Has anyone replaced a firing pin on a Marvel Precision Unit ?

[Art]

A torx T10 is too loose and a T15 won't fit the bolt.

Is there another drive bit that looks like a Torx?

[Alland]

Then there are Bristol spline wrenches, very common in small setscrews. I don't know what kind of screw you are dealing with.

[Art]

I don't either, never heard of bristol spline.

[Alland]

Bristol spline wrenches are the only thing that I know of that look anything like a Torx or Torx Plus.

Well I guess ther are others, see the chart in wiki
http://en.wikipedia.org/wiki/Torx


http://www.bristolwrench.com/

[bbbjim]

The t10 worked for me, but you also have to hit it with some heat as they are red loktited in. I think you also have to remove the extractor pin. I'll check mine in the am to help me remember. Jim

[Art]

thanks bbbjim,
my T10 is loose enough I'm hesitant to apply much torque.

[Jerry Keefer]

Originally Posted by Art

thanks bbbjim,
my T10 is loose enough I'm hesitant to apply much torque.

Hello Art;
I have never seen anything other than the 10 Torx in the conversions. The screw is #4 X 40 X .250
The smaller Torx drivers can round/wear off and appear small. I have a set of Snap On drivers, and even those tend to round off in the small sizes. I grind .015/.025 off the tip to square up the spline, and it will be good for a while..
They are loc tited, but I have never had an issue removing them, and I have never had to resort to heat.
The extractor pin needs to come out from the bottom towards the top, just enough for the extractor to slide out.
The pin that retains the firing pin, is usually tighter than all get out. I don't know why they fit it that tight, since it is trapped in the slide, and can't come out . If you support the breech block well, and select a stout tapered punch to just start it, it will come out, again just enough to release the pin. I use a press to push it back in to avoid the hammering/beating method. It must be perfectly flush or the breech block will not fit into the slide recess. I grind/shorten the pin .010/.015 to insure a sub flush finish. Also, take care when installing the new pin, that you have breech face clearance in the event of a dry fire, and that the retaining pin notch is aligned to receive the pin, or it will gouge the firing pin and create problems..

Hope this helps
Jerry

[Art]

Thanks Jerry,

That's the answer and then some I was looking for.

Art

[Art]

I got the firing pin out and a new one ordered.

I did this operation on another Unit 1 several years ago, the torx bolt was a tighter fit on that one.

Jerry reminded me how tight the cross pin that holds the FP in the steel block is.

I learned something this time, driving the pin out on a bench block that rests on a rubber mat does not work as well as having the bench block on a concrete floor. I know, duh....

Holy Cow! are we fortunate to have true experts like Jerry Keefer on this forum.

[obenourb]

While not obvious - you must remove the extractor in order to get the firing pin steel block out of the aluminum slide assembly.