Lug setback? What am I missing?

[bigngreen]

So BG,
Lets say we load the 150g and 300g to the same pressure. Everything else remains the same. Would the recoil be equal?

Regarding the recoil computation, I think we can make it based on bullet, psi, velocity and rifle weight. We know the energy at the muzzle, thus wouldn't we know the recoil relationship??

We all know recoil goes up with the mass going up on anything going out the barrel.
We do not use pressure in the recoil calculation nor do we use anything in recoil to calculate chamber pressure.

 

[Mram10us]

If the question is would the recoil be equal in the same gun with two different weight bullets at the same pressure the answer is no because of the bullet weight.
Easy example of that is shoot your 30-06 with 110s & 220s (assuming they are both max pressure) the 220s kick way harder.
Not many of us can accurately test for pressure but using pressure indicators we can prove this to ourselves in our own rifles.

Good discussion has moved from bolt lug strengths to recoil management and back several times.

It keeps moving because we all have to agree on many other variables before we can agree on energy transferred to lugs. Others in this thread have said the energy to the lugs would be the same, this recoil would have to be the same, in my mind, which we know is false

 

[Mram10us]

We all know recoil goes up with the mass going up on anything going out the barrel.
We do not use pressure in the recoil calculation nor do we use anything in recoil to calculate chamber pressure.

I think recoil and energy transferred to the lugs is the same. That is why I'm pointing out mass of the bullet is related to bolt lugs not just pressure

 

[bigngreen]

I think recoil and energy transferred to the lugs is the same. That is why I'm pointing out mass of the bullet is related to bolt lugs not just pressure

They very clearly are not the same or we would use the same calculation for both.

 

[Mram10us]

They very clearly are not the same or we would use the same calculation for both.

If they are not the same, they are very closely related. We can feel it with our shoulder and the lugs obviously feel any increase as well

 

[adam32]

They very clearly are not the same or we would use the same calculation for both.

I'm still really curious, talking strictly bolt lug set back, if you would encounter it as often running a 338 Lapua at the same pressures but a 300gr compared to a 200gr. I know the math and everything that has been presented thus far that says it should be the same, but I'm just wondering if anyone has experienced it in real life? For some reason I seem to recall a long time ago guys saying that either the Edges or AM's were easier on actions when running smaller bullets?

 

[Mram10us]

I'm still really curious, talking strictly bolt lug set back, if you would encounter it as often running a 338 Lapua at the same pressures but a 300gr compared to a 200gr. I know the math and everything that has been presented thus far that says it should be the same, but I'm just wondering if anyone has experienced it in real life? For some reason I seem to recall a long time ago guys saying that either the Edges or AM's were easier on actions when running smaller bullets?

I know for a fact that the edge with 250s is much easier on my shoulder than the 300s, thus much easier on the bolt lugs

 

[bigngreen]

Personally I've seen the most extreme lug set back in smaller Cal's, the worst I've seen was a 6.5-338 Lapua which the owner never said he even had a heavy bolt on but clearly it had been pounded back but the lugs clearly were smooth and didn't show they typical galling or other effects of gross over pressure.

I've built pretty extreme wildcats on the Lapua from 25 to 375 skipping the 358 though and BY far the smaller ones make me the most nervous, I won't build below 30 Cal on that case head size anymore in fact.

 

[Mram10us]

Personally I've seen the most extreme lug set back in smaller Cal's, the worst I've seen was a 6.5-338 Lapua which the owner never said he even had a heavy bolt on but clearly it had been pounded back but the lugs clearly were smooth and didn't show they typical galling or other effects of gross over pressure.

So we agree that ALL chambers can be over pressured thus causing lug setback.
Do the lugs feel the same amount of force from a 300g @ 3000fpm from a lapua and edge? I would contend they do.

 

[bigngreen]

So we agree that ALL chambers can be over pressured thus causing lug setback.
Do the lugs feel the same amount of force from a 300g @ 3000fpm from a lapua and edge? I would contend they do.

Well since we know the physics behind that comparison as clearly stated already we can only conclude your continuing to not understand because your seeking attention or your just being willfully ignorant. If the inside diameter of a case is different that changes the thrust at the same pressure.

 

[Mram10us]

Well since we know the physics behind that comparison as clearly stated already we can only conclude your continuing to not understand because your seeking attention or your just being willfully ignorant. If the inside diameter of a case is different that changes the thrust at the same pressure.

We are NOT in agreement about the physics how recoil and lugs are related. Stop always bashing people for disagreeing. I just asked if a lapua and an edge have the same recoil with the same bullet and speed. It warrants an answer by someone with numbers which I don't have since I don't have a lapua. Do you have both? Post numbers not opinions

ps- I really like I can give you an angry face now. Nice upgrade

 

[Alex Wheeler]

The math is staight forward, in theory. But the chamber walls actually help a lot, (dont believe it? oil a case and you will get a lot more bolt thrust) and we also are talking about the pressure vessel, not the od of the case head. So its tough to calculate exactly how much thrust the bolt face sees. But if you just compare it in the simplest form, its psi multiplied by the area of the inside of the case head. Large diameter cases like the Normas and lapuas produce considerably more bolt thrust. Lug set back is something I am very concerned about with these cases and I only use actions with increase lug seat surface area. Its the seat area that resists setback (not length) if the rest of the action is up to it. Think fat tires on sand.

 

[Alex Wheeler]

Internal case pressure/bolt thrust has nothing to do with recoil. You can produce the same pressure with a 22br as a 30-06, both will stick a bolt at about equal pressure.

 

[Mram10us]

The math is staight forward, in theory. But the chamber walls actually help a lot, (dont believe it? oil a case and you will get a lot more bolt thrust) and we also are talking about the pressure vessel, not the od of the case head. So its tough to calculate exactly how much thrust the bolt face sees. But if just compare it in the simplest form, its psi multiplied by the area of the inside of the case head. Large diameter case like the Normas and lapuas produce considerably more bolt thrust. Set back is something I am very concerned about with these cases and I only use actions with increase lug seat surface area. Its the seat area that resists setback. Not longer lugs. Think fat tires on sand...

In your experience, how does recoil differ in an edge and lapua with same bullet and speed?
Also, how Does recoil relate to forces on the lugs?
thanks Alex