Gunsmithing Win. M70 Magazine Feed/Retention Problem

[CNJarvis]

Guys, I'm hoping someone on here can help me out with this.

I have a Winchester M70 that I believe is an early black shadow model (push feed)with a blind box mag that will not retain the first round into the magazine. I've tried a new follower and a new magazine spring with no improvement. If I stretch the original spring out significantly it will sometimes hold the first cartridge but it pops out of the mag too soon and goes sideways in the receiver before I can chamber the round.

Any ideas how I can cure this without going to a DBM such as CDI or such?

Thanks.

 

[boltstop101]

I had one doing the same thing and it was the lips on the mag box .

 

[CNJarvis]

There aren't any lips on the mag box. They're machines into the bottom of the receiver.

 

[Turd in the Pool]

There aren't any lips on the mag box. They're machines into the bottom of the receiver.

Sounds like there might be a communication gap here. What cal. is it? Most mag boxes are cal specific. Regardless, opening the width of the top of the box will usually fix it. The WSMs are cut out completely at the top so the resting cart. in the mag only rides on the receiver.

 

[CNJarvis]

I suppose I should have specified the caliber... D'oh!

300 Win Mag.

 

[Turd in the Pool]

If the top of your mag box is bent in it needs to be opened up. If the walls are straight I suspect the rails on your receiver are too wide. If that's the case you can only widen the top of the box or get out the tig. Best bet would be to get another mag. cal. rifle and measure.

 

[CNJarvis]

The mag box is straight. I don't know anyone who has a winchester m70 in a magnum caliber unfortunately. I wonder if someone on here could measure theirs and report back.

If it has to be TIG welded, how much would something like that cost?

 

[Turd in the Pool]

The mag box is straight. I don't know anyone who has a winchester m70 in a magnum caliber unfortunately. I wonder if someone on here could measure theirs and report back.

If it has to be TIG welded, how much would something like that cost?

I have one here but I won't have time to measure it soon so if anyone else can help, please do.

I would only tig it as a last resort. I would charge 3 or 4 bills so DBM comes into play. The simple solution is to open the box to allow more space under the rail. Do you have any problem with the left side or rnd 2?

Something else to check is the position of the spring. Make sure it is all of the way back. Sometimes people push them forward too far and it will cause this.

 

[CNJarvis]

I'd considered the position of the mag spring and tried to position it to the rear but being a blind mag, there doesn't seem to be much I can do.

At 300-400, I wouldn't consider anything less than a DBM. Frankly, I don't know that I'd purchase a new bolt action unless it had one anyway.

Thanks for all your input! Hopefully someone else can chime in with those dimensions.

 

[CNJarvis]

Ok, I did some tinkering this afternoon and THINK I've come up with at least a temporary solution. We'll see how it holds up...

I've noticed that the follower tilts quite a bit in the mag box and when loading the first cartridge, the follower tilts toward the opposite side of the magazine. The tilting appears to be preventing the follower from pushing the cartridge into the side of the magazine box/receiver. To correct the slop, I cut two pieces of plastic laminate (.036" thick) and placed them inside the left side of the magazine box at the front and rear and trimmed them flush at the top and bottom. They were held in place with double-sided scotch tape. I reassembled the rifle using a new magazine spring and loaded a couple of empty cases. The first case no longer barfed out but the follower bound up in the mag box as it appeared that the shim at the back wasn't allowing enough clearance. I removed the shim and loaded the magazine full. The binding issue was corrected, the magazine no longer barfs rounds out and empty cases feed smoothly.

Now let's see how long that lasts...

In the meantime, I've ordered a new Magazine box from Winchester just in case.

 

[Turd in the Pool]

Ok, This is not a push feed action but the numbers should be the same. Feed rails at rear .610" ft .655" rear of mag box .965" It's mag spring has a "hump" in the 1st bend at the bottom like the 375's & 458's.

After reading your last post it made me think. Haven't seen too many blind mag 70's but most if not all have a stamped metal piece attached to the bottom of the spring to keep it centered in the well. If you don't have that, we may have found the problem. ;-)

 

[CNJarvis]

Haven't seen too many blind mag 70's but most if not all have a stamped metal piece attached to the bottom of the spring to keep it centered in the well. If you don't have that, we may have found the problem. ;-)

That may indeed be the problem. I do not have that. From digging around on Numrich's website, it appears that part is called a "stock floor plate". I'll call Winchester first thing monday morning and see if that's required based on my serial #.

ETA: After looking at the original tupperware stock, there is a depression cast into the bottom of the magazine well in the stock that appears to serve just that purpose. I had the retention issue prior to replacing it with a Boyd's stock but that may have been due to improperly locating the magazine spring in the mag well on reassembly. Now the trick will be keeping the spring in the correct location in the Boyd's stock. I may be able to do some judicious wood removal in the same location in the Boyd's stock to create the same depression.

 

[Turd in the Pool]

Just cut a piece of cardboard or something that will hold the spring in place for a test drive.

 

[CNJarvis]

Great idea but I'd already chiseled out a recess in the stock by the time I read it...

It worked like a charm but I decided I'd really rather have bottom metal so I ordered the aluminum Oberndorf bottom metal from PT&G and installed it. I did have to order a new magazine box from Winchester as once I inletted the stock for the BM, the original mag box was too short by about 1/8". For those wanting to make the conversion: the new mag box is from a current production M70 with one-piece bottom metal as req'd for your particular cartridge. I did have to fit the new mag box as the angle on the bottom wasn't quite right for the stock.

This is what I wound up with:

 

[Turd in the Pool]

Looks good!

 

[CNJarvis]

Looks good!

Thank you and thanks for all your help!