How can I improve CO2 TSS shot consistency?
I put my CO2 powered TSS to Chrony test last night. I tested three power settings 10, 7 and 2 with .22 JSB Exact and 10-shot string at each setting. Here are some of the results:
*** 10 ***
Lo = 542.1
Hi = 562.7
Av = 551.1
Es = 20.54
Sd = 6
*** 7 ***
Lo = 480
Hi = 527.1
Av = 495.2
Es = 46.98
Sd = 15
*** 2 ***
Lo = 346.4
Hi = 389.1
Av = 363.9
Es = 42.6
Sd = 14
I’d say that I am not quite impressed by the shot consistency here because the extreme spread or the standard deviation seems too high. I am NOT looking for high muzzle velocity (~400fps would be ideal), so what can I do to improve the consistency? Thanks.
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The 12″ barrel isn’t real good for turn down consistency. How are the pellets hitting the target? That’s what matters most anyways.
May be you would like the consistency better with a more efficient 24″ barrel.
First of all, thanks again for the help. I’m learning everyday.
I have another CO2 related issue – I have a fresh filled CO2 tank (12oz). My gun shot fine yesterday. However, this morning when I picked up the gun and made the very first shot, it was so weak, so low as if there was no much CO2 left. I fired the 2nd shot immediately, the 2nd shot and every shot thereafter were normal and hit the paper target right on. What’s going here? I did lay the gun flat for overnight. Does that matter? Shall I always do some dry-fires before taking a real shot? I am from Southern California and the weather has been quite warm lately. Thanks.
The bolt has two o rings, one at each end, that are suppose to seal the barrel to the top hat when the bolt is closed.
They often leak…you’ll notice that no matter how you muffle the muzzle, there is still a good bit of noise coming from the breech.
Now the odd thing about 0-rings is that on air, it makes LESS difference what the hardness of the o-ring is…but on co2, soft o-rins tend to swell up as they absorb co2.
What I noticed is that the factory o-rings leaked on my talon SS…but running on co2, after a certain number os shots (rather rapidly shot) the noise stopped.
So i did some experiments with different (cheap) o-rings. I never really expected them to swell up so large.
test chamber: stuck the different types of o-rings into a bulk fill rifle (gathered by a wire to make removeal easy), charged the rifle, and let them stew in co2 for an hour.
not that the breech orings on our guns get soaked in liquid CO2, but a nice test and good info on your part. Thanks for posting that.
Really shows how much orings can change/distort depending on aplication. i for one would not have expected to see that much difference.
😀
[quote=”ribbonstone”]One other place to look.
The bolt has two o rings, one at each end, that are suppose to seal the barrel to the top hat when the bolt is closed.
They often leak…you’ll notice that no matter how you muffle the muzzle, there is still a good bit of noise coming from the breech.
Now the odd thing about 0-rings is that on air, it makes LESS difference what the hardness of the o-ring is…but on co2, soft o-rins tend to swell up as they absorb co2.
What I noticed is that the factory o-rings leaked on my talon SS…but running on co2, after a certain number os shots (rather rapidly shot) the noise stopped.
So i did some experiments with different (cheap) o-rings. I never really expected them to swell up so large.
test chamber: stuck the different types of o-rings into a bulk fill rifle (gathered by a wire to make removeal easy), charged the rifle, and let them stew in co2 for an hour.
[/quote
So what was the outcome which are best?
One other place to look.
The bolt has two o rings, one at each end, that are suppose to seal the barrel to the top hat when the bolt is closed.
They often leak…you’ll notice that no matter how you muffle the muzzle, there is still a good bit of noise coming from the breech.
Now the odd thing about 0-rings is that on air, it makes LESS difference what the hardness of the o-ring is…but on co2, soft o-rins tend to swell up as they absorb co2.
What I noticed is that the factory o-rings leaked on my talon SS…but running on co2, after a certain number os shots (rather rapidly shot) the noise stopped.
So i did some experiments with different (cheap) o-rings. I never really expected them to swell up so large.
test chamber: stuck the different types of o-rings into a bulk fill rifle (gathered by a wire to make removeal easy), charged the rifle, and let them stew in co2 for an hour.
Most likely, the difference is in the barrel being contained within the frame “tube” on the SS, and being of much less mass/weight. The SS frame is containing the cooled co2 gas and keeping it right against a skinny short barrel, making it cool down faster than the 850 where the entire barrel is exposed to ambient air and escess co2 is expelled out the end meaning it takes a lot more shooting to change the temperature of the barrel.
Also may be that the 850 uses less co2 than the TSS so the tank does not cool as rapidly during a shooting session.
Thanks guys for the great information. The cooling effect you guys mentioned is quite interesting. I wasn’t shooting particularly fast or slow but perhaps I should have taken more time between shots. When I exame the 10-shot string at level 10, it is actually just like what you guys said.
1 – 562.7
2 – 559.6
3 – 553.4
4 – 551.1
5 – 552.6
6 – 547.6
7 – 549.0
8 – 546.0
9 – 547.1
10-542.1
FPS’s are on the downward trend! I go back to the data I collected for my .22 RWS850 with standard 88 gram CO2. They are just like those shots above, except, the variation is relatively small.
.22 RWS850
1 – 631.0
2 – 630.2
3 – 630.1
4 – 629.0
5 – 629.8
6 – 630.3
7 – 627.5
8 – 630.7
9 – 628.1
10-627.1
I don’t know what are the contributing factors that make RWS850 more consistent than TSS. Perhaps … it is just the Nazis make better shit 😀
Cool off. Esp. not that the season has changed and the ambiant temp. is lower.
The talon SS…or any shrouded version… captures the co2 and lets if run around inside the frame, bathing the barrel in cold gas from both sides. They tend to cool off quickly.
If you look at your shot strings, might find that the average vel. of the last 3 shots is less than the average vel. of the first 3 shots. Pretty good idication of cooling.
Basically, if you want to shoot more consistently with co2, are going to have to pace your shooting.
One other thing of note. As a co2 tank gets close to empty (but not empty…lets say when there is about 2-3 oz. left in a 20 oz. tank) will find the variation goes up. Am at a loss to fully explain why this is, but i’ve seen it time and time again.
Another factor to be aware of is that each time you shoot with CO2, the gun cools off. The shorter the time between shots, the more everything cools and the less pressure available from the CO2. If you take some time between each shot, the gun warms back up and the pressure is more consistent.
Mike T.
At those velocity levels, you may find a lighter pellet is more consistent.
Also be aware of gun position while reloading, pointing the muzzle downward to reload can get varrying amounts of liquid co2 into the valve area resulting in inconsistency.
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Outcome is the same when not soaked in liquid co2, but to a lesser extent. AirForce bolt o-rings do absorb c02 from shooting, but it takes a good number of shots to get them to swell a little. In one that leaks a little co2 and gives a bit of noise from the breech, might find that after a bit of shooting the noise stops…and that gas that use to make noise now serves to drive the pellet.
Might notice, with the 12″ barrel, setting the spring tension past #4 or #5 doesn’t do jack for vel., just makes more noise and shoots snow out the barrel.
Got to thinking about that and made a LIGHTER hammer. With this hammer, have to move the spring setting to a #8 or #10 to bet the same vel. as before, but so far a light/fast hammer has resulted in more consistent vel. for co2. the fast sharp “jab” of a light hammer seems to work better (with co2) than the low round-house punch of a heay hammer.