I cleaned up the inside receiver tube, degunked the seal, and stuck a JM Global Tarantula XL spring in the gun. No tuning was done.
The gun was shooting 325 +/- 25 fps with a totally worn out factory spring. I lubed it up with a 50/50 mix of axle grease and 30 Wt oil ( Perish the thought!!)
Seal was soaked in Neatsfoot for one hour and then expanded and let sit overnight to stiffen the wider set.
The gun shoots 700 fps with 7.7 gr R-10 Lites now, but my son could no longer cock it. So the old worn out factory spring was put back in. Now it shoots 225 fps +/- 2 fps & he's grinning from ear to ear!
There is room for another 3/8" spacing with the JM spring, but it caused a loss of 15 fps when I tried putting .375 delrin spacer in the piston.
If you're looking to spruce up a Diana 27, the Global Tartantula XL small spring from Maccari will do the job---just drop it in.
Now I've got to find a softer spring for my son. There ain't enough poop in that old spring to keep the seal set.
ZVP about a model 25: "I consulted with Lewis Reinhold, of Beemans Au. and Jim Macarri to have their expert opnions on replacing it's origonal Low Velocity, "factory" Diana-5 Pistol Mainspring".
I suppose if this spring fits in a 25, it also fits in a 27.
consult:
www.chambersgunmakers.co.uk
part 300294: same spring for 25 and 5G pistol.
Joris, the compression chamber and piston travel on the model 27 are considerably longer than for the model 25. They could not share a spring, at least not without some heroic spacing efforts!
.......you can get an R-7 spring in a 27, and you can make it VERY easy to cock.
If you put .40 spacing in the piston the spring will just work, although there isn't quite enough pressure to keep the sear housing from occassionally binding on the receiver tube pins during some cocking cycles. There's not much more room for additional spacing in the piston due to the length of the rear guide. Velocity in this condition is only about 150 fps.I think this might increase to around 200 fps with a somewhat looser spring. The one I used was very tight on the guide.
There is room for an additional 26 mm for rear guide spacing using an OEM R-7 spring and about 31mm using a JM R-7 spring. Rear Spacing shims need an ID of about .500" and a max OD of .73".
Somewhere I have an R-7 supergrade spring that is a slip on fit for this guide. This looks like a good solution for a boys rifle. My 8 year old son can hold and shoot the gun easily, even though he has to tuck the butt under his arm. My idea is to start off low and increase the spacing as he grows.
Many years ago Tim at RWS put a 27 spring in a 34 for me to reduce the harshness. Made a very nice gun out of it and I have been enjoying Diana guns ever since. So if it looks like it will work, try it. Might turn out better than you ever hoped for.
Have fun!
Chris
I've been thinking about the Global Tarantula XL Small.......
September 19 2005, 6:38 AM
.......spring for just that gun. The solid height is the same as the GSI spring. The rear guide might be a bit of a challenge. The stem thickness may dictate a metal rear guide.
My used 27 (1980) came from the previous owner with an additional Diana factory replacement spring. I had also purchased the JM Global Tarantula XL Small spring. If I had not labeled them, I would not be able to tell them apart visually.
BTW, the previous owner of the 27 did a complete rebuild, and saw no need to replace the original factory spring. Seems the 27 factory springs are relatively understressed. Wonderful gun, the 27!
Got myself mixed up a bit. Damnit, I hate when I post incorrect information. The Diana replacement spring does indeed have 40 coils, and the JM Tranny Light has 34. Sorry for putting bad dope on the web.
Too many springs, too little brain left. LOL (at myself!)
Got myself mixed up a bit. Damnit, I hate when I post incorrect information. The Diana replacement spring does indeed have 40 coils, and the JM Tranny Light has 34. Sorry for putting bad dope on the web.
Too many springs, too little brain left. LOL (at myself!)
