I have had a Wisner magazine spring istalled to my Winchester m70 Stainles Classic. This gives me four rounds down in the magazine.
The problem is when I close the bolt over the ful magazine and then retract the bolt again to start feeding from the magazine the front end (bullet end) of the first round popps out while the rear end i stil in the magazine causing a jam. With three rounds in the magazine the rifle feeds just fine.

Is this a problem that can be fixed, any ideas as to what is the reason for this malfunction?

The reason for the malfunction is that you don't have enough clearance for that 4th round. Go back to using three in the magazine and practice your marksmanship.

If you still have the factory mag box you aren't going to get 4 rounds down and make it work (here's the important part) right.

Thanks for your replys!

I am however not sure that what you suggest is the acctual problem. I have a Blackburn triggerguard/florplate wich I intend to install ont this gun. This setup i designed to give four rounds in the magazine using the factory magazine spring. To make it fit you'll have to cut about 1/4 inch of the magazinebox. If I assembel the gun with Blacburn botommettal and uncut magazine box I have ample room for four rounds in tha magazine but still have the same feeding problem.

Does this give someone any idea as to what is causing this problem?!

Carl,
I don't know the cause, I'm no gunsmith, am not particularly mechanically inclined and didn't stay at a Holiday Inn Express last night. I do know the solution however. Send the rifle and a hundred dollar bill to Dennis Olson. It will feed empty beeer cans then, to quote our buddy Ray, who is on hiatus.

LD

quote:

Originally posted by Carl:
I have had a Wisner magazine spring istalled to my Winchester m70 Stainles Classic. This gives me four rounds down in the magazine.
The problem is when I close the bolt over the ful magazine and then retract the bolt again to start feeding from the magazine the front end (bullet end) of the first round popps out while the rear end i stil in the magazine causing a jam. With three rounds in the magazine the rifle feeds just fine.

Is this a problem that can be fixed, any ideas as to what is the reason for this malfunction?

Put 4 rounds in the magazine and take a good look at how the last round sits under the feed rail. It should sit fairly snug under the rail and against the side of the magazine. Push down on the round and estimate how much verticle room you have between the top round and the bottom of the bolt. If there is not sufficient verticle play, the round may not be sitting under the feed rail with enough side pressure to keep it in place as the bolt drags over it. Try reducing the spring tension a little by holding the floor plate slightly open while you try to feed the round.

I assume you are running into this trouble with a magnum cartridge? If so the problem is that the cartridge stack needs to be made wider. To make the cartridge stack wider you have to make the magazine box wider. On those winchester boxes there is a jog in the back of the box on each side. You will need to forge the jog out on each side. You can do this by clamping a piece of barstock that's 3/4 square in a vise, then grab the box with a pair of pliars and use a torch to heat up the jog area red hot, place the heated box so the barstock is going thru the box opening hold the box nice and flat on the bar stock while red hot and use a hammer to flatten out the jog in the back of the box.

step two: on the top of the mag box there are two long ears the run almost the length of the box, you'll have to file or grind a taper that points down into the box this will leave the top of the box ears sharp. Then just slightly knock the sharp edge off those ears with a file.
polish out the marks you've left. These changes will allow the top round to sit over farther and get under the rail. The stack will also be spread wider leaving some more vertical room so you can run the bolt over 4 rounds easier and more smoothly. As the top round climbs the feed ramp the back of round also pushes down on the other three below it this effect causes a tight situation and can be minimized by bowing the front 1/3rd of the feed rail slightly with a dremel and the orange tapered stone they sell or you can shape your own stone with a dressing block. The feed ramp on those are rough and should be polished as well. Check the end of the chamber to see that it has a good corner break on it I've seen sharp brass snagging edges there before. As far as the sunny hill metal you can taper the top of it too the same as on your stock winchester box. Then it will do what you want it to do.
Timan