Repairing and Restoring the Crosman Power Master 760

I wouldn’t think that the Crosman Power Master 760 would need an introduction, since this air rifle has been in continuous production since 1966. Briefly, the 760 is a single-shot bolt-action air rifle, propelling a .175 caliber BB or a .177-caliber pellet. Crosman calls it a short-stroke level pump, or multi-pump pneumatic. Over 11,000,000 have been produced to date in many variations. To make the identification of air guns a little easier, there are several fine books. I found The Blue Book of Airguns by Dr.

Robert D. Beeman and John B. Allen to be particularly useful. The Blue Book gave me the information I needed to identify the variant I had acquired. It’s the Second Variant, which is self-cocking, with a styrene stock and forearm, and scope-mount grooves. The Second Variant was produced from 1971-74. That would put its age at 30 years or thereabouts, and believe me, it looked that old and then some. Until I intervened and rescued it, this air rifle was destined for the scrap heap.

Abuse and years of neglect were written all over it. I decided that, if I could obtain the parts to restore it, fine; and if not, I could still gain some useful knowledge. In addition to an overabundance of rust, there was apiece of the forearm missing. The air system was ka put—totally incapacitated. But with the exception of the missing forearm piece, it appeared to be complete.

First on my agenda was to contact Crosman Corporation East Bloomfield, NY 14443; for a copy of the schematic, parts and price list, and an owner’s manual, if possible. All big "ifs." Imagine my surprise when the young lady on the other end of the line said: "Yes, we still carry parts for that variant, and yes, we have the literature. I’ll mail it right out." Ten days later, I had the literature from Crosman.

But, unfortunately, there was one very important section missing from the owner’s manual— the disassembly instructions. That, of course, did not discourage me. Disassembly and Inspection Crosman recommends a maximum of ten pumps to pressurize this air system.

Upon trigger release, air pressure forces the sear block rearward, Top of page: The Crosman Power Master 760 air rifle has been in continuous production since 1966, with over 11,000,000 produced to date. which allows the valve cap to move forward off its seat on the exhaust valve body. This releases its charge of air upward, and out the hole in the top of the exhaust-valve ring.

Because we lack the specific disassembly instructions, I’m going to be using the time-honored gunsmith’s method; that being, pay close attention to what you’re doing and to the schematic. Thinking things out, using a logical sequence for disassembly, and keeping parts in order as they are removed, makes reassembly that much easier. I’ve used this method many times in the past, with complete success. As always, use screwdrivers that fit the slots, and roll-pin punches that fit the roll pins.

I first removed the front and rear sights, putting these in a small bag to keep them from getting lost. The front sight was still in good condition; the rear was a little rusty.

(I’ll attend to this later.) Next to be removed was the stock. This required a thick-blade screwdriver. The stock appeared to be in good condition, but needed a good cleaning, and the stock bolt was in surprisingly good shape and had no rust. The stock does not necessarily have to come off for disassembly; removing it just makes the gun easier to work on. Up next is the forearm. You’ll need a 1/8-inch roll-pin punch. I used wooden blocks to support the receiver, and one to support the forearm.

Be careful, you don’t want to bend the lever or link assembly, so make sure your support is good. Drive the pins out in either direction. My forearm was broken off at the rear pin hole. How this got broken is a mystery. From this point on, all parts should be placed on the bench in the order in which they are removed. Subassemblies can be placed in bags if need be, to keep them from getting lost. There are some small springs and other small parts that you’ll have to keep a close eye on, so be on guard.

The exploded drawing included here is for the variant made after July 1975. There were a few minor changes made at that time, mostly to the pump rod assembly. Disassembly continues with removing the front barrel guide (760- 0080, but before you can do that, you have to remove the pivot pin (760-071). The barrel guide serves two purposes. First, it gives forward support to the barrel, and second, it gives forward support to the compression tube.

Removing the roll pin frees the barrel guide and will also free the lever (761A023). The lever pivots on this roll pin. Using my wood blocks again for support, I removed this pin with a 5/32-inch roll-pin punch. Here again, be careful, you don’t want to disfigure the end of the tube. A small Allen wrench will be needed At the bottom is the left half of the receiver half with the trigger assembly in place. to loosen the set screw (788-004) on the top of the barrel guide.

Slide the guide off to the front and set it aside. All support to the forward part of the barrel and compression tube have been removed, so don’t let them flop around. The lever and link can remain as is for now. When you separate the receiver halves, keep an eye on the BB detent (760-018) and its spring (760- 029). Now remove the two receiver screws (760-025) on the right side, then the clamping screw (760-024) along with its lock washer (140-095). Remove the two clamping screws along with their washers.

On the back of the receiver you will see the BB retainer button (760-021). Attached to this button is its spring (760-036). Cup your right hand over the top of this button, reach down to the trigger with your right thumb, and disengage the trigger from the sear block by pulling it slightly to the rear with your left hand, and lift up on the left half. The BB detent and its spring will no doubt fall into the receiver half. There is atrick getting these back in the gun upon reassembly, which I’ll explain later.

The barrel (760-004) and the compression tube (760-003) remain in the right receiver half; take note of their location. Also take note of how the breech bolt aligns through the right side of the receiver. Fix it in your mind, for it will help you greatly when it comes time for reassembly. With your left hand, grasp the barrel and compression tube and move them forward until the breech bolt clears the barrel. You can now lift them out.

What we have left in the receiver halves are the trigger assembly in the left half, and the bolt-latch assembly in the right half. Let’s not forget the stock-bolt nut (99-007). The stock bolt nut is something you don’t want to forget, especially when it comes time for reassembly. To disassemble the trigger group, with a small screwdriver lift up on the bottom of the trigger spring (760-030). This spring also doubles as the safety-button spring (760-017). Take note of the relationship.

Let the safety button fall free, and pull the spring, pivot pin, and trigger clear of their recess. The BB-port cover (760- 020) and its spring (760-028) can be removed if necessary. To remove the bolt-latch assembly in the right side, first remove the spring nut (760-039), bolt-latch spring (760-038), bolt latch (760-035), and the pivot-pin bushing (760-040). Place the barrel and compression tube in front of you and take a good close look.

Notice what appears to beapiece of rubber between the barrel and compression tube. This is the

breech gasket (760-037). Inside this gasket you will find the gasket sleeve (1930-016). Remove the barrel set screw (761-015) and let the breech gasket, along with the sleeve, fall into your hand. If the gasket seems hard or brittle, replace it with anew one. We now come to the part that makes this rifle tick, the compression tube. It just might take some effort to pull this down, and a little more to put it back together. Before you pull this unit down, look it over very well.

At the rear of the tube, on the underside, you will notice a slot. Inside this slot you will see a portion of a spring. This is the sear spring (111-030). You will also see the rear end of the sear block (760-011). This is the location where the cam that’s at the top of the trigger makes contact with the rear of the sear block. When the air system is pressurized, the cam stops the sear block from moving rearward. Take note of the center hole on the left side of the tube.

This is a very important hole as you might guess. Don’t forget to check out the hole in the top where you removed the breech gasket. Now, remove the cross pin (760-034) at the rear of the tube. Tip the tube up and the sear-block stop (760-013) should fall out, along with the sear spring and sear block. Go to the other end of the tube, grasp the lever-link assembly, and being careful to avoid bending the link, pull it straight out.

This might take some effort—mine certainly did—as you’re pulling out the piston assembly and related parts. It’s all attached to the link and will come out as a unit. Once removed, take a good look at the piston assembly (760-042). The cup and felt wiper are what you want to inspect. If the cup looks chipped or cracked or if the wiper is worn out, order new ones. Also, check the condition of the link-pivot pin. Set this aside for now.

You’re going to need a length of 1/4-inch dowel or something similar to force the rest of the air system components out of the compression tube. Go in from the sear-block end, and force them out the lever-link end of the tube. They will come out as one unit. This is the only direction they will come out. If you look on the bottom of the tube you will see a slit, just forward of the sear block, that keeps these components in this area of the tube. We’re now looking at the final components of this system.

Take note of the threaded hole in the check-valve body (130-005). This hole must be aligned with the center hole in the left side of the compression tube. If it Left top: This is the compression tube showing the center hole. The threaded hole in the check-valve body must align with this hole. Left bottom: The hole in the top of the exhaust-valve ring must align with its corresponding hole in the top of the compression tube. is not, reassembly will be impossible.

The left front clamping screw (760- 024) anchors the check-valve body in place inside the compression tube. Also take note of the O-ring (130- 035) on the front of the valve body. Inspect it for flat spots. If it looks good, you can leave it in place, if not, remove it. The exhaust-valve body (140-004) screws onto the checkvalve body (right-hand thread). You might be able to unscrew this with your hands. If not, vise grips might be in order, but be careful not to mar the components.

Once removed, you will find one O-ring (130-034), the check valve (1400A29), valve spacer (760-041), and the check-valve spring (111-026). My components would not come out of the check-valve body. They were frozen in place from dried up oil. A small shot of penetrating oil took care of this nicely. Also, the O-ring was shot, which is why the air system had failed in this gun. Inspect your components well. If you have any doubts, replace them. Next we have the valve cap (130- 057) and its O-ring (140-058).

Again, check for flat spots. Last we have the exhaust-valve ring (140A056). Have you taken note that it slips over the valve cap, and that it has a hole in one side? Upon reassembly, this hole should align with the hole in the top of the compression tube. Study all these components well, and get them set in your mind for reassembly. Reassembly Tips If you have to order parts, be sure of the variant that you have.

Due to the age of my 760, plus the abuse and neglect it had received, I chose to order the complete air-system seal kit; that set me back $12.51. I also ordered anew forearm ($3.26), plus

Crosman Power Master 760 Bolt-Action Air Ri le (Speci ications subject to change without notice) 99-007 Nut 99-055 Front Sight Hood 101-019 Lock Nut 101-033 Plunger Guide Pin 111A026 Check Valve Spring 111-030 Sear Spring 130-005 Check Valve Body 130A005 Check Valve Body 130-034 O-Ring 130-035 O-Ring 130-057 Valve Cap 130-059 Forearm 140-004 Exhaust Valve Body 140A056 Exhaust Valve ring 140-058 O-Ring 140-095 Lock Washer (2) 160-028 Front Sight Screw 160-029 Rear Sight Screw (2) 262-200 Rear Sight 600-024 Screw 760D008 Front Barrel Guide 760-009 Pump Guide 760-010 Forearm, Wood 760G010 Forearm, A.

B. S. 760-011 Sear Block 760-012 Gold Trigger 760-013 Sear Block Stop two forearm pins ($.50 each). With shipping and handling ($4.00), it came to a grand total of $20.77.

Just for the fun, on a recent trip to my local Wal Mart, I looked for the Crosman 760-015 Stock Screw 760-016 Trigger Pivot Pin 760-017 Safety 760-018 BB Detent 760-020 BB Port Cover 760-021 BB Retainer 760-024 Clamping Screw (2) 760-026 Receiver Screw (2) 760-027 Barrel Set Screw 760A027 Barrel Set Screw 760-028 Cover Spring 760-029 Detent Spring 760-030 Trigger Spring 760-034 Cross Pin 760-035 Bolt Latch 760-036 BB Retainer Spring 760-037 Breech Gasket 760-038 Bolt Latch Spring 760-039 Spring Nut 760-040 Pivot Pin Bushing 760-041 Valve Spacer 760A041 Valve Spacer 760-042 Piston Ass’y 760D043 Lever & Link Ass’y 760-044 Breech Bolt Ass’y 760-046 Exhaust Valve Ass’y 760A046 Exhaust Valve Ass’y 760B, and found it selling for $19.95.

Crazy, I suppose, but think of all the knowledge I gained. Before reassembly, be sure that all the air components are clean.

No 760-050 Bolt Knob 760-053 Lock Washer 760-054 Lock Washer 760-058 Space Washer 760-059 Trigger 760-061 Lock Washer 760-070 Stock Screw 760-071 Pivot Pin 760-072 Pivot Pin Retainer 760A106 Forearm Pin (2) 760-140 Pump Cup 761-005 Trigger Spring 761-006 Front Sight 761-015 Barrel Set Screw 761A023 Lever & Link Ass’y 766-107 Sight Elevator 781-A012Barrel Band Screw 788-004 Barrel Band Screw 788-005 Barrel Band Nut 1322C020Pump Rod Ass’y 1400A029Check Valve 1930016 Breech Gasket Sleeve lubricant should be applied inside or outside the air-system components, other than a very thin film on the O-rings.

You can put a little lube inside the compression tube, but don’t

get carried away; use just enough to protect the metal. While I waited for my parts order to arrive, I had a little restoration work to do. I cleaned the barrel with #0000 steel wool, degreased the metal with some isopropyl alcohol, and to match the factory bluing, I used some Formula 44/40 Instant Blue from Brownells (a perfect match). I did some touchup on the compression tube, a little on the pump lever and rear sight, and the little air rifle looked darn good. When my parts arrived, I had to refit the forearm.

Pin location was not the same, which required drilling anew hole for the rear pin. This forearm was ABS; the original factory styrene one was not available. By the way, don’t forget to put the stock-bolt nut back in the receiver before you button everything back up. If you forget, you’ll be sorry. Just ask me. I also promised you a reassembly tip concerning the BB retainer and its spring, as well as the BB detent and its spring.

With the right receiver half down, and everything in its proper place, put the BB detent in place in the side of the barrel. (Don’t forget its spring.) Place the BB retainer and its spring in position, and with two small strips of masking tape, tape it in place, front and rear. When you set the left receiver half in place, be sure the BB detent spring is in its recess in the receiver, pull the trigger back slightly to clear the sear block, line it up, and pull the tape free.

The receiver screws come next, then the clamping screws. Conclusions/Recommendations I enjoyed this project, and gained some useful knowledge. The guidelines and methods used here can be used successfully with other makes and models of multi-pump pneumat ics, as long as you’re willing to pay close attention during disassembly. I’ve heard it said that the air system in the Crosman 760 is complex. Nonsense, I say. I can almost put it together blindfolded.

Old junkers, like the one I ran across, can be found at yard sales, pawn shops, and through friends or neighbors. When you run across one, don’t pass it up. It’s one good way to gain knowledge of air guns and how they function. ■