Need help with mag bolt speed/pressure

[Skoad]

Ok with how much force is the bolt/spring hitting the stopper in the middle of the body just back from the breach area?

How would I go about calculating this? What im trying to see is how much force does that little piece of body need to be able to withstand per shot.

-Skoad

[bjjb99]

If I remember correctly, Tom Kaye mentioned that in a properly functioning Automag, the bolt/spring never "bottoms out" on the steel ring behind the breech. If this is the case, then perhaps the easiest method to get an idea of the force exerted on that ring during firing would be to figure out the force required to completely compress the bolt's main spring. That should be close to the maximum force exerted on the steel ring if the bolt does not bottom out.

A good scale and some weights should do the trick just fine.

BJJB

[Skoad]

hmm good call, i have no weights nor scale
lots of books i could use ;)

still could use some sort of approximation

[bjjb99]

Unfortunately, without knowing some basic properties of the spring itself, an approximation is just a bit out of reach. What I was suggesting was the means by which to obtain the basic properties needed to make the approximation you want.

Next time you go to a mall that has stores dealing with either bathroom or kitchen supplies, take your bolt spring and a ruler with you. Find a bathroom or kitchen scale. Place the spring on the scale and measure its height. While holding the ruler next to the spring, smash the spring down a half inch or so, make sure you note how much the spring is compressed; while you're doing this, note the reading on the scale. You now have enough information to determine (roughly) the spring constant for your bolt spring, and thus get an approximation for the force required for full compression.

spring constant = force per unit compression.

Convert the scale weight from pounds (assuming it's a non-metric scale) to kilograms by dividing by 2.2.

Convert the amount of spring compression you measured from inches to meters by multiplying by 0.0254.

Divide the scale weight in kilograms by the compression in meters to get the spring constant.

Measure how long the spring is when you squash it completely. Subtract this value from the spring length when it's just sitting there. Convert this difference from inches to meters to get the maximum compression distance.

Multiply the spring constant you calculated by the maximum compression distance to get the force required to completely squash the spring. This should be the maximum force on the steel ring behind the breech, assuming the bolt does not bottom out.

I'm sure AGD knows the spring constant for their bolt springs; perhaps Tom could chime in with that tidbit of information? :)

BJJB

[Skoad]

that's what i was hoping for in the first place :)

anyway thx for the input, i guess i will have a little physics homework when i go home this weekend :(