I am trying to modify my 54 for FT competition use, so far the internals have been stripped, buttoned, new delrin spaces fitted to reduce volumes etc. Am now thinking of having a light weight piston manufactured also the transfer port size elarged am just wondering if any of you guys had tried doing this and to what effect?
Have heard of people reducing the volume by sleeveing the compression chamber and then reducing the diameter of the piston, would this be the way to go?
don't enlarge the transfer port. there is nothing to be gained and some to lose.
i guess the guestion is, what are you trying to gain with these modifications?
the 54 has more than adequate power for FT. it is vertually recoil free. it is accurate. i can see maybe trying to REDUCE power.
tell us what the performance goals are and the experts, like hector and others
(but not me) will tell you how to get there.
Why would you button a piston you are replacing???
June 13 2009, 6:25 AM
Anyhow, besides my subject thought, I was also wondering if a lighter piston would have a negative effect on the 54's recoil compensating mechanism. I know it can be adjusted; will this allow compensation for the change in weight?
Are you doing this to meet the 20fpe limit? Haven't heard you mention Maccari spring kit and seal.
PS If you do all you mentioned you may have a TX200 54. Might need a TX200 spring.
Re: Why would you button a piston you are replacing???
June 13 2009, 1:42 PM
I am trying to get the rifle usuable at the 12ftlb limit, sorry forgot to mention it is fitted with a tx200 FAC spring to get it to 12ftlbs.
Reason for buttoning the piston was to smooth the action, it was a quick fix.
To answer Larrys questions: What am I trying to achieve, basicly looking to improve on an already reasonable gun, suppose trying to make it on a par usability wise to my Venom 77's (77's are mac1 barrelled, triggered and lazaglided). The action is geared around power and unfortunately this is not one of my priorities more concerned with reliability and accuracy with a gun that makes you want to shoot it, have faith in it.
bowket used to sleeve the 52 cylinder down to 25mm for 12 ft/lb guns, add weight to the piston for smoothness and increased efficency for a given spring(maybe not as relevent on a 54)and only enlarged the transfer port on .22 high power tunes, i think that was to get the ratios better matched 25mm:28mm and/or the pellet size 4.5mm:5.5mm
would a moly filled delrin sleeve be a possibility i wonder, although only 1.5mm thick sides and it might be difficult to get it to stay inside the piston
I am considdering the sleeved cylinder and 25 mm piston, just in process of buying another Weihrauch 77 but will then look at getting the cylinder sleeved and piston made.
With regards the spring, yes it does run pretty hot, but I have mine detuned and it runs wonderful at 788, 786, 788, etc, etc.
Why reduce the capacity in an airgun that was designed to operate well at high power ?
Unless it is quite worn down and a prime candidate for extensive refurbishing, and unless you will be doing the work yourself for enjoyment, I would think twice about it.
It will probably be more viable cost wise to buy another 2nd hand airgun that has a smaller cylinder and tune that for smoothness and 12ftlb power.
It will probably need less extensive machining to tune for smoothness.
Good luck whatever you decide.
D
Suppose the answer is because I am trying to get something that I cannot otherwise buy off the shelf - basicly a 12 ftlb FT SR spring rifle one that makes you want to shoot it. At the moment the 54 is a good gun but it is not how I want it to be so I have to invest time / money to achieve what I want.
When I get round to having the work done am wondering if it would be possible to have it modded so a rekord trigger unit could be fitted, well one of my MAC1 replacements. This was discussed on another forum and it was deemed achieveable.
Matt I can understand what you want, as I have achieved what I wanted with my 460, But my project was not in your class and it will be interesting to see what you end up with.
I cant get my head around a rekord on a Diana though.
is very good with some mods. a second screw can me added to the trigger so you can fine tune the sear engagement. springs can be replaced that allows a lighter pull. it may not be a record but i like the one on my 46 (with second screw) very much. it has a very distinct second stage with no creap. you can also fit a metal trigger blade from the ruger airhawk.
Yeah the rekoprd unit on a Diana got my interest when someone mentioned it on Airgunbbs, for my project though it would be fitting a venom mach1 unit not the rekord.
By July 11th I'll be done with the prototype testing of a piston precisely to achieve what you're looking for.
Testing will start in Monterrey, México next Monday.
There will be two models of the piston for all Diana 48-52-54's:
The "HH" (for Heavy Hitter).-that will yield 19-23 ft-lbs and is designed to shoot heavy for caliber pellets.
The International.- that will yield 12 ft-lbs in 0.177"
I would prefer using the Diana T-05 trigger with the second screw added, it will give you better adjustment range and higher reliability that an "adapted" trigger. But that is JMHO.
Drop me an EMail, or harness some patience and I'll post here how things are going.
Part of the idea is to reduce the time elapsed from the trigger pull to the pellet actually leaving the barrel. If we are going to reduce somewhat MV (about 50 fps reduction using a lighter pellet is all it takes to reach the 12 ft-lbs level), then we need to make up with other aspects.
So, the plan is to make the stroke very short but very fast.
This will also allow us to move the pivot point of the cocking lever a little and should make for a more "comfy" cocking process.
I've been toying with this idea for about 18 months now, and patent has been applied for as "improvement upon prior art", so I am more at ease with the idea of putting a product out there.
As soon as I am convinced that it works as I hope, I will keep you all posted.
I will be extremely interested in the project you are working on - I will get round to sorting out a metal blade for my T-05 or is this something you can supply?
Quick question how difficult would it be to mod the piston and rear end of rifle to take a rekord unit?
We are also working on that, a universal ramp to put in any Lyman/Williams/Marbles/etc. front sight.
It should make the Mendoza peep suitable to the 48/52/54 family. Mendoza peeps are very strong and adequate for most purposes. Only drawback is that the windage adjusts inversely to most sights.
On the Rekord trigger, I am sorry, but I do not think it is a good idea. Go for the T-01 unit with it's two screws, it adjusts real nice.
Mendoza peep sights are STRONG but you have to apply them into an air gun that has a HUGH amount of barrel droop like the RWS brand and the fps of these air guns
they have to clamp to the RWS rail without any slip after 20, 40, 60, 80 shots unlike the Daisy Avanti peep sight which moves all over the rail (2 screws) to the rail, very poor design, good for 550 fps but worthless for the 800 in the 48/52/54
the match between the front post and the Mendoza peep sights have to be a perfect combination and I have not found them yet
I would rather have a trusty peep sight than a scope in my M34 but they have to deal with the droop and they have to stay in place not moving all over the PLANET besides peep sights have NO problem with a double recoil
warren
warren
and remember "it's 30% the gun and 70% the shooter"
The special ramp we're working on will deal with those issues
July 7 2009, 11:47 AM
Warren;
If you recall, the 48/52/54 models have a front muzzle piece that has a ramp. This inclination, though the dovetail were the right size makes it useless to put in most globe fronts. Whether they are Walther, Anschütz, FWB, etc. And the Lyman, Marbles, Williams, Redfield, Pedersoli, etc. have a dovetail that runs ACROSS the LOF (Line of Fire)
Our design turns that problem into an advantage: Quality American (and the best Italian reproductions) front sights by any of the companies mentioned can be slid across the block, that compensates the inclination of the Diana ramp.
Once the ramp is in, you can put in any front sight you want that has a 3/8" / 11 mm's dovetail that runs across the LOF.
You would like a Fiberoptic?, Globe?, Aperture?, Iris?, Windgauge?, . . . any with the appropriate dovetail will fit and will be adjustable. Of course I would suggest a Davide Pedersoli windgauge front sight with all the 4 steel template apertures (from Silhouette, to hunting, passing through posts, peeps, grains and everything in between), but not everyone will spend upwards of US$120 on the front sight alone. They are fun anyway.
The other one I would suggest is the Lyman 17 in it's various heights. I just happen to like the 17 AML. It has about 7 types of inserts and it is not that hard to make the inserts according to your own particular liking. Another that has worked wonders in the hunting field for me is the Williams FireSight. A tall very slender FiberOPtic sight that is really useful. It stands out like its name implies, it is strong, impervious to all elements and really well made.
The ONLY caveat is that the ramp will be fabricated for the 48/52/54 family in the beginning. We may come out with something suitable for the 350/34 family, but it is not IN the works right now.
The ramp wil tighten sideways and thereby eliminate all the uggggggggly screw marks in the ramp.
I can honestly say that the Mendoza rear peep sight came into being after a very interesting afternoon chat with the Mendoza plant people in Xochimilco, México; almost 10 years ago. Some of the things they got right and some of the things they went for cheap. But let me tell you that the Mendoza peep sight WILL stay put WITHOUT any scope-block device. It has the same screws as the BKL mounts, 2 of them, and when you tighten that sight, it really will NOT move. One possibility is getting them in bulk and correcting them (three small "operations"), so that a $30 sight becomes a $50 sight, just because it works well and proper. However, before doing that I will give Mr. Héctor Medoza the benefit of getting the sights corrected. It is really very, very, simple to get them real good...
I'll keep you posted about the progress of this project.