ballpark.

I have a slow lot that clocks in at 2760. This is a 2019 lot that I fought with Hornady for awhile, before they admitted it wasn't up to MV spec. But it's really accurate, producing 1/4" groups at 100 yards.

I have limited boxes of a fast lot that clocks in at 2850-2860. This is what I used at the ELR match this year, and it was great. Unfortunately, I only have enough for one more ELR match.

My MVs are for a 26" Bartlein with a TBAC Ultra 9 suppressor.

I would add some info on the Crony's. I have two of the the Beta Master units, one using the IR light screens from Midway (no longer sold separately). These Chrony units work OK, but one needs to note there is a sweet spot to put the shot across. I put blue tape on the screen rods marking this area.

All this to say you can get pretty good numbers with care in the setup(screen angle same as muzzle etc.) Setup on a busy range is just one reason a MS3 or LabRadar is in my future. All the fiddling to get it all lined up is wearing thin. I did manage some sweet accuracy and single digit SD's with some 130 ELD/H4350 loads. My Bergara seems impressed with this bullet