GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: 1nmartin on October 19, 2012, 10:40:24 AM
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Hey guys.
Would it be possible to make a bolt actiion pcp gun that cocks like a centerfire rilfe? Where the hammer/striker is cocked on the upswing of the bolt. Or would the bolt throw be too much to be comfortable or practical? Do they already make one?
Just a thought.
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Hey guys.
Would it be possible to make a bolt actiion pcp gun that cocks like a centerfire rilfe? Where the hammer/striker is cocked on the upswing of the bolt. Or would the bolt throw be too much to be comfortable or practical? Do they already make one?
Just a thought.
My 1917 .30-'06 cocks on close...it is a centerfire I think...:)
cheers,
Douglas
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Y
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Hey guys.
Would it be possible to make a bolt actiion pcp gun that cocks like a centerfire rilfe? Where the hammer/striker is cocked on the upswing of the bolt. Or would the bolt throw be too much to be comfortable or practical? Do they already make one?
Just a thought.
My 1917 .30-'06 cocks on close...it is a centerfire I think...:)
cheers,
Douglas
It was also one of the last designs to do so :). That being said, a cock on opening bolt action would be difficult as most center-fires are striker fired and not hammer fired. The valve would have to be part of the bolt and be able to move, an engineering nightmare with 3000PSI in such a small space.
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Y
On a centerfire it separates the cocking effort from the effort needed to chamber the round, which can increase greatly in less than ideal (combat) circumstances. I don't think we could gain anything in an air rifle.
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Hey guys.
Would it be possible to make a bolt actiion pcp gun that cocks like a centerfire rilfe? Where the hammer/striker is cocked on the upswing of the bolt. Or would the bolt throw be too much to be comfortable or practical? Do they already make one?
Just a thought.
My 1917 .30-'06 cocks on close...it is a centerfire I think...:)
cheers,
Douglas
It was also one of the last designs to do so :). That being said, a cock on opening bolt action would be difficult as most center-fires are striker fired and not hammer fired. The valve would have to be part of the bolt and be able to move, an engineering nightmare with 3000PSI in such a small space.
Hammer cocking is the same force for both styles and there is no need to put the valve in the bolt. All that has to happen is for the bolt to pull the hammer back, against its spring, until the sear catches. Then the the bolt can move forward freely to close into battery. The hammers is still below the bolt and would translate back with a simple pin and slot arrangement.
Tom
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I know we wouldn't gain anything from such an invention but it would be cool.
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I don't think that there would be enough rotary motion to facilitate the required rearward travel. (rotary to linear motion cam) Looks likes the Marauder has about 30deg of rotation and with the diameter of the bolt, that won't give you the .550" of rearward motion required to make the sear. I do like the idea though. The bolt is a bit combersome when down on the rifle. If the hammer where set with the rotation of the bolt, the open and close would be much smoother. Probably speed up cycle considerably.
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How many degrees of ratation would be needed to set the hammer? Some powder burners have as much at 60 degrees of bolt throw.
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The amount of movement would largely depend on the degree of camming action imparted by the bolt cam on a follower. One cam bearing on another similarly angled follower/cam could produce twice the " push distance" of a single cam.
The idea is surely possible but it may not be the simplest or the most economical approach in a manufacturing point of view for airguns.
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I don't think that there would be enough rotary motion to facilitate the required rearward travel. (rotary to linear motion cam) Looks likes the Marauder has about 30deg of rotation and with the diameter of the bolt, that won't give you the .550" of rearward motion required to make the sear. I do like the idea though. The bolt is a bit combersome when down on the rifle. If the hammer where set with the rotation of the bolt, the open and close would be much smoother. Probably speed up cycle considerably.
That's why you have side lever and lever action guns, fast and easy, beats bolt actions anyday :) :)
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The amount of movement would largely depend on the degree of camming action imparted by the bolt cam on a follower. One cam bearing on another similarly angled follower/cam could produce twice the " push distance" of a single cam.
The idea is surely possible but it may not be the simplest or the most economical approach in a manufacturing point of view for airguns.
It may not be economical but neither is a high end airgun ;D
It wouldnt serve anygreat purpose, it would just be different from all the others. And different usually sells.
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I think, even with high end airguns, the manufacturer still looks at the most economical approach at each production step in order to maximize his profits.
It may be true that high end guns are not exactly the most economical airgun for the end user (to buy) but the manufacturer's cost in production is a different issue.
Just like what I have said, the idea is surely doable but the manufacturer still has to really consider its practicality when compared to other sound design approaches. Hobbyist may not have similar concerns or restrictions in time to produce a unique part.
If you really want to make one you could try the telescoping bolt with a helical design cam action.
It's just like installing an externally rifled rod inside a matching rifled tube. A rotation of the rod or the tube would impart or translate a linear motion to either one. Visualize a long pitch nut and bolt working together.
The hammer would have to be installed adjacently and mechanically moved through a link or a protrusion from either one of the moving components as necessary.
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Manny is correct, the side lever is a excellent compromise. The lever gives leverage that is not found in bolt systems and allows almost effortless cocking on the back stroke and seating of the pellet on the front stroke. The only diss-advantage of the side lever that I have found is when in carrying with an "open bolt", the lever sticks out to the side and can get snagged by brush etc. Standard bolts are more compact when open. This is not a big deal, I leave the last mag pos empty so when I cycle the action in the field I don't get a double load.
As for the camming action, it is certainly possible but would need at very precise and friction free design. Possible the use of balls as rolling elements. A classic case of how bad do you want it.
Tom
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There's just something about a bolt action that everyone loves. I am not particularly fond of side levers, not because of mechanical function, simply my taste.
This idea is just one of those things that if I had the tools to make one, I would. But I don't have the tools :-\ If it was something that could be crafted out of wood I would've already made it.
I have the design of how it would work planned in my head, but if I attempted to describe it I would probably just confuse most of you guys ;D
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Use a solenoid to strike the valve stem, like the Drozd. No hammer needed.
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Today I grabbed my Mrod with a full mag and went outside to dispatch a squirrel I saw out the window. BY the time I got outside the squirrel was gone... And I had a revelation.
A real application for the cock on opening design.
We all have times when we cock our guns, but end up not shooting. So to avoid danger, I pull the bolt back and pull the trigger to gently uncock the hammer with out firing the gun. BUT, When a rotary magazine is used, like the in the Mrod, one must remove the magazine to avoid chambering another pellet.
With a gun bolt action gun that cocks on the upturn of the bolt, this could all be accomplished without the need to remove the magazine.
It would also cut down on shooting a follow up without chambering a pellet cuz a dummy (me) forgot to put the mag back in ;D ;D
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Today I grabbed my Mrod with a full mag and went outside to dispatch a squirrel I saw out the window. BY the time I got outside the squirrel was gone... And I had a revelation.
A real application for the cock on opening design.
We all have times when we cock our guns, but end up not shooting. So to avoid danger, I pull the bolt back and pull the trigger to gently uncock the hammer with out firing the gun. BUT, When a rotary magazine is used, like the in the Mrod, one must remove the magazine to avoid chambering another pellet.
With a gun bolt action gun that cocks on the upturn of the bolt, this could all be accomplished without the need to remove the magazine.
It would also cut down on shooting a follow up without chambering a pellet cuz a dummy (me) forgot to put the mag back in ;D ;D
I think the problem is that PCP require much longer hammer strike when compared to the firing pin movement in powder burners. That would then necessitate much longer upwards movement to keep it from coming too heavy. There are PCPs where bolt and hammer are operated separately if you want a hunting gun that can be de-cocked. That's actually the reason why I use MMC BSAs as my grab and go backyard pest control guns.
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I agree, the hammer travel required in a PCP would be difficult to achieve with a "cock on bolt lift" arrangement....
Bob
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Either Cock on open (std) or Cock on close is readily achieved with the QB78- 79 air guns. As delivered, these are CO2 powered, but many have converted them to HPA /PCP
Search QB-79 cock on open, and see what you get
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Cal, the op was referring to cocking the hammer on the unlock (up swing) of the bolt, not the back stoke. This makes a solution more difficult and complicated. I misread the post the first time as well. Using this feature as a de-cocking mechanism, I would think there many other ways to accomplish that task.
Tom
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Thanks for the clarification.
"Words are the source for all mis-understanding"