Servicing the Remington M504 Bolt-Action Rimfire Rifle

An owner’s manual is delivered with every new Remington Model 504. Like all similar booklets, it will not be studied by the owner and, in all likelihood, will be promptly lost. From that common scenario come many of the problems you’ll encounter with the 504—and most other firearms. This, of course, is good for your bottom line; so don’t be too hard on these gun owners, and be sure to listen patiently to their complaints, showing no sign of contempt for their carelessness.

Some of the problems with the 504 are certain to be ammo-related. That’s because the owner’s manual advises that the diet for factory testing the firearm was of Remington manufacture, and recommends its continued use. This is actually good advice. You see, small-bore guns are among the most finicky eaters—the 504 is no exception—and .22-caliber cartridges do vary dimensionally from maker to maker.

These variations may be slight, but the gun will show the difference by not shooting as accurately or by reacting in other unpleasant ways. Usually, the cure for minor small-bore problems is to try several different brands. The one that works best should become the gun’s standard ammo. Another test, not solely for the 504, is to ask a customer complaining of feeding problems to load up a magazine as you watch. In every case, around should be inserted with pressure being applied exclusively to the rim.

When a clip magazine is correctly loaded, the forward three-quarters of the topmost bullet will protrude above the lips of the clip. Incorrectly loaded, nothing is visible. This indicates the bullet(s) have been pressed down by the nose and the rims are overlapping. What happens? Bolt override. No cartridge stripped off. No chambered round. Nothing but the dreaded "click" of a dry fire.

Of course, not having a magazine fully inserted causes the same problem, as do really dirty magazines or damaged magazine components. The owner won’t know that. Since he never read the manual, he won’t know how to properly clean his 504, including the bolt, magazine, receiver, and trigger assembly. You haven’t read the manual either, but since you’re reading this you’ll know more about the gun than your customer. And that’s the way it should be.

Field Stripping The chamber’s empty, the safety is "on," the magazine has been

removed, and you’re wearing eye protection. Raise the cocking handle, pull it partially to the rear, depress the bolt stop on the side of the receiver, and slide the bolt assembly all the way out. There are two takedown screws; one (#37) is located forward of the magazine housing, while the other (#35) is just forward of the trigger. A 1/8-inch Allen wrench will remove both. There’s no need to remove the rear guard screw. With parts #37 and #35 out, the action can be lifted from the stock (#28).

The receiver (#18) and trigger assembly (#17) can be cleaned as a unit. As you might expect, Rem Action Cleaner is recommended by the manufacturer. Spray both components inside and out with the cleaner. Place the safety in its "fire" position, and pull and release the trigger several times. The sear is clearly visible at the rear of the receiver (see photo). Holding the trigger to the rear, depress and release the sear at least five times. It should move freely in both directions.

Apply more cleaner, blow-dry the assemblies, and spray Rem Oil into both holes on the right side of the trigger assembly between the bottom of the safety and upper ledge of the trigger, plus on the area of the trigger-adjustment engagement screw (see diagram). Operate the safety lever a few cycles to ensure there are no hangups, then leave the safety in the "fire" mode. Pull and release the trigger. Do it again, and once again.

After being rotated into the uncocked notch, the head will clear the bolt plug which can be removed as described in the text. If it fails to return forward, or if the sear has failed to pop up completely during your previous test for free movement, the reassembled rifle may have to be returned to the factory or an authorized repair center. A call to will identify the nearest one. Then again, maybe you will be able to fix the problem after you read the rest of this article.

Beyond Field Stripping To clean the bolt assembly, get a grip on the bolt body with one hand. With the other hand, grab the bolt handle. For what’s next, I’ll assume you’re holding the bolt body in your left hand. Place your thumb over the bolt-stop slot. Looking downward, the bolt plug (#15) will be pointing away from your chest, and the lug on the firing-pin head (#14) will be easily seen. Look closer. There’s a small, curved cut in the body where the lug seats. It’s the cocked notch.

Angled toward you is a larger, V-shaped cutout just above the base of the bolt handle. This is the uncocked notch. Maintaining your grip on the body and handle, rotate the handle upward a quarter turn to move the firing-pin head from the cocked to the uncocked Aposition. The firing-pin head must be clear of the bolt plug before you can turn the plug counterclockwise and are able to lift it away. The entire firing-pin assembly slides out to the rear for individual cleaning and lubrication.

To clean the magazine assembly, use a small-blade screwdriver or small punch to compress the magazine spring toward its feed lips through the slot in the magazine housing (#39). Keep the pressure on while you slide the base from the housing. Control and slowly release the spring. Remove the retainer, spring, and follower. Beyond the Owner’s Manual Disassembly of the Firing-Pin Assembly. Compress the spring by pushing on its retaining sleeve (#16), rotate the sleeve 90 degrees, and slowly ease off.

Be aware that the spring is under pressure and has to be kept that way before removing the retaining sleeve. Once the retainer is off, maintain control of the spring pressure while sliding it from the firing-pin shaft. Remove the firing pin from the shaft and slip off the mainspring sleeve. All non-restricted bolt and all firing-pin components are

interchangeable at the gunsmith level. Disassembly of the Extractors. No pins retain the extractors (#8 and 9). Both are under tension from their individual springs (#11). One at a time, each extractor has to be swung outward approximately 90 degrees, but it’s best to block their individual holes in the bolt face before reaching the full 90 degrees. Otherwise, the extractor plungers (#10) may depart the bench. These plungers are less than 1/2 inch long, are dull black, and wear a .060-inch-diameter boss at one end.

When lost, they’ll become permanently invisible. The extractors are not interchangeable. Right is right. Left is left. Keep track of which is which. I might as well add a reassembly tip here: When replacing the extractors, I used a 3/32-inch punch to compress the plunger and spring after starting each extractor in its bolt slot. When compressed sufficiently, the plunger clears the rear of the extractor. I pressed down to seat it while simultaneously removing the punch. Magazine Housing/ Ejector Disassembly.

Two housing pins (#24) are involved. Remove the forward one first to free the magazine-release assembly.

The housing 1 Barrel* 2 Bolt Stop 3 Bolt Stop Spring 4 Barrel Set Screw 5 Barrel Clamp Screw* 6 Bolt Stop Pin 7 Recoil Lug 8 Left Extractor 9 Right Extractor 10 Extractor Plunger (2) 11 Extractor Spring (2) 12 Bolt Body* 13 Bolt Cam Lock Assembly* 14 Firing Pin Assembly 15 Bolt Plug 16 Bolt Plug Ball Plunger 17 Trigger Assembly* 18 Receiver* 19 Ejector 20 Magazine Latch 21 Magazine Latch Spring 22 Magazine Release 23 Magazine Latch Pin 24 Magazine Housing Pin (2) 25 Housing Screw Lock Washer (4) 26 Housing Screw (4) 27 Magazine Box Assembly 28 Stock 29 Rubber Butt Pad 30 Recoil Pad Screw (2) 31 Swivel Spacer (2) 32 Rear Swivel Stud 33 Trigger Guard Screw Insert 34 Trigger Guard 35 Trigger Grd/Takedown Screw (2) 36 Escutcheon 37 Front Takedown Screw 38 Front Swivel Stud 39 Magazine Housing 40 Bolt Assembly 41 Receiver Plug Screw (4) 42 Barrel Guide Pin 43 Magazine Release Pin *Restricted

Frequent checks are required in the process of working the Model 504 to ensure there is no interference with sear movement. screws (#26) come off next—and don’t misplace their lock washers (#25). The rear housing pin retains the ejector (#19). It’s drifted with a small punch. The ejector lifts out easily, and then you can get back to the release assembly. Drift out the latch pin (#23) to separate the latch (#20) and latch spring (#21) from the release (#22).

Here again, all parts are interchangeable and the housing pins are identical. Way Beyond the Owner’s Manual Barrel Disassembly. Back out the barrel-clamp screw (#5) with a 10/32 Torx socket, loosen the barrel set screw (#4) with a 3/32-inch Allen wrench, and pull the barrel from the receiver. That’s hardly a complicated operation, though be aware that the barrel-clamp screw and the barrel are restricted parts. You won’t be able to get replacements for either from Remington, so keep both under maximum security.

When you reinstall the barrel, after touching up a damaged muzzle perhaps, the trigger assembly has to be mounted to the receiver with its screws torqued between 10 and 15 foot-pounds, and there will be head space adjustments required. But that happens after you remarry the barrel to the receiver. The barrel design is intended to provide a slip fit between the barrel hub and the receiver’s counterbore.

I should point out here that the barrel breach must be seated past flush with the face at the bottom of the counterbore. Details of barrel replacement and headspacing follow together, since they are critically interrelated. A Setting Headspace. The safety remains in its safe position. A small amount of Loc Tite #648 is placed on the barrel clamp screw, and the screw started into the receiver but not tightened.

The bolt is inserted in the receiver, the bolt handle moved to its upward or out-of-battery position, and the barrel placed in the receiver. The barrel-guide pin (#42) must be in line with the slot on the low side of the barrel boss. Secure the receiver between protective vise jaws, and push the barrel inward by hand so the breech and counterbore are past flush. Keep pushing as you move the bolt into battery. Tighten the barrel-clamp screw somewhere between 115 and 124 foot-pounds. Stop pushing.

Open the bolt and insert a "go" gauge

in the chamber. Factory specifications call for a .047-inch gauge. When you try to close the bolt, it may be stubborn or not close completely. Whatever you do, don’t force it. The aforementioned specs lead me to believe .047 or even .048 is okay. Apply #242 Loc Tite to the barrel set screw and tighten it hand tight. But don’t overtighten; you might strip the threads. If you do, no sweat. The set screw isn’t restricted. Trigger-Assembly Adjustments.

The sear should be checked for free travel after stock replacement, bolt-assembly work, reinstalling the trigger assembly to the receiver, or after you have adjusted trigger pull and/or travel. Remember, you can’t purchase a complete 504 replacement-trigger assembly.