The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading do you use a chronograph?Go | New | Find | Notify | Tools | Reply | |
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quote:Hey Seafire, 1. I don't think I've ever had a 32Spec, so I've no idea at all which is better. Also don't know how this relates to the subject of this thread. 2. I agree that it gives you a "Refrence Point". However, anyone attempting to shoot Game, at l-o-n-g distances, without first actually shooting groups to verify the Drop Rate understands much less about real life trajectories than he thinks he does. 3. Absolutely! 4. I agree the Velocity "can be useful", but it can also be misleading as to the actual SAFETY of a particular Load. ... For anyone using Velocity "ALONE" as their sole indicatior of when to stop adding Powder, I'd strongly encourage you to learn more about what is actually going on when a cartridge is fired. Best of luck to all of you. [ 06-05-2003, 16:48: Message edited by: Hot Core ] | |||
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FYI, As I've moved up a increasing load of powder, I've had the POI move all over, higher, lower, left, right. I guess the barrel harmonics changes with each increase. ![[Big Grin]](images/icons/grin.gif){kind=icon} | |||
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You simply can not work up a good long range load with out a chrony PERIOD. Take a load that gives extreme spreads in the 40 fps to 50 fps range and put it on paper at 1000 yards and see what happens. And the only way you are going to know what the extreme velocity spread is for that load is by using a chrony. Hunting loads that are used to 300 yards can have that kind of spread and not really affect the outcome of the shot by having a 40 to 50 extreme spread. Not so with long range target shooting. Buy one you will never regret it! Just becareful and don't shoot your chrony. I saw that done once.....Funny as hell since it wasn't my chrony. Pieces flew everywhere! Shoot Safe, Shoot Straight.....RiverRat | |||
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quote:Correct me if im wrong but I always thought a faster moving bullet will hit higher then a slower one regardless of distance.. Here is my logic in thinking this.. Lets say we are using a 7-08 with 139 gr bullets with a bc of .392 sighted in @ 100yds with a MV of 2320 and your hiting dead center in the target @ 100yds.. Now if you make no adjustments at all and shot @ 500yds that bullet will drop roughly 112" and @ 1000yds it will drop roughly 367"... Now you are shooting the same bullet with the same bc out of the same gun but this time the MV is 3200 before you make any adjustments at all that should hit a tad higher @ 100yds so you make the adjustments to have it hit dead center @ 100yds.. Now once that is adjusted to 100yds you shoot 500 yds without adjusting a thing and that bullet will only drop roughly 56" and drop roughly 179" @ 1000yds... So that is how I would think that no matter what the distance is the faster bullet should allways hit higher then the slower one... Since you are pushin the bullet faster the arch is lower which results in a flatter shooting round in return = hitting higher then the slower rounds... Hope that made sense lol 6.5 Bandit | |||
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[ 06-05-2003, 17:46: Message edited by: 6.5 Bandit ] | |||
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socal hunter - Are you going to get one now or no? Lot of thoughts on this thread. I,like many, handloaded for years without a chrono. I had some extra monies left over from a barrel purchase and got one. Now I use it for most all my load development. I don't use it to find my fastest load. It merely lets me know what the loads are doing (without guessing). Could I handload without one? Yeah, heck I did it before. Would I not use one if I had one? No, if I have access to one, it will be in front of my barrels. Now the question is - which one to get? ![[Roll Eyes]](images/icons/rolleyes.gif){kind=icon} | |||
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I have a chronograph, and do not use it all the time. I work thru different powders until I get my best accuracy just shooting paper. THEN the chrony comes out. I record the accurate load, and then begin trying different seating depths, and different primers for the fine tuning. This is the best use of a chrony to me. | |||
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I loaded without a chrono for years. Now I have no clue why. The infor that it give is very invaluable. They are cheap enough to get as the next major purchase after the press and die. Safety first | |||
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Gentlemen - Please allow me to make my case once again for using the relationship between velocity and pressure to advantage. Assume we are shooting over a chronograph and working up loads for my 300 WSM, using the Nosler 5th Edition and the exact components specified. I have worked up about 5 other complete loads and am familiar with the rifles pressure velocity quirks. Since its a Savage, it has a tight throat, and seating to the lands is easy. Other loads seated to the lands have been requiring 2 to 3 grains less powder than the manual indicates to reach the top velocities listed, and there have been no signs of high pressure. We do NOT add more powder to get more velocity, even though the manual says we can without exceeding a MAX load. There are 9 chances in 10 that we are within plus or minus 2% of the pressure the manual used as max. We are working now with Hornady 220 gr RNs, NOT the Nosler partition SMP. We back off the lands .030, use the start load listed of 60.5 grs R22 and get 2675 fps instead of the listed 2546 fps. We back off the gharge to 58.0 grs, and get 2530 fps, very close to Nosler's starting point. Now we seat to the lands and get 2655 fps with 58.0 grs. We work slowly up to the max velocity Nosler lists at 2752 fps with no signs of excess pressure. The charge weight is 61.8 grs of R22. This is our max load, NOT Nosler's 64.5 grs. Without the chronograph, this type of control over pressure would not be possible. | |||
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quote:Ok so if we are now using Hornady bullets and NOT Nosler why are we still using the Nosler data? Why not use Hornadys? If I read this correctly you are stopping when you hit the max speed 2752 and you have no signs of pressure which I agree with but here is the thing just becosue you meet the speed that is in the book @ a lower charge of powder doesnt mean you should stop there.. Now I agree 100% if there is pressure signs to stop there.. But if you go say .5 grains more makin the total charge 62.3 grs and still not showing any signs of pressure and the speeds increase is this now dangerous?? I would think not.. Now lets say that extra .5 did show some slight signs of pressure then I would go back to the orignal charge of 61.8.. Now lets say you didnt have pressure signs with that added .5 and you now go with .5 more to make it 63.3 and now you are showing signs of pressure then I would back of to 62.3 and NOT back to 61.8 grs just becouse the book lists a max speed of 2752 for Nolser bullets and NOT for the Hornady bullets we are NOW using.... 6.5 Bandit | |||
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6.5 Bandit, I agree with your example completely. ![[Wink]](images/icons/wink.gif){kind=icon} What I was refering to was not with the extreme velocity spread as in your example, rather that of say 50 fps and while shooting a group of the same load. If for example you shot two rounds in a group and the one that impacted low was the faster shot and the one that impacted high was the slower shot, which if you use a chrono you know happens all the time, the slower shot will shoot flatter for a ways until gravity finally causes the slower ones trajectory to fall below the trajectory of the faster one. This is considering the fact that this is not a .0001" group either, and say for instance a 1" group. If the slower bullet has an instant 1 MOA correction advantage over the faster one, it's only worth a bit over 10" at 1000 yards. When the slower bullet reaches the range at which point the faster bullet has a 1 MOA advantage in trajectory, the faster bullet will now hit higher from there on out... even though it started out on a 1 MOA lower trajectory angle than the slower one did. Sabot, I agree with and like your example too, very nice. ![[Smile]](images/icons/smile.gif){kind=icon} 6.5 Bandit, The switch to Hornady from Nosler is going to change things but, not anymore than switching lots of powder could. Hornady's data would be worth a look at and could possibly be more accurate but, it could be the other way around too. I take a look at a few manuals before I decide what's a safe max "average." Work up slow watching for pressure signs and you ain't going to blow it up... unless you ignore them. | |||
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socal - the chronograph......what did you come up with? And which one do you think you're going to shoot. ..oops, I mean use? | |||
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quote:Hey Sabot and Brent, Still looks like pure speculation to me. But, I'm willing to learn. What do you base the above statement on? What gave you that impression? Of course, since "Velocity DOES NOT equal Pressure" due to all the Variables, it obviously can't be that. Are you all basing this irrational statement on "gut-feel" and "guessing"? [ 06-06-2003, 16:17: Message edited by: Hot Core ] | |||
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Brent, Thanks for clearing up the speed issue and which one will hit higher.. Now it makes total sense to me and I do agree with that now... As far as the other exp. with Nolser manual and the Hornady bullet The point I was tryin to make was this.. Say you have 2 differnet bullets both way 220gr.. Both loaded with the same powder and same amount of grains.. I have seen instances where one would shoot from a couple fps (10-20) faster to a couple hundered (100-200) fps faster.. Just becouse the bullets are a differnet style and one may fly better/faster just based on aerodynamics itself.. But what I did NOT think about was this.. If Nosler was claiming 64.5gr's to get to the max speed of 2752 and that speed was reached @ 61.8 the only way that could happen is if you have the same amount of PRESSURE as what the 64.4gr that Nosler had.. Ok now that does make sense to me as well.. But before I stop and say ok thats it im @ max.. I would have to look @ Hornadys manual and compair it to Noslers to see what they are claiming for speeds with the charge you have loaded.. If by chance you are = to Hornadys but not Noslers then I would raise it .5 to see what happens.. But on the other hand if both are claiming the speed of 2752 @ 64.4 grs then YES I would stop at the charge of 61.8 to be safe... So in this instance velocity DOES = PRESSURE.. Thanks for helping me understand this better.. 6.5 Bandit | |||
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Since all rifles do not produce the same velocity with equal pressure,it is possible that your own rifle may produce more velocity than the one used in the reloading manual and still be at a safe pressure.Then again you could see signs of pressure and still be producing less velocity than stated in the manual.The safest bet is to watch for signs of pressure and trust them more than any velocity figures given in manuals.Remember that the data in the manual is for one specific gun and it may vary considerably from your own. | |||
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The problem with adding an extra .5 grs is that we are already at the theoretical maximun energy for the case. For modern bolt action rifles and beass, this is estimated by raising the product of the square of the bore in inches times the case capacity in water grains to the 0.6 power, and multiplying by a constant applicable to the case. In out 300 WSM example, the constant is 1177 and the usable water case capacity is 70 grains. This gives us: 1177 (.308 X .308 X 70)^.6 = 3665 Foot Pounds of muzzle energy. Our load already gives a bit over 3700 FPE, so we are pretty much at max, unless we increase pressure above max. Cases held tot 52,000 to 54,000 CUP generally have a constant of 1111, so the short and fat techology is increasing the energy efficiency by nearly 6%, or velocity by 3%. All of this assumes that the barrel is of optimum length for rifles, given by: (70/ .308 X .308 X Velocity) ^.22 or 24.4 inches. Our bbl is 24.0 inches, so we are close to the optimum. | |||
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Published data are generated in a special lab barrel that is cut to minimum chamber dimensions. As a rule of thumb, data from the test barrel will be roughly 3 KPSI higher and 60 fps lower than a "typical" rifle. For their pressure tests, Hodgdon uses a special batch of powder that is dead-bang in the middle of spec. The powder in your jar may be a little hotter, or a little cooler. Bore diameter, plus or minus a thousandth, has very little effect on pressure (Ackley). Of course, those are not ALL the variables, but what it adds up to is that if you're getting the published muzzle velocity, there is an odds-on chance that you have reached maximum safe pressure for your rifle. Of course, adding a strain gauge will give you additional "comfort" on the pressure issue. But if you have only a chronograph to go by, my theory is that if you're getting the published MV, you'd probably better stop increasing load. | |||
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A chrony will certainly help judging the usefulness of powders in your more oddball calibers,such as 264.Very high pressure and 200f/s slow to me ,is a reject.BTW the book said it should have worked well. In a 30.06 a chrony is fun. | |||
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Ooops... meant to say that the test barrel will be 3 KPSI higher pressure, and 60 fps faster than a "typical" rifle. | |||
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I have no doubt that one can get by without a chronograph, you really don't need one. We went for many years without them and didn't suffer any great disasters... I now have two of them and I use them all the time and they certainly are entertaining but they are not the solve all of reloading IMO...A couple of up to date reloading manuals and a little knowledge of pressure, and good reloading practices will serve you well. Where I do believe they are necessary is when one graduates to reloading the English double rifles, there I would not like to play without my chronograph.... | |||
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Ray,the latest Nosler Manual,264 is just a reprint the earlier one.Why have a 264 at 30.06 speeds? | |||
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Guess I am the odd man out. I've never really been concerned with how fast the bullet is going. I am only interested how accurate it is when it hits the target. Comparision of groups will let you know whether your loads are moving in the right direction or not. As for safety, if you can't read the signs of excessive pressure without the use of a chronograph, you shouldn't be hand loading anyway. Just more crap to lug to the range. | |||
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Hot Core, Hey Sabot and Brent, Still looks like pure speculation to me. I'd characterize it as more of an edjucated guess. But, I'm willing to learn. What do you base the above statement on? What gave you that impression? Sabot explained what he based it on in the full context of what you quoted him as saying, I believe. Mine is based on the same thing and the additional aid of the Oehler 43 data too... which you seem to dismiss, amoung other things.  Hook up strain gages to 10 different rifles and do some PSI vs. MV evaluations and we'll have more to talk about. I await the day... breathing the whole time of course. You know you are a stubborn cuss don't you... Of course, since "Velocity DOES NOT equal Pressure" due to all the Variables, it obviously can't be that. Are you all basing this irrational statement on "gut-feel" and "guessing"? Of course, nobody said it was exactly equal to MV... just another real close indicator, probably as close or closer than that of CHE and PRE... based on the accuracy level you've described here over time, a whole other debate I'm sure. How is using another aid like a chrono to help determine where you're at with pressure going to place you in a dangerous situation... that's what I'd like to know, and you seem to be implying that? | |||
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quote:HC: Obviously a wise statement from me! Brent: Mine is based on the same thing and the additional aid of the Oehler 43 data too... which you seem to dismiss, amoung other things. Hook up strain gages to 10 different rifles and do some PSI vs. MV evaluations and we'll have more to talk about. I await the day... breathing the whole time of course. HC: Nahh, no need to totally waste the money on unnecessary toys with questionable accuracy when PRE and CHE work so well. But, if a person has wasted the money on such way toooooo expensive and totally unnecessary foolishness, then by all means use them. And use them every chance you get. Brent: You know you are a *stubborn* cuss don't you... HC: Apparently you mis-spelled *knowledgeable*! HC: Of course, since "Velocity DOES NOT equal Pressure" due to all the Variables, it obviously can't be that. Are you all basing this irrational statement on "gut-feel" and "guessing"? Brent: Of course, nobody said it was exactly equal to MV... HC: Like I thought, nothing but "gut-feel" and "guessing"? Brent: ...just another real close indicator, probably as close or closer than that of CHE and PRE... HC: HAHAHAHAHAHAHAHAHAHAHAHAHA Brent: How is using another aid like a chrono to help determine where you're at with pressure going to place you in a dangerous situation... that's what I'd like to know, and you seem to be implying that? HC: You need to take an Asprin, put on your reading glasses, then go back and re-read my posts. I believe in my second post to this thread I said something like, "I should have mentioned it before, but you should always use EVERY Pressure Indication method available to you. Using any "Indicator" by itself(Velocity, Strain Gauges, Sticky Bolt Lift, Pressure Ring Expansion, Case Head Expansion, Ejector Marks, Primer Pocket Expansion, etc.) is the sign of someone who just doesn't fully understand how it could get them (or someone else) into Pressure Problems. ... As usual, people using "gut-feel" and "guessing"? can mislead the Beginners into thinking Reloading is as simple as ONLY watching for some arbitrary Velocity pulled from a Manual. Those folks just lack an understanding about what all creates Pressure during the time a Bullet is being fired. Reloading can be very SAFE, but ALWAYS use every Pressure Indicator available to you. And don't be duped into thinking a Chronograph is the ONLY indicator you need to keep you out of Pressure Problems. Best of luck to Brent and all the other Beginning Reloaders. [ 06-07-2003, 17:44: Message edited by: Hot Core ] | |||
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Socal hunter, and to get back on topic--- quote:Put a checkmark in the 'I do' column. I handload for 5 different pistol calibers and use it for every one. Hell, I even use it for 22 rimfire. Why? Any chronograph (I think) does more than just record the speed of the bullet flying over its screen. It gives you data for a string of shots. You use that data to compare: Bullseye to WW231, heavy crimp to medium crimp, powder shifted toward the bullet vs. powder shifted toward the primer, and on and on and on. It's a very useful tool and gives me, at least, lots of fun. Your use may vary. quote:Absolutely not. If you're the kind of guy who loads for max economy or just likes to 'pop a cap' now and then, investing in a chrono won't make one whit's difference. I guess it all boils down to what you want out of the sport. | |||
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Hot Core, The "Gut Feel" or "Guessing" is just pure BS and you know it. You tellin me that you aren't taking an "edjucated guess" at pressure when you use the PRE and CHE measurements, give me a break... Where have I or anyone else misled a beginning reloader here. ![[Confused]](images/icons/confused.gif){kind=icon} If your consistancy in the measurments you claim about PRE and CHE are 100% true, which I "don't" doubt that are, I still know it's resolution is much less than that of any strain measurement system. You are unwilling to accept this FACT and this therefore proves to me and others that it is you that are indeed spreading BS. Denton has clearly pointed out the "best possible" resolution in PRE and CHE and why you can't accept this and move on is clear... it works well enough for you. The fact is, you make it out to be more accurate than strain systems and that's pure BS. I was a beginner reloader once, but even back then I still wouldn't have just taken someones word for something just because they act like they know what they're talking about. I can think about things for myself and don't need nobody to that part for me. ![[Razz]](images/icons/tongue.gif){kind=icon} I see the inaccuracies in the various pressure indicators even if you fail to. Good day Sir. | |||
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Re. point of impact higher with lower velocity: sure this is possible, changing barrel whip has been mentioned, but there are very basic things like wind, mirage, shooter's error, defective scope or mounts. And how often did this happen - can a statistical relevance be claimed ? By no means the trajectory theory as a.m. holds water: having the same point of aim and any condition being the same except the speed of the bullet, the trajectory of the slower bullet will always and at any distance be lower than the fast one (except at the muzzle). I use the chrono to check if my loads are consistent - if not, something is wrong with my load. The variables as mentioned above do not come into play and need not be considered at that stage: it's handy to know that speed variance is no factor when you check grouping. I use the chrono when I start with a new lot of powder. And I use the chrono for curiosity: -my P17 yields the same muzzle velocity as my Spr1913 with the ~2" shorter barrel, - many of the .22 lr ammunition I cannot influence by reloading have a tremendous spread, - in a discussion somewhere in the net is maintained H322 to be faster than N133 (in fact, the new VV burning rate chart shows this in contradiction to 10 or more other charts) - but this is nothing but paperwork: the chrono tells me that (in my cases and my rifle, with the powder lots I own) N133 is faster, and more than just just a little bit. and so on... Have a chrono and you'll have more trust in your loads - and a lot of fun. And the shooters around you will like you - when you shoot your chrono. | |||
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There was an earlier post that just broke me up... hope my recollection doesn't distort the original: Right after Christmas, some guy shows up at the range, with is kid in tow, and a brand new Oehler chronograph. He sets up the chronograph, and steps out in front of the table to set it up, while the range was "hot". The range officer called a cease-fire, got the safety issues straightened out, and ask the guy to wait until the range was declared safe. So the guy pouts a little, but waits. When the regular cease-fire was called, he chambered a round, laid his gun down on the bench, and stepped out to set up his chronograph again. The range officer caught it, and there was a little fuss as the guy unloads his rifle. Finally, he is set up and ready to go. The range officer declares the range hot again, and the guy, now a little miffed, gets ready to squeeze off his first shot. The guy next to him advises him that his chronograph looks a little high for the shot he is trying to do. Does he think he ought to move it a bit? By how the guy is kind of huffy, and says that he knows what he is doing, and to leave him alone. First shot: Kerblooey, right through the center of the Oehler. So the guy grabs his kid, jumps in the car, and sprays gravel as he exits. As luck would have it, the other shooters were able to salvage some nice sunscreens and such.... | |||
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Waitaminit-When a person is shooting consistant groups and the next group strikes noticeably low even though it is of a higher velocity I am going to be suspicious that the point of impact has changed.When the next group at the same velocity strikes the same point of impact as the previous one I know that the point of impact is changed.You can come up with any excuse you want but the fact is that increasing the velocity can and does often result in a lower point of impact.I am not talking about 1-1/2" groups moving 1/8" where shooting error can be blamed.I am talking about 1/2" groups moving 1/2" in any direction and staying there as long as the same load is used.When the load is switched back to the original load the point of impact also switches back to the original position.This is not theory but is fact based on actual experience. | |||
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Waitaminit, The direction the barrel is pointing when the bullet exits will have most to do with POI, which is why slower bullets DO OFTEN hit high. This is affected by barrel time, recoil, internal ballistics and much more. If they leave on the same INITIAL trajectory angle, true, the slower bullet will always fall lower and lower than the faster... too much goes into the initial angle it leaves the muzzle on though. If I shoot 5 shots at 100 yards, each at 20 fps intervals, they WILL NOT hit the target in order from high to low with the slowest shot on bottom.... I guarantee it! If they did, it would be more luck than anything. What you'll see most likely is no trend at all. Shoot the same thing at 1000 yards, or maybe even 500 yards and the results would be quite different indeed. If the spread at 100 yards was quite large, say MOA, you might not see any difference yet at even 200 yards.... some slow shots still hitting high. POI shift "can" have alot to do with the same things that cause low shots to initially go high too. When you change a load, you've changed the internal ballistics possibly enough that POI shift takes place, sometimes change in temperature, or rifle hold, rest type, will cause the same exact thing. Consistancy is KEY. | |||
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Look at any long range exterior ballistic table. Example: muzzle vel 100yds 200yds 300yds 3000fps +1.5" 0 -6.9" 2900fps +1.7" 0 -7.4" 2800fps +1.9" 0 -8.1" 2700fps +2.1" 0 -8.8" B.C.=0.42 (Note that at 100 yards the bullet hits higher as velocity DECREASES)! I have seen this in actual load developement for a fact. The flight of the bullet is rising out to mid-range trajectory and falling afterwards. This is affected by velocity and is a law of physics. I don't think Hornady, Speer, Nosler and Sierra could all be wrong. Check it out!BLR7 | |||
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BLR7, sorry, but I cannot accept that. I do not doubt the tables, but the sights (= point of aim) has been corrected for hitting the x at a 200yrd distance. This means: knowing the lower speed of the bullet in advance, one increases the inclination of the barrel. We are talking about random changes in velocity with the barrel always at the same inclination. Both of us accept the rules of physics, but the definition of start conditions of the experiment are formulated differently. | |||
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quote:Hey Brent, I gave serious thought to just passing on posting, but I do believe you are worth SAVING! 1. Where you(and other posters) mislead someone is when you make statements based on "gut-feel, guesses, speculation, limited experience, etc." without stating so. It really doesn't effect me, cause I can see through the ignorance(meaning a simple lack of knowledge). The problem is if you continue to do so it will cause your credibility to suffer among people, with actual hands-on experience, who do know better. I'm not saying that to make you mad, I'm saying it to help you out in the long run. That is why I'm taking the time to make this post. It is up to you "if" you are able to learn from this or not. 2. Your second statement " implies " that you have first hand experience using PRE and CHE. After following your posts for awhile, I now understand you are quite often negatively critical of things where you have ZERO first-hand experience or actual knowledge. It makes me wonder how much actual first-hand experience you have using PRE/CHE. I'm betting on "NONE AT ALL". So, do tell us all what actual problems your first-hand experience with PRE/CHE has created to lead you to this TOTALLY WRONG conclusion. 3. & 4. I don't accept it simply because you are TOTALLY WRONG! Again, making statements such as this based on ZERO first-hand experience makes you look like a fool. No need to be mad at me about it, you are doing it to yourself. 5. You are at the most dangerous phase of Reloading - you have some "limited" knowledge and "very limited" experience. Due to your Rookieness, you end up making statements which are simply not true and you don't know it. Then when someone bothers to point out the errors, you defend them with personal attacks and speculation. Not wise at all. But, as you can see, I can dish it out as well as I can take it, with one added bonus - my statements are based on LOTS of knowledge and over 4 decades of experience. ... So, let me encourage you to say, "this is ONLY a guess" when you are speculating on matters where you really have limited knowledge and experince. People will have respect for that. I'll not respond to any more of your personal attacks or total ignorance "on this thread". I do hope you are smart enough to "learn" from this. And, as strange as it may seem, I'd bet you are. | |||
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quote:Hey Denton, Great story. I'm kind of surprised I've never seen one as it was "being" shot. Seems like more folks show up at the Ranges with them all the time. Quite a few strange looking rods to hold up the sun shields on them though. | |||
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quote:Hey Phantom Duck, 1. I think you may have accidentally "overlooked" a few posts in this thread that do not make you the odd man out. 2. Try not to "confuse" the Rookies with sound logic. 3. A HUGE - AMEN!!! 4. Pardon me if I find great humor in that statement. ... By the way, I "occasionally" get down to Coral Springs. It would be nice to tip a cool one or two with you some time in the future. | |||
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quote:Hey Waitaminit, I have to agree with Stubblejumper. It is often impossible to predict which way the "Point-Of-Impact" will move when a Load is changed. I do agree it "seems to make sense" that a faster bullet will impact lower on a target due to reduced barrel time. But, the good old "Barrel Harmonics" cast an over-riding vote on all this "sense" and can send the POI in any direction. Lots of Trigger Time using different rifles and different Loads will verify this for you. Best of luck to you. | |||
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There are three reasons a person would not believe that increasing velocity could cause a lower point of impact: 1)Not enough experience developing loads to see it happen for themselves. 2)the inability to shoot small enough groups to notice it 3)lack of confidence in their own shooting so they blame it on shooter error or some other excuse | |||
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Thank you for the compliments, Stubblejumper. You may find this thread intersting: http://www.benchrest.com/forums/showthread.php?s=&threadid=3537 I reviewed my posting "Re. point of impact higher with lower velocity: sure this is possible, changing barrel whip has been mentioned, but there are very basic things like wind, mirage, shooter's error, defective scope or mounts. And how often did this happen - can a statistical relevance be claimed ? By no means the trajectory theory as a.m. holds water: having the same point of aim and any condition being the same except the speed of the bullet, the trajectory of the slower bullet will always and at any distance be lower than the fast one (except at the muzzle)." and find nothing wrong with it: it's a very theoretical situation as usual in considerations about physics. I am absolutely aware of the phenomenon high velocity/low impact for which I mentioned reasons and add that a lower speed causes a lower drag and maybe a different kind of bullet motion. I experienced this several times myself. The ladder test (=search for sweet spots) is a good example for this phenomenon being general wisdom. I think, and this has been postulated in several postings of this interesting thread, barrel dynamics are the most important factor. [ 06-08-2003, 21:01: Message edited by: waitaminit ] | |||
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Waitaminit-I read the thread to which you refer and in those cases one or two shots dropped low but the following shots returned to the group.The result was a larger than average group but it retained the original POI.What we are talking about here is entire groups changing POI and remaining there as long as the same load is used.These are entirely different situations.Your theories would hold true if the barrel remained absolutely still during firing with no harmonics but as we all know this is not the case.That is why your theories do not hold true. [ 06-08-2003, 22:21: Message edited by: stubblejumper ] | |||
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