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Weatherby .22 Light Strike Problem

Gazz

Stainless
Joined
Sep 7, 2004
Location
NH
Hopefully somebody can help me with this. The rifle is one of the Japanese made Mark XXII (??) semi autos(it's at the shop now and I forget the actual model name/number) that is box magazine fed. Sometimes, I can get at least 9 of the 10 rounds in a full magazine to fire, other times less with just a click when the trigger is pulled. Ejected rounds show a very shallow mark in the rim from the firing pin. When it fails to fire, I can withdraw the bolt just enough to cock the hammer without ejecting the unfired round and it will work on the second strike. I have tried a variety of ammunition with the same results. So far I have;

1. Put a new hammer spring in

2. Clipped a few coils from the firing pin spring and thoroughly cleaned out the bore in the bolt where firing pin is.

3. Set the shoulder in the firing pin back a few thousands of an inch to allow a bit more forward travel of the firing pin and polished the firing pin.

4. Removed some material from the hammer as I wondered if the hammer was striking the bottom of the bolt before hitting the firing pin. No material was removed from the hammer where it contacts the firing pin.

5. Added a slight radius to the rear of the bolt where it contacts the hammer to cock it when the rifle is cycling.

6. More thorough cleaning and have tried both wet lubes and dry moly lube.

None of these has changed the problem! One thing I do wonder about is a roll pin immediately in front of the hammer that restricts forward movement of the hammer when the hammer, trigger sear assembly is removed from the firearm. The hammer or pin show no indication that the hammer is hitting the pin during normal operation when everything is assembled but at this point, I am suspect of just about everything involved in the way this thing cycles.

This is the third time I have run across a problem like this - the other two times it was with two different High Standard semi auto rifles. I was unable to get them to work and told the customers the cost of repair would be more than the rifle was worth.

Anybody have any ideas on how this might be fixed?
 
No, I have not called Weatherby. I did once call Ruger to ask them a question about one of their firearms and they will not give any advise whatsoever on working on any of their firearms. I suspect Weatherby would be the same but will try them later today. My guess is that their response will be "send it in". I was hoping that a member here had experienced a similar problem and would offer some useful advice.
 
Thanks for all the comments!
GGaskill, I hadn't examined the fired cases actually. I'll try it again and be careful to collect the empties.
UncleFrank, I had though about a headspace issue and had checked to be sure that the bolt was up tight against the breech end of the barrel when the gun was in battery. It seems as though there is no extra space there and while I do not have the rifle here with me at the moment to look at, I am thinking that it is the bolt that is counterbored to accept the rim of the cartridge and not the barrel. I would guess that the if the counterbore is to deep it would show this kind of problem.
 
As noted in my original post, a vareity of ammo. Last time out was CCI minimags and before that some Remington stuff (not the cheap stuff either). Time before that I am not sure exactly what brands but I do have bunches of Federal xxx.

Looking at it today, I decided I am going to silver solder a shim of maybe .020" onto the rear of the fp. The conterbore in the bolt face is about .046" deep and it is circular "dovetail" kind of shape. I imagine it is providing a space for carbon crud to accumulate. When I depress the rear of the fp with my finger, it extends nearly to the face of the bolt so close to .046". But that is with my finger which can push the fp slightly past the rear of the bolt. While the fp may have momentum from being struck by the hammer, if the rear of the fp is flush to the rear of the bolt, I may be only getting .015"/.020" fp protrusion which I don't think is enough.
 
The first thing that comes to mind is that the chamber has a depression or "dent" where the firing pin aligns with the chamber. I have seen this on several occasions with numerous rimfires. Oftentimes these can form after a firing pin stop pin wears from repeated use and often does it slowly without enough damage to stop the gun cold. What you need to do is to obtain several "misfires" and carefully inspect them after only one strike, if they have the dent on the forward leading edge of the case rim, look for the depression I described.

The other fix I have used on some rifles was to reduce the surface area of the firing pin by forming a more defined chisel tip, that produces a faster crush rate of the priming compound.
Good luck!

Mark
 
Headspace is my suspicion. File off the front of your bolt to give 0.043 rebate. Not sure of extractor setup on yours but you may need to deepen that too.
Check that FP isn't binding anywhere in it's travel, and is aligned correctly with the hole.
 
G'Day Fella's,

Gazz, I hope I'm not to late for this advice, I would check the following in this order;

1) I would check your firing pin protrussion, thru the bolt face (0.020" is OK but 0.025" is preferred)
2) As you mentioned in in your own #1. Was the replacement Hammer Spring you fitted, a Factory replacenment or just a similar one you had laying about?
3) Sometimes the end/Tip of the firing pin (that contacts the cartridge), changes it shape with use. Some F/Pin Tipos are a Truncated Wedge, some are Round. Inspect this and see if this has changed? It would be helpful, if you Knew what a new F/Pin tip looked like as well.

Hope that helps

D'oh!
Homer
 
Thanks for all the suggestions!
I soldered a piece of spring steel to the rear of the fp and then cleaned it all up with a grinder and the flex shaft. I took it to the range yesterday morning and just knew it was going to work. Sadly, it was worse then before. Out of 6 rounds, only one fired. And since I "knew" it was going to work, I made no provision to capture a fired case. The floor was littered with .223 cases but I did find one CCI .22rf case that I think came from the gun. I'm not sure though and hate to make any assumptions based on it. But if it is from the gun, headspace seems to be the issue.
The hammer spring was from a Brownells assortment pack. I did compare wire diameter, number of coils and compressed length and I think I have a couple of more coils with the replacement and believe that it hits a bit harder. And, it is quite tricky to replace that spring.
The breech face of the barrel shows no dent or deformation from the fp. The way this is built, the fp can never touch the barrel to deform anything.
So today I'll be removing the added shim from the fp and contemplating removing some material from the face of the bolt. Not sure what that will do to the extracter function yet.
 
Before you remove any material you might try measuring some case rims. This article shows a device to measure rim thickness but you could maybe come up with something similar using a v-block and an indicator. If the thicker ones (or the thinner ones) work better that might be an indication.

Shooting Sports USA | Rimfire Ammunition: Centerfire’s Red Haired Stepchild

If the bolt is counterbored you might try a couple laps around the edge of the counterbore with a stone to remove any potential burr. If it were my rifle I might try a layer (or 2) of scotch tape on the ends of a few rounds to take up any slack between the case and the bolt face. I just mike'd a piece of scotch tape and it was .002
 
I have decided against modifying the bolt face since the bolt is chrome plated - I would have grind through that first. I like the idea of tape to check headspace too. I have done something similar before with beat up military rifles.
 
Has this rifle always misbehaved or is this a new problem? Did your smith check the headspace? Is there a dent in the chamber from the firing pin? Lots of breat questions here... keep us posted.
 
Checking headspace in a blow back action is going to be a challenge. Before buying gauges, I would measure the depth of the counterbore in the bolt with a depth mike. Unless the bolt bears on the breechface in some strange fashion, this should give you a good start as well as an actual number.
 








 
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