I've got a 98 triggerguard that been worked on by person unknow and was wondering if it will work on a 98 Mauser in 300 Win mag. The feed rails on the rifle are currently 30-06. The internal box dimensions are: front .710", back .900" and length .340". My 30-06 measures 3.205" (a Remington 165 gr boat tail factory cartridge) and works in the box. Will this work on 300 Win Mag? If not...what will I have to do?

The mag box is too narrow to be properly dimensioned for the win mag.

3.4 would be best. This can be done by welding or soldering a piece of steel that is .100 thick to the front of the box. (first verticle wall behind the front pillar). Then set it up in a mill. Clamp it by the front tange, use a cross test level to get it level in repect to the machine, or dial it all in, (takes longer)comes out the same. Put a short stud in the rear guard screw hole and a mill jack under that, then clamp on the top of the guard with a bridge clamp and step block, snug it up. Now you are clamped in front and in back. Find center of the box in front with an edge finder. Find rear wall of the box with your edge finder.
move 3.4 minus .250 1/2 the diameter of your tool, calculate your y axis move for your width in front. Load a .5 e-mill and move to your calculated numbers minus .025 both x and y. with the quill set so you dont plunge through the whole thing, Leave .2 in the bottom of it.
Simply plunge out the old metal, then take a finish pass and your done. Cut the bottom of the feed ramp ahead .062. Put or box on the action and scribe the inside of the new front wall of the box, cut that out. Widen your action rails in back just enough to get the .530 belt through, open just the front courners of the feed ramp. bow the fornt 3rd of the feed rails as needed. Open the bolt face and refit the extractor. Silver solder method on the front of the box is a faster cleanup. The welded method you will be fileing and sanding out the welds.
Timan

Hi guys...I see a typo in my post...the box is 3.400" long already. Can somebody measure their 300 Win Mag box post the info and I'll compare the dimensions to mine. As I stated in my post...it works fine on 30-06....why not 300 Win Mag?

the original box CAN be made to work property,

take 3 300 winmags...
rubber band them together
measure the widest parts..

that, +.050, is what is required

jeffe

Get your barrel threaded and chambered first. Make a dummy round with a 200gr partition seated .020 off the lands, Then check your o.a.l. Make your box length .050 longer than the dummy round. I've been useing a 300 win. for 18 years now. I've tryed 150gr and 165gr bullets at over 3000 and they just make too big of a mess, lots of meat damage, bone frags and bullet frags everywhere. The 180gr gives the best trajectory and performance on deer and antelope; nice. 73.5gr of IMR 4350, fed. 215 primer and 180gr sierra pro-hunter seated at 3.410, at 3070 fps. Sighted 2.5 high at 100 with groups under 1 inch, it's a slam dunk deer and antelope round at 400yds. I have a the 200gr partition load waiting in the wings for Elk. If I was just going to shoot 165gr bullets I'd just stay with the 30-06.
Timan