Pair of CZ 457 MTR's, 16" and 20.5" Chrono test

P

PGW Steve

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This afternoon I finally got a chance to do a bit of testing with these two rifles. Velocities were measured with a Labradar.

SK Standard Plus

16" avg 1075 SD 11.3 (18 shots)
20.5" avg 1088 SD 11.3 (29 shots)


Lapua Centre X

16" avg 1065 SD 13.7 (10 shots)
20.5" avg 1075 SD 7.0 (10 shots)


The following with the 20.5" rifle only

SK Biathlon Sport 1117 SD 17.6
Lapua Polar Biathlon 1120 SD 6.9
CCI Subsonic HP 1109 SD 26.6
 
Well, for starters it appears that the ammo fired through the longer barrel had higher velocity. So yes, conclusions can be drawn. Thanks for the testing Steve. Was there a significant difference in accuracy between the two?
 
armorman said:
Well, for starters it appears that the ammo fired through the longer barrel had higher velocity. So yes, conclusions can be drawn. Thanks for the testing Steve. Was there a significant difference in accuracy between the two?
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As said... very little...

I am sure the shooting was fun.

To test velocities from two different barrels is virtually pointless... but there have been many tests done by cutting down a long barrel an inch at a time and recrowning each time, for a much better test of velocity vs barrel length.
 
grauhanen said:
Can any conclusions be drawn from this information?
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With rimfire PRS gaining a lot of momentum, yes conclusions can be drawn. Two rifles manufactured in the same time period with probably the same tooling and different barrel lengths show negligible difference in velocity.

hoytcanon said:
Very little...
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See above.

armorman said:
Well, for starters it appears that the ammo fired through the longer barrel had higher velocity. So yes, conclusions can be drawn. Thanks for the testing Steve. Was there a significant difference in accuracy between the two?
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You're welcome! Yes, minor velocity loss with the short barrel. The 16" averaged .384" for five 5 shot groups, the 20.5" was .414". I just shot off a bipod on a solid bench with a rear bag, so I'm happy. Wind was 15-20kph from 8 o'clock.

I'll probably pillar bed these rifles properly at some point, they are lacking from the factory. They can only get better, and the starting point is pretty good.

hoytcanon said:
As said... very little...

I am sure the shooting was fun.

To test velocities from two different barrels is virtually pointless... but there have been many tests done by cutting down a long barrel an inch at a time and recrowning each time, for a much better test of velocity vs barrel length.
Click to expand...

That's your opinion, others might find it useful. It's commonly stated that 16" gets you the max velocity out of a .22LR, this falls inline with that. Perhaps I'll drag out the 28" 40XB and see how that presents itself. it's not really valid as the bore and chamber will be vastly different to the CZ's.


grauhanen said:
Anything else?
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Yes, I had to snow blow a tunnel down to the target as I couldn't see the frame, it's close to 5' deep in my yard.
 
PGW Steve said:
Yes, I had to snow blow a tunnel down to the target as I couldn't see the frame, it's close to 5' deep in my yard.
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At least the snowbanks should cut down on wind drift. :)

I am actually a bit surprised at the low SD for most of those strings.

Interesting that the two test lots with lowest SD are the biathlon specific ones which are specifically intended for use in the type of cold weather you were shooting in.
 
PGW Steve said:
This afternoon I finally got a chance to do a bit of testing with these two rifles. Velocities were measured with a Labradar.

SK Standard Plus

16" avg 1075 SD 11.3 (18 shots)
20.5" avg 1088 SD 11.3 (29 shots)


Lapua Centre X

16" avg 1065 SD 13.7 (10 shots)
20.5" avg 1075 SD 7.0 (10 shots)


The following with the 20.5" rifle only

SK Biathlon Sport 1117 SD 17.6
Lapua Polar Biathlon 1120 SD 6.9
CCI Subsonic HP 1109 SD 26.6
Click to expand...

PGW Steve said:
With rimfire PRS gaining a lot of momentum, yes conclusions can be drawn. Two rifles manufactured in the same time period with probably the same tooling and different barrel lengths show negligible difference in velocity. ...

Yes, minor velocity loss with the short barrel. The 16" averaged .384" for five 5 shot groups, the 20.5" was .414". I just shot off a bipod on a solid bench with a rear bag, so I'm happy. Wind was 15-20kph from 8 o'clock.

It's commonly stated that 16" gets you the max velocity out of a .22LR, this falls in line with that. Perhaps I'll drag out the 28" 40XB and see how that presents itself. it's not really valid as the bore and chamber will be vastly different to the CZ's.
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My apologies. I thought that perhaps with the plural conclusions there might be something else to be drawn other than there wasn't much of difference in velocity between the barrels. That's okay. The MV info in the OP, however, suggests that the maximum velocity isn't achieved with a 16" barrel as the 20" barrel had a slightly faster average with both SK+ and Center X. Instead it would appear that what was commonly stated didn't fall in line after all.

prairieguy said:
I am actually a bit surprised at the low SD for most of those strings.

Interesting that the two test lots with lowest SD are the biathlon specific ones which are specifically intended for use in the type of cold weather you were shooting in.
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Unfortunately the sample size remains unknown. In practice it may not be possible to derive meaningful conclusions from the SD figures given for small sample sizes or a small number of samples. Standard deviation numbers gain more meaning when comparing the results of multiple samples.
 
prairieguy said:
Interesting that the two test lots with lowest SD are the biathlon specific ones which are specifically intended for use in the type of cold weather you were shooting in.
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The SK Biathlon, at 17.6 SD, was the second worst ammo tested... I've had better with it at ~8 and 12 SD for 50 shots each in two different rifles.

grauhanen said:
The MV info in the OP, however, suggests that the maximum velocity isn't achieved with a 16" barrel as the 20" barrel had a slightly faster average with both SK+ and Center X. Instead it would appear that what was commonly stated didn't fall in line after all.
Click to expand...

No conclusions re: barrel length *in this test* may be drawn, they are two different barrels and the individuality of each bore has a significant impact on MV. It cannot be assumed that these two barrels would produce the same MV if they were the same length, therefore any conclusion that the MV differential between them is due to their length alone is invalid. As has been already stated, there is very little that can be concluded from this test... Steve's 16" barrel shoots a little slower than his 20.5" barrel, that's all. I'm sure Steve will find this information useful towards his PRS pursuits for calculating DOPE.
 
Man, I hope to one day have the free time to tinker, toil and test that way that some of you are able to get out and do, not to mention all the arguing and defending against strangers on the internet with equal amounts of said time and desire to sh*t disturb.

Patrick
 
hoytcanon said:
As said... very little...

I am sure the shooting was fun.

To test velocities from two different barrels is virtually pointless... but there have been many tests done by cutting down a long barrel an inch at a time and recrowning each time, for a much better test of velocity vs barrel length.
Click to expand...

101% agree

When ever a test is done, one must keep as many parameters constant.

In the OPs tests, which is very interesting btw, thank you very much, the only conclusion I can draw is that a 16” barrel of one model delivered a minuscule lower velocity than a 20.5 inch barrel of the same model.

You can probably find the same velocity deviations in two different examples of the same rifle and in the exact same barrel length.

Objectively, no more no less can be drawn.
 
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