May 23, 2008 at 10:44 pm #2205
Today I went to the shooting range to break in a new 18” barrel and made some interesting observations
Like Triggerman noted, you need to put 50~75 pellets through it before it starts to settle down and behave consistently. Having done that, I started taking notes.
This is a SS in .22cal. It’s had a vacation in Florida, so the valve is bored and ported, hammer@65grams. With a 2700psi fill and PW set to 12, here are the 10 shot string averages:
21.1g Kodiaks @ 890 fps
14.3g CP domed @ 955 fps
16.0g JSB preds @930fps
28.0g EndJin @ 605fps WTF 😯
When the gun was stock, it shot EJs @685fps. With a 12” barrel.
Is it possible that the new barrel has an excessive amount of choke?
Can’t understand the drop in velocity with EJs when everything else predictably went up. Anyone out there been down this road before?May 24, 2008 at 4:18 am #39538mikemvParticipant
That is odd. I wonder if the chrony has a problem. Maybe try it again another day. There shouod be an 8 there. Low on air or lower PW?May 24, 2008 at 5:02 am #39539
Yep, been down that road before, my last vid on youtube i was shooting 28 grain eun jin pellets out to 100 meters. My first advice is that lothar walther barrels or even a polygon at 1:16 twist doesn’t like serrated pellets. I also bet that theyre really hard to load into the barrel cause the barrel is only 5.48 mm in daiameter (I.D.) and the Eun Jin 28 garin .22cal pellet are 5.65 mm on the skirt (Back) and 5.52 on the front. Allot of resistance if you ask me. The proof is in the pudding, after shooting Eun Jins, the flute’s in you re barrel will become blocked with bits of lead twice as fast, due to the crush in daiameter…
If you dont belive me then check this out…May 24, 2008 at 3:52 pm #39554
Mikemv – ruled out Chrony problem by varying the pellet selection during a string. Example: CP, BK, EJ, 960, 880, 599 etc. Since the gun came back from the tuner the valve only opens with the PW set to 10 or above with a <2800psi fill. I don’t understand that either with a heaver hammer and such.
Cronicash – Ejs are the snuggest pellets to load with some too big to even fit. I’ve read that others had problems with EJs in choked barrels as well. I was hoping with the mods to see improvement with this pellet as well. It’s no great disappointment as I’m not impressed with EJs anyway. Their one of the least accurate pellets of all the one’s I’ve shot with the exception of RWS superpoint. They seem poorly made from a quality control issue. But do carry energy down range. I’m sure there made to work with Korean guns.
Seems to be no problem with the barrel, just the pellet. Thanks guys 🙂August 16, 2008 at 8:50 pm #45958
Follow-up on this. Bought another tin of EJs to give them a second try. It appears the EJs that I was using in my prior posts were all OVERSIZED. The second tin is fine, shooting ~820fps with moded valve and 18” barrel in .22October 27, 2008 at 3:37 am #52653steve671Participantquote Sotxguy:
Have you had continued success with these pellets?October 27, 2008 at 4:45 am #52659
yes i have had very good resualts, 4 inch groupings at 150 meters on a calm day, with my own modified setup. I now have a 24 inch barrel on the gunpower storm chassis (frame, what ever you would like to call it). Working now on further mods. Last shooting just over 1280fps with eunjins. retaining great accuracy as long as the pellet speed was just over supersonic, remembering that my speeds back in the transoinc were giving me headaches (much alike every other airgunner with power mods) failing where coriolis effect was being amplified by an unstable transonic speed, as well as the poison effect. I think i have got a little too serious into the longer range airgun shooting. I have high speed dopler charts from my airgun thanks to the local long range rifle club. Great potential yet. I further wish for any other enthusiasts to comment without any unbias remarks.December 2, 2008 at 3:07 am #56179dpaquParticipant
cronicash what do mean the “poison affect”? I’m not familiar.
How could the earths rotation (Coriolis) change anything at transonic spead and not at supersonic speeds?
If you have a high speed radar could you post the charts for whatever pellets you’ve tested and the density altitude on that day?December 2, 2008 at 8:09 pm #56252quote steve671:
Sorry for the long reply, overlooked this thread.
I only ttied a second tin of EJs due to most peoples good results with these pellets making me the odd man out. EJ’s quality control is crap. It is a hard hitting pellet but accuracy is so-so.
Since this trial I bought 40 tins of Kodiaks. BK and CPs seem to be the best pellet for LW barrels IMO. There very accurate and consistent.December 2, 2008 at 9:49 pm #56260quote dpaqu:
The poison effect is simply a build of higher pressure offset on one side of the nose of the pellet/sabot. Normaly occurs with light calibre rifles that have a too tighter twist for the speed of the projectile.
Coriolis effect, is where once again the rotation of the pellet at high speeds is eccentric, giving the pellet an undesired corkscrew effect. In my experiance this happens excessivley with lighter pellets at too higher speeds. Same term coriolis is also used in many other rotational aspects.
Look it up in wikipedia, great read on external ballistics.
See if you can find a gun club in your area that has a dopler that can trace youre pellet downrange. Its really cool to find out what its actualy doing, helped me alot.December 3, 2008 at 2:51 am #56294ribbonstoneParticipant
Old vs. new Eun Jin pellets.
Depends on how old and what caliber. These a 5mm, and the dull gray ones are quite old . Lots of visible differnces…but the important part is that the old ones did lead the barrel quicker (are softer lead and are a little bit larger in head diameter).December 3, 2008 at 3:41 am #56298AnonymousInactive
How much do I need to spend on a camera to get close ups that nice?December 3, 2008 at 3:47 am #56299ribbonstoneParticipant
Wife’s camera…Cannon Rebel XT. I don’t ask what her photography gear costs…she doesn’t ask what the airguns cost…a good arrangement.December 3, 2008 at 4:41 am #56312AnonymousInactive
Good arrangment… more than I want to pay for a camera. 😆December 3, 2008 at 5:35 am #56317c02sniperParticipant
I use Eun Jins in .177 in my Talon SS for max hit power and stay on 8 power using stock valve no cronies as of yet. I have noticed that some fit so darn tight while other fit snug maybe 5 per tin irregular non usable lemons for this LW breech. I also have them in .25 for my Sumatra 2500 carbine and some fit very tight in the roto mag while others slide down to the bottom and fit loose. I had an old tin in .177 donated to me by a forum member and some did not fit at all and the domes looked flattened. I think maybe some might have fit overly tight to chrony low on the longer 18″ barrel???
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