GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: dcmeyer on August 03, 2019, 10:54:23 PM
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I generally have my gun dialed in for a certain pellet, right now it's the .25 JSB KH MKII. Like the JSB King's they shoot best in my rifle. It is common for me to pull other pellets out and shoot them in the same session, I don't change zero, just look at groups. I have also been trying some slugs, Polymag's, etc. Today I was switching around and noticed after I was dead zero with the KH's, shot some NSA slugs for a bit, maybe 20, then went back to the KH's my POI had shifted up and to the left about an inch. Still a near perfect group, zeroed again with the KH and back to dead on.
So in the endless search for the "perfect" projectile what is the effect of switching back and forth between different ammo. I don't usually clean the barrel until accuracy starts degrading but I'm wondering if it would be best to start clean and stick with one type of ammo at a time for a more exact determination of what a particular projectile will do.
I also noticed today the of the 2 types of NSA slugs I got one type is oiled and the other is not so on top of a barrel I haven't cleaned in maybe 300 shots I ran JSB's, NSA slugs, oiled and not, and Poymags. I could imagine the barrel would be a mess but I managed to drop 4 Pigeons stone dead on impact from a tree at 74 yards in light wind right before I packed up and left. Best I've ever done with the rifle.
I also don't clean/oil any ammo just shoot as they come, should I?
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David, that's an interesting experience. An inch of shift is an awful lot...I don't know how far you were shooting but that's a lot even if it was a fairly long distance like 75 yards. I have on occasion seen a substantial change in POI as a squeaky clean barrel gets leaded in, but nothing that significant when simply moving between different kinds of ammo. I do the same as you...once I find the best grouping pellet for a particular rifle, I zero with it and mostly shoot that particular one. But any time I get some new pellets to try, I test them without cleaning either before or after. Then when I'm done, I make a habit of rechecking the zero with the original pellet just to be sure and it's rare that I can discern a shift. Those few times I could see a difference, it either went back on its own after a pellet or two or was so subtle that I couldn't separate it from the myriad of other variables like the wind, my hold, or the like.
Having said that, it occurs to me that since you have been testing slugs, there was an opportunity for highly accelerated leading due to the increased contact area. Maybe that's the difference.
As to the question of cleaning in between when evaluating different pellets, I used to think it matters based on the wisdom of the interwebs but don't any more after doing my own testing. To be clear, I am not asserting that seasoning a barrel is bunk. A thoroughly clean barrel and a lightly leaded barrel barrel will usually group differently enough to notice, and there may indeed be some improvement in some cases after you've put 10, 20 or 30 of a particular pellet down the barrel. I'm just saying that the process of weeding out "bad" pellets from the good pellets (those favored by your gun) is coarse enough that I think fretting over cleaning and reseasoning is a waste of time.
To give an example, here is a sheet of 16 groups (16 different pellets) shot back-to-back at 25 yards.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=5781)
Notice there are a few sub-MoA groups (green) despite no cleaning in between and that's plenty discriminating enough to recognize which ones are worthy of further testing and which ones can be returned to the shelf.
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David, that's an interesting experience. An inch of shift is an awful lot...I don't know how far you were shooting but that's a lot even if it was a fairly long distance like 75 yards. I have on occasion seen a substantial change in POI as a squeaky clean barrel gets leaded in, but nothing that significant when simply moving between different kinds of ammo. I do the same as you...once I find the best grouping pellet for a particular rifle, I zero with it and mostly shoot that particular one. But any time I get some new pellets to try, I test them without cleaning either before or after. Then when I'm done, I make a habit of rechecking the zero with the original pellet just to be sure and it's rare that I can discern a shift. Those few times I could see a difference, it either went back on its own after a pellet or two or was so subtle that I couldn't separate it from the myriad of other variables like the wind, my hold, or the like.
Having said that, it occurs to me that since you have been testing slugs, there was an opportunity for highly accelerated leading due to the increased contact area. Maybe that's the difference.
As to the question of cleaning in between when evaluating different pellets, I used to think it matters based on the wisdom of the interwebs but don't any more after doing my own testing. To be clear, I am not asserting that seasoning a barrel is bunk. A thoroughly clean barrel and a lightly leaded barrel barrel will usually group differently enough to notice, and there may indeed be some improvement in some cases after you've put 10, 20 or 30 of a particular pellet down the barrel. I'm just saying that the process of weeding out "bad" pellets from the good pellets (those favored by your gun) is coarse enough that I think fretting over cleaning and reseasoning is a waste of time.
To give an example, here is a sheet of 16 groups (16 different pellets) shot back-to-back at 25 yards.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=5781)
Notice there are a few sub-MoA groups (green) despite no cleaning in between and that's plenty discriminating enough to recognize which ones are worthy of further testing and which ones can be returned to the shelf.
I have been of the same mind of your conclusions. The weird part was after I re-zeroed it just stayed there and was consistent. I have had issues with POI shifts in the past and I determined that firstly, my rifle case was to tight pushing the barrel around, and secondly even though it has a barrel band, leaning it on anything with the end of the barrel was problematic.
Just FYI, when this happened the barrel was never bumped around and it was sitting on shooting bags until the end when I used my rear bag on the roof of the car for the Pigeon dispatch. I'm really wondering about the NSA slugs that Have oil on them. Like I said I never clean and/or lube any ammo but I may remove the oil from these and clean the barrel before the next time out. I'm done shooting slugs until I open up the transfer port and clean things up because they are a bit slow and don't group well. Not planning on going crazy but if I can get 34g ammo moving at 850 or better it will be a monster. If it still doesn't shoot slugs well I guess I'll have to look in to a AirForce Condor or something for that, wouldn't that be terrible ::)