Light strikes on SIG 522

[Odd Job]

Hi All

I have a SIG 522 which is failing to fire (occasionally) with Eley Sport ammunition. This batch of Eley Sport works just fine in my other rifles (I bought 1000 rounds of the same batch number).

When I look at the firing pin impressions, they look light to me. This is also the case with other ammunition that doesn't give me any trouble (such as CCI Mini-mag and RWS high velocity).

When I remove the bolt and push the pin from behind as far as it will go, it does not protrude very far from the bolt face. If it was another 1mm longer it would still not break even with the front edge of the bolt.

I took the pin out of the bolt and looked for crud that may have been obstructing the pin at the shoulder, but didn't find anything significant.

These are the possibilities as I see them:

1) get another firing pin made from titanium, 1mm longer at the narrow end.

2) leave the pin as is but increase the rearward roll-pin slot of the firing pin by 1mm in width (this will let the pin go forward an extra mm under inertia).

3) increase the hammer spring tension (I don't want to do this as I don't think it is the problem and it will be really difficult to do).

My gut says (1) is the best option. It should be simple for a gunsmith to make, what say you?



This is the original firing pin, the rifle has had just over 10k rounds through it.

 

[Kp321]

If the pin is indeed stopping on the roll pin, option 2 would be the first thing to try.

 

[rcmodel]

Measure twice and cut once if you do that.

Too much and the FP will impact the breech face and peen a dent in the chamber mouth.

And then you will have a problem.

rc

 

[BBBBill]

How far does it protrude without the roll pin?

 

[Jim K]

If there is no problem with other ammo, it seems possible that the Eley ammo is older or less sensitive. If you think the firing pin is not going forward far enough it should be easy to put in a smaller diameter retaining pin just to try. That will keep the firing pin in place, while letting it move forward a bit more. If that works, the firing pin notch can be adjusted a bit.

Another possibility is to cut the firing pin tip so it is rectangular rather than round to concentrate the blow in a smaller area. An old trick, but it works.

Jim

 

[Odd Job]

How far does it protrude without the roll pin?

It goes about a quarter of a mm proud of the bolt.

Another possibility is to cut the firing pin tip so it is rectangular rather than round to concentrate the blow in a smaller area. An old trick, but it works.

I never thought of that! Would I have problems with dirt getting in the firing pin channel though?

 

[Odd Job]

Decided to get a spare pin made (1mm longer) before I try option 2.

 

[Odd Job]

Once again, I cannot get a simple thing like this done in the UK. Engineering firms won't touch it and I've had no luck with gunsmiths either. One tried, but his lathe is not fast enough. The second one says he won't make the pin without having the whole rifle sent to him and the third one will charge a huge amount to have it done on a CNC machine.

I would appreciate it if somebody could tell me who sells these pins (who can get them from SIG directly) in the US so I can have the spares delivered to my folks in Florida.

 

[Blue68f100]

Another thing to try is make the end of the PF like a chisel. Narrowing the impact surface to gain penetration. Just make sure your orientation is right.

I would measure the recess for the rim on the chamber and see how much room you have. You could take a file to the pin cut out stop to gain a few 0.001". Or file on the FP stop shoulder. You just want to have it short enough so it will not damage the face of the chamber.

May want to confirm your hammer is not dragging slowing down. Or even check for a broken spring.

Another way to go is make the end of the PF like a chisel. Narrowing the impact surface to gain penetration.

 

[Odd Job]

I'd like to get a spare pin made or bought before I mess with it, if possible.

 

[BBBBill]

In the end it is simply a lathe turned piece of metal from the appropriate alloy and of the correct hardness. Anyone with a lathe should be able to turn one for you. The hobby machinist community is well established in Great Britain. Should be possible to find many skilled fellows who could knock out a couple for you to experiment.

 

[Blue68f100]

You may try taking a brass brush on a drill to clean the Chamber only real good. 22's are bad about depositing lead and powder residue right at the end of the chamber. This prevents the round from setting all the way forward so the rim is solid against.

 

[rcmodel]

It's a simple enough design you could make one with a drill press & a file or two.

rc