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Old April 9, 2012, 07:25 PM   #1
thedaddycat
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Loads, chrony, or???

I took my loads for the .44 mag to the range today and shot them over a Chrony Beta to get data. This is the first time I've used it, and I had the directions with me just to be sure of what I was doing. I seemed to be getting a pretty wide range of velocities and I'm trying to figure out what the cause is.

Here's the layout:

Test platform: Smith and Wesson 629-1 5 7/8" barrel
Range: measured 25 yards to target, chrony 5 feet from muzzle
Loads: new R-P brass, Oregon Trails LaserCast 240 grain SWC, Federal 150 Large Pistol primers, COL 1.625", FCD crimp, Trail Boss charges from 6.5 to 7.0 grains in .1 grain increments (all hand weighed)
Shooting position: sitting, shooting SA from sand bag rest
Test procedure: Shoot 6 rounds of each charge weight from low to high recording each shot velocity (in a notebook, with a pen.. how old school is that? lol), mark shots on target after each cylinder, reshoot second cylinder of each charge weight at same target as that charge weight from first cylinder again recording each shot velocity.

This chrony will do six strings of ten shots and I'm not sure if I cleared it correctly to get data from each cylinder tested. I'll have to go back over the directions again.

Results were best from the 6.7 grain load (if I did read the data right) with ES of 57 fps and SD of 19 fps. Other loads were inconsistent with ES of 75 to 108 and SD of 26 to 36. Average velocities ran from 727 fps to 781 fps. Suprisingly the lowest average velocity was from the 6.7 grain load also, though not by much.

I'm wondering if I didn't set the chrony up too close to the muzzle and that's what's giving me these readings. Accuracy was OK for what I was doing and conditions at the range. I'll have to get a pic of the targets and add it to the thread.
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Old April 9, 2012, 07:42 PM   #2
rclark
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Trail Boss can be a bit finicky on what primer you are using,bullet, and powder charge. Also you should use fairly new brass and consistent crimp which helps consistency. Note 57 ES isn't bad for TB.

Here are my results for .44Mag Trail Boss .44Mag Test

You can look back through the thread and see where I compared magnum primers with regular primers in .45 Colt. You should at least do 10 shots (I like 15) per load for results you can trust. I never bother with 0.1 increments. I usually always work up to a good load in 0.5 increments....
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Old April 9, 2012, 07:47 PM   #3
1Hobie
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Did you load your .44 muzzle down and then move to the rest? If so, the powder is at the bullet end of the cartridge at start. Then the powder shifts around and changes the exposure of the powder at ignition when level.
It does make a difference.
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Old April 9, 2012, 10:54 PM   #4
Lost Sheep
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Five feet - WAY too close.

12-15 feet is a much better distance. The muzzle blast and unburnt powder will definitely give you false readings.

I set mine 15-18 feet in front of the shooting bench. The maximum the cord will allow easily.

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Old April 9, 2012, 10:58 PM   #5
farmerboy
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I was thinking the same as LostSheep
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Old April 10, 2012, 01:23 AM   #6
sc928porsche
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Muzzle blast will effect the readings. Exactly why I dont know (I have some theories). I have a 30' chord for mine and set it up on a tripod. I measure from bench to front of chrony with a tape at 25' It works well at that distance for everything except for the 50BMG Mcmillian. For it, I have to add another 10'.
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Old April 10, 2012, 06:24 AM   #7
alloy
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My chrony will not function at 5 feet.
As Lost Sheep mentioned, 12 seems to be about the minimum.
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Old April 10, 2012, 06:54 AM   #8
griz
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With the basic Chrony the last thing displayed is the number of rounds in the string. I'm assuming the Beta will do that too?
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Old April 10, 2012, 07:53 PM   #9
thedaddycat
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I was sitting at the bench loading the revolver so it was not pointed straight down, kind of sideways. The Trail Boss loads pretty well fill the cases up, even if they were pointed straight down and then brought level there would only be a little bit of a gap at the top curve of the case. After the first shot, recoil would tip the gun up every time it's fired.

I have two more sets of loads for the .44 mag, made with 200 grain Lasercast RNFP. The Trail Boss loads are 6.1 to 7.7 grains and fill the cases while the Titegroup loads run 5.0 to 6.6 grains but leave a lot of room. Both of these test load ladders are made in .4 grain increments. (Yes, I am learning from you guys and I do greatly appreciate you sharing your experience.) If I were to guess one of these two loads to be effected by having the gun tilted down it would be the Titegroup loads.

The directions for the chrony state 10 feet for high powered rifles, I just took a guess in setting it up at 5 feet. When I test the 200 grain loads I'll set it out at 12 and see how it goes. The Beta will display shots in a string, high, low, average, ES, SD and other data. I need to use it more to get used to operating it.
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Old April 10, 2012, 08:11 PM   #10
hounddawg
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chronies measure speed by timing the shadow of the bullet as it crosses the first sensor to the second sensor. Smoke, muzzle flash, unburned powder, too much direct sun or even the light flicker from the alternating current in artificial light can throw them off.

for pistol ammo I would say you had some pretty good loads there.
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Old April 10, 2012, 08:40 PM   #11
1Hobie
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Thanks for returning some input. I noticed the powder shift in some light .357 mag loads many moons ago. As you stated, if the cartridge is pretty much full, I wouldn't expect there would be much of a change by position.

Isn't this a fun sport to get involved with? I do enjoy it myself.

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Old April 11, 2012, 01:57 PM   #12
thedaddycat
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OK, I had issues with Photobucket not letting me upload the past couple of days, fixed now. So here are the targets. I was shooting off a table which was kind of low for me. I had to lean way over and since my knees are shot and my back was starting to ache a bit I did pull a few shots off target a bit. Also a lot of rounds seemed to be hitting a bit high, maybe also from the low position I was in.

I really didn't notice too great a difference when firing the different loads except a few that were significantly higher or lower than others in that cylinder full. It looks to me like the higher charges shot better as far as accuracy and as discussed my velocities are probably somewhat suspect due to the closeness to the chrony. Hmmmmm... guess I'll have to reload and retest.

The thing is that if I use the Auto Disc powder measure I may be limited as to the charge weight being whatever the disc will give me. I am not set up for using a double disc setup yet and I think the largest orifice gave me the 6.7 grain charge. Equipment upgrade time?


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