RickC.
02-16-2013, 08:52 PM
Rules of thumb.
Rules such as losing 50 feet per second per inch of barrel length. Rules of thumb may be fine for thumbs, but when dealing with ballistics, many of the “truths” held up as Gospel don’t apply when actually tested and measured. I’ve learned that dealing with rifles over the years, and have found that bullet weight and powder burn rate affect velocities in ways that can be surprising.
All that said, how does the Kahr CW45 compare to a 1911 clone? I wanted to know, and unless the differences are measured, there’s no way to know.
So I did. I picked a windy, cold day to do it-- but I did.
Today’s range session: Shooting the CW45 alongside my Llama Max I, F1 Chrony at 10 feet.
http://img.photobucket.com/albums/v334/RickC1/IMG_2252_zpsd603c8ff.jpg
Loads tested:
http://img.photobucket.com/albums/v334/RickC1/bullets2_zps436f4166.jpg
L-R: 230 grain RNL, 230 gr Hornady XTP, 200 gr XTP
Load data is in the chart below, but I thought it’d be interesting to have both fast and medium burning powders in the test since my years of rifle shooting have shown the faster powders to close the gap between longer and shorter barrels, all else being equal. The results were not quite what I expected, though that’s the whole point:
To see what is, not what may be imagined.
AA #2 and Bullseye filled in the fast powder niche, and Unique for the medium burning class. Unique is sooty and dirty burning in pistol cartridges, but AA#5 leaves quite a bit of unburned powder in the tests I’ve done with it, so Unique got the nod in this session.
The wind gusts made keeping the chronograph steady a challenge, so a mostly full gallon can of paint was pressed into service-
http://img.photobucket.com/albums/v334/RickC1/IMG_2246_zpsb54149b0.jpg
Cutting to the chase, here’s how the numbers shook out:
http://img.photobucket.com/albums/v334/RickC1/45ChronyChart_zps801d69cf.jpg
Notes:
1. The smallest difference in average velocity was with the slowest powder. A fly in this ointment may be using WW brass instead of R-P in these loads. That was done because the three loads used in this test were not loaded with this test in mind (I thought of that later) and whatever assorted brass I had on hand is what was used. It could be the WW brass has different tolerances than R-P, I’m not that scientific.
2. Five shot strings were used in this test. 10 shot strings would give a better sample, but I was after an apples-to-apples comparison and 5 shots per load per gun would give me that. Besides, it was cold out there.
3. The recoil of the 200 grain XTP loads was noticeably lighter than the 230 grain loads. Unfortunately, even at 7 yards the 200 grain loads hit 4-5” low. So this CW45’s sights appear to be regulated to 230 grain loads, and even then those still print low. Not a deal-breaker but I may look for adjustable sights for it.
4. For years I have used WLP primers in all pistol rounds using large primers, both standard and magnum. I bought 1000 of the Remington 2 ½ primers a while back when primers could just not be found, and needed to use some up. I doubt the Winchester primers would have shown drastically different results.
5. The CW45 doesn’t give up much at all to the 1911 barrel length—certainly not enough to worry about.
I'd be interested in what anyone else has seen in similar tests, comments welcome.
Rick
Rules such as losing 50 feet per second per inch of barrel length. Rules of thumb may be fine for thumbs, but when dealing with ballistics, many of the “truths” held up as Gospel don’t apply when actually tested and measured. I’ve learned that dealing with rifles over the years, and have found that bullet weight and powder burn rate affect velocities in ways that can be surprising.
All that said, how does the Kahr CW45 compare to a 1911 clone? I wanted to know, and unless the differences are measured, there’s no way to know.
So I did. I picked a windy, cold day to do it-- but I did.
Today’s range session: Shooting the CW45 alongside my Llama Max I, F1 Chrony at 10 feet.
http://img.photobucket.com/albums/v334/RickC1/IMG_2252_zpsd603c8ff.jpg
Loads tested:
http://img.photobucket.com/albums/v334/RickC1/bullets2_zps436f4166.jpg
L-R: 230 grain RNL, 230 gr Hornady XTP, 200 gr XTP
Load data is in the chart below, but I thought it’d be interesting to have both fast and medium burning powders in the test since my years of rifle shooting have shown the faster powders to close the gap between longer and shorter barrels, all else being equal. The results were not quite what I expected, though that’s the whole point:
To see what is, not what may be imagined.
AA #2 and Bullseye filled in the fast powder niche, and Unique for the medium burning class. Unique is sooty and dirty burning in pistol cartridges, but AA#5 leaves quite a bit of unburned powder in the tests I’ve done with it, so Unique got the nod in this session.
The wind gusts made keeping the chronograph steady a challenge, so a mostly full gallon can of paint was pressed into service-
http://img.photobucket.com/albums/v334/RickC1/IMG_2246_zpsb54149b0.jpg
Cutting to the chase, here’s how the numbers shook out:
http://img.photobucket.com/albums/v334/RickC1/45ChronyChart_zps801d69cf.jpg
Notes:
1. The smallest difference in average velocity was with the slowest powder. A fly in this ointment may be using WW brass instead of R-P in these loads. That was done because the three loads used in this test were not loaded with this test in mind (I thought of that later) and whatever assorted brass I had on hand is what was used. It could be the WW brass has different tolerances than R-P, I’m not that scientific.
2. Five shot strings were used in this test. 10 shot strings would give a better sample, but I was after an apples-to-apples comparison and 5 shots per load per gun would give me that. Besides, it was cold out there.
3. The recoil of the 200 grain XTP loads was noticeably lighter than the 230 grain loads. Unfortunately, even at 7 yards the 200 grain loads hit 4-5” low. So this CW45’s sights appear to be regulated to 230 grain loads, and even then those still print low. Not a deal-breaker but I may look for adjustable sights for it.
4. For years I have used WLP primers in all pistol rounds using large primers, both standard and magnum. I bought 1000 of the Remington 2 ½ primers a while back when primers could just not be found, and needed to use some up. I doubt the Winchester primers would have shown drastically different results.
5. The CW45 doesn’t give up much at all to the 1911 barrel length—certainly not enough to worry about.
I'd be interested in what anyone else has seen in similar tests, comments welcome.
Rick