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Old October 29, 1999, 07:53 PM   #1
45 Fan
Join Date: August 14, 1999
Posts: 27
Hi to all:
I am using a chronograph to develop loads for use in IDPA. I have never used a chrony before and am unsure as to how to interpret the results that I am seeing. I am loading a 230gr LRN over approx. 4.5gr of BE. I am achieving average velocities of approx. 760 feet per second. I am shooting 10 shot strings and my extreme velocity spreads are approx. 27 feet per second with standard deviations ranging 7.0 to 8.5 per string. This load seems to be pretty consistent but I am not sure how to interpret these numbers. Can anyone provide any feedback on this? Are these readings good or bad? Thanks in advance for any help given.....45Fan
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Old October 29, 1999, 10:29 PM   #2
Join Date: June 6, 1999
Posts: 42
I don't know if this will help much but 15 yrs ago when I was shooting IPSC the 230 LRN had to break 740 FPS to rate "Major" caliber.
The 200 SWC had to go 850 FPS. I don't know what limit IDPA has but I'd bet it's around this level.
A ten shot string is a long string. If your getting High - Low variation of 27 FPS that's excellent.
The IDPA web page probably list the required power factor. We used to multiply the bullet weight by velocity. it should give you a 6 digit number (740 x 230 = 170200) insert a decimal the digits down (in the center) had to be above 170.XXX to be major.
For what it's worth
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Old October 30, 1999, 04:02 PM   #3
John Lawson
Senior Member
Join Date: August 28, 1999
Posts: 281
Just reviewed the IDPA web page, and the power floor for unmodified pistols is 125,000.
Multiply bullet weight times velocity, or 230 X 760 =174,800, well within limits.
A concistent chronograph reading within 50 fps is excellent.

[This message has been edited by John Lawson (edited October 30, 1999).]

[This message has been edited by John Lawson (edited November 02, 1999).]
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Old October 30, 1999, 11:26 PM   #4
Join Date: October 10, 1998
Location: Kalispell, MT. USA
Posts: 26
According to the IDPA web page the 1911 in 45 falls into the custom defensive pistol catagory. This puts its minimum power floor at 165,000. So 45 fan is still above the limit, but the minimum velocity is around 718 fps.

-- Scott

[This message has been edited by swehrman (edited October 31, 1999).]
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