Accurizing and Improving the Marlin 900-Series Rimfire Rifles

The Marlin Firearms Company has been around for quite a number of years and has put out some outstanding firearms, especially considering the company’s reasonable pricing structure. The project we will be dealing with here involves the latest Marlin, the Model 917V in the recently introduced .17 HMR and .17 Mach II calibers. The plan is to bed this rifle so that the mating of the barreled action to the walnut-stained birch stock remains stable and peak accuracy is achieved.

Then we’ll see what can be done with the fire-control system. Taking the Measurements/Bedding the Action The large screw just in front of the magazine cutout in the stock draws the rear end of the barrel down into the stock. As you can see from the accompanying photo, the wood has already been compressed somewhat from the assembly process at the factory. The plan now is to prevent any further compression of the wood fibers in this area that would create havoc with the bedding.

We need to remove the stock from the barreled action to take a few measurements. By now you should be very aware of the need to ensure that the magazine and bolt have been removed, and that you’re working with an empty chamber. Before removing the stock, be sure to go through that routine. Looking down into the stock of this rifle you’ll observe that the front takedown screw has a receptacle for the threaded extension dovetailed into the bottom rear of the barrel.

With the depth-recording stem on your caliper, measure the depth of the large hole from the radiused face of the barrel channel down to the shoulder of where the smaller hole begins. Record this dimension. On this stock, the depth measured .844 inch. Next, measure the length of the threaded receptacle that’s dovetailed into the barrel. Measure from the bottom rim of the receptacle to the top of the barrel radius. In this case, that measurement was .498 inch.

Subtract this dimension from the depth you found the stock hole to be (.844) and we have one of the lengths we need to make the front pillar. In this case that length is .346 inch. Measure the diameter of the larger end of the hole in the stock. Figure 1. Front Pillar for Marlin 900-Series Rimfire Rifles

For this stock, that hole diameter was .500 inch, but it was somewhat eccentric, so I turned one end of the pillar’s outside diameter to .495 inch to achieve a slip fit. The smaller end of this hole measured around 7/16 (.437) inch, so the end of the accommodating pillar was turned to .420 inch, again to achieve a slip fit. The reason I maintained the stepped hole in the stock was to give a base for the pillar to sit on while the bedding compound hardened (see Figure 1).

The front pillar was a straight sleeve, 1/2 inch in diameter, with a .375-inch through-hole. The lengths of both of these pillars will vary somewhat and will need to be trimmed to fit at the bottom of the stock as close to flush as possible. Once you are satisfied with the fit of both pillars it’s time to permanently set them in place. Coat the outside of each pillar with whatever bedding compound you prefer and let the bond set up, at least overnight.

The next step in the process is to bed the action to the stock in the two areas of the pillars. Remove some of the wood around the pillars to a depth of around 1/8 inch, but stay at least 1/8 inch from the upper edge of the stock in the area where the action rests. The idea here is to give the action a firm place to sit and maintain its position in the stock once the action screws have been turned tightly into place.

T-900 Fire Control System The engineers at Marlin have developed anew trigger and safety system that’s being used on all of their bolt-action rimfire rifles. This trigger system is a well-thought-out design (except, perhaps, for the plastic trigger). On the 917s I’ve worked on, the plastic trigger had quite a bit of side-to-side wobble. My electronic trigger-pull gauge measured the pull at 5 pounds 9 ounces using the average of five readings.

Rifle Basix, Inc. of Charlotte, North Carolina, markets a CNC-machined steel trigger that has a range of adjustment from 14 ounces to 2 pounds, yet the sear maintains a good, safe purchase. We’ve all read about how aftermarket parts "drop in" with little or no gunsmithing required. Well, this trigger does just that; it actually does drop in and replacement is extremely easy. Again, after making sure you are working with an empty chamber, remove the bolt and magazine before any takedown is started.

Push the safety forward. Tighten the barrel up

in your padded-jaw vise and situate the action so that the trigger is facing you so you can work on it. You’ll notice a tiny E-clip at the bottom of the trigger housing on the left side just above the trigger. Using a small flat-blade screwdriver, push this clip rearward until it pops off the trigger pin. The trigger pin should now push through to the right side of the trigger housing. The factory plastic trigger can now be removed.

The instructions included with the Rifle Basix steel trigger recommends that the threads on the sear-adjustment screw be upset or crimped lightly—very lightly. I don’t know how to measure "lightly" to any degree that would get the intended results, so I went at this step very cautiously.

Using a pair of needle-nose pliers with a set of wire-cutting jaws, I did a very light pinch between opposing threads around 1/4 inch from the opposite end of the hex socket, and then tried the modified sear-adjustment screw in the front receptacle of the trigger housing to see if there was some resistance to turning. If you look closely, the photo below will show you what the crimp should look like. The idea behind the crimping process is to secure the sear-adjustment screw temporarily in place.

Once you have achieved safe sear engagement, place a dab of thread locker in the threads where they protrude out the bottom of the trigger. What worked best for me was to install the trigger with the sear-adjustment screw in place in the trigger housing, and then replace the retaining pin and E-clip. This may require that you wiggle the safety back and forth a bit until you can get the trigger-pin hole aligned and the trigger installed.

Then slide the weight-ofpull spring through the hole in the rear of the trigger, followed by the weight-of-pull adjustment screw. Insert the bolt into the action and try cocking the bolt. If sear adjustment is too light, the striker will follow forward as the bolt is lowered. Adjust the sear-engagement screw either in or out until the bolt closes safely and sear engagement is solid. Conclusions The final step is adjusting the trigger pull to the weight you desire with one of the hex wrenches Rifle Basix provides.

I was able to achieve a safe pull weight of 1-1/2 pounds with this trigger with a solid sear engagement. The combination of pillar bedding and the Rifle Basix trigger improves accuracy and makes the little Marlin a real joy to shoot. ■