codyadams
Well-Known Member
Well, time for the next child to get their first custom rifle!
My daughter is now 8 years old, and is enjoying 4-H shooting sports. I always thought archery would be her favorite, and it may still be, but she has taken up an interest in air rifle. My son is using my Daisy 853 that I took state with multiple times back when I used to compete as a kid, so my daughter was using a club gun. It is a Crossman 760 pump set up nicely with aperture sights, however she struggles to pump it, and the cocking spring is very stiff. Having to struggle to load the gun between every shot makes it hard to focus on good form in the 4 positions they shoot in, especially when shooting a full set of 40 shots, by the time she is nearing the end, she is quite fatigued. Sounds like a job for a pcp rifle...so, time for me to do what I do!
There are some awesome purpose built 10 meter pcp rifles, however they start around $600. For $150, and another $30 for daisy apeture sights, I got her a Beeman QB Chief, a .177 cal air rifle that shoots around 950+ fps with standard weight pellets. It has a wood stock that will be easy to cut down to her LOP, and is relatively light for her. However, besides being WAY overpowered for 10m 4 position, it only gets around 25 good shots per fill, I want at least 50. Should be doable with some modifications!
PCP's work with a balance of available air pressure, valve spring tension, hammer spring tension, hammer weight, and valve/transfer port diameter. You can tune, increase or decrease performance by adjusting these to a point, with limits being on certain parameters. What I want to do is simple, reduce power, and gain efficiency. My goal is around 450-525 fps, and at least 50 consistent shots per fill, with an 8ish grain pellet. A trip to ace hardware will get me nearly everything I need to do this! Here is the rifle disassembled, and the disassembled valve as well.
I will reduce the valve and transfer port diameter by drilling and tapping it, then threading in a brass screw with a smaller hole drilled in it. I will also make a smaller diameter transfer port for the transition from the valve to the chamber. Then, I'll replace the valve spring with a lighter tension spring. To balance that out, I will make a new, lighter hammer out of a hard nylon polymer, in place of the current steel one, and reduce the hammer spring tension so it doesn't hit the valve so hard, thus releasing less air per shot. But, I want efficiency, so I will make an ssg hammer spring.
An SSG is a stopping spring guide, and it's purpose is to reduce hammer bounce. Hammer bounce is when, at the shot, the hammer opens the valve more than once, thus wasting air. The countering forces of the valve and hammer spring cause this, as a standard setup usually has a little spring pre load from the Hammer spring, pushing the hammer onto the valve. The valve spring, and air pressure behind the poppet (the plastic or polymer seal in the valve) keep the valve closed. An ssg is different, and one is pictured below (I took this photo from an airgun website, not my work)
It may be hard to understand, it was for me at first, but I'll try to explain how it works. The plastic guide at the left of the photo, is what engages the hammer. The spring is under preload against the head of the screw on the left, and is adjustable. This also makes cocking force less, for the same amount of spring force. The hammer (not pictured here) is floating, so as the ssg stops it's forward movement, the hammer shoots forward for a small amount of time not in contact with anything. It hits the valve and opens it. Then, the air pressure and valve spring force close the valve, and since there is no countering forward force on the hammer, and it is free floating, it simply comes off the valve and doesn't bounce, or has much less bounce if it does. This conserves air, and also reduces cocking force, all good things for an 8 year old girl!
So far, I have the valve transfer port reduced. I dropped it from .150" down to .050" , possibly too small but it can always be opened up if needed. New valve port here -
Inside of valve -
Still working on the rest, and I will update as this build progresses.
On a side note, pcp's are super fun, accurate, always have ammo available, and a great cheap (after initial investment) way to keep your long range shooting skills in check. Get a quality 22 or 25 cal pcp, and start smacking starlings at 100+ yards, and you will be addicted!
My daughter is now 8 years old, and is enjoying 4-H shooting sports. I always thought archery would be her favorite, and it may still be, but she has taken up an interest in air rifle. My son is using my Daisy 853 that I took state with multiple times back when I used to compete as a kid, so my daughter was using a club gun. It is a Crossman 760 pump set up nicely with aperture sights, however she struggles to pump it, and the cocking spring is very stiff. Having to struggle to load the gun between every shot makes it hard to focus on good form in the 4 positions they shoot in, especially when shooting a full set of 40 shots, by the time she is nearing the end, she is quite fatigued. Sounds like a job for a pcp rifle...so, time for me to do what I do!
There are some awesome purpose built 10 meter pcp rifles, however they start around $600. For $150, and another $30 for daisy apeture sights, I got her a Beeman QB Chief, a .177 cal air rifle that shoots around 950+ fps with standard weight pellets. It has a wood stock that will be easy to cut down to her LOP, and is relatively light for her. However, besides being WAY overpowered for 10m 4 position, it only gets around 25 good shots per fill, I want at least 50. Should be doable with some modifications!
PCP's work with a balance of available air pressure, valve spring tension, hammer spring tension, hammer weight, and valve/transfer port diameter. You can tune, increase or decrease performance by adjusting these to a point, with limits being on certain parameters. What I want to do is simple, reduce power, and gain efficiency. My goal is around 450-525 fps, and at least 50 consistent shots per fill, with an 8ish grain pellet. A trip to ace hardware will get me nearly everything I need to do this! Here is the rifle disassembled, and the disassembled valve as well.
I will reduce the valve and transfer port diameter by drilling and tapping it, then threading in a brass screw with a smaller hole drilled in it. I will also make a smaller diameter transfer port for the transition from the valve to the chamber. Then, I'll replace the valve spring with a lighter tension spring. To balance that out, I will make a new, lighter hammer out of a hard nylon polymer, in place of the current steel one, and reduce the hammer spring tension so it doesn't hit the valve so hard, thus releasing less air per shot. But, I want efficiency, so I will make an ssg hammer spring.
An SSG is a stopping spring guide, and it's purpose is to reduce hammer bounce. Hammer bounce is when, at the shot, the hammer opens the valve more than once, thus wasting air. The countering forces of the valve and hammer spring cause this, as a standard setup usually has a little spring pre load from the Hammer spring, pushing the hammer onto the valve. The valve spring, and air pressure behind the poppet (the plastic or polymer seal in the valve) keep the valve closed. An ssg is different, and one is pictured below (I took this photo from an airgun website, not my work)
It may be hard to understand, it was for me at first, but I'll try to explain how it works. The plastic guide at the left of the photo, is what engages the hammer. The spring is under preload against the head of the screw on the left, and is adjustable. This also makes cocking force less, for the same amount of spring force. The hammer (not pictured here) is floating, so as the ssg stops it's forward movement, the hammer shoots forward for a small amount of time not in contact with anything. It hits the valve and opens it. Then, the air pressure and valve spring force close the valve, and since there is no countering forward force on the hammer, and it is free floating, it simply comes off the valve and doesn't bounce, or has much less bounce if it does. This conserves air, and also reduces cocking force, all good things for an 8 year old girl!
So far, I have the valve transfer port reduced. I dropped it from .150" down to .050" , possibly too small but it can always be opened up if needed. New valve port here -
Inside of valve -
Still working on the rest, and I will update as this build progresses.
On a side note, pcp's are super fun, accurate, always have ammo available, and a great cheap (after initial investment) way to keep your long range shooting skills in check. Get a quality 22 or 25 cal pcp, and start smacking starlings at 100+ yards, and you will be addicted!
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