60 vs. 90 degree bolt lift

[SleazyRider]

Correct me if I'm wrong, please: When the handle of a bolt action rifle is lifted, the firing pin spring is compressed, right? Does this mean that, in a smaller distance, the 60 degree bolt must do the same amount of work as a 90 degree bolt? And do the manufacturers of 60 degree bolt rifles use a lighter firing pin spring to compensate for this, lest the amount of force required to lift the bolt become objectionable?

Appreciate your thoughts on this!

 

[Jim K]

Yep. And yep. The rub is that it takes a certain momentum to reliably fire primers. Momentum is mass times velocity. In this case, mass is the weight of the firing pin and velocity is imparted by its spring. If momentum is too low, you get misfires.

So, yes, the 60 degree lift has to do basically the same amount of work to compress the spring that the 90 degree lift does. But the 60 degree lift has to do it in a shorter distance, which means the cam is steeper and the spring can't be compressed as much. So to get the same momentum, the spring has to be stronger. So the 60 degree lift is shorter, but harder. So makers get around that by making the bolt handle longer, and telling the customer it is a great feature.

In physics, as in Joe's Diner, there ain't no such thing as a free lunch!

Jim

 

[SleazyRider]

Thanks, Jim, for the reply. I suspected as much, as my 60-degree lift S&W i-bolt .30-06 has had a couple of light primer strikes that failed to ignite the primers, and has already been checked by the factory. So I'm thinking it's the "nature of the beast," and may have to find factory loaded ammunition that uses softer primers than Remington. I tried a few boxes of Prvi Partisan ammunition that fired flawlessly.

 

[chasw44]

Sleazy: I suggest Federal primers, they seem to have softer cups. - CW