The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Velocities keep decreasing with Shooting Chrony?Go | New | Find | Notify | Tools | Reply | |
| Velocities keep decreasing with Shooting Chrony? | Login/Join |
| one of us |
I haven't re-verified this, but I think it's happening so I thought I'd see if anyone else here has run into this problem. I took my 500 S&W out yesterday to check some loads over the chronograph, a new Gamma Master model. The first shot was where it should have been then over the next 3 or 4 shots, the velocities kept getting slower. Then we reset the chrony, switched to hotter loads and shot a few more. The same thing happened again. Not only that but the velocities are 100 fps. of what I believe they actually are with the hotter loads. Chrony was about 8-10 ft. from muzzle so blast should be a problem. Has anyone else run into this problem? Is there something wrong with the sensors on my Chrony? I would think that the velocities would probably increase a little as the gun got hotter, but they're dropping big time. Unfortunately, I haven't had the chance to verify the velocities over my Oehler. | ||
|
one of us |
I find the first couple shots from a clean barrel will show some variation in velocity from the vel found after the barrel is fouled. I try to check the vel after I fire a fouler or two. I haven`t noticed any difference in "average" readings when the barrel cool compared to a warm one. I don`t let ammo "cook" in a warm barrel before fireing though. | |||
|
| one of us |
I have seen some velocity drop off as a firearm heats up. Typically it isn't HUGE though. I could believe a revolver would be more dramatic than a rifle though, since the cartridges are better "heat sinked" than in most rifle chambers. As you barrel heats up the bore diameter gets bigger, this causes more gas leakage, and therefore somewhat lower muzzle velocities. As I said, I have seen this phenomena before, but it hasn't been huge. With cartridges like the 500 S&W I have seen far greater velocity variation due to inconsistent powder combustion than anything else. ASS_CLOWN | |||
|
Moderator |
Aim a little lower  Sorry, couldn't resist.I don't recall ever seeing readings decrease like that from shot to shot on my chrony. I'd replace the battery and also put the chrony a bit furher out. I have had problems with muzzleblast causing wierd readings, but typically they are unbelievably fast readings. | |||
|
| one of us |
I guess I need to break out the Oehler and find out what the hell is going on. The shooting was done out of a non-clean barrel. (It just didn't feel right to say "dirty"). The fact that the velocities keep dropping and the size of the extreme spread leads me to believe there's more going on here. It stands to reason that as the gun heats up it would expand and thus the barrel might increase a little in diameter but I don't think it works that way, atleast not as much as one would think but that's beside the point, I don't want to open a whole separate discussion on that. The fact that the metal is hot should increase chamber temps/pressures should generally cause the velocity to go up just a little, but this is exactly the opposite. Back to the range we go... with the 35P I guess. | |||
|
| one of us |
kingfisher, How shots are you firing in a string? What bullets weights / powders are you using? I can share results I have obtained with the 50 Beowulf (nearly identical to the S&W), and what another gentleman I know got the same day over my chronograph with his 500 S&W revolver. These cartridges DO NOT get consistent combustion with the lighter bullets, and velocities can vary A LOT! Extreme spreads of 250+ fps where what we were seeing if I recall. If you are interested let me know and I will dig the data up and post it. I guess I am trying to say that you may just be seeing some combustion inconsistency resulting in decreasing velocity readings. ASS_CLOWN | |||
|
| one of us |
AC, I was using the 350 gr. Sierra's out of the standard Model 500. The first loads I fired, 5 of them I think were 40 gr. loads. The other 3 or 4 that I fired were 42 gr. loads. Powder was H-Li'lGun. | |||
|
| one of us |
Kingfisher, I have had nothing but problems with bullets under 400 grains in the 50 Beowulf. Cross that line and it is like night and day. What I learned with my one day of shooting with the gentleman who owned the 500 S&W was that it liked the heavier slugs better as well. It was loaded hotter than the 50 B was, but muzzle velocities were pretty darned close, most likely due to my longer (16") barrel. If you would like I can post the data we gathered that day. If I recall correctly he was shooting 350 gr Jacketed, and maybe a 400 gr jacketed and then 420 and 440 hard cast. I have it written down though, thank goodness, I do distinctly recall the 440 HC though, as those were the most accurate, and I had not tried any of the heavier bullets in the 50 B at that time. It was the performance he got with the 500 S&W and the 440 gr HC that got me starting shooting those heavier cast bullets, and I am now much happier (not over-joyed mind you but happier). ASS_CLOWN | |||
|
| one of us |
AC, if you have some numbers for the 350 gr. loads I'd like to see them. The Sierra HP's shoot really good in this gun, so I'm probably going to stick with them. I just need to try them over another chronograph because I think there is something screwy going on. | |||
|
| one of us |
If that is what I got (I think it is) I will post the data this evening. ASS_CLOWN | |||
|
| One of Us |
Quote: Horse Shit, Ass Clown. You haven't seen anything of the such and what you know about ammunition and reloading wouldn't fill a thimble. The hotter a gun gets, the more the pressure and velocity go up. If we listened to your bullshit and fired till we got a gun REALLY HOT, then I guess the bullets would just about stop making it out the barrel due to their LOW VELOCITY.  Minor variations both UP and DOWN in chrony readings are perfectly normal and obvious on the best of equipment. There are a lot of causes for these variations. Any chronograph that's telling you the velocity is going down and down and down should be sent back to the factory to get fixed. Something is seriously dicked up with it's circuitry. | |||
|
| one of us |
Kingfisher, Here is the data: 500 S&W - 350 grain jacketed (don't know actual bullet or load details) the gentleman described this load as "PRETTY HOT". In order of shots taken and in fps: 1874 1843 1783 1847 1799 1803 1764 1793 1770 1772 1687 1694 1754 1690 1688 500 S&W 440 gr Hard Cast gas check (that is all I know about his load as well) the gentleman described it as "HOT". In order of shots taken (fps) 1475 1488 1468 1485 1459 1475 1480 1477 1509 1472 1482 1472 1475 1457 1448 I realize you did not ask, but for reference here are some 50 Beowulf loads: 335 grain Alexander Arms Magnum PISTOL primer Alexander Arms brass (Starline) 44 grains of IMR4227 1688 1642 1662 1671 1690 1632 1627 1616 1643 1754 420 grain Hard Cast Magnum PISTOL primer Alexander Arms brass (Starline) 37 grains of IMR4227 MAXIMUM LOAD < !--color--> This load is the MOST accurate I have shot to date. 1505 1523 1507 1505 1499 1511 1527 1515 1497 1534 There is the raw data. I hope you find it interesting if not useful. ASS_CLOWN | |||
|
| One of Us |
I'll make up some too, Ass Clown, if this isn't enough.  | |||
|
| one of us |
Pecos, I think you are needed on the PRE thread, badly needed! ASS_CLOWN | |||
|
| one of us |
Kingfisher, It is a little-known fact that Shooting Chrony has revolutionized the speed-meter world by putting a little-bitty lawyer inside of every unit....  | |||
|
| one of us |
Haha.  I honestly think that it has a timing problem. I'm going to pull out the Oehler just to make sure, but I've got a pretty good idea that is what's going on. | |||
|
| one of us |
How does the Chrony know that you have changed loads?. It is even smarter than I thought. The data looks like a slow drift downwards of varying velocities. The variation is most likely real, the drift is most likely real also and measuring dimensional changes of the pistol. All pistols for example "drift" upwards as the pistol gets lighter and the recoil raises the barrel more. By all means check with another chronograph, but please let us know the results. Good luck! | |||
|
| one of us |
Pecos, Quote: Please explain the problem with the circuit that shows a velocity string which consistently starts out high and goes down with each consecutive shot? The chrony uses a simple, simple circuit. If there REALLY was something wrong with the electronics, the problem would be inconsistent reading or NO reading at ALL! What this gentleman has described does not surprise me in the least. It is VERY consistent with what I have seen with the 50 Beowulf and the 500 S&W, and even the 44 Magnum, when light weight bullets are used (350 grain 50 caliber bullets are damned light weight ones). The problem seems to revolve around a wide short powder column and a very high expansion ratio, resulting in inconsistent powder combustion shot to shot. Minor variations in bullet resistance to the expanding gas column has a DISPROPORTIONATELY SIGNIFICANT EFFECT on the combustion characteristics of the powder column; therefore resulting in the previously stated documented large variations in muzzle velocity and dropping off of said muzzle velocities over long shot strings. ASS_CLOWN ASS_CLOWN | |||
|
| One of Us |
I would never dare to explain anything to you, Ass Clown. You already know it all! Could you please explain to me how them little electron things know how to find their way around the circuit boards and don't go flying off just willy nilly? And how come they only go when we want them to? If they are so damn smart, why don't they stay home in the battery sometimes and do nothing? Gee, maybe that's why your velocity is going down and down, Ass Clown! Every time you fire, fewer of the electrons are going around the circuit as more and more of them stay home because they already told your dumb ass the velocity once. Why tell you again? DUH? Life is just full of mysteries when you're an Ass Clown. | |||
|
| one of us |
Pecos, Ol' man, I assume by the proceeding quotation you seem to feel the battery is dying. Quote: Well you once again show your ignorance with spades! If the battery is getting low on a Shooting Chrony the display flashes "lb" (that would be the acronym for "low batter"). Better luck next time old chap!  Of course you could just better your odds, and only SPEAK TO THOSE TOPICS OF WHICH YOU KNOW OF WHAT YOU SPEAK! That would be VERY refreshing for us all, I should think. ASS_CLOWN | |||
|
| Powered by Social Strata |
 | Please Wait. Your request is being processed... |
|
The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Velocities keep decreasing with Shooting Chrony?
Visit our on-line store for AR Memorabilia