9mm Evanix Blizzard / Rainstorm tuning

[rkr]

The USS Ohio called. They want their main hatch handle back.

Seriously though - would you make more to sell?

Took me about 3-4 hours to make this one with hand tools and it's not even finished yet. I think I'll be throwing some meat on hot coals over the weekend and then use that BBQ for some heat treating experiments of some left over steel pieces from the project. If they turn out as planned I can solve the hardening and surface treatment in one go.

Edit, I think one of the reasons why the lever feels so good is that I filed it to fit (thus the time it took to make it). The linkage connector slot in the breech is 9mm and I made those connector lips 8.8mm thick, in practise they guide the lever to the slot very snugly. The stock one is 8.0mm so there's bound to be some up and down movement with those Korean tolerances.

[Big Bore Bart]

  What material is it?   The heat treatment will vary for different steels.     It's possible you could reduce the aft section by half and still be Battleship strong.

[rkr]

  What material is it?   The heat treatment will vary for different steels.     It's possible you could reduce the aft section by half and still be Battleship strong.

It's something from metal recyclers scrap steel bin Thus the need to experiment with heat treatment. I think it would last without treatment but it's nice to experiment with things. I followed the old east german production principle when making the lever, the more metal I use the more I get paid

[Big Bore Bart]

  I personally like old car springs, they are easy to work with and take a good heat treatment. 

[rkr]

Here's the result of my heat treatment efforts:



I buried the lever in hot coals after BBQing some steaks and left it there for 20 minutes. After that I dropped it in used engine oil. I don't know if any case hardening happened but the color matches the gun which is enough for me.

[QVTom]

Sweet!

[rkr]

Then a friendly word of warning for wannabe tuners, it's not advisable to go much higher than 180 fpe. If you recall I mentioned a local chap getting 220+fpe from his Blizzard. It seems that the linkage parts start bending at that level and worst of all the aluminium breech block is deforming at around the lever connector bolt. Personally I haven't noticed any other problems than the bent lever and I've put few hundred bullets through the gun in 165-180 fpe power range.

[wwonka]

Then a friendly word of warning for wannabe tuners, it's not advisable to go much higher than 180 fpe. If you recall I mentioned a local chap getting 220+fpe from his Blizzard. It seems that the linkage parts start bending at that level and worst of all the aluminium breech block is deforming at around the lever connector bolt. Personally I haven't noticed any other problems than the bent lever and I've put few hundred bullets through the gun in 165-180 fpe power range.

Does some of that depend on how/what he did to squeeze 220 FPE out of the Blizzard? Perhaps part of his tuning approach involves a very heavy spring which is causing havoc with that lever and linkage? If so, that might be the thing to steer away from.

[rkr]

Then a friendly word of warning for wannabe tuners, it's not advisable to go much higher than 180 fpe. If you recall I mentioned a local chap getting 220+fpe from his Blizzard. It seems that the linkage parts start bending at that level and worst of all the aluminium breech block is deforming at around the lever connector bolt. Personally I haven't noticed any other problems than the bent lever and I've put few hundred bullets through the gun in 165-180 fpe power range.

Does some of that depend on how/what he did to squeeze 220 FPE out of the Blizzard? Perhaps part of his tuning approach involves a very heavy spring which is causing havoc with that lever and linkage? If so, that might be the thing to steer away from.

I just checked and he was above 260 fpe the last I heard. I don't think you can stuff in heavy enough spring to start bending linkage parts - there just isn't enough room in there. It is the force of pressurized air behind the bullet trying to move the probe back. Quite logical really: at 150-160 fpe level we start to see bent sidelevers. Above 200 fpe the lever bolt and linkage parts start to bend. In the mid 250s fpe the breech starts to give up if the lever and linkage have been beefed up.

Personally I'm back at 150 fpe level to see if it works for silhuettes, shooting JSBs at 910 fps and 88 grainers at 880 fps. There's still the option of 103 grain wadcutters if I need more oomph, they fit in the magazine but they fly at only high 700 fps with this tune.

[rkr]

In preparation to next weekends silhoutte competition I did some longer range groups. What do you say, should I be happy with these or get a new barrel? They are OK for silhouette shooting but not for benchrest. They also show how poor shooter I am

[rkr]

Another one:

200 bar, 88 grain bullets, 2 shims for inner spring, one coil off the outer spring
880fps
885fps
889fps
886fps
875fps
150 bar

That's 14 fps spread and estimated 1/2" vertical POI shift at 100M at 154 fpe. I think that's good enough for some longer range testing.

This tune wasn't quite enough for silhuette shooting. Rams at 100M were knocked down when I hit high but low hits didn't do it. I guess I need to find a bit more powerful tune for these bullets.

[rkr]

The tuning project moves to stage 2. I have now achieved enough quiet power to knock down those black powder pistol ram silhouettes at 100M while making the gun survive the power level. It's time to look at ergonomics. The gun is horribly nose heavy with the big can at the barrel end so I need to fix that. This is the progress so far:



I chose the traditional bullpup rail approach as I've never built one. It is very rigid so as far as the air tube points to the right direction things should work well. I have two weeks before our next competition, we'll see if I can finish the build by then.

[rkr]

Woodworking next:



The trigger is on the edge of being too light, I may have to swap in the original sear spring.

[dogwood]

Are you doing all that with hand tools? Wow :

Could you post a close up of the trigger block? I'd like to see what you did there

[rkr]

Are you doing all that with hand tools? Wow :

Could you post a close up of the trigger block? I'd like to see what you did there

Bench drill, hacksaw, file and lots of patience

I don't know weather you meant the original trigger block or the new one so here are close ups of both. The linkage point on the rear can be adjusted up and down and the front is basically as simple as it gets. The block in front of the trigger stops it so the linkage is kept under suspension by the sear spring, takes the slack away from the linkage.

[dogwood]

Thanks for the Pictures, that is very impressive work, especially considering the tools 

[rkr]

Some more progress:



What do you think should I lower the rail a bit? It's about 5mm higher than it needs to be.

[dogwood]

are you going to make a cheek pad that goes over the magazine?  height might be about right for that.

[QVTom]

Looking good.  The scope does look a bit high but I'm no expert on BPs.  I found side view pictures of the Edgun and Cricket from their respective sites then scaled up some of the dimensions for reference. 

Here's an example of one I scanned in to CAD - The top of the Picatinny rail is 1.25" (32mm) above the barrel center line.

[rkr]

The original plan was to make a cheek pad that's on the level of magazine and use low scope mounts - thus the high rail. The gun feels rather comfortable without the pad so I think I'll drop the rail a bit. Bullpups usually have medium to high scope mounts so they can have the rail low.

I also found a problem when test firing the gun. The full 180 fpe tune makes so much pressure for the hammer that the M3 rod that I used starts bending sideways when I pull the trigger causing poor trigger feel