Broken Pistons - FN SLP - Has It Happened To You?

[jnewell]

There are a few people out there in internet-land who repeatedly post about broken SLP pistons. Have you ever had one break on your SLP? Have you personally seen one break? I've searched around a lot with Google and found exactly one first-person report of a broken SLP piston. This seems like the place to ask about this, since folks here run their guns a lot harder than most. Thanks for your answers.

Edited May 23, 2010 by jnewell

[smokshwn]

I have run 3 different winchesters and have never had nor heard of a broken piston.

[zero-down]

I have run 3 different winchesters and have never had nor heard of a broken piston.

same here. my SX2 has been beat to hell and have never had nor heard of a broken piston

[Big Bore]

I have had the same SX2 for a few years now and have had no issues nor have I seen any issues with the gas piston in any others I know of.

[kurtm]

I broke a piston once, right at the wrist pin and the rod came out the side of the block all at 7500 rpm in a Pro-Stck....it had a Winchester sticker on it so I thought that would count.

[00bullitt]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

[kurtm]

Yeah, but how many pro stocks have you worked on??

All joking aside if that is all Todd has seen I would guess it is a non issue!

[bushmeat]

So what does this mean for all the folks who put in SRM sealed pistons and Surecycles?

[kurtm]

I guess the bottom line is, although those parts will help a bunch, I still wouldn't twist it over 7500 rpm.

[Rivr_runnr]

my SLP shelled a piston on the first shot of a 22 target stage at the 2009 FNH. It was an ugly single shot after that. The groans from my squad and the next squad at having to watch that spectacle were not nearly as painful as the hole I ripped into my hand racking the slide 22 times on the clock.

[DocMcG]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

Tod,

How would the shell hang up as it tried to go into battery on the "short stroke" you are referring to?

Here's the reason I ask. I am having some failure to feed issues with my SLP as well. I have come to the conclusion that it may be the welded gate, but not 100% sure. When the gun is full I will have one or two shells that hang on the right side of the chamber as they go into battery. The failure takes a quick bump of the charging handle to clear. Is this a lifter issue, as I have assumed, or is it something else? (Like a faulty piston?) The gun just started this and has always run fine.

Here's what I have done to this point:

- Several thorough cleanings

- Cleaned and lubed the inside of the magazine tube. Outside polished down with steel wool - no oil.

- Shouldering the shotgun in different positions

- Running a variety of ammo. It seems to do it with everything I feed it.

- Polish job with steel wool on all moving parts related to feeding.

Cheers,

Kyle

Edited June 5, 2010 by DocMcG

[ninefan]

my SLP shelled a piston on the first shot of a 22 target stage at the 2009 FNH. It was an ugly single shot after that. The groans from my squad and the next squad at having to watch that spectacle were not nearly as painful as the hole I ripped into my hand racking the slide 22 times on the clock.

This. If you rack the thing under duress more than a few times with the stock bolt handle you will have pieces missing from your finger/hand. It sucks.

I replaced mine with the Nordic handle - and luckily I haven't had to try tearing flesh off yet.

[ninefan]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

Tod,

How would the shell hang up as it tried to go into battery on the "short stroke" you are referring to?

Here's the reason I ask. I am having some failure to feed issues with my SLP as well. I have come to the conclusion that it may be the welded gate, but not 100% sure. When the gun is full I will have one or two shells that hang on the right side of the chamber as they go into battery. The failure takes a quick bump of the charging handle to clear. Is this a lifter issue, as I have assumed, or is it something else? (Like a faulty piston?) The gun just started this and has always run fine.

Here's what I have done to this point:

- Several thorough cleanings

- Cleaned and lubed the inside of the magazine tube. Outside polished down with steel wool - no oil.

- Shouldering the shotgun in different positions

- Running a variety of ammo. It seems to do it with everything I feed it.

- Polish job with steel wool on all moving parts related to feeding.

Cheers,

Kyle

Kyle, have you tried replacing the lifter spring with two Glock extractor springs? Wolff part # 32259 (for 10 of them), best to order from Gunsprings.com

You might also try replacing the factory lifter spring with a new one also.

[DocMcG]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

Tod,

How would the shell hang up as it tried to go into battery on the "short stroke" you are referring to?

Here's the reason I ask. I am having some failure to feed issues with my SLP as well. I have come to the conclusion that it may be the welded gate, but not 100% sure. When the gun is full I will have one or two shells that hang on the right side of the chamber as they go into battery. The failure takes a quick bump of the charging handle to clear. Is this a lifter issue, as I have assumed, or is it something else? (Like a faulty piston?) The gun just started this and has always run fine.

Here's what I have done to this point:

- Several thorough cleanings

- Cleaned and lubed the inside of the magazine tube. Outside polished down with steel wool - no oil.

- Shouldering the shotgun in different positions

- Running a variety of ammo. It seems to do it with everything I feed it.

- Polish job with steel wool on all moving parts related to feeding.

Cheers,

Kyle

Kyle, have you tried replacing the lifter spring with two Glock extractor springs? Wolff part # 32259 (for 10 of them), best to order from Gunsprings.com

You might also try replacing the factory lifter spring with a new one also.

Ninefan -

No I haven't! Matter-of-fact, I have not even heard of that mod. How much stronger are the Glock springs?

Kyle

[00bullitt]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

Tod,

How would the shell hang up as it tried to go into battery on the "short stroke" you are referring to?

Here's the reason I ask. I am having some failure to feed issues with my SLP as well. I have come to the conclusion that it may be the welded gate, but not 100% sure. When the gun is full I will have one or two shells that hang on the right side of the chamber as they go into battery. The failure takes a quick bump of the charging handle to clear. Is this a lifter issue, as I have assumed, or is it something else? (Like a faulty piston?) The gun just started this and has always run fine.

Here's what I have done to this point:

- Several thorough cleanings

- Cleaned and lubed the inside of the magazine tube. Outside polished down with steel wool - no oil.

- Shouldering the shotgun in different positions

- Running a variety of ammo. It seems to do it with everything I feed it.

- Polish job with steel wool on all moving parts related to feeding.

Cheers,

Kyle

Kyle....the short stroking is usually an ejected shell and one on the lifter. Sometimes an empty is still in the chamber with one sitting on the lifter or partially out of the mag tube.

The feed issue you are having is the crimp of the shell getting snagged on the ejector notch which robs bolt momentum and causes the shell to get hung on the transition into the barrel requiring a slight nudge to put the bolt into battery. I have seen this happen with welded and unwelded lifters. I use a 240 grit flapper snading wheel to add a slight rolled edge to the right side of the barrel. It smooths the transition of the crimp as the shell enters the barrel. Since I have started doing that....feed problems have disappeared. I also cut a 1/4" wide slot in my lifter to help guide the rear of the shell up as well as give me an entry point to stick my knife into if I have two shells pop out of the mag tube.

[DocMcG]

I've worked on about 20 different SLP and SX2/SX3's and have seen 3 pistons with broken springs. They have all been on FNH SLP MKI's. I have an SX3 and it has about 3-4000 rounds on it and I watch the spring and piston closely. It has yet to break. If your gun starts short stroking sporadically.....the piston is the first thing I would check.

Tod,

How would the shell hang up as it tried to go into battery on the "short stroke" you are referring to?

Here's the reason I ask. I am having some failure to feed issues with my SLP as well. I have come to the conclusion that it may be the welded gate, but not 100% sure. When the gun is full I will have one or two shells that hang on the right side of the chamber as they go into battery. The failure takes a quick bump of the charging handle to clear. Is this a lifter issue, as I have assumed, or is it something else? (Like a faulty piston?) The gun just started this and has always run fine.

Here's what I have done to this point:

- Several thorough cleanings

- Cleaned and lubed the inside of the magazine tube. Outside polished down with steel wool - no oil.

- Shouldering the shotgun in different positions

- Running a variety of ammo. It seems to do it with everything I feed it.

- Polish job with steel wool on all moving parts related to feeding.

Cheers,

Kyle

Kyle....the short stroking is usually an ejected shell and one on the lifter. Sometimes an empty is still in the chamber with one sitting on the lifter or partially out of the mag tube.

The feed issue you are having is the crimp of the shell getting snagged on the ejector notch which robs bolt momentum and causes the shell to get hung on the transition into the barrel requiring a slight nudge to put the bolt into battery. I have seen this happen with welded and unwelded lifters. I use a 240 grit flapper snading wheel to add a slight rolled edge to the right side of the barrel. It smooths the transition of the crimp as the shell enters the barrel. Since I have started doing that....feed problems have disappeared. I also cut a 1/4" wide slot in my lifter to help guide the rear of the shell up as well as give me an entry point to stick my knife into if I have two shells pop out of the mag tube.

Wow! Thanks so much Tod! Any chance you have a picture of the modification to your lifter? Thanks for the advice! Sounds like I did not polish in the right places.

Cheers,

Kyle

[00bullitt]

Below is a pic of the lifter slot. This actually was done after the feed problem was solved by throating the area around the extractor notch in the barrel. That sharp edge transition into the barrel was causing all the problem. I just cut the lifter to give me access through the lifter in case I had a double feed on top the lifter. This entrance point allows me to get my knife blade or multitool in to clear it. I DO also believe the slot helps guide the shell to some degree also.

[DocMcG]

Below is a pic of the lifter slot. This actually was done after the feed problem was solved by throating the area around the extractor notch in the barrel. That sharp edge transition into the barrel was causing all the problem. I just cut the lifter to give me access through the lifter in case I had a double feed on top the lifter. This entrance point allows me to get my knife blade or multitool in to clear it. I DO also believe the slot helps guide the shell to some degree also.

Thanks again Tod! I have sent you a PM because I feel as if I am hijacking this thread. I have additional questions about the extractor polish.

Cheers,

Kyle

[Charles Bond]

Below is a pic of the lifter slot. This actually was done after the feed problem was solved by throating the area around the extractor notch in the barrel. That sharp edge transition into the barrel was causing all the problem. I just cut the lifter to give me access through the lifter in case I had a double feed on top the lifter. This entrance point allows me to get my knife blade or multitool in to clear it. I DO also believe the slot helps guide the shell to some degree also.

Thanks again Tod! I have sent you a PM because I feel as if I am hijacking this thread. I have additional questions about the extractor polish.

Cheers,

Kyle

Actually half of us are glad you hijacked it and the other half are waiting for the appearance of the Hints from Tod thread.

[EmanP]

Any pics of the barrel where it was smoothed over? I've been having this issue lately and need to solve it.

[00bullitt]

I don't have software that lets me draw in little arrows. But the extractor notch is on the right.....you should be able to see the rolled edge just inside of the barrel at that notch and just above and below it where I polished lightly with a 240 grit flapper wheel. That is the area that needs addressed. When you have your barrel off....just take your index finger and jab it in the chamber......you'll find out real fast where the sharp edge is that needs addressed.

[EmanP]

Awesome picture, thank you!

[RufDog]

I have broken 1 piston.

[Team Adam Carter]

I have broken 1 piston.

Get a Benelli!

[strat81]

Looks like I won the lottery:

Can't see it? Look closer...

The spring is broken. I picked this SX2 up off Gun Broker a few weeks ago for $450. It won't cycle with 1 1/8 oz, 3 dr, 1200 fps loads. If I bump it up to 3 1/4 dr, 1250 fps, or 1300 fps, it'll work. The slugs and buck I've run through it have worked well too. If the gun is hot, the 1200 fps stuff will work.

To Winchester's credit, the gun still works with a broken piston. Unfortunately, the only place I've found that even sells those springs is in Europe somewhere. SRM (the Sure Cyle folks) can weld in an insert. I called Winchester and asked about a warranty replacement. I was told that they'd have to see the part first and then they'll make a decision.

So, I'll box it up in the next few days and hopefully get a replacement from Winchester. I'll probably send my shell lifter off to C-Rum to be welded at the same time.

This is a 3" Composite model, and only came with one (black) piston. I noticed the crack as I was comparing a new piston from Brownell's. I picked up a red, 1 1/8 oz or less, sporting clays piston. I'll keep that piston on the side for now, because if Winchester repairs or replaces the broken one, I'll send the clays piston back to Brownell's and get my $85 back.

Since the gun was used, I have no idea how many rounds are through it. It's not in terrible condition, but it was definitely well used. Some scratches on the barrel and receiver, some missing finish on the stock and forearm, etc. No rust was present in/on the barrel, receiver, or recoil spring tube.

Edited August 6, 2010 by strat81