In my first post on the Streamline, I omitted some of the gory details of my quest for accuracy using the JSB pellets. I see that some people are having what sound like similar problems with their FX rifles, and thought this post might be of interest.
Because the Streamline is my first .22 caliber airgun, the first shots were over a chronograph at 3 and 50 yards to develop BC numbers for the pellets I hoped to be using. I started with the JSB 15.9 pellets, and encountered no real surprises. Group size for 10 shots at 50 yards was a little less than an inch, and the spread on the chronograph readings at that same distance was 16 fps. I did omit the reading from the first shot, because at that time the first shot readings at both distances tended to be a little lower.
The experience with the 18.1 pellets was an entirely different story. My first attempt at chronograph readings at 50 yards produced a 4" group with several low shots that just missed my chrony! I The spread on the chronograph readings was 118 fps. I decided to try again, and here are the results:
Date Spread (fps) Group (in)
6/16/17 94 2.43"
6/17/17 50 2.30"
6/17/17 34 1.33"
6/17/17 26 0.84" (omitting one flier)
Note that each subsequent set of 10 shots produced a reduction in both velocity spread and group size. The large velocity spread at the beginning of the series was caused by one or more unstable pellets in each group. These lower velocity pellets would often produce keyholes in the target.
Even though I had decided to standardize on the 15.9 grain JSBs due to their apparently greater inherent stability out of my gun, I thought I would give the 18.1 grain pellets another try since I have continued to see a steady reduction in group size with the 15.9 pellets since those early June trials. Here are today's results for four 5 shot groups at 50 yards using lubed 18.1 JSBs:
Group Size(in)
#1 0.42"
#2 0.38"
#3 0.56"
#4 0.42"
I had hoped to see some improvement since June, but these are really good groups, almost on a par with what I am getting from the 15.9 JSBs. As I mentioned in my first post, after running into accuracy issues with the 18.1 grain pellets in June, I stopped cleaning the Smooth Twist barrel in my rifle, and began seeing improvements in accuracy. In the case of the 18.1 grain pellets, the improvement is dramatic, having gone from the initial 4 inch group to the under 1/2" groups shown above.
My take on all of this is that the FX rifles, probably due to the design of the Smooth Twist barrels, may need to be shot for a while before developing top accuracy. My rifle now has almost 1000 pellets through it, and I don't envision it improving much more. I don't know why accuracy/stability improves over time. I have not been cleaning my bore. Is the resulting coating of lead on the barrel ID somehow responsible? Is the barrel being polished after all those shots? If I cleaned the bore would accuracy go away, and I would have to start all over with seasoning of the bore? I don't know, and don't plan to try to find out as long as the rifle keeps shooting well.
So if you encounter some initial accuracy problems with your FX rifle, it may be that you just need to season the bore by putting some more pellets through it. In my case, I would guess it took at least a couple hundred pellets to develop consistent accuracy.
Chuck
Because the Streamline is my first .22 caliber airgun, the first shots were over a chronograph at 3 and 50 yards to develop BC numbers for the pellets I hoped to be using. I started with the JSB 15.9 pellets, and encountered no real surprises. Group size for 10 shots at 50 yards was a little less than an inch, and the spread on the chronograph readings at that same distance was 16 fps. I did omit the reading from the first shot, because at that time the first shot readings at both distances tended to be a little lower.
The experience with the 18.1 pellets was an entirely different story. My first attempt at chronograph readings at 50 yards produced a 4" group with several low shots that just missed my chrony! I The spread on the chronograph readings was 118 fps. I decided to try again, and here are the results:
Date Spread (fps) Group (in)
6/16/17 94 2.43"
6/17/17 50 2.30"
6/17/17 34 1.33"
6/17/17 26 0.84" (omitting one flier)
Note that each subsequent set of 10 shots produced a reduction in both velocity spread and group size. The large velocity spread at the beginning of the series was caused by one or more unstable pellets in each group. These lower velocity pellets would often produce keyholes in the target.
Even though I had decided to standardize on the 15.9 grain JSBs due to their apparently greater inherent stability out of my gun, I thought I would give the 18.1 grain pellets another try since I have continued to see a steady reduction in group size with the 15.9 pellets since those early June trials. Here are today's results for four 5 shot groups at 50 yards using lubed 18.1 JSBs:
Group Size(in)
#1 0.42"
#2 0.38"
#3 0.56"
#4 0.42"
I had hoped to see some improvement since June, but these are really good groups, almost on a par with what I am getting from the 15.9 JSBs. As I mentioned in my first post, after running into accuracy issues with the 18.1 grain pellets in June, I stopped cleaning the Smooth Twist barrel in my rifle, and began seeing improvements in accuracy. In the case of the 18.1 grain pellets, the improvement is dramatic, having gone from the initial 4 inch group to the under 1/2" groups shown above.
My take on all of this is that the FX rifles, probably due to the design of the Smooth Twist barrels, may need to be shot for a while before developing top accuracy. My rifle now has almost 1000 pellets through it, and I don't envision it improving much more. I don't know why accuracy/stability improves over time. I have not been cleaning my bore. Is the resulting coating of lead on the barrel ID somehow responsible? Is the barrel being polished after all those shots? If I cleaned the bore would accuracy go away, and I would have to start all over with seasoning of the bore? I don't know, and don't plan to try to find out as long as the rifle keeps shooting well.
So if you encounter some initial accuracy problems with your FX rifle, it may be that you just need to season the bore by putting some more pellets through it. In my case, I would guess it took at least a couple hundred pellets to develop consistent accuracy.
Chuck
