What's new
What's new

Locking Block material for a Charles Daly 20gauge

mjk

Titanium
Joined
Oct 20, 2005
Location
Wilmington DE USA
I've been tasked by a friend to replicate a "locking block" for a Charles Daly 20 gauge.
The failure surface implies a casting, possibly a forging.
Apparently an unobtainable part.
Suggestions for material?
 
Is it just worn or broken? If broken, Id silver braze it back together. If worn, its common practice to weld up the surfaces with Hardfacing rod and machine/grind back to dimensions.
 
I thank the responses so far.
Most of my work involves as a poster in another part of this site calls "shiny wood" but I've done my share and been witness to parts of this required detail in a variety of carbon and stainless steels.
My plan was to first create a drawing with all the details primarily for my first op.
If I go the replace route I will start with a laser cut blank as the one detail, what I'll describe as the pivot point (right pic upper left corner)just looks like a pita evan with a cnc.
The rest of the work I believe I can accomplish with patience.(and possibly the 2nd or 3rd laser blank)
This will not be a money maker, a bit of a personal challenge and for someone who has done me many a favor without asking for payment..
I hadn't really considered repair until brazing was mentioned above.
I have experience with tig brazing.
These are pics of the part as given to me.

AT20-2.jpgAT20 1.jpg

Is it possible the manufacturer cast this part, the break looks like a casting fracture, not a tear I would expect from a wrought material ?
I also have the mechanism it needs to fit in.
Although I don't know the mechanics of operation I was shown what the locking block should do when fitted.
 
Ditto on the half hard 4140. Blank it out cold. No welding, duplicate it exactly as possible, put it in and forget about it.
 
The 20 guage locking block is a cast part, and has a high failure rate in these guns .No replacements are currently available . 4140 would be a good material, but braising is not a good idea . The part is under a ton of stress, during the firing and cycling of firearm. It could lengthen part and mess up head spacing. The headspace of gun should checked with new part installed. I own two of these guns, one has a failed locking block. Let me know if you have any luck replicating.. thanks, Bill
 
If the factory cast part has a high breakage rate, and the spare parts are long gone, then the casting was never up to the task originally. No amount of repairing will make it so. Replicate it in half hard 4140, and make a mechanical drawing for the other folks as you get it out.
 
Although I agree that 4140 would be a GOOD substitute, and no doubt much better than the original cast part, I would argue that 4140 is not the best choice in this case. If I were to make this part I would go with 8620 and case-harden. I just think it would wear better. However, EITHER would work well.

Both are readily available. And if all else fails McMaster carries them... The 4140 in a coice of flavors from annealed to pre-hardened.
 
I've been tasked by a friend to replicate a "locking block" for a Charles Daly 20 gauge.
The failure surface implies a casting, possibly a forging.
Apparently an unobtainable part.
Suggestions for material?

For material I would agree with the 8620. I feel it is a solid all around choice. I have also used 1144 fatigued proof ultra strength from McMaster on a few items, and was very please with performance and machineability .

Ultra-Strength Easy-to-Machine 1144 Carbon Steel Rods

Yield Strength: 125,000 psi
Hardness: Rockwell C30 (Hard)
Heat Treatable: Yes
Max. Hardness After Heat Treatment: Not Rated
Specifications Met: ASTM A108
Also known as Fatigueproof, these rods have enhanced strength and resistance to breaking from repeated impact compared to High-Strength Easy-to-Machine 1144 Carbon Steel Rods. Containing more carbon and manganese than other easy-to-machine carbon steels, 1144 carbon steel offers higher yield strength and hardness, even without further heat treatment. Use it to fabricate parts that require stress resistance.
 
I am in complete agreement with using materials that are more suitable and can be made harder than prehard 4140, so long as one has the capability and knowledge to heat treat them. Or if the person wants to take the extra step and expense to have them professionally heat treated. Prehard 4140 tops at about 38 Rockwell hardness. The beauty of it is that it machines well at finished hardness and is thus ready to go for most any pressure application that you are going to encounter in shotgun work. Just my 2 cents worth.
 
Any luck?

I've been tasked by a friend to replicate a "locking block" for a Charles Daly 20 gauge.
The failure surface implies a casting, possibly a forging.
Apparently an unobtainable part.
Suggestions for material?

Wondering if you have had any luck making that locking block? I have the same problem with mine. It has been sitting in the gun cabinet for 4 years because I cannot find a replacement part.
 
Any luck?



Wondering if you have had any luck making that locking block? I have the same problem with mine. It has been sitting in the gun cabinet for 4 years because I cannot find a replacement part.
As fate would have it I was tasked with making one of these a month ago. A neighbor of mine had this same failure. I made one from Type 01 Oil-Hardening Flat Ground Stock. Not sure if this is ideal. Long story short, I made one and with some sanding and filing to get it to fit. He took a few test shots and it worked. I plan to make 10 more or until I run out of stock.
 








 
Back
Top