25-06 to 264 win mag


Feb 13, 2018
I've got a older Ruger MKII varmint/target rifle in 25-06. I'm expecting the barrel to being closed to shot out. Will the action be long enough to convert to a 264 win mag round? Thanks for any info.
That I am not sure as I have no personal experience with that particular rifle. I imagine spare bolts for that particular rifle would be difficult to find.

If you can't machine the bolt face one other alternative you could look at would be the 6.5 Weatherby RPM, similar performance to the .264 Win Mag but has a standard .473 rim so you wouldn't have to modify your action.

If I found a left handed-magnum bolt could it be taken apart to build a correct bolt for my possible bui9ld?
I would prefer to convert the .25-06 to a 6.5-06 or a 6.5-06 AI (Ackley Improved). Same size .473.

The Ruger M77 MKII is a controlled feed bolt gun, & in .25-06 is of the length for .30-06 rounds

As mentioned the bolt face would need to be opened up and the extractor modified, an extra expense. The hardened steel bolt face requires some attention to open up.

The magazine box would need to be replaced with a magnum type. Comparing the .30-06 magazine boxes with 7 Rem Mag boxes it can be noticed that the mag box is fatter and the follower slightly wider. The stock would need minor modifications to accept the fatter mag box.

The 6.5-06 is a high performance round and is very popular meaning easy obtained brass using .25-06, .270, & .30-06 and relatively low cost dies. Lots of reload data available.

The AI (Ackley Improved) version gets about 100 fps more velocity but requires fire forming and additional expense dies.

Both rounds like H1000, RL26 with 140 grain bullets and RL23, H4831 with 120-123's and H4350, RL16 with 100's. More than adequate big game performance with 140's, fine long range yote/chuck with 120-123, and real good splat factor with 100's (3400 fps) but no prairie dog gun.

I would suggest, if more is needed than a 6.5-06 get a rifle chambered for a real big 6.5.
Lots of input here.

Looking at the receivers for both standard and magnum cartridges, R M77, MKII shows that they are essentially equal in dimension. Ruger/Pine Tree Castings claims they can hold tolerances within .007 for their investment castings.

The difference is in the magazine box. The front top (bent in feed lips) of the magnum magazine box measures .805, for the standard magazine box .695 - a big difference of .11 inches. The bottom front(s) of both magazine boxes are much identical, .925 standard, .955 magnum. The lengths are about equal .010 (+-). All this means is that a standard long action M77 MKII will accept a magnum M77 MKII magazine box. Very minor stock work might be involved - like less than 5 minutes.

The front of the standard follower measures .680 and the magnum .715.

My thinking is that I would need to pay $75 to open up the bolt face, modify the extractor and get a new magazine box and follower for the fatter cartridge. I guess the additional cost would be $110, depending on availability of parts. This is more of an incentive to stay with a .473 cartridge and live with 100 fps or so less velocity. This is why I have 2, 6.5-06 rifles. Just love the cheap brass also.

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