Opinions please on Wiselite Sterling carbine firing pins

[Bullzaye]

I'm sorry if this seems a stupid question, but I've been seeing some various conflicting notions on several forums.

I'd love to hear any and all opinions on these. but in particular I'm looking to hear about firing pins.

The story here is that I went shooting recently with a buddy, and I took my Feather AT-9, and he fell in love with it. Unfortunately, it's a bit more than he wanted to spend, and when I suggested the Kel-Tec SUB2000, he made a face...he dislikes the look of the Kel-Tec. After he did some online searching, he found the Wiselite for sale. Now he wants to get one, and after reading about them, I kind of want one too. But...we're both a bit troubled by some of what we've read regarding firing pins breaking. So, for those of you familiar with these...what has been your experience?

Thank you,
Tim

 

[Traveler]

When you look inside some WLA bolts you can see what look like very fine thread marks. They are from drilling the hole in the bolt for the firing pin. The sharp edge at the top back of the firing pin tang can get hung up in that roughness.

Polishing the rough edges away inside the bolt and on the tang will nearly always fix it.

I use some of the copper spark plug thread lube in the firing pin channel also.

 

[Bullzaye]

That is excellent information, just the sort of thing I was looking for! Thank you very much, sir!

If anyone has any other comments on the Wiselite Sterling, I'd be glad to hear them.

Tim

 

[LORD of WAR]

Great gun! I had a older style pin break in mine and they were quick to do the repair, great customer service from wiselite. Have had no problems with the new pin and i shoot it several times a week. It looks like APEX has pins at a very good price so dont sweat it... gun has a major cool factor when people see it for the first time also note it is so easy to bump fire these with the horizontal magazine.

 

[scubasteve]

When you look inside some WLA bolts you can see what look like very fine thread marks. They are from drilling the hole in the bolt for the firing pin. The sharp edge at the top back of the firing pin tang can get hung up in that roughness.

Polishing the rough edges away inside the bolt and on the tang will nearly always fix it.

I use some of the copper spark plug thread lube in the firing pin channel also.

Sorry for my confusions, but how does this cause/prevent the tip of the firing pin breaking?

 

[Traveler]

Good question.

I don’t know for sure, but here’s what I think happens.

The tip gets broken off because the pin gets stuck forward (with the tip extended).

When the bolt comes forward, picking up a round, the lip at the base of the cartridge snags on the extended firing pin tip. Now all of the force of the bolt coming forward is concentrated laterally (sideways) on the firing pin tip as the cartridge is fed into the chamber and it shears the tip off.

It’s the roughness in the firing pin channel causes the sticking.

Lessening that roughness by polishing it reduces the chance of the pin sticking. Same with firing pin and tang. You don’t want to take metal off. You just want smooth surfaces, so they slide freely.

The copper lube seems to help too. Only use a little bit. It sticks to the surfaces better than oil and fills into the little grooves. Oil runs out. I put a little on with toothpick. If you put too much on it will make a big mess. It’s the same stuff you see inside the slide of new Glocks when they come from the factory. You can pick a small pack of it for about $2 at just about any auto parts store. Just ask for sparkplug antifreeze or sparkplug lube.

If the tang is too loose on the firing pin it can be a problem too.

When WLA converted the bolts they just drilled the hole through the block in the bolt. That’s why it has the rough surface. It would have been better if they would have used a reamer. But you have to remember these are in the $400 range. And the original design was for an open bolt SMG. They were not initially designed to be closed bolt guns. And while Sterling did an excellent job of engineering the closed bolt, it was only done to comply with US gun laws.

I guess it really just depends if you are a glass half empty or a glass half full person. If your glass is half empty, and you want to find fault with ever thing and dwell on it, then one of these is probably not a good choice for you. Now, if you are a glass half full person, and you see a great value, that’s a really fun gun to shoot, then the imperfections won’t bother you and you will enjoy owning a WLA or MPA Sterling.

 

[scubasteve]

Thank you for the explanation, I can see how that could cause a problem.

I have speculated that the broken pins were caused by an oversized inside diameter inside the bolt. There is a long hole through the bolt that is approx. .195" that the ~.185" diamter portion of the firing pin rides in. I have a bolt that the diameter is ~.210" and I was getting broken pins. Wise Lite supplied an oversized firing pin that had a shaft diameter of ~.200" and that has so far cured the broken pin issue with that bolt. I figured that the larger inside diameter was allowing the front of the firing pin to dip down, or up/over/etc., while the pin was traveling forward through the bolt. This excess play was allowing the tip of the firing pin to strike the back side of the bolt face and "deflect" the pin through the hole in the bolt face to fire the bullet. I read that many people had problems after 200-400 rnds and I figured that was the point the tip would fatigue and snap off.

 

[Traveler]

Thank you. I can see how that would fatigue the tip and eventually cause it to break.

I think WLA has produced three different firing pins over the years. I hope the one you have now solves the problem.

 

[Traveler]

Got the borescope out today and took a few pictures inside some bolts.



Above is a real Serling SA bolt.



This one is a WLA bolt. You can clearly see the ridges from drilling... and not following up with a reamer.

The same roughness is evident inside the hole the firing pin sits in. I couldn't get the borescope that far in. It's just too big.

 

[Traveler]

Real Sterling firing pin above.



This one is a WLA. Looks a little rougher than the Sterling, but not too bad.

 

[Traveler]

Here is a better picture of the roughness on the firing pin.

 

[Traveler]

This is after it has been lightly smoothed with some 2000 wet-dry. LIGHTLY being the key here. You're just knocking the roughness off and making the ridges smoother. You're not trying to remove them. That would take too much off and you would have other problems.



The sharp edge at the top back of the tang is also smoothed.



Finished with some black oxide. A blue pen will work too.

 

[Traveler]

Inside of bolt after being lightly smoothed.



Tools...... Chopstick, pencil, tape, wet-dry, oil.

 

[Traveler]

There is a long hole through the bolt that is approx. .195" that the ~.185" diamter portion of the firing pin rides in. I have a bolt that the diameter is ~.210" and I was getting broken pins. Wise Lite supplied an oversized firing pin that had a shaft diameter of ~.200"

I think you are right. A .210" hole is way too big for a normal size firing pin.

That long hole is where the fouling pin plunger assembly goes in the full-auto guns. Sterling made the hole deeper to accommodate the firing pin when they converted it to a closed bolt. I just checked to make sure, and the hole is a little over 3/16" (.187"), around .190" on a real Sterling.

Anyone who has a bolt with a large hole like the one you have, should probably get an oversized firing pin from Wise Lite Arms.

A quick way to check the size of the hole is with two commonly available drill bits. A 3/16” drill bit should just fit in the hole. A 13/64” (.203) drill bit should be too big and not go in the hole.

 

[M38]

Does anyone know the shank diameter of the Apex firing pin?

 

[Traveler]

Does anyone know the shank diameter of the Apex firing pin?

This latest batch,,, .180"

Hole in the bolt is .200"

 

[Tom5390]

View attachment 21518

Inside of bolt after being lightly smoothed.

View attachment 21517
Tools...... Chopstick, pencil, tape, wet-dry, oil.

Very good info, thanks for posting this. BTW, I took my 2 Sterlings out again yesterday and about ever other mag the type I is now getting a light primer strike. Not a big deal, but enough to be annoying. It had me scratching my head because all the other empty cases show extremely good FP hits (using steel case brown bear) so I don't think it's an issue with it not hitting hard enough or the FP being short.

What you are showing here would makes sense though if it's rough inside causing problems occasionally. I'm going to try smoothing it out and lubing it like this and see if this improves it. Could even be the ammo, but the last time out it didn't exhibit this problem, that and I had the type II out at the same time, putting the same number of rounds through it, same ammo and it has been flawless.

I'll give this a try and see if it fixes the issue. Might save me from a future broken FP as well.

 

[rough rider]

roughness in bolt

When you look inside some WLA bolts you can see what look like very fine thread marks. They are from drilling the hole in the bolt for the firing pin. The sharp edge at the top back of the firing pin tang can get hung up in that roughness.

Polishing the rough edges away inside the bolt and on the tang will nearly always fix it.

I use some of the copper spark plug thread lube in the firing pin channel also.

I read your posts regarding the Sterling pins issues. Thanks for the very good information. Mine has had no problems. It's an early serial number. The last time I cleaned it I looked at the bolt and pin. The pin was quite smooth. Also, I could see no marks in the bolt and the pin seems to glide smoothly. Why do you think some have problems and others do not.

 

[Traveler]

I really don't know the answer to that question. It could be a lot of things.

The MPA built or "Type II" guns don't seem to have the problem. At least I haven't heard of any. That makes me think it was something in the manufacturing process.

If your firing pin is smooth and there are no marks in the bolt, sounds like you got a good one.

 

[Tom5390]

I read your posts regarding the Sterling pins issues. Thanks for the very good information. Mine has had no problems. It's an early serial number. The last time I cleaned it I looked at the bolt and pin. The pin was quite smooth. Also, I could see no marks in the bolt and the pin seems to glide smoothly. Why do you think some have problems and others do not.

I work in a tool making company in a machine shop. What happens is sometimes cutters/inserts don't get changed as often as they should. In other words, you start out with new cutters/drills milling/drilling steel parts and as they wear out you start to see mill marks, roughness, burrs and tolerances change. Yours could have been cut when the cutters were new, others with rough milling were most likely cut on worn out cutters/drills. Comes down to cost and inspection (quality control) to keep parts within specs.

I'm not knocking WLA, because for the cost of these guns I'll gladly smooth out a little rough milling if need be, just stating IMO what causes these types of issues in so many guns we see being manufactured/re-manufactured for the US commercial market. You don't see this as much in military contract parts (except of "last ditch" guns) because cost in not so much a factor as opposed to manufacturing commercially.