doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com English game loads data 2 1/2" shells.

Methinks you guys are fulla beans... again.

Butler in 'The American Shotgun', quotes a series of SAAMI tests. On page 197 of his book he shows a 'three foot coil measurement' of an undescribed load as 1336 fps. He equates that to a muzzle velocity of 'slightly over 1350'. That's 14 fps folks, or a little more, not 100.

The discussions and graphs in the same source refer to 'muzzle exit' conditions of a 3 DEq one ounce load as 1,284 fps, a figure we've accepted as reality for good long time.

The other references in this chapter are to 'muzzle velocity', not three foot velocity. The one instance of a discussion of exterior ballistics refering to a 'three foot' measurement shows the above mentioned +14 fps loss.

My own chronograph experience shows very little difference in recorded velocity with several feet variation in muzzle location relative to the screens.

Factory velocities are very close to advertised over my machine, and my handloads usually chrono scarry close to the published velocities. Again, I can back off a few feet or stick the muzzle almost even with the back of the machine and I don't see very much velocity difference. Certainly nothing approaching 100 fps in the first three feet!

I call BS on this one.

As a little PS to the above...

A few years back, when the guy in TX (Crocker) was importing them I bought a flat of Eley Hawk Grand Prix 65mm paper shells. I still have a couple boxes.

This is a fiber wad, 1 1/16 oz load of English sixes. The box shows '3 dram eq.'.

Their web site shows a 395 mps velocity for that load, which is 1295 fps.

My notes show that from an unaltered Fox 30" barrel they chronograph at 1265 fps. That's at 'roughly' 2.5 feet from the muzzle.

Their website now shows several faster loads in a 65mm case, comprabale to their competition (Hull).

Of course, I can't get my hands on either right now because nobody finds it profitable to import English shells to the USA.

Not sure about the BS in the difference between true MV and measured 3 foot velocity, Jones. The velocity figures in John Taylor's "Shotshells and Ballistics" come from the shotshell manufacturers themselves. And numerous shotshell companies, both American and foreign, are represented. The difference between the two figures is pretty consistent at around 100 fps, give or take a little in either direction. And it makes sense to me that pellets will slow down quite a bit shortly after their initial exit from the bore, because they're no longer being pushed by the burning gas from powder, and encountering more resistance from the air.

As for terminology, muzzle velocity in anything written by an American writer is assumed to be that measured at 3 feet, not at the muzzle--unless specified that it's true muzzle velocity. The measured 3 foot velocity is the only number SAAMI lists in its official charts for shotshell loads.

It is thus specified. 'Muzzle exit conditions'. And shown as such by internal ballistic charts.

Butler was an actual firearms engineer who worked for Winchester.

I just can't accept a 100 fps loss in velocity in the first yard. There is no mechanism for it.

I fully realize that drag increases with the square of the velocity, but 100 fps just cannot be so.

Butler seems to agree and as much as I respect the writings of ancient sources, my chronograph is better than anything Burrard et al had access to. Certainly Hull Cartridge has the same or better, and if they want to actually measure muzzle velocity instead of using a function (observed velocity) or a simple SWAG correction (+100) to calculate it they are quite capable of doing so.

I would thus expect to be able to measure the advertized velocity on my little chronograph here, and I'd expect it to be pretty close to what they claim for 'velocity'. Certainly within 30 fps or so, it is thus with Eley and I can't imagine Hull letting Eley get away with any BS to competitive advantage.

Larry- there are 3-1/4x1-1/4 loads still available at 1200 in a 12 bore. I use them. I have patterned them with satisfaction in a 12 bore Fox. I don't know the hardness of the shot these days. Mike

As I recall this applies only below the speed of sound. When you break that sonic barrier drag increases dramatically. As the shot exits the muzzle it does so as a mass acting much like a single projectile, but very quickly begins to separate into individual pellets, all occurring at a much less distance than that 9'.The Ballistic Coefficient of an individual pellet is far less than that of the compact mass at exit. These two factors of the drag swapping from a single mass to individual pellets, plus the vastly greater drag above the speed of sound" Very Easily" account for far more loss of velocity over those 9' than 14FPS.

Online references appear to show no significant or abrupt change in drag coefficient as a sphere goes subsonic.

http://arc.id.au/CannonballDrag.html

Don't be afraid to look at the NASA links, they're pretty good.

The biggest change occurs at about .8 Mach.

Sonic velocity is 1115 fps at sea level in dry air.

There is a well known drag reduction at about .3 M, depending on Reynolds number and a nifty effect on smooth vs. rough spheres that accounts for dimples on a golf ball.

Other than that, I can find no drag spike even at transonic speeds.

I just don't believe the huge variation in actual muzzle velocity vs. 3 foot measured velocity is at all real.

I'm open to actual data. My experiments are admittedly limited, and there may be effects I don't know of. But for now, I'm unconvinced.

Well Jones, here you go: From "Shotgun Stuff", a collection of Don Zutz's columns in Shotgun Sports magazine, in a chapter entitled "Waterfowl Loads and the 'New' Ballistics":

"Work done by Ed Lowry of Winchester and summarized in the December 1989 issue of American Rifleman magazine shows there can be a velocity loss of 50 to 100 fps during the first yard of free flight. For example, the new shotshell ballistics table worked out by Ed Lowry indicates a shot charge which reaches 1330 fps for a 3-foot chronograph reading needs an actual muzzle velocity of 1384 fps with BB's and 1447 fps with 7 1/2's to retain 1330 fps at 3 feet."

Ed Lowry was Winchester's ballistics guru for a very long time.

Thanks for the reference Larry. I do appreciate it.

Do Ed or Don offer any further explanation why they think this is so?

Perhaps someone has that issue of AR and can enlighten me.

Larry, Thanks for this information on 3' vs. muzzle velocity.

I've been attempting to confirm how the published velocity data for the more common English & European loads is obtained. So far I have found references to CIP standard velocity measurement being both 1 meter & 2.5 meters but the only manufacturer supplied data is from Rottweil which states velocity @ 2.5 meters so I'm still unclear of the CIP standard for velocity testing.

Eley lists velocity @ v-1 which I take as @ 1 meter & I have E-Mailed Eley for a conformation of this.

Hull, GameBore & B&P simply state "velocity" however I did find a "Cartridge Review" article in an old Sporting Clays magazine in which the writer stated that Hull & B&P velocities were measured @ 1 meter but this needs conformation from the manufacturers.

If 1 meter is the standard for CIP, comparison to SAAMI loads obtained @ 3' should be meaningful but this conflicts with some test data published over on Shotgun World that showed some of the English loads being slower than the published data when tested by SAAMI 3' standards. You have to wonder if some manufactures are taking CIP & SAAMI data & making a conversion back to muzzle velocity in an effort inflate the velocity figures for sales appeal.

One would think that cartridge manufactures would clearly state the distance @ which the of velocity their products are measured & especially if it deviates from the testing standards in place for the country where it is manufactured.