Wear patterns......

[Bill Calfee]

Wear patterns......


CYA friends:


During my 2-1/2 hour conversation with a RFBR action maker a few days ago, about a properly executed, MD-PAS triple, for the masses, I suggested a radical departure from the existing Turbo Class Actions.........

This "radical" departure is really not radical, in a way..................I'll leave it at that...for now.



Anyway, no SAP rimfire ignition system has the uniformity of ignition as does a well blueprinted, MD-PAS system...


So today I decided to explore the wear patterns of the SAP ignition system, as pertains to the firing pin passing through the bolt shroud.

Exactly how does the OD of the firing pin body, and, the ID of the bolt shroud wear, in a SAP system?


And what an eye opener. ( No wonder SAP rimfire ignition doesn't produce ignition uniformity like a well blueprinted, MD-PAS system.

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I've spent this day tearing down and inspecting a bunch of SAP, Remington ignition firing pins and bolt shrouds, both centerfire and rimfire for their wear patterns.


(By the way, 95% of all rimfire SAP ignition is based on the Remington SAP ignition system......)


More later......as this is so important for the future of rimfire accuracy...


Your friend, Bill Calfee

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PS:


CYA friends, even me, after all these years, knowing that SAP rimfire ignition doesn't produce ignition uniformity like well blueprinted, MD-PAS ignition, even I was surprised at the wear patterns between the firing pin and the ID of the bolt shroud in the SAP ignition system....

And I've been doing this for the last 30 years..

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[Bill Calfee]

The Remington pattern trigger effect...

The Remington pattern trigger effect...


CYA friends:

The angled sear engagement surfaces of the Remington patter trigger mean the only thing that allows the action to stay cocked is the breech bolt body restrained by the rear receiver ring.....otherwise the cocking piece would simply override the transfer bar of the trigger.


This arrangement causes a tremendous upward pressure against the firing pin passing through the bolt shroud.....

The same thing is present in the MD-PAS system, but, there is no bolt shroud in the PAS system, and of course the firing pin does not pass through the firing pin spring that's deflecting under compression, like in the SAP system......


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I spent a long day today tearing down these SAP firing pin/bolt shrouds, checking the wear patterns between the two, and, the wear pattern of the firing pin springs against the firing pins proper, as the pin passes through the spring.


I did this not so much for the issues associated with SAP ignition, but to see how they apply to the MD-PAS system and the modification I've recommended for the new MD-PAS triple...




Your friend, BC


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PS:

CYA friends, even though I've done this for a lot of years, I got a little refresher course today about the complexities of the SAP ignition system compared to the simplicity of the PAS ignition system.

No wonder there's a difference in ignition uniformity between the two.

__________________________

 

[Bill Calfee]

How time flies by....

How time flies by....


CYA friends:


I've had a most interesting refresher course as to the complexities of SAP ignition....


And I've also answered the question I had about a mod I suggested for the new MD-PAS triple....


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Anyway, time does fly by....


Back in the 70's I needed a tool to keep the firing pin spring compressed so I could drive out the cocking piece retaining pin so I could disassemble the firing pin.....


So I cobbed something together......


And now 40 plus years later I'm still using it......


Actually, as it turned out it works pretty good, and super fast....


You just screw the bolt shroud into the sliding plate, while placing the firing pin tip in the hole in the bottom plate, then simply squeeze the two plates together and tighten the two tee handle locking screws, which are tipped with nylon....


And then drive the pin out.....


Your friend, BC

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PS:

If you wonder what the two steel balls are on the fixed plate; they were used, along with two steel balls on the sliding plate, which are missing now, so I could indicate the roundness of centerfire cases.....

A dial indicator was clamped to the angle on the fixed plate.....

This allowed me to adjust the distance between the steel balls for different length cartridges....

There was also a stop for the case head on the sliding plate......