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I chronographed three loads that I thought were identical. I weighed the powder and carefully dipped the shot. Same hull,(RMC brass) same primers (Win 209) same powder (Trail Boss)and same wads. The wads were: Nitro card two filler wads and one overshot card. The velocities were: 1240, 1210 and 1184 fps. One reloading variable that comes to mind is wad pressure, something that I paid little attention. An other possibility is weather conditions. Cloudy day for first shot, second shot partial sun and third shot mostly sunny. More sun with each shot. Chrony directions say accuracy is best on cloudy days. What say ye experts?

Guest

Pretty normal for shotshells and card wads, The only way to know for sure is send 5 loads to Mr. Armbrust and let him test them. But you really aren't experiencing anything abnormal. Even factory ammo can give some very wide EV's.

Weighing each powder and shot charge is wasting a lot of time, and it won't help much if at all. With the exception of a few bulky/fluffy powders(800X and Steel) the correct powder/ shot bushing will throw charges well and are not the reason for shot to shot variation.

I use my chronograph on sunny days, Not many cloudy days here in the Desert.

Consistant wad pressure will make for a more consistant velocity using fiber cushion wads.

Are your cushion wads lubed or plain ?

Member Joined: 08 Nov 2005 Posts: 3438 Location: Illinois

That may be the norm for that combo of components where another combo would yield greater/lesser variance fps

Mark
The load data for the shells tested came from Tom Armbruster via a telephone call. When it is below 0 outside it is to cold do do anything but the necessities, which leaves me a lot of time to pursue indoor activities. During warmer weather I use my powder and shot dispensers which are located in my shop, but until the cold snap ends, I’ll be using a Lee Loader and a scale indoors.
Art
Good to know about shade vs sun. Today will be sunny and I will shoot three more rounds using waxed wads with 60 lbs. of pressure measured on the bathroom scale.
I also have unwaxed cushion wads and will try those after the waxed wads. I haven’t got around to loading one piece plastic yet because I was waiting for the ProChrono arrive. The weather has slowed me down but I’m looking forward to velocity testing and patterning.
Hoashooter
We will see.
My ProChrono is new and the three shells were randomly selected from my best patterning loads and I don’t remember which wads I used. I have very old Alcan waxed wads and newer (no lube and no wax)cushion wads and can’t tell the difference on the pattern board. They were the first and only loads tested on the new chronograph. When I saw the first velocity recording of 1240, I said to myself “perfect” and it went downhill from there.

Guest

jschultz

When Tom ran the load, what was the Extreme Variation for the velocity.
The variation that you have is not out of the ordinary. Extreme Variation and Standard Deviation numbers are not shown in reloading manuals, only averages. You have an advantage working with Tom Armbrust, as he can give you those figures. The EV and SD are just as important as the averages, as they give you an idea on how consistent the load will perform.

Run enough loads over a chronograph, and you will see stuff run a lot more EV than the 50 FPS or so that you are concerned about.

Just because a load doesn't exceed a maximum average pressure figure, doesn't mean that it is a good load.

Jim;
Another thought. Rolling Eyes

When you do your testing over the chrono. make sure you use only one barrel. The choke difference will change the Velocity. Select the barrel you use the most for your first hunting shot. Also clean that barrel after each shot with a bore snake.

Since most of your shots will be at game and not clays your barrels will be, most of the time clean & not fouled.

My opinion is if you shoot targets, test with a fouled barrel.

Guest

Lefty Dude,

For nice consistent chronograph readings, you really should fire 2 or 3 fouling shots. Clean cold barrels are not ideal for consistent velocity readings. This is standard operating procedure throughout the industry.

I think most folks are looking for exact velocity readings, forget it. Look for consistent loads, velocities you get will reflect a close approximation, which for a shotgun is more than fine.

The best idea to get velocities, is fire 5 or 10 shots through one shotgun with a cylinder or skeet choke in place. Take the average to get the velocity, subtract the extremes to get the Extreme Variation and then figure Standard Deviation. The more loads you shoot when velocity testing the more accurate the numbers get. I also like to use bushings and bars to drop powder and shot and run the loads through the reloading cycle. That way the loads you are testing are just like the loads you will be using for hunting or clay targets.

Target loads (fast powders) reloaded on a progressive press will typically run 10 - 15 FPS EV and about 3 - 4 FPS SD. I have seen 12 gauge loads better than that.

35 FPS or less for 5 shots on Extreme Variation is fine. Standard Deviation should be 10 FPS or less.

Heavier hunting loads will run a bit more because of the slower powders used, but never more than the above figures. You might not like what I have written but, if you are really looking for good loads, then you need to get picky.

One last thought, I have used a Chrony, a Pro-Chrono and Oehler Chronographs, the best and most consistent velocities, were recorded when the start screen was a measured 2 feet from the muzzle, regardless of brand. I never had to correct for more then 15 FPS, when I used this method.

Member Joined: 16 Nov 2006 Posts: 1338

The recipe that I’m testing is my modified barrel pet pheasant load and uses 1 1/8 oz. of #5 1/2 np shot. I plan to do the same with my 1oz. #6 np load pet pheasant load shot from the Imp. Cyl barrel. I have not cleaned the modified barrel and so far I have shot 12 rounds. My next two sets of three (6) shots were carefully assembled and each had 60 lbs. of bathroom scale wad pressure. The six shots averaged 1230 fps., with an ES of 39 fps. It appears that my original expectations were higher than reality, but and extreme spread of 39 fps may not be to awful bad. I thank you all for your information and advice.

I like consistant velocities in my serious hunting reloads. I like the the idea that I am doing all I can to hit the bird with a clean killing, sufficient load that will do the job well every time. I also like consistancy in my serious target ammo for registered targets and league play. Consistant target ammo performance gives me one less thing to obsess on if I'm feeling the pressure a bit. In reality, the minor differences between my practice ammo and my serious stuff is so minor, it should not really matter. Like they say, once you learn how to break the targets regularly, 90 percent of very consistant shooting then takes place between the ears. What is actually in the chamber is far less important as long as it is safe to shoot.

I don't really care that much about consistancy for my 12 gauge recreational and practice ammo. I am more concerned with saving time and money by simplifying the reloading process and getting the most powder I can for the least cash at the time regardles of the brand.

This reasoning would apply to my 16 ga recreational ammo too, but powder choices are far more limited here. I use Green Dot because it gives me good results, is easy to load, and is not that expensive. However, I'd use any of a couple of other closely related powders if I could get them easily and more cheaply. I'm certain any of them would work very well for my needs here.

Just about all of the fastest burning disc shotgun powders are suitable for my 12 gauge practice ammo needs (I avoid sphericals--don't like them one bit for this use). I choose a powder bushing that throws a safe and suitable load for any of a half dozen of them. I then just pour the stuff into the powder hopper and crank the loads out as efficiently as I can.

Any one of the powders I might use here will produce velocities between 1100 and 1160 FPS out of the common bushing in the reloader I'm using. I've found over time that Red Dot, Clays, Promo, the two fastest Scot powders, Red Diamond and several others I've used but can't remember the names of all work just fine and all throw safely from one bushing. I Reload both 7/8 and one ounce practice loads this way. They all work very well for me.

The minor differences in velocity I might get do not bother my shooting one bit. I can't really detect any difference between 1100 FPS and 1160 FPS on trap singles and doubles targets or for skeet shooting either. Any velocity between these points will crush the bird just fine. The few microseconds difference in actual pattern flight time to target won't matter at all if I'm centering the target with the pattern.

Adjusting my hold points has more importance than the ammo's velocity on any given day. Available light, trap background, wind, or any one of a half dozen other things have more affect on my performance than the few dozen FPS plus or minus my ammo is producing. So I adjust my hold points to get on the bird at the right time to swing through and break it smoothly and consistantly.

For practice handicap, I adjust my hold points to compensate if I can see I'm hitting a bit behind the target. I'm almost never too far ahead in the beginning on handicap targets. A small adjustment to my hold point usually puts me right back on the target. Velocity difference might or might not be involved here. It could also be a matter of how fast my brain is picking up the target out of the trap as well. It does not matter why. What does matter is adjusting to compensate so I can hit every one consistantly again.

So slight velocity variations in my practice ammo have actually taught me an important lesson in consistant shooting. Break the first two or three birds on that particular trap or skeet field and pay extra attention to the break, then adjust hold points as needed to crush the rest. Then it is a matter of seeing the target and swinging through it consistantly by rote.

If I have an upcoming registered shoot, I will use my standard target loads to shoot a line or two of warm up targets. Doing so retunes me to the primo ammo just fine, and calms me down as well. When I take my station, what is in the gun will not matter all that much, so I do not worry about it.

Unlike rifle ammo where consistant velocity and good gouping are everything, shotgun ammo only needs to produce a pattern effective enough to hit the target with enough pellets to do the job at hand be that to kill the bird or to break the target. It is the wingshooter's job to put that effective pattern on the target at the right place and time. Seeing the target as well as we can and a consistant swing through are much more important. In short, timing is everything in wingshooting.

Guest

jschultz

Card wads will always have a little more variation than plastice wads, as they just can't seal as well. But, you have a decent load there. Shoot it and have fun!!