The Dianawerk Collective: Detailed Step-by-Step 48-52-54 Tuning Instructions

RWS 48-52-54 - Disassembly/Reassembly, Replacing Springs, Guides & Seals - Step by Step How to Do It (this is very long!)

I first wrote this several years ago and posted on Straight Shooters forum. I have updated it recently. I have done close to a hundred tunes on these guns, and also have now worked on 46s. Good luck!
john stewart

Read all of this before starting to do anything to your gun. Be sure you are careful. You could HURT yourself seriously if you are sloppy. The spring in a 48-52-54 is under great pressure and can hurt or kill if it is launched by mistake out of a gun! Be sure you have reasonably good skills working with tools.

There has been some interest in how to disassemble, replace the internals, and then reassemble the RWS sidelevers. I have owned both a 52 and a couple of 54s. The 48-52-54 series all uses the same springs, guides, piston seals, breech seals. I know having done probably 50 or more tunes on my guns. Initially I had them tuned by Russ Best, and boy, what a difference! You lose some power from the harsh, stiff factory springs, but the Maccari springs and guides are powerful enough, and give a nice, smooth firing, non- buzzy gun. So anyway, wanting to save a bit of money, and being adventurous, I decided to change the internals myself. I bought a B-Square spring compressor (Kevin and Craig at Straight Shooters can get one for you, just ask). You will need it. Russ says he does not use one, but he outweighs me by quite a bit, and I don't want to risk being impaled by a heavy duty spring.

These instructions assume you have bought a Maccari tune kit for your gun, which has a spring and rear guide. You will also need to buy a piston seal and a breech seal to do the job right.
First, take the stock off the gun. On a 48 or 52, this means removing the largish Phillips head screw under the front of the forearm nearest the end of the barrel, and another largish Phillips head screw at the front end of the trigger guard. On the 54, it is the front Phillips head screw near the front end of the forearm, and another Phillips head screw located about an inch in front of the front trigger guard screw. On the 54, note when you pull the action out of the stock that there are rubber and metal washers - try to keep these in the proper order so you get them back in properly when you are reinstalling the stock. While you have these screws out you may want to replace them with Allen head screws - I did and the gun looks better and is easier to work on now.
Now that you have the action out of the stock, put the stock well away from the work area in a safe place so you don't accidentally scratch it. Make sure the work table is covered in soft large towels or such to protect the action and the table.

Now remove the cocking arm by removing - carefully - the little c clamps on the bottom of the two pivot pins on the cocking arm. One is located toward the rear of the action and secures the back of the cocking arm to the receiver tube. The other is a few inches forward and secures a thin arm to the larger cocking arm that you grasp when you cock the gun. The other end of the thinner arm attaches to the front of the sliding compression chamber, up near the loading port. To remove those little c clamps I usually use a little screwdriver - a large jewelers screwdriver - and my finger nail. The finger nail holds one end of the c clamp so it won't spin, the screwdriver tip is pushed against the other end of the c clamp to push it off the pin. Be careful as these can fly across the room and get lost when they pop loose! (use a towel behind the cocking arm to catch it). Pull out the pins and put them and the c clamps in a plastic bin or something to hold them so they don't get lost. (NOTE: I have replaced all my c clamps with little rubber washers I got in the plumbing supply area at a hardware store. They go on and off easily and are readily replaced if lost). Now remove the cocking arm, but be careful as there are little washers on the rear end of the cocking arm where the large rear pin fits through and they are hard to see and easy to lose.

Now take a hammer and a dummy pin (5 mm diameter, and a little shorter at 1.1" long), and punch out the rearmost pin of the two pins that are visible from the left side of the action, just in front of the rear end cap and the safety. Be sure it is the rear pin, not the front of the two pins. The rear pin is not the one carrying most of the stress of the spring, but the forward one is. You only want to release the front one when the gun is in the spring compressor! Be careful of this, it could be dangerous!!! Note that you should use dummy pins to knock out each of the two pins, and that leaves the dummy pins behind in the trigger unit, where they will keep the trigger safety wire inside the trigger block in the right position. Also be sure to set the safety to the on or downward position if it is an older gun (with the two adjustment screw T01 trigger, pre about '04?), or the plactic safety lever is sticking all the way out on the newer guns.

Now fit the bore end of the barrel down onto the nub in the bottom end of the spring compressor, and then adjust the length of the spring compressor so that when the large screw head that contacts the end cap of the receiver (the end where the safety button is) is turned all the way out (counterclockwise) you have about 8 inches of clearance between the end cap and the end of the screw head of the spring compressor. Now clamp the action just in front of the cut out for the loading port with the plastic covered heads of the sspring compressor's holding screws so the action will stay in place when put under pressure when you go to release the spring. You will need to turn the action in the compressor so you can get to the remaining pin on the side of the gun that is back toward the rear of the action. Take a thin piece of leather, and fit it over the end cap. Now fit the special RWS adapter that comes with the B-Square compressor and fit it over the leather covering the end cap of the gun. Now screw the head of the sring compressor down to the adapter until the nipple on the adapter fits into the hole for it in the cupped end of the spring compressor head. Once it is snugged but not too tight against the end cap of the gun, tap out with the hammer and dummy pin the remaining pin. The dummy pin remains in place. Make sure both dummy pins go in right behind the exiting pin with no space left between them, or things under tension will not remain in their proper position. And make sure the dummy pins are in far enough that neither end catches on the walls of the receiver tube. The spring is now being held only by the spring compressor. Unscrew the spring compressor and the end cap will start to back out of the gun. Once all pressure is off the spring, loosen the spring compressor a bit more, remove the end cap, then take the gun out of the compressor. Be sure the dummy pins remain in place in the end cap/trigger assembly. If you don't use these pins, it is a pain to get the thing back in the gun properly. Maccari's web site has info on how to do this. I learned the dummy pin trick from Russ Best.

With the gun out of the compressor, now remove the spring and rear guide. If you want to do a thorough job, replacing the piston seal and the breech seal, you will want to be able to remove the compression chamber. To do this, slide the compression chamber back enough so you can see the end of it where the breech seal resides. Next to the air vent hole there is a hex head screw that is visible on the end of the compression chamber. If you loosen this with an Allen wrench, the lug that attaches the end of the thin cocking arm to the compression chamber will come out. Now you can slide the compression chamber backwards and out the back of the gun.

To replace the breech seal, use a quarter inch diameter drill bit and insert it into a drill, then stick it into the opening of the breech seal. Slowly drill it just slightly into the breech seal. Not too far or you can damage the air vent hole! You can now pull on the drill and you should be able to pull the seal out. Another method I like even better - use a nut driver (like a screwdriver with a head that holds a nut or in this case the hex head of a one quarter inch, several inch long lag bolt). Screw a lag bolt into the breech seal, then pull on the lag bolt and the seal should come loose. You can also use a dental pick like instrument, but trust me, the breech seal is hard to get out and requires more muscle than you can exert with a dental pick. Install the new seal by using a 3/8ths inch diameter wooden dowel to gently tap it down into place. Make sure the cupped side of the seal faces out, the flat side down. If your gun has had velocity variations and shifting POI, the culprit can be a burned or damaged breech seal. On one new 54 I had at one time, it was all mangled - a large bur on the end of the breech end of the barrel was cutting it to ribbons, and the gun's velocity was therefore very irregular.

Pull the piston out of the compression chamber. Pull off the old piston seal - a hair dryer may be used to heat up the seal and make it pliable and easy to remove. VERY IMPORTANT-Don't use a screwdriver, or you risk burring the piston knob that holds the seal in place, which will then make the new seal fit irregularly and give poor results!!! You will want to clean all the old lubes off of the piston and from the inside of the compression chamber. You can just wipe them down with a clean cloth. Don't overdo it, you want some lube left behind in the compression chamber's walls in the fine crosshatching.

Install a new piston seal - from Maccari's web site- with the cupped side away from the piston. Use the hairdryer to heat it up to make it easy to install. DO NOT use a screwdrive through the center of the piston seal donut to help you stretch it over the kobb on the end of the piston, or you risk damaging the piston knob, and this will lead to velocity inconsistencies as the piston seal will not fit correcly in the compression tube. See Maccari's piston seal page for further info on this.

Check inside the piston to see if there is anything left behind from the old guts, such as a spacer or a front spring guide. If there is, remove these, and install only the parts from the Maccari kit, nothing more or less.

Now smear a thin film of moly paste on the piston seal,being careful not to get any on the front end of the piston seal. Just a light coating right up to near the edge of the seal - but you don't want any actually getting ahead of the seal once it enters the compression chamber. Also put a coating of moly on the back end of the piston, where it rides against the inside of the receiver tube. In fact, to do a good tune, you should take super fine sandpaper like 1500 grit used for auto paint final coat finishing and polish the rear of the piston were it rides on the inside walls of the receiver tube. Then apply the moly, just a light coating.

Now insert the piston seal end of the piston into the compression chamber being careful not to damage or cut in any way the piston seal. This is best done by tilting the piston a bit and letting part of the seal fit into the chamber. Now rotate and tilt and slightly push in the piston so the seal will fit in, rotating it a full 360 dgrees until the whole seal is inside the compression chamber. This is tricky and takes some practice. But never ever damage the edge of the piston seal or it will not work well and you will have an erratic and dieseling gun.

Now coat the outside of the compression chamber tube with a thin coating of CLEAR tar (clear lube grease -buy from Maccari), then slide it with the piston inside it, back into the receiver tube. You will need to depress the anti bear trap button on the left side of the receiver to allow the compression chamber tube to slide all the way forward. But leave a little room at the front because you are now going to reinstall the lug that holds the thin cocking arm to the front of the compression chamber. You may want to degrease the screw hole and the hex head screw and then use blue loctite on it. Tighten it up snug but not too tight, as this screw head is easily stripped.

Now it is time to install the spring and guide. However, first rub with your fingers a very fine film of heavy black spring tar (comes with Maccari's spring and guide kits) on the front two thirds of the spring - make it very thin and fine, not a thick coating. Too much and the gun will be temperature sensitive and or shoot slow. Also put a thin film of moly paste on the outside of the spring guide tube, and maybe a touch of clear tar on the inside of the guide. Now slide these into the back of the piston. NOTE on heavy black tar: DO NOT think that putting a lot of this on the spring will tame buzz/vibration. Yeah, it will for a few hundred shots. But what really and PERMANENTLY stops buzz/vibration is tight fitting front and rear guides! - not tar. Maccari's kits come with tight fitting guides. They fit snug to tight within the spring. Note that stock guides fit stock springs loosely, and this is what causes the buzz and vibration. NOT LACK OF HEAVY TAR! The heavy tar is just a lube to prevent the spring from rubbing the heck out of the inside of the piston and inside of the receiver tube. And it is heavy so it will not fly off too much - though it does anyway a bit - when the spring releases on firing the gun. PS- I have tried the heavy tar in heavy quantity on the spring, only to be disappointed, so I know of what I speak. Many people will wrongly assume that a lot of heavy tar is needed. But ALL lubes should be used sparingly. MORE is NOT better. Just enough to coat things with a fine layer, whether it be the piston seal edge, the back end of the piston, the spring, etc.

Now install the action back into the spring compressor. Fit the piece of leather and the adapter over the end of the end cap and screw down the compressor head. Once you see the holes in the receiver line up with those in the end cap, it is time to reinstall the forward most of the two pins you previously removed. Install from the left side. Once the pin is reinstalled and the dummy pin punched out, you can safely take the gun out of the compressor, because the spring and end cap are held in place. Now tap in place the rear pin, driving out the dummy pin. When driving out the dummy pins, be sure the end of the retaining pins go in flush up against the ends of the dummy pins and stay that way through the whole sequence - don't let a gap form between them, or the whole point of the dummy pins, to hold the safety wire in its proper place, will be lost.

Now reinstall the cocking arm. But first put moly paste on the holes the cocking arm retaining/pivot pins fit into, and on the pins themselves, as these receive a great deal of wear and stress. Install the pins and the c clamps (or the rubber washers if you have replaced the c clamps with them)

Recoiling Mechanism on 54- IMPORTANT- you will need to set the recoiling mechanism adjustment screw. You will need to do this by inserting an allen wrench into the rear brass sledge that runs on two rails, where the rear stock screw fits in. ****erclockwise loosens the spring tension on the recoiling mechanism, clockwise tightens it. You want it just so that the action remains in the forward position when the gun is cocked and will only slide backward with a modest shaking of the gun when held muzzle up. Too tight and it will not work well. Also be sure to moly the little bearing that fits into a hole in the bottom of the receiver that holds the action in the forward position when cocked. This ball bearing is in the top of the rear sledge, out of sight, but you will see the hole when the action is moved to the rearward position as it is after firing. There has been a lot of debate about loose or tight setting of this tension adjuster. I have tried all extremes and everything in between. And loose is best, so the action is just barely held in place in the forward position when you hold the gun vertical. Too tight and it defeats the consistency of the recoiless mechanism and leads to inaccuracy. If you don't believe me - experiment! You might get a different result. That is how you learn, just be sure to take your time and HAVE a lot of time available.
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Now you should be able to reinstall the stock. YOu should first degrease with acetone all of the stock screws and use a Q-Tip with acetone on it to degrease the screw holes. Use blue loctite on the screws and let them dry in place in the gun for 24 hours. (note- lately I have found that on the 54, the stock screws don't require Loctite, due to the rubber washers and the recoilless mechanism, but the 48-52 need it very much).

If you have done everything right, you will have a nicely shooting gun. A little smoke for the first few shots is ok but I usually find if I have lubed it right, I get virtually no smoke after a few dozen shots.

Maccari's site has some good tips on the 48-52-54 disassembly and reassembly especially on the installation of the pins and the safety wire issue if you do not use the dummy pins. But I HIGHLY recommend the dummy pins, without them it can be tough to get the pins back in as the safety wire is very recalcitrant. ALso helpful is the website eddie.colwell.tzo.com/RWS-54.htm. But much of what you read here in my instructions I learned by trial and error. The RWS guns are not terribly hard to work on- just be patient and allow yourself plenty of time. Don't try it when you don't have a large block of available time. Plan on a few hours. Use your head, too - you can usually figure things out if you don't get nervous and you stop and think! (hard to do when you are scared you have ruined your expensive gun!) This past summer when I experimented with several different springs and guides on both my 52 and 54, I got it down to about 20 minutes to take the gun apart, install a spring and guide, and get it back together. The first time took about 4 hours but I also changed piston and breech seals- with the challenges being the breech seal, the piston seal removal and reinstallation, and the installation of the rear pins and the safety wire getting in the way.

You may find you need to adjust the tension on the cocking arm. If when you close the action after cocking it, the cocking arm does not have a slight snap to it and stay in place, you probably need to tighten this up,and the breech seal is probably not sealing properly either! To do this you will need to take back out the forward most of the two rear cocking arm pivot pins, then rotate counterclockwise the thin cocking arm that attaches to the front of the compression chamber tube. Do one half rotation counterclockwise, then reinstall the pivot pin ant try it out.

Adjusting the trigger - I can't speak to the post 2004 triggers with only one adjustment screw, but can speak to the T01 two screw trigger block (the T designation is on the top of the receiver where it says the gun model number). If you want a nice, two stage trigger, not too hard to squeeze, adjust the front trigger screw almost all the way out, turning counter clockwise. Then adjust the rear screw out all the way. Then try it out. Turn clockwise the rear screw just enough to give you a second stage. You will have to pull slowly on the trigger to detect it. You want the rear screw in just enough to provide the second stage. Too much and it will make the trigger pull too difficult. Too little and the second stage disappears.

Good luck with all of this. Best regards, John Stewart

f any questions, email me at johnrstewart@optonline.net. I was lucky enough to retire last year at age 55, so I have tons of time to answer questions, and like to help others with their tunes.

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