RWS Diana RWS 48- Inconsistent Velocity

[NoRecoil]

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

Hi Mark, I appreciate your input. I decided on the Vortek tune because of the plastic top hat it comes with. You can cut the spring and re-install the top hat, avoiding the reheat process of the cut end spring. Getting feedback from the forum, I think I needed to apply more lube to the piston. I still have the factory spring, so I can swap it in if this spring is too far gone lol.

 

[NoRecoil]

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.

This is great to know. You are referring to the 15.89g JSB, correct?

 

[markhooper]

Hi Mark, I appreciate your input. I decided on the Vortek tune because of the plastic top hat it comes with. You can cut the spring and re-install the top hat, avoiding the reheat process of the cut end spring. Getting feedback from the forum, I think I needed to apply more lube to the piston. I still have the factory spring, so I can swap it in if this spring is too far gone lol.

just my honest opinion you trashed your good spring with a clip.. never do that on just about anything in spite of what the know it all's say..
there's not enough money to get me to do that.. especially for the main spring on a spring gun..
I believe your problem was you wanted a tame gun but instead you bought a magnum..
if you wanted a similar gun you can get a HW with a lighter spring instead of destroying the spring by cutting it..
just my worthless 2 cents as a mechanic and machinest.. and welder
you have no idea the damage a cut off spring will do.. there's reasons why they are wound and then they are made flat on each end.. they actually rotate when compressed and released.. and now you have a point to dig itself around.. and heating it up would only make it worse because not being a steel worker you have no way to correctly temper it.
I'm sorry but I'm only telling you the facts.
Mark

 

[JamieUK]

One last thing to check....as you bought it used, has someone messed with the transfer port? It should be 4mm from factory.

 

[extradrygin2001]

This is great to know. You are referring to the 15.89g JSB, correct?

Yes 15.89, I have the FX branded ones so they are labeled 16.

 

[cjtamu]

Very strange. Because if you told me your D48 was low on power and ES was 25 FPS I’d tell you immediately you needed a new breech seal. My .177 56TH makes 18-20 FPE depending on pellet with single digit ES. My .177 52 Luxus with an older Vortek kit with slightly softer spring still makes 16 FPE with no buzz no twang, just a solid thud. These guns are designed to make power, accurately. If you’re sure the new breech seal is installed and adjusted properly then I‘d replace the piston seal and spring. You said you have the OEM spring, could try that with the Vortek seal and see what happens. If power levels don’t come up then maybe the seal needs re-sizing.

 

[1911Tex]

I may be the exception, but my only not-scoped springer is my RWS Diana 48 .177 made in 2012. I really enjoy the old school iron sights....a nice alternative to all my scoped rifles. Incredibly accurate at 30 yds which is my eye's limit. Down side to love of springers is my arthritis in arms which seems to get worse as my old age progresses. It is sad but someday I may need to sell my beautiful 48 and HW97K springers..putting it off as long as possible!

 

[DesertSilver]

Have you stated what your elevation is? Elevation kills springer power. Think of a naturally aperated engine. The higher you drive it the less power you have.

 

[NoRecoil]

Very strange. Because if you told me your D48 was low on power and ES was 25 FPS I’d tell you immediately you needed a new breech seal. My .177 56TH makes 18-20 FPE depending on pellet with single digit ES. My .177 52 Luxus with an older Vortek kit with slightly softer spring still makes 16 FPE with no buzz no twang, just a solid thud. These guns are designed to make power, accurately. If you’re sure the new breech seal is installed and adjusted properly then I‘d replace the piston seal and spring. You said you have the OEM spring, could try that with the Vortek seal and see what happens. If power levels don’t come up then maybe the seal needs re-sizing.

When you say the seal needs re-sizing, are you referring to the piston seal? If so, how would I do that?

 

[NoRecoil]

Have you stated what your elevation is? Elevation kills springer power. Think of a naturally aperated engine. The higher you drive it the less power you have.

I live in Los Angeles, California.

 

[cjtamu]

When you say the seal needs re-sizing, are you referring to the piston seal? If so, how would I do that?

Depends on the equipment you have available. If you have a lathe or drill press you can use that, hand drill if you don’t. Basically sand the lip very lightly and keep test fitting until you get it where it needs to be. There are threads on here and other places that will show you. And YouTube too I’m sure. The Vortek seals aren’t really known for needing to be re-sized like the ARH ones are. But, every gun is slightly different. And getting it sized properly is a touch feely thing. If you’re sure everything else is right I’d put a couple hundred pellets through it and see if it settles in. Elevation isn’t going to drop a full powered 48 to 11 FPE unless you put a sub 12 kit in it by accident.

 

[NoRecoil]

Depends on the equipment you have available. If you have a lathe or drill press you can use that, hand drill if you don’t. Basically sand the lip very lightly and keep test fitting until you get it where it needs to be. There are threads on here and other places that will show you. And YouTube too I’m sure. The Vortek seals aren’t really known for needing to be re-sized like the ARH ones are. But, every gun is slightly different. And getting it sized properly is a touch feely thing. If you’re sure everything else is right I’d put a couple hundred pellets through it and see if it settles in. Elevation isn’t going to drop a full powered 48 to 11 FPE unless you put a sub 12 kit in it by accident.

Thank you for the explanation. I still have the original piston seal. I'm really tempted to reinstall it to see if the pellet velocity increases.

 

[Toxylon]

Cutting coils is easy to overdo, with regards to power output. Tuning springs I've learned half a coil or even less has a real effect. Lots of disassembly / assembly this way, but unless done like this (with a new-to-you spring / gun combo), 17 fpe can turn into 12 fpe just like that.

Piston seals are just as touchy as mainsprings. A piston seal just a little too tight can cut 100 fps, although as far as shot cycles go, a little too tight is preferable to a little too loose. For good velocity, consistency and behavior, getting it just right is important, and it can mean a lot of testing to get there. Like Chris said, each gun is different, even if the nominal chamber bore was 28mm or 26mm.

Whether the lube job is sufficient, the chrono string tells. Each successive shot slower than the last, but back up after a break is the tell.

 

[PEP3]

Thank you for the explanation. I still have the original piston seal. I'm really tempted to reinstall it to see if the pellet velocity increases.

You will lose 4 fpe with the factory seal, trust me, I know.

 

[cjtamu]

Thank you for the explanation. I still have the original piston seal. I'm really tempted to reinstall it to see if the pellet velocity increases.

Well Grasshopper, it appears you have all the tools you need for enlightenment at hand.

 

[DesertSilver]

I live in Los Angeles, California.

Then it's not the altitude. Try doing a shot string after you've shot it 10 -20 times. I bet the shot string levels out. As far as the power you need to just put the original spring back in. A 48 isn't a rifle to use at 12 fpe. As has been pointed out it's a magnum and never was ment to shoot like a hw97. It would be like using a Ferrari to comute to work everyday in LA traffic and it having a manual transmission.

 

[Jr007]

I use to own D48-T5 .177 for 6 years until it got stolen but what I notice its a very hold sensitive and it help me to become a better shooter. If I ever plan to buy other Diana it would the D54 .22

 

[NoRecoil]

Then it's not the altitude. Try doing a shot string after you've shot it 10 -20 times. I bet the shot string levels out. As far as the power you need to just put the original spring back in. A 48 isn't a rifle to use at 12 fpe. As has been pointed out it's a magnum and never was ment to shoot like a hw97. It would be like using a Ferrari to comute to work everyday in LA traffic and it having a manual transmission.

If I get a chance I will put the original spring back and record the readings.

 

[1911Tex]

Then it's not the altitude. Try doing a shot string after you've shot it 10 -20 times. I bet the shot string levels out. As far as the power you need to just put the original spring back in. A 48 isn't a rifle to use at 12 fpe. As has been pointed out it's a magnum and never was ment to shoot like a hw97. It would be like using a Ferrari to comute to work everyday in LA traffic and it having a manual transmission.

Yes this is correct; however the tradeoff for re-installing the original spring is a much heavier cocking force. Continue shooting, your 48 just needs a lot of rounds under its belt and will smooth out its shots.

 

[cjtamu]

I use to own D48-T5 .177 for 6 years until it got stolen but what I notice its a very hold sensitive and it help me to become a better shooter. If I ever plan to buy other Diana it would the D54 .22

This. When you talk about accuracy with the D48/52 you have to do your part. These aren’t generally put out on the first date guns. You’ll have to work for it.