M48 Topper misfiring - ideas?

[TheCoachZed]

So, I picked up an old M48 Topper for a rabbit/partridge gun, and to loan my friends when they hunt with me since they are too lazy/cheap to get their firearms licences (I'm in Canada).

I'm having problems with misfiring shells. The pin is striking the primer every time, but the shells often don't fire. I can take the same shell and put it in my Winchester pump gun and fire it, so I know it's not a dud.

Ideas? I cleaned out the firing pin channel but it didn't seem overly dirty to start with. The pin itself doesn't look like it's deformed and the firing pin spring seems to have lots of strength.

I realized very quickly that these guns are niggly to re-assemble, so I'd rather not pull out anything more than I already have (trigger group).

[quickdtoo]

Welcome! Read the trigger hone info in the FAQs and Help sticky, then you'll be prepared to replace the hammer spring which is the likely culprit, I don't know if the M48 has a single coil or double coil spring, but once you pull it apart you'll know for sure unless someone else offers advice. Wolff makes both springs.

Tim

http://www.gunsprings.com/index.cfm?page=items&cID=2&mID=27

[TheCoachZed]

I took it apart and re-assembled it again today. It fired three grouse shells with no problems, so maybe it was just a dirty pin. I guess I'll find out sooner or later.

[TheCoachZed]

Hey guys,

I took this gun out again today and ran a few more shells through it.

It shot the first few with no problems, then it started to misfire again. The firing pin makes a decent dent in the shells, but it won't set them off.

I tracked down a replacement firing pin ($20) and replacement hammer spring ($10). Before I spend $30 on a gun I bought for $40, I'm wondering if there are any other possible culprits?

[quickdtoo]

I don't think the M48 has a transfer bar, so no blame there, excess headspace may be the culprit, on modern frames, modifying the hammer will allow a deeper pin strike, I don't know if that's possible with the M48 tho. You might try some different ammo, that's been a known solution sometimes.

Tim

[TheCoachZed]

I thought about headspace, but thought that would be more consistent. Anyway, there is no transfer bar, and trigger pull seems to make no difference. Weird.

[TheCoachZed]

Upon closer inspection . . .

The teardown instructions here http://books.google.ca/books?id=zRJm6uF7TSIC&pg=PA138&lpg=PA138&dq=h%26r+model+48+topper+disassembly&source=bl&ots=T-AkmL1yf0&sig=hHPFN54T6GoV9Z_JzX8UWoVOHAI&hl=en&ei=5CWuS9bzJMHflgeOs_ykCw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAYQ6AEwAA#v=onepage&q=h%26r%20model%2048%20topper%20disassembly&f=false

show a dual coil hammer spring. I can't find one of these in my gun - the only spring that is forcing the hammer to strike, as far as I can tell, is the spring on the rod that goes through the tang, under the barrel latch.

Perhaps that's the problem - I'm missing a spring?

[quickdtoo]

The M158 shown there isn't the same as the M48, it was made long before the M158, and is made totally different, the M158 doesn't have a spring in the tang nor a swing lever barrel release, the internal parts are the same as a modern frame for the most part.

Tim

http://www.gunpartscorp.com/catalog/Products.aspx?catid=8085

[TheCoachZed]

Yes - but is that spring in the tang simply for the barrel latch, or is it intended to be the hammer spring too?

OR

Does the Model 48 have a dual coil torsion hammer spring, like most older H&R guns? Because if it is, I can't find it in my gun.

[quickdtoo]

I don't know, I've never taken my 1940 H&R 12ga apart!!  The older Toppers do use double coil springs tho, Wolff makes extra strength replacement springs for both current and old H&Rs.

Tim

http://www.gunsprings.com/index.cfm?page=items&cID=2&mID=27

[TheCoachZed]

Here is a pic of the receiver . . .  does this give anyone any more information?

[quickdtoo]

Here's are two of Numrich's parts lists for the M48, diagram shows a more modern frame tho, yours is older, the 48 was made 1943-1956, serial number may be on the bottom of the tang if it's not on the left side of the frame.

Tim

http://www.gunpartscorp.com/catalog/Products.aspx?catid=8109

http://www.gunpartscorp.com/catalog/Products.aspx?catid=8085

[demented]

I had an older H&R that did about the same as yours.  My "fix" was to add a hammer extension, the added hammer weight made it work just fine. 

[john-78]

i'm workin on a .410 for a buddy with simuliar problem.  his is a wore out hammer spring, it'll throw the hammer, but not enough to compress the firing pin fully.  his is a double spring, and midway has them for like six bucks i think. hope this helps, john

[TheCoachZed]

I like that hammer extension idea. I'll give it a try.

I took the gun apart and cleaned it again, and it seems to strike harder now. We'll see how it goes.

[quickdtoo]

Took mine apart, maybe it will help. 

Tim

http://www.gboreloaded.com/forums/index.php/topic,204954.msg1099071943.html#msg1099071943

[TheCoachZed]

Yeah, I've had the trigger group and mainspring out of mine. Still can't seem to figure it out. I think I'm going to buy a Survivor now instead.

[quickdtoo]

The firing pin was pretty well seized up on mine, although the last time it was fired 14yrs ago, it worked fine even tho it's really gummed up now. It's free floatiing with no return spring and relies on inertia since it's not full length, yours may just need to be cleaned if it's built similar.

Tim