Rich Lucibella
Staff
Kevin has let this cat out of the bag a bit early. No harm done and he deserves bragging rights for the attention he's paid to the issue.
I've been determined to find a workable solution to the problem of light primer hits with the Scout since February. Steyr's solution, as Rob points out, is an adjustable tension firing pin spring. Unfortunately, the tension necessary to fire military surplus ammo renders the Scout a Crew Served Weapon...bolt work is damn near impossible. Factory ammo proves no problem as the lightest tension adjustment is reliable and the bolt work smooth and quick.
After discussions with Kevin, Ashley Emerson, Colonel Bob Young, John (Fr. Frog) Schaefer, Wolff Springs and several others, I came to a couple of conclusions. (At this point, I can recite all manner of useless technical data on the Scout and other rifle firing mechanisms.)
The bottom line is this: The Steyr Scout employs a 60 degree bolt throw, as opposed to the 90 degree throw of most other bolt rifles. This requires that proportionately more force be applied to the bolt in order to compress a given spring. Thus Steyr uses a 15 lb vs 30 lb firing pin spring (rough numbers). However, in order to reliably fire MilSurp ammo, additional kinetic energy must be transferred to the primer.
There are only two ways to reasonably retrofit the action to allow proper bolt functioning with a stronger spring:
- Increase leverage
- Decrease friction
The leverage increase was suggested by the Steyr Tactical Bolt which John Schaefer has generously supplied. Increased leverage allows us to use a stronger spring without increasing the force necessary to compress it (instead it increases the distance over which the spring is compressed). The Tac bolt is about 1/2" longer...a fact which is not immediately apparent because it sweeps back more. Steyr, incidentally, refuses to sell the Tac bolt handle separately, which, I believe is the epitome of arrogance in Customer Service.
Looking at the LURCR rifle, which Kevin built for me earlier this year, it's obvious that we can get even more "useful length" out of a given bolt handle by using a truncated cone, rather than a ball at the end. And so it was decided to extend the bolt handle by about 1/2"-3/4", sweep it back about 10 degrees and install a truncated cone terminator.
As for the friction: Kevin has about said it all. The fit and finish leave a great deal to be desired. Not only are the surfaces of the cam sleeve, cam lugs and gas shroud woefully unpolished, but the threaded firing pin, itself, actually rubs aggainst the internals of the spring when firing...this robs it of much needed kinetic energy.
And so it came to pass that I roped the best machinist I know into the job.
I spoke to Kevin on Thursday afternoon, FedEx'd both bolts that day and he worked thru the weekend on the fix. I will have the bolt back tomorrow and will post the range results here in the evening.
Not wanting anyone to get away without sacrifice to the cause, I have comandeered Rob's own Scout bolt until May 15. By exchanging guts between the redone bolt and Rob's we'll be able to get a feel for the possibility of Scout owners resolving the problem by simply polishing the internals (vs machining the bolt handle).
I leave for Africa with both bolts on Thursday. If the redesign proves effective, I intend to corner Colonel Cooper while there, and enlist his support and/or comments.
Rich
I've been determined to find a workable solution to the problem of light primer hits with the Scout since February. Steyr's solution, as Rob points out, is an adjustable tension firing pin spring. Unfortunately, the tension necessary to fire military surplus ammo renders the Scout a Crew Served Weapon...bolt work is damn near impossible. Factory ammo proves no problem as the lightest tension adjustment is reliable and the bolt work smooth and quick.
After discussions with Kevin, Ashley Emerson, Colonel Bob Young, John (Fr. Frog) Schaefer, Wolff Springs and several others, I came to a couple of conclusions. (At this point, I can recite all manner of useless technical data on the Scout and other rifle firing mechanisms.)
The bottom line is this: The Steyr Scout employs a 60 degree bolt throw, as opposed to the 90 degree throw of most other bolt rifles. This requires that proportionately more force be applied to the bolt in order to compress a given spring. Thus Steyr uses a 15 lb vs 30 lb firing pin spring (rough numbers). However, in order to reliably fire MilSurp ammo, additional kinetic energy must be transferred to the primer.
There are only two ways to reasonably retrofit the action to allow proper bolt functioning with a stronger spring:
- Increase leverage
- Decrease friction
The leverage increase was suggested by the Steyr Tactical Bolt which John Schaefer has generously supplied. Increased leverage allows us to use a stronger spring without increasing the force necessary to compress it (instead it increases the distance over which the spring is compressed). The Tac bolt is about 1/2" longer...a fact which is not immediately apparent because it sweeps back more. Steyr, incidentally, refuses to sell the Tac bolt handle separately, which, I believe is the epitome of arrogance in Customer Service.
Looking at the LURCR rifle, which Kevin built for me earlier this year, it's obvious that we can get even more "useful length" out of a given bolt handle by using a truncated cone, rather than a ball at the end. And so it was decided to extend the bolt handle by about 1/2"-3/4", sweep it back about 10 degrees and install a truncated cone terminator.
As for the friction: Kevin has about said it all. The fit and finish leave a great deal to be desired. Not only are the surfaces of the cam sleeve, cam lugs and gas shroud woefully unpolished, but the threaded firing pin, itself, actually rubs aggainst the internals of the spring when firing...this robs it of much needed kinetic energy.
And so it came to pass that I roped the best machinist I know into the job.
Not wanting anyone to get away without sacrifice to the cause, I have comandeered Rob's own Scout bolt until May 15. By exchanging guts between the redone bolt and Rob's we'll be able to get a feel for the possibility of Scout owners resolving the problem by simply polishing the internals (vs machining the bolt handle).
I leave for Africa with both bolts on Thursday. If the redesign proves effective, I intend to corner Colonel Cooper while there, and enlist his support and/or comments.
Rich