Sticky bolt on marlin 39

[Bazoo]

I have a marlin 39as I bought. It’s in good shape. I put a 39a hammer and trigger and mainspring in it. I didn’t shoot it but a mags worth before I converted it. It shoots good and cycles well and I don’t have issues...except one. I also polished some of the guts where they rub to slick it up.

Once in a while, maybe every 30-50 it will stick the bolt/lever like it would with high pressure. It does it with CCI mini mags and stingers and it has done it with Aguila HV.
With stingers it will do it a couple times out of a mag. The cases don’t look any different. Cases look normal compared across brands and from other rimfire arms.


It doesn’t do it with armscor or Winchester wildcat (best I recall). Though it could be I just ain’t shoot it enough to do it.

It takes maybe double the force to open the bolt when this happens, but it opens and ejects and all is fine. It seems it’s more likely to do it on a swabbed chamber or if it’s set loaded a while.

Ideas? Is this just a marlin thing?

Cases ain’t swollen to indicate headspace problems and the bolt closes tight. I did not polish the lever arm or it’s mating surface on the bolt that controls headspace and lockup. It has some machine marks there as well as some polished area from wearing in.

I have not cleaned the chamber excessively. I ran a bronze brush through the bore a few times and wiped it clean, oil and dry patches. Could it be a cleaning issue? I don’t see how as it feeds and extracts fine. It looked clean when I was into it.

I’ve looked online, at rimfirecentral and marlin owners (where I’m a member but don’t say nothin) and can’t find any info of a like query.

Thanks

Bazoo.

[para45lda]

Look closely at the chamber opening. It may be peened and need swaging? I love mine but it needs a new extractor.
Good luck!

[Winger Ed.]

Due to the higher pressure of Stingers-
if there is any 'stickiness' or imperfection to be had, a scratch,
or a flaw in the chamber, the spent case will probably expand enough to find and fill it.

I haven't had a 39 for a long time,
but I remember Stingers being a tiny bit harder to extract and cycle out than the el cheapo .22s.

[Gtek]

Black Sharpie the cases and maybe a shiny spot will show and possibly reveal a problem area?

[Bazoo]

It ain’t got any damage from dry firing.

Make no mistake, it isn’t hard extraction, it’s hard lever movement like from higher pressure. The lever moves from behind the lug on the bolt before the bolt moves. Once the lever “unlocks” the bolt has no problem moving.

I haven’t done anything yet as far as scrubbing the chamber. I’m still researching it.

Preciate the replies.

[recumbent]

Stinger cases are a little longer than standard 22lr cases. That's probably the problem, solution is stop shooting stingers in that rifle.

[Gewehr-Guy]

I use a thick grease on the end of the locking surface of the lever, and the machine marks actually help hold a little lubricant there. Like an M-1 Garand, any moving part with any finish wear, gets a film of grease. Might not fix the problem, but can't hurt!

[Bazoo]

Thanks for the grease idea.

I know stingers have longer cases, mini mags and aguila don’t though. What’s the solution to those? I have a couple thousand of each mini mags and aguila, so it’s not feasible for me to not shoot them. Regardless, this isn’t something the rifle should do with any ammo.

The problem ain’t the ammo, its the gun. Where exactly the problem lies eludes me however.

[uscra112]

The bolt is held in battery by the cam surface on the lever, which bears on the underside of the bolt. Look there for something binding it. A flake of brass maybe.

The 39 was made long before hypervelocity ammo, and probably isn't chambered for it. I don't shoot it in either of my 39as. In fact I don't shoot it in ANY rifles I own. It's usually not very accurate. More a marketing gimmick than a useful cartridge, IMO.

High pressure puts more thrust on that cam, accelerating wear. I've used nothing more energetic than standard velocity in mine for decades. Mostly because it's the most accurate. And my old Dad's 39a, which is like new, is as accurate as all but the top-of-the-line competition bolt guns.

[Bazoo]

I cleaned the chamber with a bronze brush in a drill and it seems to have resolved my issue after having shot 50+ rounds.

Guess I need to invest in a bore scope cause I thought it was clean the first time. Glad it was an easy fix.

[Bazoo]

I experienced a very faint harder bolt unlock again. Not nearly like before. I gave the end of the lever where it locks a couple passes with a piece of 1000 grit paper. It has some ridges there that I’m thinking may be locking into the bolt lug like cog teeth.

I also ordered some bore tech c 4 carbon remover that should knock out any accumulated carbon ring in my chamber.

[uscra112]

Unfortunately you can't take material off that cam surface without opening up the headspace, so be very cautious about smoothing it.

[Bazoo]

I know. Been thinking of getting another lever to see if it changes. I haven’t shot it since I sanded it. The amount I did likely wouldn’t have been measured except by the .0001.

[TNsailorman]

I quite using those higher pressure loads like the Stingers years ago. Not very good accuracy and cause more problems than they are worth in my book. I stay with standard velocity ammo now. james

[uscra112]

I know. Been thinking of getting another lever to see if it changes. I haven’t shot it since I sanded it. The amount I did likely wouldn’t have been measured except by the .0001.

On the brighter side, I've got a really tired old Ballard-rifled 39 that certainly hasn't got the headspace it once had, but it still shoots. Not <2MOA like my Dad's almost-mint 39a, but it would not embarrass itself if I had to use it for small game gathering with SV ammo.

Something I'd try is smearing a very little 400 or 600 lapping compound on the cam and cycling the action a few dozen times. Wash everything thoroughly after, of course,

[Bazoo]

Update.

I have narrowed down the lever sticking to excessive headspace. The gun locks up upon firing some ammo and not others. It never does it with armscor but does it the most with aguila.

I took a cartridge that had a .043 rim, a piece of tape that measures .0055 added to the head and it closes, two pieces and it closes with a bit of resistance. 3 pieces and it won’t close. So that’s .054. My research shows .051 as max, though I couldn’t find anything definitive on this, just a couple threads where it was stated as fact. Can anyone verify this or offer a link that does?

I measured my rim on the edge with calipers. I also tried inserting the cartridge in a hole and measuring this way and both seem to be requiring a good deal of feel. How do you normally measure rim thickness?

I changed levers, and the new lever closes still on 2 pieces of tape but harder. The difference in measurements between the two levers best I can tell is .004. The new lever does reduce the frequency of lever sticking, adding grease to the locking surfaces further helps some.

So now, I think, I am looking to have the lever welded to lengthen it so I can headspace it. I’m researching all required. Questions I have include;

Do I need to heat treat the lever end after it’s welded?
Is there another approach?

If all I want is to have my lever tig welded up, is there someone that can be suggested to do this?

Also, is there a gunsmith that would be suggested to repair the headspace should I choose to go that route?

I appreciate any suggestions or direction anyone can offer.

[uscra112]

Before you go welding on it, look into having the working surface(s) built up with hard chrome plating. In my machine tool rebuilding career back in the '70s we did that a lot to restore worn shaft journals. Build up as much as .020", then grind back to size. The process has no effect on any heat treat that may be present, and is tough as nails. By using a stopoff coating, only the surface you want built up gets any plating.

http://mahovskysmetalife.com/

https://hausnerinc.com/industrial-hard-chrome-plating-services/ in Owensboro

[Bazoo]

That’s an interesting idea. Thanks.

[uscra112]

In your case you probably need only .005" or so of plating thickness.

Search ".22 rim thickness gage" for ideas on how the serious .22 shooters do it. Lots of hits. Most use a dial/digital caliper.

[Bazoo]

Well, I have an update. I found a thread that had a reference to preening the end of the lever to increase the length, and I did just that. I thought it over a while. Figured I have nothing to lose especially since I have two levers. I heated the end to maybe 400 degrees to help it move, laid it on my sledge and tapped the end with my hammer til it measured .010 longer.

Now my headspace is so tight it won’t close on the cartridge I measured at .043. So all I have to do is sand it home the lever end until I get it where I want it. I’m thinking about buying a go gauge to headspace it but I might go ahead and just use some cartridges. If I can find one that’s .045 it’ll be just right.

Anyways. I’m excited to have made some progress. I’ve been thinking it through and researching the problem and possible cures for a while. I happened onto a thread at marlin owners that mentions if you don’t need much, peening the lever is a possible solution, and by golly it’s going to work out perfect I think.

[uscra112]

Hadn't occurred to me. (adminsters dope slap). Revolver gunsmiths do that to "stretch" a hand that isn't rotating the cylinder all the way. The perfect solution for you.

Heating it that hot may have drawn whatever temper it had, though. Hope you cooled it down right away.

[Bazoo]

I’m guessing that temperature and I’m being generous. I heated the end maybe 10 seconds with my propane torch. Not enough that it got hot down on the handle, it still feels hard. I’ve tempered some knives and an confident I didn’t soften it at all.

[Bazoo]

I file tested it against the other bolt and both are the same hardness. I fitted it until it would accept a .045 rimmed Remington. Test fired it with aguila and Remington thunderbolts. It locked up I’m with the thunderbolts but the aguila was fine. It previously wouldn’t shoot them more than a couple shots without locking up. So I put some lapping compound on the mating surfaces and cycled it 100+ times. Shot some Remington and it it did lock it up but only one out of 18 this time. I’m thinking it needs to have the parts lapped more to mate them. Maybe just shooting it will wear them in enough. Not sure yet. Definite improvement though.

[Bazoo]

After thinking on it, I think the headspace being tight, and getting an occasional Remington that’s thicker rimmed, is causing the continued lock ups. Pinching a thicker rim would cause the bolt and lever to bind. I think I’ll measure some rims and cull out some thick ones and see, and maybe shoot it some with various ammos. Could be a bad batch of ammo in some way too.

[uscra112]

I think that's a good plan. Remington commodity ammo has been notorious for being sloppily made for at least a generation. I've done weight sorts that returned so pretty dismal numbers. I would be surprised if their rim thickness variation wasn't just as bad.

[Bazoo]

I opened the headspace up enough that it will accept the thicker rimmed ammo. It didn’t help. It is locking up with both thunderbolts and with golden bullets of new manufacture. It could be that I have fixed it for all others, and just Remington ammo don’t agree with the gun.

I did notice though that it will lock up solid if I fire it with the lever just short of touching the frame. Maybe .010 away.

I haven’t had the aguila lock it up since I’ve tightened the headspace. My buddy shot it today and it locked on him with aguila and I suspect maybe he just didn’t have it closed 100%.

The local gunsmith suggested that maybe something in the chamber was causing cases not to grab like they should. He suggested dirt from the Remington ammo. Since I do have some scratches in the chamber, I cleaned it and polished it with 1000 grit paper. I probably only polished the chamber 10 seconds using my drill. Not sure that would be enough to do much but im afraid to do much as I don’t want to open the chamber up. I figured if it was just a few minor burrs, it would knock the high spots off. While it never had extraction problems and ammo would chamber freely, there was some scores on the empties from the scratches in to the chamber. Not sure what’s going on as I don’t have a bore scope. I didn’t consider this a problem as it fed and extracted fine and since the headspace was generous, I just assumed it was all a headspace issue. Now I’m considering maybe the chamber being scored is causing some of the bolt trust.

Anyone have ideas in this? I’m not very familiar with polishing chambers. Anyone offer a link to a tutorial?

[uscra112]

I've always used fine crocus cloth or aluminum oxide paper on a balsa-wood stick. Balsa crushes to conform to the chamber shape. Being an RC airplane builder I of course have plenty around.

Flex-hone makes brush hones for bigger cartridges. They might have something for .22s.

Is it possible that the geometry of the lever face is such that it's going "over-center" the way toggle linkages do?

[Bazoo]

The geometry thing was mentioned to me by the gunsmith and when I fitted it I made sure it was not caming over. Make no mistake, it’s not “locking the bolt and I can move the lever some”, it’s locking both solid like a high pressure round in a bolt action rifle. When it locks the lever will not budge. Sometimes it takes a lot of force to move it. As if it was very high pressure.

[2152hq]

Does your 'local gunsmith' happen to have a No-Go gauge for a .22LR/
You really should start there and actually see what the set up currently is.
You mentioned that the lever closes w/a round in the chamber with just a little gap/daylight between the lever and the grip (.010 approx).
I can tell you from Factory experience at Marlin that that is the very picture the Final Assembler or Repair Dept Gunsmith wants to see with a No-Go gauge in the rifle and the lever gently closed.

HS should be checked with the bolt stripped but it usually is not.

Peening the lever to extend the arm a few .000" is a common repair on the 39 (and 97). It doesn't take much effort to accomplish, the part is soft even under a factory color case hardening on early rifles.
One thing to check is that after the peening is that the arm is then absolutely straight again and not twisted one way or the other.
During the peening, the metal will generally start to do just that twist and go off in one direction or another. It's just the way metal responds to the technique.
Not a big problem here. But make sure that tip is placed back in line where it belongs. It must engage the locking shoulder on the bolt squarely and not rub against the bolt when especially disengaging (opening the bolt after firing).
Even the slightest tweak in that tip can cause a hard lever opening and/or closing.
Check the side of the bolt where the lever runs along it in operating the bolt for any obvious signs of abrasions from the arm.

Check the cartridge guide spring in the top edge of the chamber.
It's planted in a recess betw the bbl and the frame and sits there only to guide the nose of the loaded rd into the chamber.
If it's bent it can jam up the bolt. You need to pull the bbl to remove it and replace it. Then reassemble the bbl to the frame.

The extractor should slide easily into the cut into the 3 oclock position in the bbl.
It should cam outward slightly on the cut in the bbl as the bolt closes. The point/hook on the extractor should only grab onto the case at the rim itself and pull it from the chamber.
If that extractor cut in the bbl is extended too far forward into the chamber, the fired case will expand into the open cut and the case can jam in that open cut sometimes depending on the ammo. Some worse than others. Some not at all.

It doesn't hurt to polish a chamber, but do just that,,polish it. Don't enlarge it or make it out of round in anyway.
Look carefully are the rear edge of the chamber and make sure the fireing pin isn't too long and leaving a burr on the chamber edge from hitting it.
That will make for tough extraction and can make all sorts of feeding issues as well if it gets bad enough.
RF Firing pin should fall a few .000" short of striking the chamber edge when struck.
Most used to be fitted to do just that.

About all I can think of at the moment.

[Bazoo]

Thank you for the suggestions. I forgot to ask the smith if he had a no go gauge. I could buy one though I spose.

I was aware not to make the lever end bent, I peered both sides evenly and it appears flat with t he rest of the lever. Though I didn’t put a straight edge in it, just sighted down it and it wasn’t obvious.

I didn’t strip the bolt but I see how that would be beneficial.

I will check the extractor cut, but best I recall it is not into the chamber. The firing pin is not hitting the barrel and there is no damage there.

I’m aware of the cartridge guide and it’s function and tuning. It feeds and extracts flawlessly.

I’ve read quite a bit on the gun, and all manner of problems associated with it. I have yet to come across a thread anywhere that has the bolt locking up like I do. If anyone is aware of a similar issue and could offer the link to it, I’d appreciate it. Sometimes the answer to a problem is just a search away using different wording.

I ordered the agi armorers dvd on it. We shall see if that helps any. I can y’all one thing. Few guns are as magical in their operations and use as the 39. If I can get this licked, it will be my favorite gun for a long long time.

[uscra112]

Check the cartridge guide spring in the top edge of the chamber.
It's planted in a recess betw the bbl and the frame and sits there only to guide the nose of the loaded rd into the chamber.
If it's bent it can jam up the bolt. You need to pull the bbl to remove it and replace it. Then reassemble the bbl to the frame.

My old 39 (Ballard rifled) has a spring in the frame, above the bolt, which might be this "cartridge guide spring". Acts to guide the nose downward into the chamber. Looking hard at it, I could believe that the end of that spring might catch the rim of a fired cartridge, preventing extraction. Especially if the rim has expanded on firing. (The rim O.D. is not supported in this design.) Fired case ought to show a witness mark once you get it out.

Taking the spring out of mine would not require removing the barrel. Just removing a screw from the top of the left receiver half. Is this different in a 39a?

Keep at it. I love puzzles.

Another thought: Measure the rim diameter of the rounds which bind the action and compare to rounds that don't. Are the bad ones bigger?

[uscra112]

Could the lever be catching on the lifter arm? Working the mechanism with two halves separated...looks possible.

[uscra112]

How far does the lever move before it binds?

[Bazoo]

The lever doesn’t move before binding. It is solidly stuck upon firing and then takes significant more pressure to move it. Once it unlocks, it cycles as normal.

The cartridge guide is not snagging the rim. And the carrier is not binding on the lever. It cycles without issue. But upon firing, will lock the bolt and lever unmovable except through greater than normal force.

[uscra112]

OK, only one more thing I can think of. There's the spring that holds the lever closed. End of it drops into a detent in the lever. Could anything be wrong there?

If not, I'm back to the cam surfaces.

[Gewehr-Guy]

One simple suggestion would be to re-snap the hammer on the breach block when it locks up. If it opens easily then, it would indicate its binding on the locking surfaces, rather than the chamber.

Another thing to look for is how much clearance is between the top of the bolt, and the reciever. If the bolt is worn on top,it can wedge upward and change the angle of the locking surfaces a bit.

Also, on my 70's model, the lever moves 1/4 inch off the frame , then retracts the firing pin about 3/16 of an inch, before the bolt starts to move. Could yours have a different style firing pin that could interfere with the bolt movement?

[2152hq]

My old 39 (Ballard rifled) has a spring in the frame, above the bolt, which might be this "cartridge guide spring". Acts to guide the nose downward into the chamber. Looking hard at it, I could believe that the end of that spring might catch the rim of a fired cartridge, preventing extraction. Especially if the rim has expanded on firing. (The rim O.D. is not supported in this design.) Fired case ought to show a witness mark once you get it out.

Taking the spring out of mine would not require removing the barrel. Just removing a screw from the top of the left receiver half. Is this different in a 39a?

Keep at it. I love puzzles.

Another thought: Measure the rim diameter of the rounds which bind the action and compare to rounds that don't. Are the bad ones bigger?

You are entirely correct! The cartridge guide spring in the 39 is held in with a small screw from the top of the frame.
I had a brain delete moment,,thinking of the same spring in the bolt action Marlin .22's. They are held captured inbetw the bbl and recv'r. They require the disassembly of bbl and recv't to replace.

Thank you for pointing that out!

[Bazoo]

The cartridge guide is not catching the rim. Also there isn’t any appreciable wear on the bolt.

The agi video was useless to me, I already knew all of that from my own observation and from my research.

After thinking it through more I think I have a 2 fold problem. One was excessive headspace and the other is a chamber burr causing casings to give too much bolt thrust. Some more than others. Originally before I did anything I had the locking up issue and I cleaned the chamber with a wire brush in a drill and the problem was better with some ammo.

Now I’m looking at polishing the chamber. I’m also looking at possibly replacing the barrel. This isn’t something that’s easily done it and is a last resort.

[uscra112]

If there is a burr in the chamber due to peening of the barrel metal by firing pin strikes, there is a tool to push the deformed metal back where it belongs. This situation is endemic in high round count .22 rimfires. Many of the old .22 caliber belly-shooting gamesters had this tool in their kit.

https://www.tandemkross.com/ChamberMadeChamberIroningSwage

Stevens Model 44s and Favorites were changed about 1900 so the pin strikes on the extractor, probably for this reason. It hurt accuracy, but it surely reduced customer complaints.

More research seems to indicate that the Tom Menck tool (above) is discontinued everywhere. A reasonable substitute can be made from a hardened steel taper pin.

What you do NOT want to do is cut the burr away. That compromises the support for the rim where the pin strikes.

[Bazoo]

I know there is a tool for ironing out the firing pin peening. It doesn’t have that however. The firing pin doesn’t protrude past the bolt face.

[uscra112]

Oh, but it has to, or the cartridge wouldn't fire. The nose of my firing pin is stepped. The upper part does protrude, the lower part only comes flush with the bolt face.

Do you have any really low-powered ammo, like CCI Quiet, or one of the "subsonic" varieties? Can you make it jam up with that?

[Bazoo]

I mean the firing pin doesn’t come past the protrusions on the bolt.

The gun doesn’t lock at all with armscor or Winchester wildcats or shorts. I’ve shot 300 rounds of armscor or more. It has locked with minimags but upon cleaning the chamber, before tightening the headspace, had stopped.

I’d like it to shoot Remington ammo cause I have 5k+ rounds of it. It I also have a fair amount of the aguila, and it’s available here most often. It has only locked up once, and with my buddy shooting it, using aguila since I tightened the headspace. So I’m hoping it was him not closing the lever all the way.

[uscra112]

So I'm wondering what peak pressure your Remington ammo is actually loaded to. You can get the same MV loading a smaller charge of fast powder as you can loading more of a slower powder, but the peak pressure is higher. Counterintuitive perhaps, but some of my research suggests that .22 rifle ammo is loaded with something like Herco, not a superfast powder like Clays. I would not have trusted the old Remington not to have loaded the lot you have with a faster powder, for "reasons". . . . . . Like they were going bankrupt.

OK, hypothesis: High pressure load expands the rim thickness, and elastically deforms the action a little bit. Pressure released, the action springs back, trapping the expanded rim in a vise, (i.e. bolt face and barrel face.) Test by measuring before-and-after rim thicknesses.

Precedent: Savage 99s chambered for the .25-35 , a strongly tapered case, were notorious for very hard extraction if the cartridge were loaded hot. Receiver would elastically stretch, letting the cartridge lengthen. (Remember the 99 locks up at the rear of the bolt.) On relaxing the action would drive that lengthened case into the chamber, sticking it but good. (Almost a locking taper like the Morse used in tool holders.) Fix was to ream the chamber to an "Improved" shape with much less taper.

Rifles that locked at the front of the bolt, i.e. turnbolt actions, never suffered this problem.

[2152hq]

Another thing to check is for a cracked bolt.
Yes the Model 39A has the reinforced HS bolt, but they can crack as well especially from the hyper vel/pressure .22LR rds. Not often a problem but it can happen. Worth a look.
The cracks if they occur will be in the same locations as the bolts had them in the '97 and the early 39 from HS ammo use.
The thin web that separates the locking surface lug from the firing pin slot and the inside angle of the extension of that locking surface from the bolt.

Use a loup or magnifier and take a careful look at the area.
In the very least you can rule out the possibility.

[uscra112]

Hmmm. I wouldn't have linked the 39 to the 1890-1915 "boys' rifles" I collect, but it isn't really all that strong, now that you mention it. Nothing but that strut on the lever holds it closed, and that bolt is not exactly solid, what with all those slots in it.

[Bazoo]

I did check the bolt for cracks but not real well. I will check again. The new rem ammo is made by the Arkansas plant I believe. I talked to a woman there in regards to a different lot number that blew a friends gun up. Anyways.

There is in my bolt, where it locks, some wear in the form of metal that has moved from the lug and is slightly mushroomed off the sides. You can feel it with your fingernail. So I had excessive headspace. Bolt thrust is battering the locking lug. What causes bolt trust? Excessive headspace causing swollen cases. Fixed the headspace. What else. Chamber that is Uber smooth, not the case here. Chamber that has gouges? Mine does. My brass comes out scored. It extracts fine if it doesn’t lock up. It feeds fine. Could it be that there are burrs or high spots causing the brass not to grab the chamber walls and allowing the casing to push against the bolt face with excessive force? That’s what I’m thinking now, but I’m still studying in it.

Unless the rifle came from the factory with excessive headspace, something has to have caused it.

[Bazoo]

Well after reflecting and research I have an idea. The firing pin. The firing pin is proud of the bolts rear in its forward most position. The agi video (while nearly worthless) said the pin should be a couple .000 less than the bolt rear when no cartridge is present. I can imagine how that could help with bolt thrust, if the hammer, after crushing the rim of the cartridge also supports the rear of the bolt. But it also would give it a jolt at about the same time pressure was starting to rise or even peak. Maybe that’s just the bit of help it needs.

All of my research shows when fitted it should be below flush on the rear. It didn’t occur to me that might be an issue and could be the root cause, that caused the wear and the excessive headspace.

We shall see if it cures or helps the problem.

[uscra112]

Interesting hypothesis. In a lot of hammer-fired single shots we count on the hammer to back up the firing pin, but in this case it backs up the whole bolt!

Have you tried measuring rim thicknesses before / after yet?

Looking at my old pre-Microgroove 39, the pin is flush with no cartridge under the pin, but proud by about .005 after firing a round of Thunderbolt. (by Mk I calibrated eyeball.). How about yours?

What is the firing pin protrusion in front? Ought to be .030" - .040". Lean toward .030" if the gun has tight headspace. I set my .22 single shots to .035".

--------------------

On closer inspection under 10x magnification, my pin without anything in the chamber is also .005" proud at the top, flush at the bottom, at the rear. Hammer is bearing on the proud part. .

What stops the pin in the forward direction is the small rectangular lug on the bottom, forward of the one the lever hits to retract the pin. Preventing dry-firing damage to the barrel face.

[Bazoo]

My firing pin was probably .10 proud when all the way forward on an empty chamber. I removed material until it was flush or about. Fired it. Immediate improvement. It did still lock up but only a few times out of 80 rounds and not so hard I couldn’t work the action but enough it was noticeable.

So I went back in and removed maybe .004 more. I also dressed the top rear of the firing pin at an angle to better match the bolt. Though it’s still a bit proud there.

I also inspected the pivot area of the frame where the lever turns. The part that the outer portion of the lever rides against had some fouling. Looked like maybe a small speck of lead got smashed there. I wire brushed that and then polished that inner surface with 1000 grit paper.

Fired 3 magazines with no issues.

All of this with the Remington thunderbolt ammo.

[Bazoo]

One point of interest, is I’ve read many hours on several forums, and I cannot find anyone that’s had similar problems as I have. It mustn’t be a common issue. It could be a specific angle or tolerance that needs attention but it would take a smith that’s seen it before to diagnose it.

Could it be that speck of lead? Maybe. But each of the other things helped the problem. First, cleaning the chamber thoroughly, then tightening the headspace. Then shortening the firing pin. So, was it all these problems? If I had shortened the rear of the firing pin to begin with would I have still had intermittent locking up issues?

The firing pin still protrudes past the rear of the bolt after I’ve fired a case, so other than changing the angle, what else could it be affecting?

[uscra112]

Three mags of the Remington that was giving you such trouble? Wizard.!

That .10 protrusion sounds like too much to be just a tolerance stackup. Wonder if there might be different firing pins for different models, and you had the wrong one. Or an aftermarket one that wasn't right.

Still wishing to see before/after cases, although it looks like it's too late now to make any new ones. I have a Ballard that has the flat type firing pin, exactly like the 39. It is a little too short, so on firing the case head bulges a good .005 or more into the slot where the front of the pin should be supporting it, backed up by the hammer. , And that's with Standard Velocity ammunition. So it's a lead-pipe cinch that your HV cases were expanding, the bolt not being backed up by the hammer.

Took a long time, but it sounds like you have it licked. Write up a summary for the Marlin forum(s).

[farmbif]

I'm in the camp that says just shoot ammo that works well in it. the rabbit hole can get pretty deep trying to manipulate the gun to make it work with all brands and types of ammo. ive got 3 39a's and the newest golden likes winchester and cci ammo, one of the mounties shoots cci quiets real well. the other mountie will shoot anything its fed well but the takedown screw likes to loosen on it and when that happens it jams up.
but my problem child marlin rimfire is a 57m which will just not fire Hornady ammo, no way-no how, a trip to a real good gunsmith who knows what he's doing, rebuilt it with all the new parts I was able to scour out of many many google searches, guess what? it still will not shoot Hornady ammo, so it gets a diet of federal, winchester, cci and armscor 22 mag ammo.

[uscra112]

With ammo in such short supply, it behooves us to make our rifles work with what we have or can get. The days of just buying six or eight brands until we find one that works to our satisfaction and buying a ton of it are gone, at least for the present.

O.P.'s battle started with the fact that he has something like ten bricks of the Remington on hand, but couldn't use in his Marlin until he sussed out the problem. What with even the cheapest commodity ammo going for $100 a brick, the effort was worth the price of a new rifle.

[Bazoo]

I am all for using what the rifle likes in terms of accuracy, or even nose profile. This wasn’t a simple my gun didn’t like Remington ammo. It was locking the bolt/lever like that of a too high pressure round would. But it did it with Remington, aguila and CCI mini mags. I have 5k rounds of Remington between thunderbolts and golden bullets, and another 5k+ combined of mini mags and aguila. I haven’t tested any federal, blazers, or other cci I have.

The mini mags didn’t do it consistently. All my research over on rimfirecentral and marlin owners shows mini mags as ammo that is likely to work well in most everyone’s 39s. All my research shows that model 39 rifles aren’t overly sensitive to ammo other than for accuracy purposes. And we ain’t talking bout bad groups, but the rifle locking solidly closed and requiring extra force to move the lever. A rifle chambered in 22lr should “function” with all 22lr ammo, exception of course being made to specialty ammo. Not to mention all the other folks that shoot tubs of thunderbolts and goldenbullets out of their 39s without problems.

Some of the cases were bulged, and still some are, but not as badly. Pretty much expect bulged cases if your headspace is set at .046 (example and a guess) and you fire cases with rims .038. While not a target headspace, if my gun is at .046, it’s acceptable and should function. No pictures though.

Thunderbolts are cheap bullets, but goldenbullets are a notch above to my thinking. Aguila is on the same as blazers or even a bit above. Mini mags are above that but below target stuff. I don’t have any target ammo but I have a brick of Norma tac22. At 10 a box, it’s not my normal fodder. For that matter, mini mags aren’t either.

[Bazoo]

I fired 4 mags full today. For a total of 7 mags. 19 per mag, so say 20 cause I can’t add well. That’s 140 rounds without a problem. At least one mag of goldenbullets today. I lost track a bit. Hope that this journey helped someone else down the line.

[uscra112]

You must be over the moon! And you deserve to be!

[Bazoo]

I’m pretty excited. I thanked God for allowing me to get it sorted out. I have a much greater knowledge of my rifle now.

[uscra112]

Most of my career was spent in manufacturing, as an engineer. I will declare here and now that, while pay was a factor, and attaboys was another factor, what really motivated us was these Eureka! moments when we'd solved an intractable problem. Massive dopamine hits!

[Bazoo]

One reason I didn’t take it to a smith to fix is I wouldn’t have learned nothing. I enjoy learning. Doing something I haven’t done, or fixing something I haven’t fixed.

Not having a smith I trust is another reason. But if I did that every time my guns needed something I’d be always having something worked on. Learning minor gunsmithing is just part of the lifestyle.

[Bazoo]

I have acquired a no-go gauge. It leaves about .10 space of closing the lever on it. This with the lever I tightened the headspace.

I installed the I modified lever I have, which was a touch tighter than the original lever before I lengthened it. No-go gage will not close on it either.

Interesting that both levers (before I lengthened one) allowed the locking issue, but after I lengthened the lever it helped the issue. So headspace plays some roll, but obviously not as much as I had originally thought.

What really gives me reason to ponder, when I shortened the rear end of the firing pin, my problem got immediately better. The only thing I can figure, is the angle at which the hammer strikes the firing pin is changed such that it’s more squarely hit. Maybe that causes the bolt to move slightly? Maybe it was causing the bolt to wedge in the action?

The thing is, why do I not find anyone else with this issue? How could it be as uncommon as it seems, provided it’s so simple?

[uscra112]

I'm back to what I hypothesized at Post #43, that the cartridge head was swelling, enabled by the hammer not backing up the bolt. After all pressure is released, the swollen head is wedging the bolt against the cam. Not wishing to be thought a nag, but I still want to see rim thickness measurement before and after firing.

For that matter, what happens if you return one of the swollen cases to the chamber (I know it's a pain) and close the bolt. Do you meet resistance before the lever is all the way home?

[Bazoo]

I measured some of the cases and they were normal in size, though I don’t recall the size. They are swollen some though and show the firing pin indent as well the square portion or the pin below the protrusion.

I have closed the bolt on a fired case and don’t recall anything out of the ordinary, but I will try a few more next time I fire her.

One point, part of the spare parts I want is a firing pin, so when I get one, testing of these hypotheses will continue.

[uscra112]

Diameter will of course be that of the chamber, less maybe a thou. If the rim thickness gage shows even a thou or two over headspace, I think that's the answer.

[Bazoo]

What do you mean rim thickness gauge? You mean, if I measure a fired rim and it was any over headspace?

I wish I’d had sense to save some of the cases, they are all in the weeds and mixed with others though. But the drive to fix it precluded sense to fully document the issue.

[uscra112]

Something like this:

https://www.amazon.com/gp/product/B0776C1DPC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

For generations it's been known that the thickness of the rim, which is a function of the accuracy of the machine operation that forms it, has a significant effect on the accuracy of the shooting. Competition shooters use a tool like this to sort through their ammo and cull out any rim thickness outliers. In these days of ammo dearth, sorting commodity ammo like your Remington would yield positive results.

The other thing they sort for is overall weight of the cartridges. Remington is well known for loading bullets that weight a full grain above or below the nominal weight.

I'm in no way a competition shooter, but accurizing commodity ammo has intrigued me for years. I've used various kludges to measure rim thickness in that tikme, but I finally broke down and ordered the one I linked to. I like that it can be used with a dial indicator as well as a digital caliper.

[Bazoo]

I mostly do plonking of tin cans and such, so I don’t need the increase of performance offered by sorting of ammo. If I want consistency for longer range I generally use better ammo. I haven’t tested the gun for accuracy for the latter yet.

I spose I could sort via rim, and just plink with the outliers. I may give it a shot and see if it’s worth it. I have heard that measuring bullet diameter offers as much or more advantage as weighing.

[uscra112]

With a tool to precisely measure rim thickness, you could detect any axial bulging of the case head. If you found some that were bigger than your known headspace, they would be acting as a spring to put pressure on the cam surface, making it hard to open. The bulging would result from the bolt being forced back with sufficient force to deform the action elastically, letting the brass distort along with it. The brass having a much lower yield strength than the steel, would want to stay in the bulged shape, while the steel springs back to trap it. That's been my hypothesis for several posts now.

As I posted earlier, this is a known problem with centerfire actions that lock the bolt at the rear. The steel between the case head and the locking surface is a spring. Actions like the Mauser that lock at the front have an extremely short spring that is extremely stiff, where rear-locking action like the Savage 99 are less so. Thus they do not handle hot loads nearly as well.

I'm now curious to know about axial bulging of cases fired in blowback semi-auto actions like the 10/22 Ruger. Unfortunately I sold mine, since it shot patterns and not groups, no matter what I did. So now I have nothing to experiment with.

[uscra112]

Bullet diameter is crucial. Most consumer grade .22s like the Marlin have fairly loose chambers, so as to handle any sort of ammo they may be fed. One thing that yields results with commodity ammo is to swage the cartridge in a die to make the bullet O.D. a consistent .2250", so it fits the "sporting" chambers better. This is commonly called "bumping". Many shooters do it to just create a different nose shape. There are tools on the market to do this. If you have a small lathe, or access to one, you can make a tool yourself for a lot less money. I drew up a design which I have been sharing around. It's just two parts that fit into a Lee "Universal Expander" (which it isn't) die body that retails for fifteen bucks. P/M your regular email addy and I'll send you a copy of the drawing.

A problem of late is finding a shellholder for .22 rimfire. They do exist, but nobody has any these days. A lathe can make one most of the way, but you need a mill to finish it. If I had CNC, I'd go into production, but my machine tools are manual and ancient. I made one for myself, but it took the better part of an hour.

[Bazoo]

Uscra, I think you had mentioned wedging of the bolt. After studying it a bit, I bet what was happening was, the firing pin, being hit at an angle was driving into the firing pin keeper, and then moving the bolt forward. Depending on the ammo, it gave bolt thrust sufficient to lock the action.

I’m considering ways to test this hypothesis.

[Bazoo]

Had one lock the bolt today. After about 200 rounds. I disassembled the bolt and there was some machine marks on the firing pin and true keeper rivet. I polished that area of both. Testing will continue.