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> Hornady “4 DOF”
Hornady “4 DOF”
@ 02:01 pm (GMT) |
Scott StruifI was looking at Sierra’s website because Nathan mentioned in his LR Cartridges book that their “tipped match king” should have been designated a “tipped game king.” At the time he published the 2nd edition, Sierra had not released the TGK. I was curious what, if any, differences there are between the two. Sierra’s literature and documentation are rather sparse, compared to, say, Hornady’s, so I found no answer to my question. However, I noticed that Sierra lists 3 different BC values for their rifle bullets, e.g., this one for their 90 grain 6mm TGK:.490 @ 2700 fps and above .400 between 1380 and 2700fps .320 @ 1380 fps and below. Yes, I knew that published BCs are just averages, so I wondered, What is your average hunter supposed to do with that? Well, first off, throw away the 3rd number, because the bullet is useless for medium game below 1380 fps. So should I average the remaining numbers? I though maybe Hornady’s literature would provide an answer, as they have all kinds of articles about such topics. There, I stumbled upon their “4 DOF” ballistics calculator. This tool has all a nerd could want, except, of course, a function to print a drop chart. Knowing that Hornady uses Doppler radar to calculate the BC of their bullets, I was curious to see how inaccurate the tool I use, Strelok , is. So I selected Hornady’s 90 grain, 6mm ELD-X from the 4 DOF dropdown box. Using Hornady’s published G1 BC for that bullet (.41), I also entered it into Strelok. Then I set all the environmental variables, as well as MV (3000 FPS), zero (200 yards), and scope height, the same in both programs. At 500 yards, bullet speed is a little below 1900 fps, and energy is in the >700 fpe range, so that, to me, is the maximum effective range for average-sized deer. (Before sniggering at using a 243 for <= 150 lb. deer at that range, I refer you to page 147 of Nathan’s book: “Maximum effective range [of 243 on <=154 lb. game] 650 yards or 1800fps with A-MAX, ELD-M or TMK.”) Surprisingy, Hornady’s program shows a drop at 500 yards of 39 inches, whereas Strelok shows a drop of 42 inches. I would have thought Hornady’s published G1 BC (.41) would be more optimistic. If I change the BC in Strelok to the first BC Sierra lists for their TGK (.49), then the drop changes to 39 inches. So it appears Hornady is perhaps more honest with their published BC number than Sierra. I’m not sure how Sierra expects hunters to use two or three separate BC numbers to calculate drop. |
Replies
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@ 06:20 pm (GMT) |
Scott StruifRe: Hornady “4 DOF”Adding to the confusion, Sierra list different numbers for the same bullet in the specs for their loaded ammunition offering (copied and pasted from their website):“Ballistic Coefficients of: 0.39 0.37 0.33 0.33 0.33 Velocity Boundaries (Feet per Second) of: 2720 2040 2040 2040” In the general description of the loaded ammo product, they state it has a BC of .390. They also show a chart, which, by coincidence, is based on the same parameters as I used above, but with a MV of 3200. The chart shows a drop of 36.5 inches. If I input the .390 BC and 3200 MV into Strelok, it show a drop of 37.4. That’s close enough for me. The Hornady program shows a drop of 34.73 with those parameters, still fine. I couldn’t shoot a group small enough at 500 yards to which of the 3 is correct. It’s odd Sierra lists useful data for their loaded ammo, but not their component bullets. It’s probably safe to say the ballistics calculators are pretty close, given an accurate BC estimation from the manufacturer. But I still don’t know what to make of Sierra’s listing multiple BCs, especially when they’re different for the component bullet vs. the same bullet in loaded ammo. |
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@ 06:37 am (GMT) |
Scott StruifRe: Hornady “4 DOF”I watched Sierra’s video demonstration of their Infinity 7 ballistics software. I see now that you can input different BCs for different speed ranges (data which only Sierra provide for their bullets.) I was going to download a copy, but it’s only available on CD (which is out-of-stock), only runs on Windows, and costs $40. This exercise has shown me that the free software that runs on your phone is just as good, even with a single BC value. |
@ 11:49 am (GMT) |
Martin TaylorRe: Hornady “4 DOF”For the benefit of any hunter reading who wants to stretch the legs of their trusty rig regardless of calibre, skill set, etc.The published BC's are basically a guide for your initial setup, either factory or hand loads. Remember your basic set up, which is a combination of rifle, ammo batch, optics, enviros, shooter, position, etc.). Zero/confirm your combo stepping out to your max range, recording drop & wind calls. Adjust your MV and/or bc in your drop chart calculations to match these findings. You have now validated this combo, not X companies test barrel or calculator. Most of us will have witnessed shooters/hunters pull out the trusty blah, blah app, dial up the "right setting" to see the shot fly high or low. I recall doing this test with a friend on some new .338 projectiles to find advertised bc was way off the actual number we needed. |
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@ 06:28 pm (GMT) |
Scott StruifRe: Hornady “4 DOF”Hi Marty. I agree. All I wanted to know was, What’s the difference between a Tipped Gameking and a Tipped Matchking? Sierra’s different BCs for different velocity ranges threw me. So what stated as a 2 minute inquiry turned into a 3 hour trip down the rabbit hole. However, it did confirm to me that the Strelok program is fine for estimating drop. I think I’ll spend the $40 on a gong and a can of spray paint rather than Sierra’s software. The maximum distance at my range is 280, so I need some way to test at farther distances. I have a range finder and spotting scope already. I assume the Tipped Gameking has a thicker jacket. They mention it’s designed for penetration. I think Nathan mentioned somewhere on this forum that Sierra wants to avoid complaints of bullet-blow-up from people who try to use their Matchking bullets at close ranges, so they refuse to recommend them to hunters, even though they work great at long ranges. |
@ 07:23 pm (GMT) |
Magnus VassbotnRe: Hornady “4 DOF”Hi Scott.I've put the Strelok Pro app, Shooter app, and the online JBM Ballistics calculator up against each other quite a few times. When I am precise with all parameters, results are basically identical. Perhaps within one click at 1000 meters. So I don't bother looking for error in that department anymore. Far greater factors are scope discrepancies, chronograph discrepancies and muzzle velocity variation due to temperature and other mysterious reasons. The number one things to do before verifying BC by drop is a tall target test, and . Most scopes I've tested have a discrepancy of 1-3%. My two chronograps have a constant disagreement of 1,8%, regardless of which one I put in front of the other. Based on an average with various loads, bullets and rifles at distance, I now know which one is closest to true. A few tenths in BC points are hardly noticeable at 5-600 meters, and far less than any of the other errors. So unless one is 100% certain about the other stuff, verifying BC by drop is completely useless. A difference drop at 500 meters beween a BC .450 and .500 is not practically measurable (as you also point out), but at the same time it means a LOT for impact velocity, and a bit for wind. So it is kinda important to know actual BC. As Martin says, think of published BC as a quide line to begin with. And as you point out, those that are doppler tested can be considered bery accurate, at least in my mimd. I also use such known, well established bullets/ BCs for shape comparison when I come across bullets of questionable BC. The Norma Bondstrike 30/180 and early LRAB BCs are examples of impossible BCs when compared to a number of similary shaped, doppler tested bullets. Just laying the 180 Bondstrike next to a Eld-X 178 and an RDF 175 makes it pretty obvious. Cheers. |
@ 04:38 am (GMT) |
Frank VallichRe: Hornady “4 DOF”Comparing the BC of bullets/ballistic calculators etc. to gather data is a good start to understand the nuances of propelling a bullet down range. The reality of finally selecting an accurate bullet for your rifle takes range time on a bench and then as stated by Scott in a separate post to practice as you would if you were on the hunt in the field. Road hunter or a bush walker (Bush Wacker).Accuracy is vital. Muscle memory is vital. Best to have an accurate bullet that is repeatable for a follow up shot than a bullet that claims destruction at 500 yards only to fail at accuracy and simulate a full metal jacket projectile. Example being a post on this forum of goat being struck by an ELD X hitting behind the shoulder - not the point of aim - and exiting near the hip area. In this scenario possibly the goat was knocked off balance, fell to the side, and hit its head on a rock and died of a concussive strike to the cranium and did not suffer a prolonged death due to failure of advertised bullet dynamics. Just saying! |
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@ 08:48 am (GMT) |
Scott StruifRe: Hornady “4 DOF”Thanks, Magnus & Frank for your input. As Nathan states in his book,“BC is not everything. I see far too many intellectual snobs beating around high BC’s along with custom made lathe turned solid bullets that if fired, could probably travel the planet and hit the shooter in the back of the head. The subject of BC is taken to the point of foolishness . . . .” Yet, as Magnus observes, a reliable BC estimate is necessary to know velocity at range, unless you feel comfortable shooting through your chronograph at 500 yards. And Nathan frequently mentions the BC of this or that bullet in his writings. Magnus recommended Strelok to me, and I have found the free version more-than-adequate for my purposes. I use it mostly to estimate velocity at various ranges . . . to know whether there’s enough left at distance to bother practicing shooting the gong, even at 280 yards. Strelok tells me that, with flat-base, soft-point spritzers with a crappy BC, at 300 yards I’ve got 2400 FPS and at least 1K FPE left . . . plenty for a 150 lb. deer. However, at 500 yards, those values are 1900 FPS and 650 fpe . . . too marginal to bother practicing with. On page 142 of his book, Nathan says, ““The G1 BC of the TMK averages out at .490 which is still very generous for a 6mm bullet.” Sierra’s specs on the bullet state: “.500 @ 3050 fps and above .490 between 1550 fps and 3050 fps .460 @ 1550 fps and below” So, it’s apparent he took the middle number as the average BC. I’m still irked at the inconsistency I found on their website, but it really doesn’t matter. The middle number they show in their component bullet specs is .400,is so close to the .390 BC they show in their loaded ammo specs is a distinction without a difference. |
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@ 02:56 pm (GMT) |
Scott StruifRe: Hornady “4 DOF”It turns out Hornady does have a system for rating the BCs of their bullets based on decaying speed ranges:Expanded BC Values for ELD-X Bullets Mach 2.25 (2512 fps* and above) - Velocities above 2,500 fps and distances out to 300 yards. Mach 2.0 (2232 fps*) - Use this for mid-range shooting where the bullet spends time in flight after slowing down. Mach 1.75 (1953 fps*) - Use this for long-range shooting where much of the bullet flight occurs after velocity loss. BULLET MACH 2.25 MACH 2.0 MACH 1.75 6mm 90gr ELD-X 0.410 0.402. 0.399 I had to fish around to find it. Here’s the link: https://www.hornady.com/support/ballistic-coefficient |
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@ 09:42 am (GMT) |
Scott StruifRe: Hornady “4 DOF”At the risk of boring the shit out of anyone following this, Berger has an interesting article in which they tout that they are the only company with the guts to try and move the industry to use G7 BC over G1. However, their software, based on the G7 BC of their 95 grain 6mm Classic Hunter bullet, using the advertised muzzle velocity of their loaded ammo, 3140, shows only a 60 FPS improvement at 600 yards, as opposed to using the G1 BC (which they say they still publish, for purposes of comparison to bullets from other companies who haven’t seen the light). The drop is similarly a little better (<2”), using G7. So, while they complain that other companies refuse to get on the G7 bandwagon because the numbers are lower than G1 values, it would be to their benefit to use the G7. To me, it’s splitting hairs. As Marty, Magnus, and Frank point out, there are too many other variables that make BC a purely academic exercise, with a tenuous connection to real life.https://bergerbullets.com/a-better-ballistic-coefficient/ |
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