Edgun Kryptonite? – Issue Discovered – Request Guidance
Cold temperature?
I shot my gun just a few days ago in 50 degrees F (10 C). It did just fine.
Today, I shot it at 35 degrees F (1 C). And it did horribly. 1-1.5″ at 50 yards. 6″ at 100 yards.
The gun sounded different – less powerful. And the POI was low at both distances. I’m assuming that the cold weather makes the hammer spring less “springy” and consequently, it is hitting the valve with less force and more inconsistency.
Thoughts? Experience?
Thanks,
Ted
All Replies
Yep, looks straight from the top.
When it starts to corkscrew, have you loaded a pellet then tried to recover it?
Mine always had a little crecent-shaped mark on the inside of the pellet, and the skirts were very slightly off center. The mark is what told me the probe wasnt pushing flush on the bottom of the pellets.
Possibly shoot into a full milkjug of water at 100y and see if you can find one.
I dunno bro, but those pellets look bent in flight.
I appreciate the brainstorming, RiffRaff.
The probe seems okay to me. Have a look.
Ted that corkscrew flight of your pellets worries me.
I know you earlier showed pictures of your bore being considerably out of alignment with the feed tray, and you mentioned you had fixed that. I remember you had chunks of lead from pellets being sheared during the load cycle.
You didnt by chance bend the probe when shooting the gun in that condition did you? Or maybe the probe doesn’t line up with the bore correctly?
The only time Ive ever seen that happen is after I bent the probe on my S410. All JSB pellets flew like that until I fixed it. I think the skirts were being bent off center during the load cycle.
Mine wasnt quite the same though, mine didnt fix itself after cleaning the bore. I had to have the probe tip straightened out.
Just something to investigate if that problem keeps popping up.
Thanks much for all the responses, guys.
Update: I chronied the gun yesterday when the temp was 60F. Average speed was 907. I did the same today when the temp was 29F. Average speed was 909. So, it appears I was wrong to assume that the gun was firing with less power. I gave the gun 1/2 hour to acclimate to both temperatures.
So, while I’m not ruling out that the accuracy issue was cold related. I can say that it was not due to power fluctuation.
I’ve given the barrel a good cleaning, and “seasoned” the barrel with 50 shots over a chrony. So, now I’ll return to the range and see if things have improved.
Update in a week or less…
Ted,
Okay, I saw that in your video, and it looked like your shots were going low on the shotgun hulls alright.
But didn’t cleaning help when you shot at the shotgun hulls? Perhaps the deposit is in a different form than before?
Good luck,
Roachcreek
I ran a patch through the barrel to make sure that wasn’t the issue…and it wasn’t. The patch was almost completely clean.
I use a small amount of silicone grease on the orings. But, that doesn’t seem to be the issue re: the POI change. The issue is that I’m getting those “corkscrew” pellets flying on every other shot. I learned this by using my camera. I don’t yet know the cause. I suspect the pellets are entering the leade very roughly. How the cold weather influences this, I don’t yet know. But, I have to learn how to fix this problem or I won’t be able to use the gun for rabbit hunting this winter. 😥
How much lead in the barrel?
Ted,
Do you run your gun dry, meaning no lube, or do you use divers grease, silicone on the O rings?
On my Condor, I know it sure cocks stiffer and the breech does not operate as smooth in the cold weather we are having here.
Pressure, will vary in temperature and is indeed a variable element, but you deal with that every day when you shoot your tank pressure down, so to me that would not be the problem.
I have no idea how your gun works, but with the Air Force rifle, you slow that breech down by making the silicone grease thicker in cold weather and it makes a difference in how hard that breech strikes the valve.
If you add variables to the speed of the firing mechanisim, unless your gun is in a vice, it will move your point of impact.
Roachcreek
Hot air expands and increases psi in your air tank.
Cold air contracts and lowers psi in your tanks.
This is “Charles Law” of Thermal Expansion for air. This is a MUST KNOW for anyone who fills high pressure air tanks. Your life can depend on it. It most definitely affects any equipment using compressed air for power.
Before you fill your rifle, be sure the scuba tank is outside, and the same temperature as the air you are shooting in. If you fill with a compressor, let the rifle cool for 20 minutes or so until the psi quits dropping, then turn on the compressor again and bring the psi back up to where you want it at the outdoor temperature. Remember, fill your rifle with the same temperature air you are going to shoot in and you will have no problems, except for air resistance against the pellet, as Ed mentioned.
Cold air will drop your psi quite a bit. As scuba instructors, it was common practice to take our scuba tanks and refrigerate them overnight after filling them to 3k. In the morning, before classes, we would find them down 200 to 300 psi and we could add more air to bring them back up to 3k psi. The result was when these tanks got out into 100 degree air in Texas, we had a tank fill that expanded to 3600 psi, which gave us more dive time in 90 degree water. It’s safe because the tanks are hydro tested to 5/3 of their rated fill pressure every five years. A 3K psi tank would be tested to around 5K+ of pressure. There’s a large safety margin built in with scuba tanks. Due to regulators, I doubt this would be helpful in PCP rifles as the deviation would be affected by the overly high fill pressure.
Regards,
Hoot 😯
Ted:
I agree with you. What you describe is not a normal behaviour of any gun. To me it looks like there is a malfunction somwhere that may be related to the cold, – may be not. Very strange indeed…..
Ed:
How much in your experience, is the difference in POI going from +20C down to 0 C. Talking about std. Matador cal.22, JSB 18 grs and distance to target 50 mts.
Had my DS AirWolf MVT out today in 0 C and tested. It was last shot in pluss 20C at my summerplace in July. POI was not a lot different at 30 mts, if at all. I did not feel a need to rezero. Have to add though, that conditions were not ideal………
Cheers…..
Trygve 😀
Don’t forget the human element.
Ted , so your groups opened up larger and poi changed?
Cold air is more dense then hot or worm one, it changes the ballistic of the pellet so usually I have to zero gun twice a year, for cold weather and for warm weather. That is normal.
Trygve, I don’t think air temperature is the direct cause for the erratic POI. I think it is an indirect cause. The cold air is affecting some part of my gun to function differently. No amount of temperature or humidity change could affect the pellet during flight to account for the differences I’m seeing. It has to be mechanical.
I’ll get the chrony out tomorrow and show that it is firing with considerably less energy (in cold temperatures). Once that is shown, we can move on from there.
I know this gun inside and out (literally), and I know when it is “off”. It sounded like it was firing with considerably less power today. But, it only did this on some shots. Other shots felt normal.
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I like that milkjug idea – no shortage of them around.
I definitely need to recover one of those whirrly-birds
and have a look. That will be interesting info for
everyone.