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Old May 6, 2007, 04:38 PM   #1
ulflyer
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Join Date: December 30, 2004
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Large Chrono Variation in Light 45acp

Been reloading for some time with a Dillon 550 and generally download to point that 19ll's cycle well. I prefer light plinking loads.

Recently got a Kahr P45 with 3.5" barrel and loaded a bunch of 200gr LRNFP with 3.3 gr Clays. Gun functioned properly with good accuracy. (This load works well in my 1911's also).

Yesterday I used my new Chrony F1 for the first time with these loads and the variation in FPS seemed way too great. For example, out of the 50 bullets fired I got a LO 510, HI 618, and everthing in between, with overall avg 576 fps. I've gone back to my Dillon and weighed a couple dozen drops and they all were very consistant with at most a half tenth grain variation...guessed at as the Hornady scale only shows tenth's.

What kind of variation in FPS should I expect? Is this normal? Suggestions, advice, appreciated.
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Old May 6, 2007, 05:11 PM   #2
Jim Watson
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I shot some light loads with Clays,
.45 ACP 3.2 gr Clays + 200 gr SWC = 715 fps ES 53
was the worst.
That was in a full size 5" Gov't Model.

I don't know what is giving you such a wide spread; certainly the short barrel is holding down the velocity. But if it works, it works. Be alert for stuck bullet "squibs" in case the low end is too low to get the bullet out of the barrel.
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Old May 6, 2007, 05:54 PM   #3
armedandsafe
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Load two magazines. Fire one by holding the piece vertical and slowly lowering it for each shot. Calculate your high, low and ES. Fire the other magazine and hold it diferently oriented for each round (muzzle down, muzzle kept level after firing, shake it abit, etc.) and see what the spread is then.

If firing all rounds using the same orientation produces a significantly tighter spread, your problem probably is too little volume in the case. We are not talking about grains/weight here, but the space occupied by the powder. Small amounts of powder are known to cause erratic ignition and burn rates. Some think that there is a volume at which one can get "detonation," causing a "kaboom," whereas a larger volume of powder won't.

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Last edited by armedandsafe; May 6, 2007 at 06:31 PM. Reason: can't spell sometimes
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Old May 6, 2007, 05:59 PM   #4
rwilson452
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When I made up light loads for my 45 one thing I found that helped was a tighter crimp. the only explaination for this I can think of is it gives a better initial burn. I also got less smoke and less soot.
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Old May 7, 2007, 06:25 AM   #5
ulflyer
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Some good ideas. I'm using a separate die for crimp and its pretty snug now. Will try the positioning of the powder thing to see if that makes a diff. One of the reasons a couple years ago that I went with Clays instead of Bullseye and 231 that I had been using was to get more volume in the case. Also, I will try some factory ammo for comparision.

Jim, you've give me the thought to try the ammo on one of my 1911's for comparision.

I'll post the results here, maybe this evening.
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Old May 7, 2007, 07:02 PM   #6
ulflyer
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Well, I run a few more strings this pm and rather than list a bunch of numbers I'll just report that the 200 gr/3.3 Clays came out about the same as yesterday. Yesterdays overall avg was 576 and today was 598, a tad higher. I tried "positioning" the powder, both up and down, and it did SEEM to make a slight diff, but not conclusively with the small number I fired. I did run a string of 5 thru my Springer 1911 and it avg 658...higher as one might expect. The surprise was a string of 6 (all I had) of 200 gr SWC/Bullseye 3.9 ...very consistant . Gonna hafta load up some more to see if the Bullseye is really better. a 5 shot string of XTP 230 HP/4.0 Clays produced pretty good consistant results:

200 SWC/3.9 Bullseye: hi 739, lo 682, avg 689.
XTP 230hp/4.0 Clays: hi 767, lo 740, avg 754

Then, when I went to factory stuff it really got consistant:
Rem GS 185 HP: hi 921, lo 901, avg 913.
WWB ................ hi 796, lo 781, avg 789.

At this early stage, it almost seems as tho a light load of Clays cannot produce the consistancy as a "normal" load. To soon to say for sure, but thats all I can see at this point. Maybe its the powder, as the Bullseye was a light load and it did good. Something to play with.

And as luck would have it, one shot clipped the rear of the Chrony and bent the top edge of the metal, but did'nt damage the electronics! Wheww!

edited to add: I loaded up some Bullseye in 3.5, 3.7. 3.9gr with 200 RNFP and got reasonably consistant FPS. As these are light loads, don't understand why the Clays produce more variation than the Bullseye. I ran a bunch more of the Clays and it is indeed INconsistant. However, and this is weird, its more accurate than the 3.5 & 3.7 Bull. Haven't tested the 3.9 yet for accuracy. In the tests initially reported above I didn't shoot for accuracty, just wanted to compare FPS.

Last edited by ulflyer; May 9, 2007 at 05:15 AM.
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