I read that a scope is damaged when it is fitted to a heavy recoiling rifle if the rifle is fired in a LeadSled or similar device held down by more than 25 pounds or even with the rifle butt against a tree or similar unmoveable object. While not doubting the results of the various authors, I am confused how the damage occurs. One question continues to confuse me: How do the forces on the scope when fired attached to a rifle held down in a LeadSled holding 50 pounds of weight affect the scope differently than if the rifle itself weighed 60 pounds?
What causes the damage?
- Thread starter Ray B
- Start date
I believe it has to do with stopping the recoil. When it is stopped it is more abrubt. I have seen videos where they strapped guns in heavy sleds and the action, barrel and stock would bend. It just abuses the gun and scope. Kinda like a stock car hitting a concrete wall in a car or hitting a soft wall. When the gun moves with recoil it softens it. Matt
A heavy bench gun has most of the weight in the barrel and action and recoil on a well balanced rifle is straight back. Nothing restricts the recoil except the shooters shoulder in most cases. It has massive bedding surfaces to distribute the recoil energy. The Caldwell unit is nothing more than a poorly designed add on weight system which haphazardly distributes recoil energy on mass produced rifles that were not designed to restrained from recoil. The Caldwell will tend to flip up at the muzzle. CF and RF Scopes were designed for rearward recoil, not excessive upward or lateral shock.
The Lead Sled never made sense to me - does not mimic what happens when one shoots a rifle from the shoulder so any zero information is mute. In my neck of the woods (rural Oregon) many hunters use the lead sled, set their zero's and go long range hunting and then can't figure out why they missed their Elk at 500 yds. when they had a 'good' zero from the bench at that range.
A return-to-battery set up (Skor-Hy for example) is somewhat better but one still needs to zero from the shoulder if that is how one is going to take the shot.
A return-to-battery set up (Skor-Hy for example) is somewhat better but one still needs to zero from the shoulder if that is how one is going to take the shot.
Lead slead is a great product . A friend put his custom double gun on and cracked the stock . He wated 8 years for the build and now another 2 for a new stock . Think how many buff life he saved . Larry
Addressing the original question, i think what dkhunt said is pretty accurate. Guns (barrels) flex alot and if you direct that flexing in other ways besides rearward it can have some strange effects.
I personally believe the erector tube gets smacked around around pretty good when the recoil is directed toward a hard stop. If the erector spring(s) arent very stiff, i think the recoil could bottom out the erector tube against the spring and then slam it back into the windage and elevation spindles. Usually shifting a zero or even possibly jarring lens loose.
I personally believe the erector tube gets smacked around around pretty good when the recoil is directed toward a hard stop. If the erector spring(s) arent very stiff, i think the recoil could bottom out the erector tube against the spring and then slam it back into the windage and elevation spindles. Usually shifting a zero or even possibly jarring lens loose.
I've alway had a hard time with the standard answers. My 300 rum (no muzzel brake) just flat out hurts to shoot. So what people are saying is the scope is designed to handle the energy transferred from firing but not the energy transfer from an abrupt stop.
Toolbreaker
Gold $$ Contributor
The best way I've heard it put is as an analogy. Imagine driving in your car at 30 mph & then standing on the brakes. The car (the rifle) comes to a relatively soft-ish stop (your shoulder): you (the scope) are pulled forward heavily, but not overly abrupt. You're still very much intact. Same scenario again, but this time you hit a tree (lead sled) with your car & come to an immediate stop. How are you (the scope) doing now?
carlsbad
Lions don't lose sleep over the opinions of sheep.
Ok. A little physics for the layman.
Energy is conserved. So all the energy in the recoil goes into your rifle. This energy is dissipated many ways:
1. your shoulder
2. moving the rifle. the heavier the rifle, the more energy it absorbs moving it.
3. compressing the recoil pad on the stock.
4. any bending of any rifle components. I remember a thread here recently about how much a rear-lugged bolt compresses. that absorbs energy.
5. other minor losses.
Most of the energy goes into the first 3. Your rifle is accelerated by the round and stopped by your shoulder. This is a very elastic collision (when you hear "elastic collision" think of dropping a ball of modeling clay and it hits the floor and sticks). In an inelastic collision, all the energy is absorbed by the collision over a fairly long distance of travel. Lets say the modeling class makes a flat spot about 1/2" deep so the deceleration takes place over 1/2". Very gentle from a physics standpoint.
Elastic collision: Now drop a ball bearing. the steel surface of a ball bearing compresses maybe .0001" and the energy goes right back into the ball bearing causing it to rocket back up. This is a mostly elastic collision. it is very violent and puts almost all the energy back into the ball bearing.
We can say from a practical point of view that there is no such thing as a perfectly elastic collision since 100% of the energy would be returned and the velocity would reverse instantaneously. to change velocity instantaneously, the acceleration must be infinity.
I make that point on purpose. the more elastic the collision, the shorter the time and the shorter the travel of the moving object being stopped the higher the accelerations. (quick review, force=Massxacceleration. So when you hear the word "acceleration" you can just think "force").
So the shorter the allowed travel of the moving rifle, the more inelastic the collision, and the higher the acceleration. if you put a rigid rifle against a concrete wall and pull the trigger it would bouce forward. That should make intuitive sense to you. So the more you constrain a rifle, the less you let it move in recoil, the higher the g-forces experienced in the stop. And we attach the scope very rigidly to the rifle so it feels about the same forces as the rifle.
It was suggested above that using a double braced scope (for air rifles) will solve the problem. I don't know if that will be adequate or not. But these increased forces from stopping are the forces that the air gun scope is braced for.
So a heavy gun doesn't have this problem because the energy is mostly absorbed trying to accelerate the gun.
--Jerry
Energy is conserved. So all the energy in the recoil goes into your rifle. This energy is dissipated many ways:
1. your shoulder
2. moving the rifle. the heavier the rifle, the more energy it absorbs moving it.
3. compressing the recoil pad on the stock.
4. any bending of any rifle components. I remember a thread here recently about how much a rear-lugged bolt compresses. that absorbs energy.
5. other minor losses.
Most of the energy goes into the first 3. Your rifle is accelerated by the round and stopped by your shoulder. This is a very elastic collision (when you hear "elastic collision" think of dropping a ball of modeling clay and it hits the floor and sticks). In an inelastic collision, all the energy is absorbed by the collision over a fairly long distance of travel. Lets say the modeling class makes a flat spot about 1/2" deep so the deceleration takes place over 1/2". Very gentle from a physics standpoint.
Elastic collision: Now drop a ball bearing. the steel surface of a ball bearing compresses maybe .0001" and the energy goes right back into the ball bearing causing it to rocket back up. This is a mostly elastic collision. it is very violent and puts almost all the energy back into the ball bearing.
We can say from a practical point of view that there is no such thing as a perfectly elastic collision since 100% of the energy would be returned and the velocity would reverse instantaneously. to change velocity instantaneously, the acceleration must be infinity.
I make that point on purpose. the more elastic the collision, the shorter the time and the shorter the travel of the moving object being stopped the higher the accelerations. (quick review, force=Massxacceleration. So when you hear the word "acceleration" you can just think "force").
So the shorter the allowed travel of the moving rifle, the more inelastic the collision, and the higher the acceleration. if you put a rigid rifle against a concrete wall and pull the trigger it would bouce forward. That should make intuitive sense to you. So the more you constrain a rifle, the less you let it move in recoil, the higher the g-forces experienced in the stop. And we attach the scope very rigidly to the rifle so it feels about the same forces as the rifle.
It was suggested above that using a double braced scope (for air rifles) will solve the problem. I don't know if that will be adequate or not. But these increased forces from stopping are the forces that the air gun scope is braced for.
So a heavy gun doesn't have this problem because the energy is mostly absorbed trying to accelerate the gun.
--Jerry
Air-guns (spring-piston) recoil in a completely different fashion. Though not felt by the shooter, due to the immediate change in direction, the actual recoil in an air-gun is substantially greater than that of a centerfire rifle, sans the larger big boomers.
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carlsbad
Lions don't lose sleep over the opinions of sheep.
What kinda pressure they runnin in "air guns" these days?
quality air guns have a spring driven piston that is released by the trigger. at the end of it's stroke, it has to stop quickly so it gives the rifle an acceleration toward the muzzle which is not the direction that scope is braced to accept. Muzzle velocities are up to 1300 fps, but that isn't the problem.
now top end competition air guns have two springs going in opposite directions to eliminate the impact on the rifle. Assuming they are timed perfectly, which they need to be to be effective, these rifles must be pretty smooth. I passed on them because they only generated about 600 fps when I was buying a rifle for shooting nuisance birds in the backyard.
--Jerry
You either need to use a brake or put a bag of shot on your shoulder. This will help with recoil and also help absorb the energy. Stopping the gun too hard is not good for the scope or the rifle. I saw a video where they slowed it down and drawn a line for reference. I swear the barrel bent an inch. The action flexed and the stock looked like it was going to break at the wrist. It definitely can't be good to induce that much stress in the rifle. Matt
swd
Silver $$ Contributor
Some of the really powerful tuned springers approach 10K psi.What kinda pressure they runnin in "air guns" these days?
As others said its the type of recoil they produce that tears up scopes. Solidly mounted lead sleds, trees etc. can start to simulate that type of recoil when the rifle bounces back hard in the opposite direction.
It is not recoil (directly) that affects the scope. It is acceleration in g's (or g force) that affects the scope. Having a gun locked into a lead sled is the same as having more weight in the gun. The less recoil on a gun, the less acceleration it goes through. Yes, you can break a stock having your gun locked in a lead sled. That is because the stock is more brittle than the rest of the gun and it absorbs the force of the recoil. If your gun has enough recoil to break the stock putting a scope for an air gun on it is not going to help. In the large caliber light weight (relatively) guns the forces will accelerate the rifle and the scope at nearly the same velocity with the bases absorbing the shear stresses. The vertical g forces are very small compared to the rest of the forces on the gun and scope. Either the scope is made to handle those forces or it is not. Get a scope that is made for your caliber of gun. If you want the stock to stay in one piece don't back it into a solid backstop.
Limiting the travel with the addition of weight will reduce the acceleration and thus limit the forces on a scope.
I think we need a physicist and a mechanical engineer to show the math behind recoil and acceleration.
Limiting the travel with the addition of weight will reduce the acceleration and thus limit the forces on a scope.
I think we need a physicist and a mechanical engineer to show the math behind recoil and acceleration.
Send your $3,000.00 scope to me, and I will quickly destroy it on my spring-air FWB. Who produces scopes that are caliber specific? Use a scope designed for an air-rifle on your centerfire rifle and you won't damage it.
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