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Old August 28, 2009, 07:01 PM   #1
Magnum Wheel Man
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what is a good extreme spread in velocity for 8-10 shots ???

spent the afternoon running small rifle cartridges ( albeit through a handgun ) through my ( almost antique but never used before ) chrony... it belonged to my father in law, & had never been used... it works great, but has tiny openings in the sky screens...

I'm probably putting the cart before the horse, but I haven't run any factory rounds of this cartridge through this chrony...

so... how close should my rounds be ??? ( I'm scaleing each round during developement, but I have a pretty crappy almost worn out old beam scale, & I question how close each charge is to what it's supposed to be )... I know it's not off an "unsafe" amount, but I could see myself having an extreme spread of .4 or .5 grains in 10 loads

I will run a couple handfulls of factory rounds through tomorrow, just to see what the factory Remington rounds are running ( both for velocity & spread )
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Old August 28, 2009, 07:35 PM   #2
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What do you think? Perhaps you should review statistical terms and their meanings. For most hunting ammo I would go with accuracy rather then chasing prime stats.......now if you were a long range HP shooter or into long range hunting one might want to decrease the numbers to increase the accuracy potential....http://www.pilkguns.com/Chrony.shtml
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Old August 28, 2009, 07:38 PM   #3
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when i load my .243 for long range shooting I like to see less that 25 fps extreme spread. With consistent, careful loading this is not hard. I would think less than 15 fps ES would be superb! This is of course with a 5 shot string.
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Old August 28, 2009, 07:42 PM   #4
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With charges that are the same within 0.1 grain, the extreme spread in a 3000 fps type rifle cartridge can frequently be over 100 fps, and around 30 fps is pretty good. There are some cartridges that are noted for small spreads. Big magnum cases tend to have bigger spreads.

What cartridge are you shooting?

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Old August 28, 2009, 10:26 PM   #5
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I shoot & load alot of different cartridges... today was my fast twist 22 Hornet revolver... I shot one powder with 5 different charges for 36 grain... one powder with 5 different charges with 45 grain, & one powder with 5 different charges with 55 grain bullets... I'm trying about 6 different bullets, 4 different powders, & my charges are all in 0.5 grain increments... lots of loads to test... best extreme spread was aproximately 50 fps... worst was around 200 fps... bear in mind, this was in a revolver...

I'll try some factory loads tommorow...
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Old August 28, 2009, 10:59 PM   #6
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I go by <100 fps ES. Of course the lower the ES the better. Some cartridges seem to have inherently lower spreads than others overall.
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Old August 29, 2009, 01:17 AM   #7
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Always going to be wider out of a handgun, if you can keep the spread down to 50 fps you are doing really good. I wouldn't lose any sleep over an occasional 100 fps difference but do try to keep your loads with .2 or less in that small a case.
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Old August 29, 2009, 01:25 AM   #8
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I think you should look at ES as a percent of velocity. 100fps ES in a .45acp is very erratic while 100fps in a .22-250 may be acceptable.

But then I don't have a chronograph.
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Old August 29, 2009, 02:32 AM   #9
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It matters a great deal that this is in a revolver.I will suggest that you focus on absolutely uniform case lenghths,to contribute to a very uniform crimp.I suggest crimp as a seperate operation from seating,and ,perhaps by a mic reading at the case mouth,a repeatable degree of crimp.
In a wheelgun,the crimp is vital to consistent ignition.

Just a fun aside bit of trivia,it is hard to beat the velocity spread some black powder cartridge shooterts get.You will have extra fingers to count the fps with!!S9ome get less than 10 fps.
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Old August 29, 2009, 05:42 AM   #10
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ES

I used to shoot a mild cast bullet load for the .30-30 in my T/C Contender pistol (10" bbl) that had a an ES of 12 fps. It was a very accurate little combo.
A 120 grain Lee RNGC bullet pushed by seven grains of Unique, CCI LR primers.
It was the only load that I've ever paid attention to ES. Kinda just caught my eye when I was chrono'ing one day.
Pete
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Old August 29, 2009, 10:38 AM   #11
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In a revolver

there may be substantial differences among the AVERAGE velocities from each chamber in the cylinder. SO, if you are testing AMMO, it is best to look at the results from only one chamber to get an appropriate ES.

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Old August 29, 2009, 02:06 PM   #12
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had to get some yard work done this morning... I'll be going out again in about an hour...

I went through 7 of the loads I shot yesterday & went through with a calculator & a ruler... I'm honestly not a very precise handgun shooter, so I'm throwing out the worst shot & averaging 7 rounds ( the revolver is an 8 shot )

all targets were shot off my chrony bench, through the chrony, & to my pistol backstop at 50ft...

the gun is compensated & is a big heavy revolver... recoil is almost nill, & I'm only using a slight taper crimp on all my loads ( most bullets are seated past the widest part of the bullet, & most bullets I'm using have no crimp groove ) my best group yesterday was 2.25" & had an extreme spread of 136 fps & used 4227 powder behind a Sierra 55 grain BT spitzer at an average of 1410 fps... my 2nd best shot yesterday had a group of 2&3/16" & had an extreme spread of 68 fps & used AA#9 behind a Barnes 45 grain banded solid BT spitzer at an average of 1944 fps...

bear in mind I have alot of combinations loaded for testing, like 6 different bullets, 4 different powders, most using 5 different powder charges, varrying by a 1/2 grain, & most with 2 different primers... so I expect alot of these to be lost causes, & will go back through the best of them to tweak... I expect the Lil Gun loads should be promising when I get to them...
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Old August 29, 2009, 05:51 PM   #13
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ES is nothing more than what is called "range" in statistics. While a very low ES can indicate excellent consistency, just one bad round can cause it to be lousy, what's called an outlier.

I think that under 25 would be fairly good, except I'd be looking at a string of 10 instead of 5.

And if I had a much larger ES I'd want to see if there were simply one outlier causing a wide ES.

I like Standard Deviation much better as a measure of consistency. With handgun rounds, if I have a SD of 10 or less for 10 rounds, I consider that very good.
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Old August 29, 2009, 06:01 PM   #14
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true, standard deviation would definately be better....
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Old August 29, 2009, 06:26 PM   #15
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I just have an old single recording chrony... maybe if my math was ( "smarter than a 5th grader" ) I could do the math...

I'm noticing a few oddities... ( still testing )

it seems Barnes 36 grain Varmint Grenades have more resistance going down the barrel than Barnes 45 grain banded solids ??? I seem to be able to push the solids harder than the VG's...

the Speer 33 grain TNT's are looking good so far...

I've also come to the conclusion that Lil Gun is strange powder... my minimum loads are so close in velocity to my maximum charges... I've yet to take a calculator to the targets but thats an initial observation with 45 grain bullets anyway...

the older Remington yellow box factory rounds I tested are neither more accurate... in fact less accurate than most of my loads out of this gun... & not any more consistant... still doing the math on that one...
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Old August 29, 2009, 06:44 PM   #16
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MWM,

I am guessing that you are shooting a .22 Hornet in your revolver?

Groups of 2"+ at 50' seem a little large for testing ammo. Most handguns will give that size group at 25 yards, and maybe closer to 1" at 25 yards with their best handloads. So, there is probably something that you need to discover about yourself or your gun that would improve your groups, maybe more than changing powders and charge weights. If you are using iron sights and have "old eyes" like mine, then a pair of glasses that are set-up to focus at front-sight distance might help - - it did for me. And, a target shape that suites my sights for really precise alignment also helped me.

Of couse, none of that will affect the velocities, EXCEPT maybe shooting all chronographed rounds from the SAME chamber in your cylinder.

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Old August 29, 2009, 08:24 PM   #17
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A standard deviation should be less than 1 percent of the average velocity and you are doing good. With standard velocity pistols 10 to 20 is good with rifles, 50fps might be ok.
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Old August 30, 2009, 09:46 AM   #18
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The groups are only of secondary importance right now, as I'm shooting through an old chrony with a 2.5" hole in each "card" that inserts over the sensors... I think the group size give me an idea only, of which may be better than others... to continue to load & work on... I'm also turning the gun to the side, & getting up & walking down to the target between each shot to mark each shot on the actual target... between the excercise for an old dude of getting up & down & walking back & forth for each shot, I have to reposition the gun each time... things I wouldn't be doing if I was shooting fot tightest groups...

also...I'm not too expirienced with revolver iron sights, as I got into ( all ) guns later in life, I went right to mounting scopes on almost everyhing... litterally ( it was easier to shoot well )... I've since pulled the scopes off all but my long range stuff, & am trying to "force" myself to learn how to shoot them better with irons... ( Appleseed training last year, seemed to help with the rifles )

also there are so many combinations I'm trying, that there must be some that are the loads fault, right...

I had one load yesterday that was a 2" X 1/2" horizontal string of 8 shots... I'm guessing that that load has promise if I could tighten it up as the shooter

any explaination as to why the 1st shot is almost always the lowest velocity, even if I shot the last target only 5 minutes before ???
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