Ammo Testing Velocity

B

BAJ

Guest
I just read an interesting article about ammo testing. In the article the author mentioned that changing the torque settings on the action screws and tuner settings would cause the speed of a certain lot of ammo to change. It was said that as the rifle approached being tuned you would see a smaller extreme spread and standard deviation of velocity in the ammo.

Can someone please explain to me why the velocity of the ammo would be changing with different torque and tuner settings? I don't understand how that would have any affect on the velocity. I would think that the amount of powder in the cartridge, primer, temperature and humidity would be the factors responsible for changes in velocity.

Brian
 
I don't believe the speeds printed on Ammo boxes. I found a speed that worked in one of my rifles in one grade of Eley and the same posted speed in another grade of Eley wouldn't shoot inside an inch @ 50 yds.
 
BAJ said:
I just read an interesting article about ammo testing. In the article the author mentioned that changing the torque settings on the action screws and tuner settings would cause the speed of a certain lot of ammo to change. It was said that as the rifle approached being tuned you would see a smaller extreme spread and standard deviation of velocity in the ammo.

Can someone please explain to me why the velocity of the ammo would be changing with different torque and tuner settings? I don't understand how that would have any affect on the velocity. I would think that the amount of powder in the cartridge, primer, temperature and humidity would be the factors responsible for changes in velocity.

Brian
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Brian,

I’ve been involved in several discussions recently that are similar, but not quite the same as your question suggests.

I know of no means of tuning that would change “muzzle” velocity, but what I and a few others have been investigating and testing for, is whether a better tuned rifle will improve ballistics “at the target” enough to be measurable.

If a better tuned barrel causes a more "consistent" reduction in aerodynamic drag, then you should see an improvement in ES and SD at the target that’s not attributable to only the decrease in velocity.

Landy
 
HuskerP7M8 said:
Brian,

I’ve been involved in several discussions recently that are similar, but not quite the same as your question suggests.

I know of no means of tuning that would change “muzzle” velocity, but what I and a few others have been investigating and testing for, is whether a better tuned rifle will improve ballistics “at the target” enough to be measurable.

If a better tuned barrel causes a more "consistent" reduction in aerodynamic drag, then you should see an improvement in ES and SD at the target that’s not attributable to only the decrease in velocity.

Landy
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is whether a better tuned rifle will improve ballistics “at the target” enough to be measurable.
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I'm not sure of all your statement but this sentance has me wondering -how else is there to determine a better tuned rifle other than measuring at the target?... i'm probably lost again as usual... joe
 
Joe,
I believe he’s talking about measuring SD / BC at the target compared to SD / BC at the muzzle during strings of shots.

A bullet takes a short distance to stabilize or go-to-sleep as quite a few people call it, before it goes-to-sleep it is more affected by the wind (drag & drift) and should show a lower BC down range at the target.
There’s a chance the hot rifles in completion today stabilize the bullet very quickly when using a tuner setting that also gives the best groups on the target. That’s why you hear people saying their new hot rifle “shoots through the conditions” better than anything they‘ve shot before.
It would be interesting to compare the winning rifle’s target BC from a windy match to someone in the middle of the pack wouldn’t it? The rifles agg potential may be the same in a tunnel.

You see this in 100-200 yard center fire quite often when people ask why not use a high BC bullet on windy days. The problem is, a high BC bullet takes longer to stabilize and while its unstable the wind “randomly” moves it off its intended flight line. The low BC bullets commonly used may drift farther in the wind, but if you can read the conditions accurately they have better accuracy potential.
 
My original post did not intend to have anything to do with the speeds printed on the boxes of ammo but rather the velocity of the bullet at the target. I should have been more clear with my original post.

About the speeds on the boxes, however, I have to agree that they cannot be trusted 100%. The reason being, that the velocity of the ammo is determined in England at a certain altitude on a certain day with certain environmental conditions. At lower or higher altitudes the speed of the ammo is going to be different, its simple physics.

Brian
 
Hi Brian,

Perhaps in this discussion, we should take a step back and ask the question - why does Eley for example - 'advertise' their speed deviations and others such as Lapua - do not see the same need. Interestingly, Eley say (on their web-site) that their ammo speed is 1085 fps but I've never seen anything above 1071 fps and as low as 1044 fps. Perhaps as fuel for thought - the manufacturing process of which Eley are so proud, does in fact produce such a spread of results (i.e. in speed) that instead of attempting to fix the obvious problems, they believe it's a marketing edge. I however, would suggest that their manufacturing is in fact - by their own stated evidence - incapable of delivering a consistent product. Of course the reverse is true for Lapua and we'll never know what sort of spread they produce other than recognising a good 'batch'. I'm sure we all experience the odd dropped shot or two per box which would (generally) indicate a slower round.

Perhaps someone could ask Bob Collins to explain this difference between published speed and reality which given modern manufacturing excellence, I find quite strange and has become the subject of many discussions.

I think we should start there

Cheers from downunder

Cary
 
It was my feeling that 1065 should be 1065, regardlless if it was sugar or The Pink stuff. If it's about speed then any of them should work if one of them do. ( Ebonics, I like to include some of it from time to time)
 
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Well as I see it Eley shoots and chrono's out of there own barrels, so our measurements on speed will be different . I really don't care what speed ammo I get as long as my rifle likes it ......I have found that good lots shoot in any of my rifles doesn't matter the speed or the machine as long as there is no flyers i'm happy ..........
 
tuna921 said:
Well as I see it Eley shoots and chrono's out of there own barrels, so our measurements on speed will be different . I really don't care what speed ammo I get as long as my rifle likes it ......I have found that good lots shoot in any of my rifles doesn't matter the speed or the machine as long as there is no flyers i'm happy ..........
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Now, this is the truf. The good stuff goes quickly, and there is a compelling reason for it. However, Eley marks their speeds so they should be somewhat accurate, one would think. I think the truth is the speed may not be as important as some other yet to be discovered item.
 
AussiFlyer said:
Hi Brian,

Perhaps in this discussion, we should take a step back and ask the question - why does Eley for example - 'advertise' their speed deviations and others such as Lapua - do not see the same need. Interestingly, Eley say (on their web-site) that their ammo speed is 1085 fps but I've never seen anything above 1071 fps and as low as 1044 fps. Perhaps as fuel for thought - the manufacturing process of which Eley are so proud, does in fact produce such a spread of results (i.e. in speed) that instead of attempting to fix the obvious problems, they believe it's a marketing edge. I however, would suggest that their manufacturing is in fact - by their own stated evidence - incapable of delivering a consistent product. Of course the reverse is true for Lapua and we'll never know what sort of spread they produce other than recognising a good 'batch'. I'm sure we all experience the odd dropped shot or two per box which would (generally) indicate a slower round.

Perhaps someone could ask Bob Collins to explain this difference between published speed and reality which given modern manufacturing excellence, I find quite strange and has become the subject of many discussions.

I think we should start there

Cheers from downunder

Cary
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It's been the topic of many discussions here primarily because there's quite a few folks that deal in unbridled speculation instead of fact. The speeds are for their test barrels and only a broad indication of varience between lots. If you think that this much varience from max to min is anything other than intentional your kidding youself, it's done the old fashioned way by metering the powder which is checked in each case by laser.
 
Pete Wass said:
It was my feeling that 1065 should be 1065, regardlless if it was sugar or The Pink stuff. If it's about speed then any of them should work if one of them do. ( Ebonics, I like to include some of it from time to time)
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Really? you have a .2165" barrel, I've got a .2173" barrel and the ammo is measuring the same? Think about it Pete, beter yet call your gunsmith.
 
Tim, I have no vested interest in any of this except as a consumer. I could care less how Eley does what they do but what would be nice is much better consistency, lot to lot, so that we wouldn't have to play this Russian Roulette testing game all the time; speaking only as a consumer you understand. My business is not manufacturing anything, it is being stuck on the other end. They might as well leave the speed off the box as far as I am concerned becuase I have yet to see any relevence to it. It's always Russian Roulette (sp?) for me, anyway, regardless of what the numbers say. A consumer shouldn't need to know Eley intimately and feel sad for them.
 
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Pete Wass said:
Tim, I have no vested interest in any of this except as a consumer. I could care less how Eley does what they do but what would be nice is much better consistency, lot to lot, so that we wouldn't have to play this Russian Roulette testing game all the time; speaking only as a consumer you understand. My business is not manufacturing anything, it is being stuck on the other end. They might as well leave the speed off the box as far as I am concerned becuase I have yet to see any relevence to it. It's always Russian Roulette (sp?) for me, anyway, regardless of what the numbers say. A consumer shouldn't need to know Eley intimately and feel sad for them.
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Pete, you need to get with somebody and have them help you with ammo selection. Most guns will shoot a broad range of velocities well say 1053-1063 but it probably boils down to that plus which machine some guns prefer. Truth be told most of this stuff shoots quite well "somewhere"
 
tim said:
Pete, you need to get with somebody and have them help you with ammo selection. Most guns will shoot a broad range of velocities well say 1053-1063 but it probably boils down to that plus which machine some guns prefer. Truth be told most of this stuff shoots quite well "somewhere"
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Well, I tested around 8 lots of it in The Barn the other weekend,some of them close together, in two rifles and found only two, one for each rifle, that was even close. I couldn't see any difference with this process than I use to find 13 or 14 years ago, using the same Harrels type tuner. One is lucky to find a good lot of ammo. Something I did notice, being pitted directly across from an Ammo vendor was certain lots were snapped up quite quickly and some were still sitting there when I left Sunday afternoon.

I suppose it depends on what kind of accuracy someone is satisfied with, eh. Me, I only want to see one tiny hole.
 
Tim,

I appreciate the comments but the gist of what I'm suggesting is that there is a substantial (and to me, unacceptable) difference between Eley's advertised performance (in fps) and what is delivered and this worries me, given today's modern manufacturing methods and their much advertised factory processes. Let me be clear here - I'm an Eley Match user and remain a fan. That said - and again, quoting Eley, their ammo is graded following their many, many inspection processes and from what I can see - (especially when downunder - we're paying $24 a box) I would expect their grading system to put the lower grade ammo into Team or Club by example - not charge us a premium for ammo that fails the test of consistency and as Pete rightly suggests - is in itself the source of much conjecture due to the very nature of the variance they so proudly (it seems) promote.

I doubt that Bob Collins will answer my original question and if he does, will no doubt push the Eley 'buggy' and while I have nothing but respect for Bob - the simple fact remains - and it's just my humble opinion - this level of manufacturing inconsistency is in todays world - unacceptable and I talk from experience as a qualified engineer and process consultant with A LOT of experience in repetative manufacturing.

This then brings us right back to Brian's original comment - if we saw ANY reasonable consistency in the production of ammo - then discussions such as spread and deviation would all come back to the trigger puller. Wouldn't that be nice - we could blame ourseleves for a change insead of seeking every excuse (for our poor performance) every devised.

And hey - happy to admit - my wife kicked my derrriere at the range on the weekend - the jokes are still coming...

Enjoy your weekend guys

Cheers

Cary
 
Landy,

I do it the old fashioned way, I buy test lots of ammo, sit down and shoot groups with it. At the barn, I had a rifle with a new barrel. I had quite a bit of different lots of ammo with me, one that shot "pretty good' but not great. I chose some lots that were close to the speed listed on the box that shot "pretty good".

Bottom line was the next lot that shot Pretty Good was over 100 FPS, listed on the box, faster than the first pretty good lot. A few FPS one side or the other wouldn't come close to grouping.

I have been shooting Benchrest since about 1996, the first three or so years just Rimfire. I have shot IBS score since 1999. I picked a couple of RF rifles to shoot this winter in Florida and perhaps, the coming summer in Maine, where I will be living. I am not a newbie at this game as some are hinting at here. I don't know any other way of testing ammo, be it RF or CF other than sitting down and shooting it in rifles at paper, trying to find a single hole made by 3 shots that is smaller than the actual bullet size. I expand that number to five shots if 3 are good. I am certainly willing to learn a new one if it is better and easier.
 
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