Bobbed hammers?

[1911_Hardball]

I though momentum is kinetic energy?

Not, they're different.
Momentum increases are linear. Mass x velocity. If the weight doubles the momentum doubles.
Kinetic energy is exponential. It is calculated by mass x the square of the velocity. If the velocity doubles the energy quadruples.
e.g. a 200 grain bullet at 800 fps has twice the momentum of a 100 grain at 800 fps but a 100 grain bullet at 1600 fps will strike with 4 times the kinetic energy of the same bullet at 800 fps.

 

[44 AMP]

Here's another example to illustrate the difference between KE and momentum.

A 55gr .22-250 and a 400gr .45-70 can both be loaded to IDENTICAL amounts of kinetic energy (ft/lbs). But the .45-70 will have a much larger amount of momentum.

Given the exact same amount of energy, which would you choose to discourage an angry 800lb bovine quadruped from mayhem??

I wouldn't be choosing the .22 despite its paper energy.

 

[Moenie]

Here's another example to illustrate the difference between KE and momentum.

A 55gr .22-250 and a 400gr .45-70 can both be loaded to IDENTICAL amounts of kinetic energy (ft/lbs). But the .45-70 will have a much larger amount of momentum.

Given the exact same amount of energy, which would you choose to discourage an angry 800lb bovine quadruped from mayhem??

I wouldn't be choosing the .22 despite its paper energy.

?

You do know we are speaking about making a dent in a primer with sufficient velocity to ignite it, as apposed to penetrating animal tissue and creating a large as possible wound channel right?

 

[T. O'Heir]

1,130px is too big.
Use a holster not a pocket. Pockets attract dust and lint.
New hammers require fitting. That takes more than 5 minutes. Mind you, hammer edges can be rounded smooth without much fuss.
Momentum is the product of the mass and velocity of an object. P = MV.
Kinetic energy of an object is the energy that it possesses due to its motion. It's moving so it has energy.
Read this. Test is Monday. snicker.
https://www.real-world-physics-problems.com/difference-between-momentum-and-kinetic-energy.html

 

[Moenie]

That depends on whether it's a floating firing pin or a fixed firing pin. A floating pin gun will be more reliable as it relies on kinetic energy transfer. A hammer-affixed pin gun relies on momentum so may not be more reliable with a lighter hammer.

Neither kinetic energy or momentum is at play. The important variable velocity.

The bulk of the kinetic energy (and momentum) is absorbed by the frame as the hammer hits home. All the firing pin need to do is to make a small dent maybe 1/32" to 1/64" deep on the primer which requires very little energy, but it needs to do so with sufficient velocity to ignite the primer.

Too slow and even a thousand pound hammer will not ignite the primer.

Light hammers work well as they can get up to sufficient velocity even with a relatively low spring tension. They have an added benefit as they shorten the lock time.

There is a reason why people produce lightweight replacement hammers and why most manufacturers today equip their guns with lightweight hammers. Because they work better than heavier ones.

 

[1911_Hardball]

Neither kinetic energy or momentum is at play. The important variable velocity.

Uh, velocity effects both energy and momentum. (See post #21 for the explanation)

The bulk of the kinetic energy (and momentum) is absorbed by the frame as the hammer hits home. All the firing pin need to do is to make a small dent maybe 1/32" to 1/64" deep on the primer which requires very little energy, but it needs to do so with sufficient velocity to ignite the primer.

Too slow and even a thousand pound hammer will not ignite the primer.

Light hammers work well as they can get up to sufficient velocity even with a relatively low spring tension. They have an added benefit as they shorten the lock time.

Exactly.
That was the point of my post. As I said, in response to a statement regarding light weight hammers, "A floating pin gun will be more reliable as it relies on kinetic energy transfer."

 

[AK103K]

All the science aside, how many who actually have guns with bobbed hammers, with a proper spring in the gun, have light strikes?

 

[tangolima]

Primer ignition requires energy and power. The hammer needs to have enough kinetic energy (mass and speed) to dent the primer, and it needs to dent it fast enough (speed).

Too heavy a hammer won't work, as it moves too slowly. Too light won't work either. It moves faster, limited by the spring mass. But its low mass doesn't store enough energy to dent the primer deep enough.

So there exists a optimum hammer weight, around which there is window of operation. As long as the bobbed hammer is in that window the gun works. Gun doesn't fire reliably after hammer is bobbed. It is because energy has become too low. A stronger spring will help. Gun becomes more reliable after bobing the hammer. It is because the hammer was too heavy to begin with. But removing more weight will eventually make it unreliable.

How do I know my gun with bobbed hammer is reliable? Test fire is the only way to find out. Any doubt, put in a heavy spring. It always helps.

-TL

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