Velocity and accuracy studies?
- Thread starter L. Boscoe
- Start date
Precision air pistols can drill one-hole groups at under 400 fps. Benchrest competitors drill single holes with rifles shooting over 3,000 fps. So, velocity by itself is not an accuracy determinant overall. That said, the projectiles used have to be designed for the velocity range and the target range involved. Some individual guns like some load combinations better than others, and those combinations may have a velocity preference or a powder preference. This can have more to do with ignition delay consistency than anything else. That is, assuming your hand mechanics don't hold the gun perfectly still and you have some measure of motion from the hammer fall or from trigger slap, a longer ignition delay in one round than you had in the previous round provides added time for the muzzle to move further off the point of aim than the previous one did, thus adding space between the points of impact on the target (group fattening).
Toward limiting that variable ignition time effect, velocity consistency is generally desirable because it tends to be an indicator of how regular ignition is. You can set up a chronograph with several load levels to see if you can identify the charge weight that produces the lowest velocity SD as a percent of the mean velocity. Be aware that sub-nominal primer seating is most often a culprit in poor velocity consistency rather than powder charge in a short powder space cartridge like the 45 Auto. Usually, with 45 Auto pistols like the 1911, how the gun is fit up matters most, and loading matters second.
Toward limiting that variable ignition time effect, velocity consistency is generally desirable because it tends to be an indicator of how regular ignition is. You can set up a chronograph with several load levels to see if you can identify the charge weight that produces the lowest velocity SD as a percent of the mean velocity. Be aware that sub-nominal primer seating is most often a culprit in poor velocity consistency rather than powder charge in a short powder space cartridge like the 45 Auto. Usually, with 45 Auto pistols like the 1911, how the gun is fit up matters most, and loading matters second.
I get confused about this subject myself alot. I’ll tell you what I have seen and what I have read.
In my reloading experience shooting std calibers with book loads across 20 or so guns, using OCW methods, I found that best accuracy was obtained at max load or just below max. I found the second best load came at the book min load.
In watching the Hornady series, “Miles” says his experience in large group shooting is that lighter loads are generally more accurate than heavier loads except in a few rare cases.
I have also found “forming” loads for wildcats (~40000-48000psi estimated for a 65ksi rifle) are generally quite accurate considering I’m usually using a complete SWAG for OAL and some leftover bullets. I throw that mess in Quickload and look for about 45000 psi. I’ve shot 0.25” - 0.75” 3-5 shot groups regularly and often due to case forming, concentricity is off the mark and varies from 0.000” - 0.020” TIR.
Paragraph 2 applies to pistol also. I’ll add that my best 38 spcl wadcutter load is down around min or 1 increment over min.
Back to bolt action rifles, most of the 6PPC types seem to indicate they regularly get vertical groups at low charges. Increasing charge weight gets them to horizontalish by getting both lugs to touch consistently. Increasing more gets them to an early diagonal group which looks to most as a round dot. Just above that, is too hot and creates flyers. I can only back this tendency up slightly as I only have one rifle (6PPC with 45x scope) that is consistent enough to show this kind of thing. My skills and load development just are not there enough to say I see more than a tendency.
In my reloading experience shooting std calibers with book loads across 20 or so guns, using OCW methods, I found that best accuracy was obtained at max load or just below max. I found the second best load came at the book min load.
In watching the Hornady series, “Miles” says his experience in large group shooting is that lighter loads are generally more accurate than heavier loads except in a few rare cases.
I have also found “forming” loads for wildcats (~40000-48000psi estimated for a 65ksi rifle) are generally quite accurate considering I’m usually using a complete SWAG for OAL and some leftover bullets. I throw that mess in Quickload and look for about 45000 psi. I’ve shot 0.25” - 0.75” 3-5 shot groups regularly and often due to case forming, concentricity is off the mark and varies from 0.000” - 0.020” TIR.
Paragraph 2 applies to pistol also. I’ll add that my best 38 spcl wadcutter load is down around min or 1 increment over min.
Back to bolt action rifles, most of the 6PPC types seem to indicate they regularly get vertical groups at low charges. Increasing charge weight gets them to horizontalish by getting both lugs to touch consistently. Increasing more gets them to an early diagonal group which looks to most as a round dot. Just above that, is too hot and creates flyers. I can only back this tendency up slightly as I only have one rifle (6PPC with 45x scope) that is consistent enough to show this kind of thing. My skills and load development just are not there enough to say I see more than a tendency.
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I am a bullseye shooter, 22 and 45. Load my own, 185gr hp and 200gr hp behind VV310.
Do any studies exist that compare accuracy and velocity?
The AMU has done several studies, but they don't usually see public dissemination. They have some data that is bullet MV minimums vs. barrel length for the common calibers. From what I understood talking to one of the Armorers, most of it is related to getting the bullet out of the bore prior to the firearm moving in recoil, which for almost all pistols, at all practical velocities, happens. The secondary aspect is related to powder speed and how much the ejecta plume interacts with the base of the bullet. The combination makes sense to me, that the slower the MV, the faster you want the powder to be.
An ancillary discussion was related to shotgun slug barrel length and velocity. They found better accuracy from shorter barrels for some of the same reasons. The shorter the barrel, and the higher the velocity, the less time the barrel movement affects the point of aim vs the movement between ignition and the time the slug leaves the barrel.
Don't know if that is helpful to you or not. I did, BTW, ask to see some of the actual data, and was told no.
It sounds like someone is trying to rewrite the laws of physics. Gun movement starts as soon as bullet movement starts, as far as I know.
Nope. Inertia is still a part of physics.
Not sure how you're applying that, but gun movement starts as soon as bullet movement.
My simple understanding is that a stationary gun starts to move when a force is applied to it, and that force is the same force that is applied to the bullet. Newton's third law is that for every action there is an opposite and equal reaction. I don't think his law says there is a delay in when this equal reaction starts.
The gun starts to move before the bullet has exited. This is demonstrated with slo-mo video here:
https://www.recoilweb.com/when-does-the-pistol-slide-start-to-move-127274.html
You can't apply force to an inertial mass without initiating its acceleration, so a gun does start to pick up recoil velocity simultaneously with the bullet starting to move. This is due to Newton's equal and opposite force imparting equal and opposite momentum to the gun and its mount. And the gun has to have acquired all the recoil velocity it is going to get by the time the bullet and propellant gasses have cleared the muzzle. There is no other source of force to cycle the action after that.
As shown in the link, you can see this movement in super-slow-motion videos of people firing guns. You often have to take a video editor and insert a muzzle mark in the frame where the hammer is falling and compare that to the muzzle position at the bullet exit, but the change is there.
As shown in the link, you can see this movement in super-slow-motion videos of people firing guns. You often have to take a video editor and insert a muzzle mark in the frame where the hammer is falling and compare that to the muzzle position at the bullet exit, but the change is there.
That is pretty obvious, but based on your responses, not sure you want to learn what actually happens, or just snipe with off-topic comments. As the OP seems to have what he needs, not going into the weeds on this.
L. Boscoe,
Reading your second post, I note that the only 45 ACP ammo Norma currently catalogs at just over 850 fps (853 fps) is loaded with 230-grain bullets, not 200-grain bullets. If this is what you have, it is full-power hardball ammo for combat training and steel plate shooting, and with a power factor of 196, it easily surpasses the major power factor for all the practical shooting disciplines. It is not a bull's-eye match shooting a load. An old standby load for copying commercial and military bull's-eye match ammunition is a 185-grain JSWC over 4.2 or 4.3 grains of Bullseye. That's going to do more like what you are looking for and will have about 46-48% less recoil energy, so close to half the felt recoil.
P.S.
The actual military spec is for a 185-grain bullet at 765 fps measured 15 feet from the muzzle. Most of the big commercial makers seem to have gone for the much faster, higher power factor numbers, even with 185-grain bullets. The only commercial bull's-eye match ammo I see off hand is Federal Gold Medal. It is the 185-grain JSWC at 770 fps. The same loads of Bullseye will still get you there, give or take. You can set up a chronograph to check if you want to.
Reading your second post, I note that the only 45 ACP ammo Norma currently catalogs at just over 850 fps (853 fps) is loaded with 230-grain bullets, not 200-grain bullets. If this is what you have, it is full-power hardball ammo for combat training and steel plate shooting, and with a power factor of 196, it easily surpasses the major power factor for all the practical shooting disciplines. It is not a bull's-eye match shooting a load. An old standby load for copying commercial and military bull's-eye match ammunition is a 185-grain JSWC over 4.2 or 4.3 grains of Bullseye. That's going to do more like what you are looking for and will have about 46-48% less recoil energy, so close to half the felt recoil.
P.S.
The actual military spec is for a 185-grain bullet at 765 fps measured 15 feet from the muzzle. Most of the big commercial makers seem to have gone for the much faster, higher power factor numbers, even with 185-grain bullets. The only commercial bull's-eye match ammo I see off hand is Federal Gold Medal. It is the 185-grain JSWC at 770 fps. The same loads of Bullseye will still get you there, give or take. You can set up a chronograph to check if you want to.
Nick, you are right about the current offerings. What I have is left over from a few boxes I got on sale last year or the year before. It is their "Hexagon"
hollow point, and they call it Match ammo, and I wrote down the fps as 850.
The don't know when they will offer it again, but it is 200grain. I have some left, all in my plastic bins, so no boxes for a photo. It still has a pretty strong recoil, not so much as 230 hardball.
hollow point, and they call it Match ammo, and I wrote down the fps as 850.
The don't know when they will offer it again, but it is 200grain. I have some left, all in my plastic bins, so no boxes for a photo. It still has a pretty strong recoil, not so much as 230 hardball.
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I can't site a "study" but from all my reading on the subject of Handguns / Accuracy / Loads in regards to Bullseye Match Shooting in 38 special and 45 acp and all my years competing in the sport of NRA Target Bullseye Match :
The 38 special is most accurate with a 148 gr. lead wadcutter @ 700 t0 750 fps .
2.5 - 3.0 grains of Bullseye will do the trick ... but loading the 148 gr. wadcutter to between 700 to 750 fps with 700X , Red Dot or W231 will get you the same results .
Each revolver will have it's own "Sweet Spot" powder charge that you have to work out .
My Target gun dotes on 2.7 grs. Bullseye ... not 2.5 and not 3.0 ...2.7 grs. Bullseye and they make one ragged hole groups at 25 yards .
The other powders will do Almost as good as Bullseye but none can beat Bullseye .
The 45 ACP - My 1911's like a 200 gr. cast lead SWC at 700 to 750 fps also ... any powder listed for the 38 special above ... Bullseye , 700X , Red Dot and W231 all work well when loaded to 700 to 750 fps velocity .
My pet Target Load was a 200 gr. cast SWC - 4.3 grs Bullseye .
A good general purpose load is 5.2 grs Unique @ 765 fps .
The 45 acp seems to like 700X , Red Dot and Unique equally well .
I can also tell you most accurate loads aren't at the Maximum end or at the Minimum end of the load data ... but somewhere in the middle between Max and Min.
Gary
The 38 special is most accurate with a 148 gr. lead wadcutter @ 700 t0 750 fps .
2.5 - 3.0 grains of Bullseye will do the trick ... but loading the 148 gr. wadcutter to between 700 to 750 fps with 700X , Red Dot or W231 will get you the same results .
Each revolver will have it's own "Sweet Spot" powder charge that you have to work out .
My Target gun dotes on 2.7 grs. Bullseye ... not 2.5 and not 3.0 ...2.7 grs. Bullseye and they make one ragged hole groups at 25 yards .
The other powders will do Almost as good as Bullseye but none can beat Bullseye .
The 45 ACP - My 1911's like a 200 gr. cast lead SWC at 700 to 750 fps also ... any powder listed for the 38 special above ... Bullseye , 700X , Red Dot and W231 all work well when loaded to 700 to 750 fps velocity .
My pet Target Load was a 200 gr. cast SWC - 4.3 grs Bullseye .
A good general purpose load is 5.2 grs Unique @ 765 fps .
The 45 acp seems to like 700X , Red Dot and Unique equally well .
I can also tell you most accurate loads aren't at the Maximum end or at the Minimum end of the load data ... but somewhere in the middle between Max and Min.
Gary
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I found the box
Turns out I still had a couple of boxes of the 200 gr Norma Hexagon
hollow points. They list 856fps as velocity on the box-they are touting the "hexagon hollow point" as something special for accuracy, which sounds like ad speak. Anyway, my original question was why so hot for target load, which I would expect to be a lot slower as Nick says above. Is there a competition that requires the 326 ft lbs this load delivers (stated on box)?
Many thanks to all who posted. Gotta love this forum.
Turns out I still had a couple of boxes of the 200 gr Norma Hexagon
hollow points. They list 856fps as velocity on the box-they are touting the "hexagon hollow point" as something special for accuracy, which sounds like ad speak. Anyway, my original question was why so hot for target load, which I would expect to be a lot slower as Nick says above. Is there a competition that requires the 326 ft lbs this load delivers (stated on box)?
Many thanks to all who posted. Gotta love this forum.
First point, 850fps is not all that "hot" for a 200gr bullet.
Next point, "Match" and "Target" are often the same thing, but they don't have to be. "target" implies a light load made for accuracy in paper punching and minimal recoil.
"Match" might refer to a number of different things, "match quality" bullets for example, or it might refer to a specific class of load for a specific match/game.
Cowboy Action Loads could be considered "match ammunition", after all, it is ammo loaded to be used in Cowboy Action Shooting matches.....
There are other kinds of games and matches, and some of them (IPSC??) do have power requirements. Perhaps "match hollowpoints" in this case means ammo for a combat type match??
Last point, when dealing with people/companies who are not native US "American" speakers, valid and accurate translations may not accurately reflect the slang or common usage of terms in a specialized field, such as shooting. To many in the US, English (as spoken in England) is a "foreign language". It's possible the people naming things at Norma simply have a slightly different understanding of what the word "Match" means than you do.
I imagine you could google it, I'm not going to bother, but wasn't it Shaw who said that the British and Americans were "one people separated by a common language" ?? Imagine where the Swedes (or anyone else) might be with English or American specialty terms.
The maximum power factor required to make IPSC Major is 170. A 200-grain bullet moving at 856 fps, has a power factor of 170.2. I strongly suspect that's the reason for the particular velocity they chose to load it to. USPSA and IDPA use 165 as the Major line, so they are covered by it.
A good reference and PF calculator at Dillon.
A good reference and PF calculator at Dillon.