Converting the Ruger 10/22 to .17 Mach 2: here's one person's story of the problems encountered and the solutions devised while converting this popular Ruger rifle from .22 to .17 M2.
By the time we returned home from Camp Perry and got back into the daily grind, it was the end of August. I started researching what was needed and began planning my project. Due to the higher pressures, I needed a heavy bolt handle, a quality barrel, and a new stock. I ordered the parts from Midway USA (800/243-3220)--all of which were advertised as "bolt-on"--and started the assembly. I did have a little trouble installing the barrel, as the shank was the same size as the receiver hole. I called the manufacturer and they suggested I just put it in a vise and sand it down until it fit. Since I have a lathe, I decided I could do a better job with it than with a piece of sandpaper. And I didn't mind the extra work as it allowed me to get a better fit of the barrel to the receiver.
With the new barrel and heavy bolt handle installed on the receiver and this bolted into the new Houge (800/438-4747) overmolded rubberized stock, it was time to go to the range. On the drive to the range I had visions of shooting tiny groups with this rifle. What a disappointment. The best I could do was about 2-inch groups at 50 yards. I tried three different brands of ammo. The results were the same.
I decided to take a closer look at some of the cases, and found them to have bulged bases and some of them were ruptured at the rim and necks. I first suspected the bolt handle and spring might not be heavy enough for the extra pressure. After a long conversation with the bolt-handle manufacturer and some proper measuring of the headspace (specification: 0.042 to 0.045 inch), I found the headspace to be 0.047 inch. I corrected this and tried the rifle again, but still had bulged and ruptured cases.
By this time, Carl had ordered a new bolt and handle combination from another manufacturer, and he offered it to me to try in my rifle since he was still waiting for his barrel to come in. The results with Carl's bolt and handle were the same--bulged and split cases. I weighed Carl's bolt and handle against mine and found them to be within a few tenths of an ounce. The headspace of both bolts were within 0.0005 inch.
After more head-scratching and phone calls, I was beginning to suspect the barrel, so I decided to send everything back. I must say the folks at Midway USA were great to deal with; after explaining what I'd been dealing with, they took everything back without hesitation. After doing some more research on the 10/22 bolt for the. 17 Mach 2, I decided to purchase a bolt from Connecticut Precision Chambering (860/343-0552). What I liked about CPC's bolt is that they put the weight in the bolt and not on the handle. The bolt came jeweled, polished, pinned, and headspaced to 0.0425 inch.
Now I had to decide on a new barrel. I have used barrels from most of the major barrel makers on my match rifles. After giving it some thought, I remember I had rebarreled a Remington 700 from .17 Remington to .223, and still had the old barrel lying around. After finding the barrel and taking a few measurements to be sure the bore diameter was correct, I decided to use this old barrel. Step 1 was to turn off the threads and turn down the barrel to match the chamber end of the stock Ruger barrel.
After turning the chamber end to the proper diameter, I re-chucked the barrel in a four-jaw chuck and centered it off the existing chamber. After the barrel was centered, I measured the old chamber to get as close to the end of the chamber as possible without taking too much off. I then faced the barrel off and cut the barrel shank to fit the Ruger receiver and it was ready to be chambered. If you've ever held one of the little. 17-caliber reamers in your hand, the thought of chambering under power ought to scare you. I know it scared me. So I locked the head and turned the chambering reamer by hand.
After turning the shank to fit the receiver and chambering it, it was time to move the barrel to the end mill to cut the extractor slots and the slot for the receiver block that would hold the barrel to the receiver. I first cut the slot for the receiver block, as this gave me a reference point for cutting the extractor slot. (You may notice that some of the photos show a finished barrel. I got involved and forgot to take photos as I was doing the work.)
The extractor slot is 10 degrees off of 90, so you need to set it up in an indexing head so you can rotate it to the proper angle. I don't have the type of machine or cutter to make the slot look like they do it at the factory, so I simply milled out the 3/8-inch slot to the proper depth and then used a 1/2-inch 45-degree dovetail cutter for the barrel block. I went slowly during this step, as I was making a cut to full depth and it's easy to snap the cutter if you feed it too fast. Once finished, I removed all of the sharp edges from the slot.
Once this step was done, I rotated the barrel and changed to a 1/8-inch woodruff cutter to mill out the extractor slot, taking care not to cut into the chamber wall. After finishing the extractor slot, the only thing left to do was to remove all the sharp edges, polish and blue the barrel, assemble the rifle, and go to the range.
With its factory-stock barrel contour, the rifle still looked very much like the original Ruger 10/22 at this point, except that the barrel is about 4 inches longer. The barreled action fit nicely into the Hogue overmolded rubberized stock made for a factory barrel contour.
After test firing and zeroing in, I fired several groups at 50 and 100 yards just having fun with the rifle. Then I fired a five-shot group at 50 yards to see just how well it did. After seeing the results, I couldn't help but put up a prairie-dog silhouette at 200 yards and see what I could do. (All five were "lethal" head shots.)
Although I wasn't able to go on the trip to Colorado, I was able to complete a very satisfying project that turned out even better than I expected. I hope you enjoyed reading about it as much as I enjoyed doing it.
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|Title Annotation:||The Custom Shop|
|Author:||Driscole, Robert E.|
|Date:||Dec 1, 2008|
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