[450 Sniper]

Ok - went out to get a warm up session to shoot some Postal Match groups.

I'll be d*mned! 1 out of 3 shots had a FTF. I would cock the hammer again and 95% of the time she would go BANG.

So I read Swany's fix.

Popped the retaining pin out just far enough to remove the firing pin.

The OAL (to the step) on my pin was 2.760". I relieved the step on mine down to 2.745" - so I removed about .015".

I'm going out behind the house right now with 100 rounds. I'll report back in a bit.

 

[450 Sniper]

Re: My rebounding hammer finally caused me grief!!!

That solved most of them. I still had 3 out of 100. One was a Rem Golden Bullet - I hit it 5 times and it simply did not have any primer material in it.

The other two were Win Super X. One more cock of the hammer and they fired. Unacceptable.

Here's a picture of the firing pin strike. It is well defined with sharp edges. I noticed a couple of spent cases had a little bulge in the middle area of the case head (below the pin strike) - probably due to the area I relieved from the firing pin. I don't believe it's a safety issue, just an observation I noticed.

I'm going to go into the rebounding hammer spring area and see what I can do. If I can 'eliminate' it, I will.

I really believe this has to do with pin strike speed. Although well defined, the strikes were not as deep as I am used to seeing on a rimfire. That hammer is getting slowed down somewhere on the way to the firing pin. When it gets there it is not hitting full force.

More to come.

 

[IlikeMounties]

Re: My rebounding hammer finally caused me grief!!!

What is this "rebounding hammer" you speak of? My 39 is a 1955 so I'm assuming mine doesn't have this.

 

[450 Sniper]

Re: My rebounding hammer finally caused me grief!!!

Ok. I did it.

First off, I DO NOT ADVOCATE WORKING ON A FIREARM YOURSELF!!! USE A QUALIFIED GUNSMITH!!!

Having said that, here you go:

I found that the hammer spring guide has 2 lobes. One goes into the hammer and acts like it has since 18??. The 'new fix' is a lower camming lobe that sets your hammer to the half cock position after firing.

The problem and reason for FTF's? Your hammer is being slowed down half way to hitting the firing pin. The lower camming lobe begins resistance against the same hammer spring that just brought the hammer forward.

Now, I could have simply cut off the lower cam lobe and called it good. But I'm not half assed and I like to do good work.

SO - I re-shaped the lower cam lobe and hand file/fitted it until it BARELY has any tension against the hammer spring.

The pictures are all self explanatory.

How much did I take off? Quite a bit. Look at the photos. I didn't measure before and after because I was in new territory for me.

;D

You can see in the final assembled picture the trigger is NOT set into the half cock notch. It does however still set back safely from the firing pin. I'm pretty sure the function of this rebounding hammer is to lock the hammer in the half cock notch so if the rifle is dropped on the hammer it cannot mechanically fire. PHOOEY!! It doesn't mechanically fire when I want it to.

Why is this important to me? This is my survival rifle. Read: it purpose is to feed me. If I get ONLY 1 shot and this sucker does not go BANG I might starve. She needs to be 100% for 100% of the time.

Someone might want to sticky this fix for those 'garage gunsmiths'. I just used my Dremel and a flat file. It took about 5 minutes to fit it correctly and have the 'just right' camming action still present.

 

[Radar 1]

Re: My rebounding hammer finally caused me grief!!!

Sniper, how much attention have you given the internals? I have done the firing pin mod, while I was there I polished the pin surfaces, and the channel in the bolt. When I did my trigger(a little over 2# now) I cleaned up all the machined edges in the action, and polished all the contacting surfaces and pins.
I use CCI standard velocity and Blazers, Federal Champion and Auto Match, and just tried out the Remington Target standard velocity-which I was impressed with. I haven't had any FTF with any of this ammo. I haven't tried the Federal bulk 550's, only because I haven't seen it at my LGS(his prices are low, so I buy from him).
Good luck getting her running right, it'll get there!

 

[Radar 1]

Re: *Renamed* Rebounding Hammer Delete (almost)

Sniper, looks to me like you angled the cam back and took away about 1/8" does this sound correct? Great idea and fix!

 

[450 Sniper]

Re: *Renamed* Rebounding Hammer Delete (almost)

I would say a GOOD 1/8". Then at the 7 o'clock position on the bottom of the lower cam I gave it a half round profile with my Dremel.

I just went out and shot another 50 rounds. This time I used Win Super X and still had 2 FTF's. But it ABSOLUTELY was not my rifle - it was the ammo. I hit 'em a couple of times to be sure.

Comparing fired cases from before the spring guide mod to after, the firing pin indents are now TWICE as deep and look like they are supposed to.

I can say with 100% certainty if my rifle fails to fire it is the ammo's fault.

;D

Now I am inspired, so I'm going to sit down and give her an action job. After 4000 rounds she's still stiff to work the lever.

 

[450 Sniper]

Re: *Renamed* Rebounding Hammer Delete (almost)

Well, I also gave her an action job and a trigger job.

The two grittiest points were on the bolt.

The contact point on the bolt where the lever engages had already polished itself up pretty good.

One area was where the bolt made contact with the top of the receiver - the other was on the side of the bolt where the ejector rubs against it.

A few swipes with a fine cut flat file across the top and 10 seconds with my Dremel and the right bit where the ejector went - REAL smooth action!

I brought the trigger down to a crisp 2#'s. That was a 2 minute job with a fine cut triangle file.

The only part that made the action feel 'heavy' was engaging the the hammer spring. SO - I installed a Wolff reduced power hammer spring.
NOW it was real slick & easy.
Out to test fire....................
The FTF's were back. Upon inspection of the case rims the firing pin indentations were identical or even a little less than before I started this venture.

Wolff spring back out and factory spring back in.

Project complete.

 

[rhendrix]

Re: *Renamed* Rebounding Hammer Delete (almost)

Guys let me tell you how to take care of all these problems. Take your new 39As and trade them for an older model. Pre 70 preferably but anything prior the rebounding hammer and cross bolt safety will do fine. Then you will have yourself a fine .22 that you can be proud of and one that will shoot when you pull the trigger. My 1965 model shoots anything I put in it.

 

[450 Sniper]

Re: *Renamed* Rebounding Hammer Delete (almost)

Mine works great now that I took care of Marlins 'fix'.

 

[CKB]

Re: *Renamed* Rebounding Hammer Delete (almost)

Nicely done Captain!

So am I to take away that the rebounding function is pretty much gone...........or does it still come back a little? I have a new, unfired, 39A that I need to put through it's paces and this gives me great hope should I have any issues.

Thanks for posting this. 8)

 

[450 Sniper]

Re: *Renamed* Rebounding Hammer Delete (almost)

The rebounding function no longer rebounds. It functions as though it was never built that way.

Just cutting off the lobe will result in a 'floppy' hammer when it is not cocked or placed in the half cock position.

The way I did it, you would never know............................

Want to test just how much tension is in that rebound?
With an unloaded firearm, tang safety 'off', holding the trigger down in the 'fire' position - using your thumb, see how much force it takes to push the hammer forward towards the firing pin.

See what I mean? Get rid of that.

I would save yourself any future trouble and do the 3 main mods:
replace the extractor with a Wisners
mod the firing pin (make the step about .008" - .015" deeper)
and 'kill' that damn rebound!

DISMISSED! ;D

 

[badfish314]

Thanks for the before and after pics. I worked on mine last night but Im still having some resistance moving the hammer forward so I'll need to go back in and do alittle more file work. I really hope this fixes the FTF on my 08', I already did the FP mod and it helped alittle.

 

[swany]

Now if want to use the safety you will have to pull the hammer back a little, but you do have a half cock now

 

[Radar 1]

Swany, I was waiting for your input on this mod. I knew it wouldn't be long, so now without further delay I'll perform it on mine

 

[450 Sniper]

Thanks for the before and after pics. I worked on mine last night but Im still having some resistance moving the hammer forward so I'll need to go back in and do alittle more file work. I really hope this fixes the FTF on my 08', I already did the FP mod and it helped alittle.

Just take off a swipe or two at a time. Put it back together (just the guide, spring and retainer) and see where it is at. Mine comes back about 3/16" from all the way forward.
If you take off too much the hammer will be sloppy when it's all the way forward.

I use my 1/4" screwdriver with the bit removed to put the spring and retainer back together.
Put the spring guide and spring in place, angle the retainer into place (the top will point forward and down), then simply put the driver bit hole over the end of the spring guide and push the retainer into the slot.
It makes it really easy.

I just got back from running mine until my fingers were sore from levering it. NOT ONE SINGLE FTF!

If you've got 5 minutes or so, this IS the cure.

 

[Radar 1]

I did mine last night, turned out perfectly! After the initial trim I was a little apprehensive about how it was going to work, but after several fittings I got it down to zero rebound and still had a tight hammer. For those doing this mod, be aware that the hammer will still drop from the half-cock position when the trigger is pulled. I don't know if there is enough force to fire a round, but I assume it's possible.
Thanks for the great tip, this rifle is perfect now.

 

[450 Sniper]

Your welcome, Radar.
I did forget to mention the 'drop' from half cock. I don't think it would fire a round but I wouldn't chance it.
Now the tang safety has a purpose! (The best safety is still in between your ears).

Have you shot it yet?

Mine shoots ANYTHING I put in it now. It truly is 100% reliable.

 

[bowhunter472401]

I did the same fix to my 39A last fall with no ftf's. A couple of days ago I placed an order with Midway USA and ordered me a Wolff reduced power spring and installed it this evening when I got home from work and needles to say that gun action is SLICK!!!!! I also performed an action job on it back in February. I loaded the magazine tube up and went out back behind the barn and shot them. There were no ftf's and the firing pin mark looked as strong as with the factory spring. I know it was only 19 rounds, but so far so good. I will update later when I can get a good afternoon plinking and let you know how it turns out. Dan

 

[450 Sniper]

Dan - Let me know. I've had bad luck with TWO guns with the Wolf reduced power spring. maybe it's the spring I got? I first tried it in an 1894 44 mag. FTF's. It sat in my goodie drawer for a couple of years. I read the package and it includes the 39A, so I thought 'what the heck?' and put it in. Right back to FTF's.

Maybe I'll stretch it out some and see if that helps. It really did help with making the action cycling smooth vs. kinda chunky.

Is yours the 'straight body' design? Do they make a 'tapered body' design?

I also have the reduced power finger lever plunger spring, but I never installed it.

Let me know how yours does.