Originally Posted by BobbyL
Some good points and some bad ones but either way im not about to touch this one.....
Good advice !!!
But this is a discussion web site .so I will attempt to shed a little light on some of these
statements if I can.
First= as cowboy said it is not a problem with light bullets unless you have an extremely
light barrel contour like a #1 and even then it probably wont have enough effect to worry
about. most people use heaver barrels and this all but eliminated this phenomena.
This does occur in large bore rifles with heavy bullets and light barrels but not as bad as
the poster made it out to be. It does not straighten the barrel rifling out. In fact the high
speed film of a tank barrel upon firing only showed about 3 to 4 degrees of rotation with
a very large projectile.
So with proper bedding and barrel diameter this effect can be controled to a point of no real
effect on accuracy. one of the main reasons that bench rest shooters use heavy barrels is
stiffness and torque resistance.
Fast twist barrels are to stabilize the heaver bullets at the slower velocities they reach. But
can be problematic if lighter/faster bullet are used because of jacket separation from the
Inertiaof the bullet when coming in contact with the rifling. This a good place for gain twist rifling.
The slower the twist with the same velocity the less chance of this happening but the greater
chance of not stabilizing the bullet, so the proper twist rate is very important.
As to the issue of velocity difference between a 1 in 14 and a 1 in 8 twist = it is no where near
25% more like 25 to 50 ft/sec at best.
Now for the fireing pin issue.
The main reason for going to a lighter fireing pin is to improve lock time !!!! the reason to
improve lock time is to make up for inconsistent trigger control by the shooter (The faster
the ignition process the less time the untrained shooter has to move positions or follow
through). this is one of the reasons that the well trained and practiced shooters find no
advantage in them.
The heaver spring improves the lock time but it also makes up for the loss of inertia of the
lighter fireing pin.
Also any fireing pin will move the case forward if the head space is improper but it can't "Drive"
the case beyond the allowable headspace. And if the firing pin protrusion is correct the firing
pin stop prevents very much of this from happening.
Another reason that I use the speed lock springs Is the diameter . they are smaller and will
normally reduce the drag of a serpent like spring inside of the bolt (The smaller diameter
spring coils in line and does not touch the inside of the bolt.
All of the things he mentioned can cause some problems if combined in the wrong
combination but most gunsmiths that build accurate rifles know how to avoid these problems
areas and don't worry about the theory just work around it.
This is just my opinion based upon my experiences and is certainly not the last word in these
J E CUSTOM