R3 .30 caliber problem and fix
The Problem:
I first noticed after about 2K rounds my velocity dropped off. That can be common, sometimes the HST needs to be readjusted. So I screwed in the HST 1/4 turn and I was back at the 890 fps I was before. I was fine for about another 150 rounds until the real problem started. The gun started behaving erratic when trying to find zero on my target. I put the Matador on the chrony and I found a strange phenomenon. When the gun was full (220 BAR) no manner where the HST was set the most I could get out of the gun was 750 fps. As the pressure in the reservoir dropped the speed conversely would rise until below 150 bar the speed was at 912. I concluded that the valve must be stuck and the reason for the change in speed is that the valve gets more resistance from the air in the reservoir the higher the pressure. The valve must be allowed to move freely in the regulator. The belleville washers are clean, the O rings are perfect and the regulator is assembled correctly. What I found was the valve stem was slightly bent. I know this problem developed over time because the gun was super consistent when I was new. . The valve stem was not too long as it was in Ed’s factory specs. I straightened the valve stem reassembled the gun and I still had the same problem.
The fix:
what I found was the valve stem was slightly oversized and a little rough. Because the stem is steel and the valve stem housing is brass the valve was getting caught/sticking and in my opinion the valve couldn’t open enough. When the gun fell below the 150 pressure setting the valve didn’t have to work as hard to move forward when the hammer hit the stem. I polished the valve stem with 220/20/400/600/800/1200/2000 grit paper on a lathe until I could see my reflection in the valve stem. The valve moved like it was on ball bearings inside the housing. The regulator gave me 24 shots with the average at 880 and the ES at 2.6 fps.
I welcome any criticism you may have about my fix. It’s is possible that I just got lucky. Hell, it’s better to be lucky than good anyway.
All Replies
The new valve that Wp1 has is the only valve I have with my gun.
:hoot:
Confusion…is the valve “w1lp” got different at all from the one you received? He says his is different from his original. Help an old man out here.
Hoot:
I should have been more clear, the new valve WP1 got is just like the one that came with my R3 .30 which was exactly like the new one Tony sent me.
:hoot:
What’s the Russian word for “Screwed”???
I’d ask for a current version. “Old-New Stock” is what the Ebay sellers call such items that have been replaced with newer improved versions.
Hoot:
That is strange I got a new valve from Tony and it looked exactly like my original valve.
i was shooting my Gen 2 .30 last week when the valve did not seal and the gun lost all it’s air. The steel stem was ever so slightly bent and rough. I straightened it out but it still leaked. I tried unsuccessfully to resurface the valve seat on my lathe. I purchased a new valve from Tony and it came in the mail today. I’m back in business now. I did notice the new valve is larger than the original Gen 2 valve. The brass housing and seat are much larger so there are at least 2 versions of the Gen 2 valve already. The original is the one on the left with the spring on it…..
:hoot:
Swagged slugs might be the answer. Someone must know where someone makes them. Here’s one place that talks about them. He comes on here from time to time: http://castboolits.gunloads.com/showthread.php?162263-30-cal-swaged-bullets
Hoot:
PS: Keyser, “ROT” affecting your slugs is very unlikely, being that they are made of lead. If you keep them dry…my experience has been they will keep indefinitely. I wouldn’t eat them, but I’d keep them in a bag or jar, in case one or two of them does happen to turn sour!
Peter is the owner of Top gun airgun. He and I talk all the time. I have intimate knowledge about his Cricket project.
Peter who?
Peter has the same problem that I just discribed in my prior post. He found sub 900 was also the best speed. So back to zero I guess.
I do not think it is correct that JSB .30 cannot handle more speed than 900 FPS without spiralling. We can simply ask Pavel about that.
I can see that the guys from MROD Air created a barrel which can handle 1000 FPS with JSB .30.
http://mrodair.com/mrodair_p-30_velociraptor_caliber_30_jsb_1000_fps
Here is Cricket conversion to .30:
http://www.topgun-airguns.com/30-cal-Cricket_p_117.html
It took them 3 years to design a barrel which can achieve MOA with .30.
Ed did a pretty similar thing with .22 to get the optimal twist rate. However I do not know if he did the same for .25 and .30.
You’re correct I cannot answer the question of ROT. I can tell you that the rifling looks very unique in the EDgun .30. Soon I will have another large bore with a ROT much slower and I’ll report of it makes a difference.
I suspect given (I have more experience with powder burners than airgun) the shape of the JSB .30 that great speeds may not be capable. The drag profile of pellets sucks and the larger the pellet the worse it is. A large drag profile can make normal air act almost like water to the projectile.
This EDgun is my 3rd .30 caliber. I had an FX and a RAW before. They all were accurate at 880. I suspect the projectile is inferior and cannot handle high speeds. I don’t discount that ROT may play a role in speed.
My answer to shooter3, what if you want more speed? Switch to a slug with a G1 or G7 profile would be my answer.
:hoot:
Shooter3 makes an interesting point, one that neither Keyser nor anyone on this forum is likely to have enough knowledge to answer.
That point is the ratio of the barrel rifling’s “twist per inch of barrel” for this caliber. The .30 caliber pellet is longer, wider, heavier than we have seen in past experience. How do we know how the spin ratio for each weight pellet was determined? This is a problem powder burners addressed a century ago, but new to us.
Here’s the question…with large caliber bullets, each barrel maker determines a “twist ratio per inch of barrel” for the rifling of their barrels. This twist rate determines how fast the projectile spins, and if it spins too slow, or too fast, it will lose stability and begin to tumble, keyhole, and behave with a weird trajectory en-route to the target.
I don’t expect Keyser to have such an answer…however, if Ed knows the weight/FPS that the .30 Edgun MUST achieve to have a predictable and stable flight, then we need to know that information. Obviously, we don’t have the luxury or availability of various pellet weight/pellet speed selections with the .30, as we have with the smaller and lighter calibers. There appears to be an “effective operating parameter” in which the .30 seems to require in order to achieve its maximum performance and accuracy.
Those parameters, (pellet weight, fps, barrel length, etc) once known, might well resolve some of the very weird results some of the owner/operators are having with their guns. This may be a set of complex results that can be corrected with the right formula of weight, velocity, barrel length.
Short of changing the rifling of the barrel, perhaps the current rifling is perfect, IF the gun is operated within the proper weight/speed parameters…..that’s a question I poise to Ed, and anyone else who cares to chime in.
If we know the operating limits of the .30 Edgun, perhaps it’s perfect for what it does…that may be unique to low velocity, large caliber projectiles in pcp air guns. Good to know, IF it is a fact! It’s not a proven fact, and smarter people than me might wish to address this issue.
Hoot:
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:hoot:
So w1lp got a bum valve, prior to the new improved valves were shipped!
Where do we stand with the current .30 valve situation?
Has the user reported valve stem deformity problems been finally resolved, or is further investigation and modification required?
I’m under the impression that the current, newest valve stem material is still lacking….subject to bending, circumference problems, surface roughness, am I correct, or still confused?
Hoot: