RWS Diana RWS 48- Inconsistent Velocity

[NoRecoil]

Hi Everyone,

I'm new to the forum and this is my first time posting.
I purchased a Diana RWS 48 (T06, .22 cal) about two months ago second hand.
I was really excited to use it because I heard great things about the accuracy, but to my surprise it has been a headache trying to shot with it.
I tried the rifle with the stock spring, but the accuracy wasn't there, so I purchased a Vortek kit (PG4 HO kit w/ piston seal & Breech seal) to help with the shot cycle and accuracy.
The shot cycle improved a little, but the accuracy was still not there. I decided to cut three coils in hopes to reduce the shot cycle a little more and in turn help with the accuracy.
This didn't help much either. I purchased a chronograph and below are the results using H&N FTT 14.66 grain 5.53mm head:
(The chrony was placed 30 feet away)
1. 599 FPS
2. 596
3. 600
4. 592
5. 593
6. 594
7. 588
8.585
9.580
10.575

The readings seem to be all over the place. Can anyone help?

 

[Ievgen721]

How many shots did you fire with the new seal and spring? 500-1000 shots and the velocity will stabilize. Cutting the spring was a mistake. Did you treat the end after cutting the spring?

 

[boscoebrea]

I take you are trying to improve accuracy by having a more gentle shot cycle? I ask that because accuracy is more about finding the right pellets that your gun shoots better with. Yes, new parts need a break end period, I go a step farther as I have the model 52, which is like the 48, it is a large powerful air rifle, you have tried to "tame" it because you can not shot it accurate, it is known as an accurate springer. The spring has nothing to do with accuracy; it has everything to do with power and shot cycle.. Your readings are not all over the place, though the last ones are weaker,maybe because the spring or tune is starting to "break in".
In a way, you tried to correct a problem you thought was hurting your accuracy, but actually, you needed to find the right pellets and take more time getting used to that springer; that springer is one of the harder ones to "master". You will learn a lot from trying to tame it and also become a better shooter. Of course, this is my opinion right after watching "Mayday, Mayday", why airplanes crash. I have made several assumptions here; I hope you don't mind.

 

[borne2fly]

Have you seen any signs of dieseling? That can lead to erratic performance

 

[Toxylon]

How's your sidelever tension? That is critical with the sidelevers. Easy to dial in, and it changes everything (if out of whack). If there's not enough pressure against the breech seal by the breech face, no hope of consistency. Too much is bad, as well.

Another common and easily fixed issue is a damaged breech seal. Dieseling does a number on it, with drastic effect on accuracy / consistency.

Changing mainsprings is way down the list, but no harm done by doing that.

With the above two caveats, my second hand sidelever Dianas have been the most easily accurate springers I've had. I still miss my D48 .22 cal, which I should never have sold.

Edit: your velocity numbers are extremely low for a D48. A full-power D48 .22 cal should shoot FTT's at around 820 - 850 fps. Is your kit a 12 fpe kit or something?

25 fps extreme spread is not OK, but not terribly terrible, either. You can get down to 3 fps spreads with these guns, IME.

30 feet is a really long distance from the chrono. I use 4 feet or so.

 

[Toxylon]

Another point sprang to mind:

Vortek kits have piston seals that need several hundred shots to start working as they should, as they gradually size themselves to the chamber. If you haven't put a pellet tin or so downrange, I wouldn't even consider sighting in, or even chronoing.

Lubing issues can also be a culprit. Insufficiently lubed chambers can really cut velocities. The current view of "use as little as possible" doesn't always work, IME. This also often clears with lots of shooting in, but not always. A tell tale sign would be velocities that decrease shot by shot, but come back up if you rest the gun for a while.

Too much lube, or lube in the wrong places, is another barrel of issues, but low velocities is not among those.

 

[markhooper]

like others said check the breach seal and the side lever adjustment.. also did you lube it correctly when putting in the kit.. your velocity is horrible for that gun and you definitely ruined the main spring by cutting it.. never ever cut the main spring.. if you are searching for a low power tame gun get the weaker spring 12 ft lbs I think it is..
that gun is a magnum and it takes a lot of shooting to break in but even during break in mine shot well but it was my second springer so I had already developed a steady hold..
I recently got a chronograph for checking my PCP guns and I'm doing major modifications to them.. making actual compact PCP pistol.. so I needed to compare velocity to get the regulator and hammer spring adjustment correct..I have the chronograph no more than 2 ft away from the muzzle..
you, in my opinion need to immediately get a new mainspring for the kit you got or.. reinstall the factory one.. the cut spring is trash.. unless you have experience as a spring maker and redid the cut end.. also I believe that if you shoot the cut spring in the gun very much the cut end will do internal damage to the gun..
what you have basically done now in powder guns is turned a magnum 30 caliber into a 22 rimfire..
maybe a magnum is not your style so you should have a different model that shoots the lower speeds,I don't know what your wishes are.. but the 48 definitely should be shooting 800+ fps and it's not going to be tame.. just like a 30.06 isn't a BB gun..
I hope this thread helps you..
I currently don't have a 48, wish I had never sold mine..it was 35+ years ago and well you can't get them like that anymore..
mine was a rws Diana 48.. best spring rifle I ever had.. prior one was a rws Diana 34.. the 34 is not a magnum so might suit you better.. less power and hold sensitive.. but I'd never scope a 34..or for that matter any break barrel.. breach block lockup I don't feel is good enough to keep zero on the scope because the barrel moves separately from the scope..
Mark

 

[markhooper]

like others said check the breach seal and the side lever adjustment.. also did you lube it correctly when putting in the kit.. your velocity is horrible for that gun and you definitely ruined the main spring by cutting it.. never ever cut the main spring.. if you are searching for a low power tame gun get the weaker spring 12 ft lbs I think it is..
that gun is a magnum and it takes a lot of shooting to break in but even during break in mine shot well but it was my second springer so I had already developed a steady hold..
I recently got a chronograph for checking my PCP guns and I'm doing major modifications to them.. making actual compact PCP pistol.. so I needed to compare velocity to get the regulator and hammer spring adjustment correct..I have the chronograph no more than 2 ft away from the muzzle..
you, in my opinion need to immediately get a new mainspring for the kit you got or.. reinstall the factory one.. the cut spring is trash.. unless you have experience as a spring maker and redid the cut end.. also I believe that if you shoot the cut spring in the gun very much the cut end will do internal damage to the gun..
what you have basically done now in powder guns is turned a magnum 30 caliber into a 22 rimfire..
maybe a magnum is not your style so you should have a different model that shoots the lower speeds,I don't know what your wishes are.. but the 48 definitely should be shooting 800+ fps and it's not going to be tame.. just like a 30.06 isn't a BB gun..
I hope this thread helps you..
I currently don't have a 48, wish I had never sold mine..it was 35+ years ago and well you can't get them like that anymore..
mine was a rws Diana 48.. best spring rifle I ever had.. prior one was a rws Diana 34.. the 34 is not a magnum so might suit you better.. less power and hold sensitive.. but I'd never scope a 34..or for that matter any break barrel.. breach block lockup I don't feel is good enough to keep zero on the scope because the barrel moves separately from the scope..
Mark

I also used to lube the chamber through the port where the air goes through the breach seal with the needle and the special silicone oil at least every tin..if not more often.. anytime I felt it was shooting off I'd put in a couple drops and then a few shots and it would settle in..
again you got a magnum and it is not a tame gun.. it's made to get the job done.. and they are very accurate with quality pellets in the 14 grain range..
Mark

 

[JamieUK]

Unless I'm missing something, your chrony figures (considering it has a fresh seal) are good at a 15fps ES? I don't see anything to suggest you have any seal issues.

As the piston diameter/ weight is set up for FAC levels however, it'll have a very slow lock time now you've cut the spring, and probably shoot like s##t.

Sorry to be a party pooper, but maybe the accuracy issues werent with the tune. How many different pellets did you try? How were you shooting/ supporting the rifle? Is the scope defo ok (if you used one?) Have you rodded any pellets to check what the bore (crown) is like?

 

[markhooper]

Unless I'm missing something, your chrony figures (considering it has a fresh seal) are good at a 15fps ES? I don't see anything to suggest you have any seal issues.

As the piston diameter/ weight is set up for FAC levels however, it'll have a very slow lock time now you've cut the spring, and probably shoot like s##t.

Sorry to be a party pooper, but maybe the accuracy issues werent with the tune. How many different pellets did you try? How were you shooting/ supporting the rifle? Is the scope defo ok (if you used one?) Have you rodded any pellets to check what the bore (crown) is like?

I totally agree with you.. but most quality pellets in the 14 grain area should be fine..I mostly shoot RWS pellets but some Beeman pellets too. I think I saw rws pellets in pyramid air.. but there's JSB, jts, FX.. all of those should be good.. yes how you hold and support the rifle makes a difference.. and of course the scope..if it is not magnum springer rated it's likely trashed the first shot or two.. and even if it is a magnum rated scope you really need a one piece mount with the scope stop screw in it's special hole on the rail.. regular rings won't work..
also yes a cut mainspring is trashed.
my question for you is how do you rod a pellet through it?? I assume that you know it's not a brake barrel.. I don't know of any way to rod a pellet through the breach without destroying the rifling.. maybe you tear the gun down and go through the area where the piston was?? just wondering how you actually rod a pellet through a side lever?????
also I have seen guys doing custom d48 guns in 20 caliber.. always wondering how the barrel is attached, if you know I'd love to hear about it and picture or diagram would be awesome.. back when I had my 48 id have never considered tearing it down to even change the mainspring or seals.. I'd have taken it to a shop..
now I've been making barrels for FX guns and doing others as well.. I've found the lothar Walther barrel to be very good.. HW and airforce uses them.. but I'd like to try TJ barrel someday.
Mark

 

[JamieUK]

I totally agree with you.. but most quality pellets in the 14 grain area should be fine..I mostly shoot RWS pellets but some Beeman pellets too. I think I saw rws pellets in pyramid air.. but there's JSB, jts, FX.. all of those should be good.. yes how you hold and support the rifle makes a difference.. and of course the scope..if it is not magnum springer rated it's likely trashed the first shot or two.. and even if it is a magnum rated scope you really need a one piece mount with the scope stop screw in it's special hole on the rail.. regular rings won't work..
also yes a cut mainspring is trashed.
my question for you is how do you rod a pellet through it?? I assume that you know it's not a brake barrel.. I don't know of any way to rod a pellet through the breach without destroying the rifling.. maybe you tear the gun down and go through the area where the piston was?? just wondering how you actually rod a pellet through a side lever?????
also I have seen guys doing custom d48 guns in 20 caliber.. always wondering how the barrel is attached, if you know I'd love to hear about it and picture or diagram would be awesome.. back when I had my 48 id have never considered tearing it down to even change the mainspring or seals.. I'd have taken it to a shop..
now I've been making barrels for FX guns and doing others as well.. I've found the lothar Walther barrel to be very good.. HW and airforce uses them.. but I'd like to try TJ barrel someday.
Mark

On sliding cylinder guns you have no choice but to remove internals and rod through maintube, I use the carbon rod (cleaning rod) that I use on my powder burners. It has a threaded end, and spins at the handle. I cut a section of ear bud stem (plastic or wood) which sits in the thread at end of rod. This little stub sits in the tail of the pellet, so doesn't push/ flare the tail, or touch rifling, and as the handle spins freely, allows it all to turn with barrel twist as it goes in.

I haven't swapped out barrels on a 48/52 platform, but believe they're splined/ presses in, and then taper pinned.

With the piston weighing well over 300gr, a huge swept volume, and the TP being very short, these rifles should perform well (velocity wise) with most mid weight pellets.

Whilst I need (and have) an FAC over here in the UK to run high power airguns, I didn't with my 48. Instead I sleeved it to 25mm (for a nicer 12fpe cycle), run a modified TX piston, and bullpup'd it -

 

[boscoebrea]

I forgot to mention the scope mounts ,you need one piece good one plus I needed the 20degree one..I know it is not a break barrel never-the-less mine needed the 20degree one, another thing their are known as scope eaters......I going to find mine today and shoot it ,it been a long time.
A lot of good info from members here

 

[PEP3]

Probably shouldn’t have cut that spring, mine really likes the 18g pellets. It’s much quieter, has a very low es and accuracy that rivals my pcps. I did have a loose breach once and my es opened up to 33 over 10 shots, so I don’t think that is the problem but worth checking anyway. I’m running a pg4 HO and the barrel has been tweaked to optical center. Here are some of my crony numbers.

 

[extradrygin2001]

Before you rip the gun apart again try a different pellet. My T06 .22 48 hates FTT pellets.

You need to try JSB 16 grain pellets, I am willing to bet your groups will tighten right up,

 

[borne2fly]

I second using JSB pellets.
I run those exclusively in my 48.

 

[extradrygin2001]

The breach on the 48 is very loose, the JSB is softer and the skirt is wider.

However you will lose some velocity, JSB 16’s in my full power 48 make 19.8 FTLBS every thing else is over 20.

However the 16’s are very accurate, I have shot a field target course with this setup. And no I did not win but I did better than I thought I should have.

 

[NoRecoil]

How many shots did you fire with the new seal and spring? 500-1000 shots and the velocity will stabilize. Cutting the spring was a mistake. Did you treat the end after cutting the spring?

I shot a little more than 300 shots. When I cut the coils I smoothed the ends to remove any sharp edges. Apart from that I didn't treat the end spring. I just re-installed the plastic top hat that came with the kit.

 

[NoRecoil]

I take you are trying to improve accuracy by having a more gentle shot cycle? I ask that because accuracy is more about finding the right pellets that your gun shoots better with. Yes, new parts need a break end period, I go a step farther as I have the model 52, which is like the 48, it is a large powerful air rifle, you have tried to "tame" it because you can not shot it accurate, it is known as an accurate springer. The spring has nothing to do with accuracy; it has everything to do with power and shot cycle.. Your readings are not all over the place, though the last ones are weaker,maybe because the spring or tune is starting to "break in".
In a way, you tried to correct a problem you thought was hurting your accuracy, but actually, you needed to find the right pellets and take more time getting used to that springer; that springer is one of the harder ones to "master". You will learn a lot from trying to tame it and also become a better shooter. Of course, this is my opinion right after watching "Mayday, Mayday", why airplanes crash. I have made several assumptions here; I hope you don't mine.

You are correct on your assumption. I have gone through several types of pellets to try to find the right one for the rifle. Crosman hollow point, Crosman premier (19g), Crosman piranha, Gamo Red fire & swarm hollow point, H&N Hunter Extreme, and JSB 18.13g.
I do want to note that I have a Tuned (TBT kit) HW97k .22cal that is a beauty to shoot and is not pellet picky at all.
My D48 shot cycle compared to HW97k is really aggressive.
Am I asking too much from my D48? I really want it to shoot like my HW97k .

 

[NoRecoil]

How's your sidelever tension? That is critical with the sidelevers. Easy to dial in, and it changes everything (if out of whack). If there's not enough pressure against the breech seal by the breech face, no hope of consistency. Too much is bad, as well.

Another common and easily fixed issue is a damaged breech seal. Dieseling does a number on it, with drastic effect on accuracy / consistency.

Changing mainsprings is way down the list, but no harm done by doing that.

With the above two caveats, my second hand sidelever Dianas have been the most easily accurate springers I've had. I still miss my D48 .22 cal, which I should never have sold.

Edit: your velocity numbers are extremely low for a D48. A full-power D48 .22 cal should shoot FTT's at around 820 - 850 fps. Is your kit a 12 fpe kit or something?

25 fps extreme spread is not OK, but not terribly terrible, either. You can get down to 3 fps spreads with these guns, IME.

30 feet is a really long distance from the chrono. I use 4 feet or so.

After installing the spring kit, I had to adjust the side lever tension since I also replaced the breech seal, so I don't expect it to be the culprit.
I was also surprised to see low velocity. I purchased the High Output kit which is rated for 21 ft/lb, so removing three coils should put me around 16.5 ft/lb (1 coil reduces to approximately 1.5 ft/lb), but from the readings I'm at about 11 ft/lb.

 

[NoRecoil]

Another point sprang to mind:

Vortek kits have piston seals that need several hundred shots to start working as they should, as they gradually size themselves to the chamber. If you haven't put a pellet tin or so downrange, I wouldn't even consider sighting in, or even chronoing.

Lubing issues can also be a culprit. Insufficiently lubed chambers can really cut velocities. The current view of "use as little as possible" doesn't always work, IME. This also often clears with lots of shooting in, but not always. A tell tale sign would be velocities that decrease shot by shot, but come back up if you rest the gun for a while.

Too much lube, or lube in the wrong places, is another barrel of issues, but low velocities is not among those.

When I installed the kit, I used a small amount of the provided lube because I was trying to reduce dieseling. You think I should take it apart and apply more lube? You think this might help?