I didn't know there was a Model 70 300 RUM, and if that was a 3.6" long. I could be wrong. I found a 300 Ultra Mag which I modified. (Right length and width, just had a ridge to shave down)
Model 70 magazine limitations
- Thread starter reggart
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XSIVSPD
Well-Known Member
Yep, I just realized after I finished typing. Yes, that's the one I found, but still needed some modification. Worked for me.
Rhett Crider
Well-Known Member
measure your factory magazine box and see how long the internal measurements are if you were to drill out the back plate spot welds and if that gives you the length you don't need any new box. I changed a 1917 enfield into a 375H&H years ago and used the original follower so try your and I'll bet it will work. The bolt stop can be carefully ground on to allow the bolt to travel farther to the rear just look in there and you can see how it works. If it has a plunger ejector in the bolt face nothing needs to be done.If it is a controlled feed with a mauser style extractor you will have to get creative and modify the ejector or with a piece of steel make one. I just did these types of modifications to a short M70 action because I wanted to chamber it in 284 and I was able to get it to feed 3.080 rounds, don't be nervous to attack your action to create what you want, nowadays everybody thinks you need a gunsmith to do everything but how do you learn unless you give it a try. I would be carefull about grinding feed ramps or rails because you don't want to remove too much or don't remove any spot that is a bolt abuttment just use common sense and give it a try. People make it seem that working on these guns is voodoo and only gunsmiths can do it. very not true. I like building anything and build whatever I need so when I started shooting Highpower I used up a barrel a year so I bought the reamer and floating reamer holder and headspace gauges and put my own barrels on, then if you have the gear I cut an inch off the breach end after the throat wears and rechamber to get more life out of the barrel. so if I can do this I'm sure you can jump in there and attack that action and make it do what you want just rationalize what needs to happen to allow the bolt to travel farther to the rear and how to make the box longer. M70's were made in 375 length and the action was no different than a regular long action just the bolt stop and ejector if controlled round and magazine box. good luck
