Range Report 6.5CM Hornady Factory Ammo: 140 vs. 147 ELDM Comparison

[vh20]

I've been struggling to do an evaluation on the factory Hornady Match 6.5 CM ammo, 140gr. vs 147gr. I started out this new gun (26 in. Krieger Rem. Heavy Varmint, 1:8 twist) back in March with the 140s, working the distance back. It did great at 1000, really good at 1200, and pretty fair at 1400. Then they came out with the 147gr. version. I put their figures into my Kestrel AB and sure enough it theoretically outperformed the 140. In terms of real world drops, this has born itself out (for instance, at 1330, DA around 2700, Elev. is 13.5mil for the 140, and 13.1 for the 147). So I stocked up on 147s and started shooting them exclusively. They did great up to 1000 as well, fair at 1200, but have been giving me a lot of trouble at 1330. I kept thinking it was me, then it dawned on me - I don't remember having this kind of trouble with the 140s... So, I switched back to the 140s and it seemed my hit ratio improved. I hung two IPSCs side by side together at 1330 and tried doing head to head comparisons, but with this crazy weather this summer (it rains every day) it seems the wind always changes before I can get switched over from one to the other, then I'm poking around again trying to find the target. Today I started with the 140s, fired two center-mass hits on the 1000 target to confirm my wind call, then went straight to 1330. I went 5 for 5 on the left target, group measured 13 inches vertically, and only 5 inches horizontally (which is outstanding because the ES on the Hornady stuff is like 50s and 60s). Weather was dead calm so I hurriedly switched over to the 147s and re-indexed the scope elevation for what I know is correct for that load, and left the windage alone because there's very little difference in windage between them. So, I fired 5 rounds at the right target, and didn't TOUCH it. Couldn't spot a single miss either (green, wet vegetation everywhere). Reloaded and started poking around - holding 0.2 left, then 0.2 right, then added another 0.2 UP, etc. Never touched it. Got really frustrated, so I loaded up single round of 140, re-indexed and went back to the left target. It hit a little low and right, made the now 6-round group grow to 14.5 inches, but basically still solid dope. Went back to the right target and 147s, poked around and scored ONE hit, up high on the neck region. Next shot I saw miss just high. Brought it down a couple clicks, kept windage the same, and missed several more before giving up. I managed ONE hit out of about 14 rounds vs. 6/6 with the 140s on the target right next to it! The 147s have NEVER shot that bad (and I've had "enough" consistency to establish known good dope at that range)! And the 140s were shooting exceptionally well. Finally, it was quitting time and I happened to wonder about maybe the semi-hot barrel walking off zero, so I put two more rounds into the 1000 target and confirmed it still shoots to POA with a hot barrel, so that's not it. It isn't my shooting because the 140s prove that, but I can't figure out what's going on. It sure would be great if we could spot misses here like they can out west. I'm kind of wondering if the 1:8 twist that works so well with the 140s might be a little slow for the 147s. I don't know why that wouldn't show up until 1330, but they shoot sub-1/2 MOA consistently at 100 and sub-MOA at 1000. Interesting conundrum. Anyway, here's the 140gr target. The five shot group excludes the one hit that is low-right. As I said, the group is 13 inches. The single low-right hit was the one I fired about a half-hour later to confirm I hadn't lost my mind after missing the other target with the 147s every time. Although wind was minimal, it had probably changed just enough to account for the slight shift to the right.

By contrast, I can't seem to put 5 rounds of the 147 on target at 1330 to give you a picture, but here's what it will do at 1000:



...and at 100:



Any thoughts on what might be going on? By the way, I forgot to mention that I tried to do a test yesterday, and with the DA and conditions virtually identical to today, I think I put 4 out of 5 of the 140s on the first target, then went 2 for 2 on the 147s before the downdraft from a nearby T-Storm swept in instantly, and made shooting the rest of the test invalid. Those two hits were slightly low, but only 6 inches apart. I used the same dope today for elevation.

A wise, fellow member here suggested to me to just shoot the 140s and don't look back. Solid advice for sure. The reason I want to pursue it a little more is: a) to understand and learn a little more about what's going on, and especially: b) according to the Kestrel AB, the 147 factory load "should" be capable of more distance than the 140, and I've got the space to stretch it out farther if I could get it to cooperate.

 

[vh20]

UPDATE:

I repeated the exact same test in reverse order yesterday afternoon. This time I shot the 147 first, then immediately followed with the 140 on two targets standing side by side. Wind was minimal. (1 mph @ 3:00, accounting for about 0.2 mil correction @ 1330 yards, which is the target distance).

First shot with the 147s was on for elevation, but 0.2 mil Right. I decided to cheat the group a bit just in case it went off the right edge, so I dialed it back 0.1 to the left and fired the second shot. It impacted 0.2 High, and 0.1 Left. No changes, I fired third shot and it was on for elevation, but 0.2 mil Left. I decided to remove the slight correction I had put in and and moved it one click back the other way where I started. Shots 4 and 5 were misses, and I have no idea where they went. So, I was 3 for 5 with the 147 @ 1330, 15 inch "group" from what made it onto the target:



I immediately switched over to the 140s, re-indexed for the proper dope for that load (i.e. added 0.3 UP, no change on windage) and fired a five shot group. The first four landed center-mass in grouping just under 6 inches. The final shot went a bit low, and extended the 5-shot group out to 12 inches. (I don't know if I got cocky or complacent, or if the large 50-ish ES of the factory load just caught up with me).



So, that's two tests in a row where the 140 load clearly just outperformed the 147 @ 1330, even though their performance at 1000 is very similar. Sure seems like a stability issue to me, but this is my first time running into this type of result.

 

[VegasHKShooter]

You don't state your M.V., so I'm not sure where you're speed starts at. My GUESS, and it's just a theory, maybe the 147 are going transonic, and getting less stable. The 140 likely moves enough faster that it's staying supersonic farther out. I know the heavier 147 SHOULD hold their velocity better, but not knowing what they exit the muzzle at, it's tough to know.

Just a guess, and I'll be interested in other opinions on this.

 

[vh20]

Thanks for the reply. MV on factory ammo varies from lot to lot, but the current lots I'm shooting, the MVs are almost the same for the two bullets. In fact, the current 147 is 2777, and the 140 is 2775.

 

[vh20]

vh20 -

As I said in the post you disliked, nothing is like a light switch as the SOS crossing, it happens WELL before, with slow dispersion, more drop and continue well past. While the longer 147 may perform better in smooth air, it may not as the decay continues. I've seen the same in my 6.5.. better trans predictability in the Amax.


My point of the post you disliked, is that we are better off not thinking of the SOS as a definitive point that is at a static distance and velocity day to day, that all is great until the projectile hits that point, that the effects are over after that point, or that at the exact SOS, bullets trajectories go bad or bullets just tumble. Generally the first sings show up before the SOS crossing as slightly larger grouping and a click here and there more drop than the calculator is asking for, eventually turning to shit; but it is not a light switch event.

Thanks for the reply. Before I respond, can you please direct me to the post of yours that I disliked. I have no recollection of that whatsoever.

Never mind. I searched and found it. I was perplexed because I have never knowingly clicked Dislike on a post in my life. Not my thing. I responded further on the other thread with the post in question.

 

[vh20]

Diver - my initial (and only) explanation for the results was instability. However, this is my first experience with it like this. I routinely shoot out to 1630 at my range, but that is with a cartridge that is capable of far more than that (338 Norma). Now that I've started stretching a 6.5 out past 1300, I'm getting into new territory , which is shooting the bullet to its limits. I am aware that transonic region is not a narrow wall, but a broader band the bullet must transit. I should do more analysis of exactly what the exact difference in velocity is between the 140 and 147 at 1300, but a cursory examination of the data would indicate the 147 is moving faster than the 140 at that distance (which is where the 147 falls apart and the 140 does not). So yes, that made me question whether or not it was instability after all. Some other folks who are more experienced with ELR than me have indicated that if the bullet were unstable, it should show up well before that range.

Anyway, there's a lot in your post to take in, so I will go back and study some more, and ruminate on it further. Thanks for posting your experiences.

 

[pitdog85]

diver this is some of the best info I have seen here Im also trying to get my head around all of your post. So what you are saying that despite vh20 gun velocity for the 147 being slightly higher at muzzle than the 140 and presumably still higher at 1000+ yards as per vh20 post above the bullet is less stable due to being heavier than the 140 out of the same barrel which is causing it to destabilize sooner than the 140 at extended ranges? This would lead one to play with the berger twist calculator closer to find a more optimal spin stabilization number would it not for long range? The berger calculator only gives a yes or no as to will your bullet be stable is there a certain number one should strive to achieve with bullet weight, twist rate etc. Based on the above it would seem vh20 would need a 1:7 or 1:7.5 twist for the 147 to match the 140??

 

[tnichols]

Diver, thanks for the insight, information, and taking the time to post.

I'm glad vh20 and yourself got that whole "dislike" thing out of the way quickly, I can vouch for him that it's not his style. Both of you acted as gentleman.

Good read, carry on.

 

[pitdog85]

WOW what a great post diver thanks so much for all that info and detail really appreciate it and I'm sure others will too. Some serious eye opening stuff there.

 

[vh20]

WOW what a great post diver thanks so much for all that info and detail really appreciate it and I'm sure others will too. Some serious eye opening stuff there.

Yep. It's a lot to take in. I'm still working through it. Thanks again.

 

[lash]

Diver, thanks for the detailed explanations. Despite how you may feel about your written communication skills, I believe that you communicated this pretty well, using the most simple and basic language to get the point across. Your information has helped to fill in a missing part of my knowledge regarding behavior of projectiles into and through transonic flight.

Just so you know, I copied your posts into MS Word and saved them, like I do with any other very good information that I want to keep for future reference.

 

[Polizei45]

Thanks Diver and vh20. A great post. I'm going to print the whole post so I can read it again and again. Right now I don't have time to reload either. I have been shooting the factory Hornady 6.5 140gr. Match ELD. The farthest I have shot is 700 yards, but will be going out 1300-1400 yards in the future. With the Prime Ammo discount and free shipping going to the end of the month, I'm going to order a case of the Prime 130gr. to see how it shoots in my rifle. Thanks again for the great information.