Cured fliers? You may want to try this.

B

Boyd Allen

Active member
A friend has a custom barreled .204 Ruger on a Remington 700 action, It is a single shot with a heavily modified pillar bedded stock. Although the rifle did well as a .222 (custom barrel, tight neck chamber), it was about to drive him to distraction trying to get the .204 to shoot. One thing that became evident was that there was a difference in the pressures that he had loaded the .222 to as compared to what he has been trying for in performance with the .204. It seemed that the only loads that would group reliably were at a lower than desired velocity. Another new problem that came along with the higher pressures was extreme cratering that looked like a short tube, evidence of excessive pin tip clearance in the bolt face. I told him that Greg Tannel of Gre-Tan Rifles would do an excellent job of fixing that problem by bushing the pin tip, reducing the tip size, and turning the tip long enough to work with a tip hole that contained the tip throughout the entire firing cycle (which the Remington does not). Eventually, he sent off the bolt, and is very pleased with the work, and the price ($60). His craters are gone, and his rifle is shooting very well, much better. There is some question as to why, because he just switched to VV140, but I remember his previous results with a variety of powders and I am poretty sure that having the firing pin tip properly guided is largely responsible. Perhaps I can persuade him to revisit some previous powders loaded to the same 3,900 fps with 39 gr. Blitzkings that is doing so well (5 shots 3/8") for him with the 140. Greg told me that the reason that he makes the bushings as long as he does is that he had traced a problem with fliers to the pin being in stock configuration, and the problem went away with the tip in a long enough bushing to guide it full stroke.
 
There are any number of actions -- some custom -- that use a Remington-style firing pin (striker). Whether the firing pin needs bushing or not, several gunsmiths believe it is important for the firing pin to not bounce around -- Dave Tooley, & I believe Jim Borden also mentioned this. Probably others. Each smith has his cure, & not all actions have this kind of striker, but when appropriate, I believe in it. I had Dave Tooley work over a custom action for this, & it did shoot a bit smaller groups. In my case, I need every little bit I can get.

FWIW
 
Good point. I believe that some of the custom actions have a deep enough pin tip hole that they work like the Greg's bushings, Stillers, Bordens, and I think BATs and Nesikas. I am not sure about the others. Maybe someone will speak up and add some information on this.

In any case, given the dollars that get spent on various types of rifles that are based on factory actions, I think that this area of action tuning is worth some "ink".

The improvement shown on my friend's rifle was significant.
Previously, the lack of accuracy had called the quality of the barrel into serious question. A major load finding effort had been mounted over a long period of time, to no avail. Another barrel of a different brand tried with little success. It makes me wonder just how many barrel jobs that did not come up to expectations could be the result of lack of knowledge of this detail.

It should also probably be pointed out that if the ID that the shoulder at the front of the firing pin slides in is a good enough fit, and concentric with the tip portion of the hole, that it should give the same sort of guidance to the firing pin.
 
Boyd and Charles:

Having the pin tip 'captured' and fully contained when it's cocked is something that most people never think of checking.

Stan Ware and I have kicked around boring the inside of the bolt body and fitting it with a sleeve of graphite impregnated Delrin. The shoulders foward and behind the spring (on the pin) would have a metal sleeve on them to increase the o.d. of that part of the pin so the spring wouldn't contact the Delrin sleeve inside the bolt body. In essence...the firing pin assy. would be 'guided' through the hole in the bolt face by these shoulders running inside the Delrin sleeve.

My belief is that this would not only accomplish the same thing as having the pin tip fully supported by a bushing..but it would also isolate the reciever from some of the vibrations that are transfered to it from the pin. assy as it fires. The pin tip could also be left in the 'standard' Rem. profile and not have to be turned to a longer/thinner profile that may be more subject to damage or bending during routine maintainence, etc.

Since the compressive strength of the bolt body doesn't seem to be an issue, I don't think that a slight reduction in the bolt body wall thickness would pose any problems. To make all this work, the threaded fit between the bolt shroud and the bolt body would also need to be addressed...some of which are horrible, even on custom actions.

As to how the Delrin sleeves would 'live' under these conditions...I guess we'd just have to try it and find out.

Ideas or thoughts from anyone? -Al
 
Al,
I sent you a PM. Also, on another matter, I have a Viper, and the .062 tip is not a problem. This firing pin/shroud area, while not a new subject, is certainly not given enough attention insofar as its effect on accuracy is concerned. I think that when more people become aware of what can be done to improve accuracy in this area it may cause some redesigning to take place.
Boyd
 
A Delrin washer captured between the spring & front stop (for the spring) works pretty well. The insdie of the bolt may need some work. Sounds like you've come up with an elaborate, albeit more permanent way to accomplish the same thing.
 
Boyd
I am thinking about making a bolt and have made a drawing of my understanding of the firing pin support. I will attach it to see if I am right.

Glenn B.
 

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? for Charles E

What did you use to clean-up the bolt bore?

The shoulder on my firing pin is .407", the bolt bore a sloppy .425" and rough as a cob. A .430" chucking reamer would probably do it but not without taking the top off the threads?

Mike
 
Mike,

As I said, Dave Tooley did the work on the one action of mine that was modified. It wasn't a Remington, but Dave does do Remington's as well.

I suppose the things to look at is (1) how much do you really need to clean up the inside, (2) can you reach with a small carbide boring bar, and (3) do you need all of that thread -- you're taking about the square threads for the shroud, right?
 
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