GTA
Airguns by Make and Model => Benjamin Airguns => Topic started by: JSR:. on August 30, 2010, 11:36:54 AM
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Ok, I'll apreciate if someone with an NP Trail in .22 verify the following and post (I have the AW version). When pushing a pellet down the barrel from the breach down to the muzzle, the first few inches (2.5 to 3 inches) at the breach the pellet has a very snug fit, from then on it feels much more loose till reaching the muzzle end where very little resistance can be felt. I am pushing a CP .22. I already replaced the piston seal, lube it, deburred most of the internals but still keeping pellets grouped is very difficult. Most of my experience is with the corssman marauders in .22 and .25 which stack them at 20 yds. This feels like the barrel is choked backwards. Is this normal for the NP series airguns???
Thxs!
JSR:.
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My guess is that, as you push that pellet slowly down the bore, you are slightly wearing it down by rubbing the soft lead away.
Keep in mind that when fired, the skirt of the pellet is violently forced outward by the sudden air blast from the piston, so this is not ordinarily a factor.
Also, you are right about the Crosman/Benjamin Marauder, which definitely has a choked muzzle area.
I'm no real expert on the matter, but I would look elsewhere for your problems with your accuracy.
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I've got an XL1100 that I'm getting ready to do a complete tune on to include hand lapping of the barrel. I find that when I push a tight fitting pellet down the barrel, I have a similar situation with the first three inches or so are snug, and then it seems to loosen up until I get to the muzzle where it just snugs-up just a very, very little bit; but I wouldn't consider it an actual muzzle choke. The reason that I'm going ahead with the hand lapping(other than plain curiosity about the potential benefit) is that in that first couple of inches, the pellet chatters it's way through the area rather than being a snug, smooth sliding movement. Can't shake the feeling that this is having an effect on the pellet and the accuracy. It will also(hopefully) allow me to create a more pronounced choke at the muzzle. All of this should help with accuracy.
pv
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JSR, what pellets have you tried shooting in your Trail NP?
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First, thxs for the previous replies...
Now, aside from the venerable CP's, I have shoot in it (.22):
- JSB Match Diabolo Exact Jumbo Heavy .22 Cal, 18.1 Grains, Domed,
- RWS Superdome .22 Cal, 14.5 Grains, Domed
- H&N Hollow Point .22 Cal, 12.65 Grains, Hollowpoint
- H&N Baracuda Match .22 Cal, 21.14 Grains, Round Nose
Of these, the H&N baracudas shoot best and indeed it looks like the np likes heavier pellets. Second in line are the JSB match. Funny thing is that the CP 14.9 grain sometimes give the impression of grouping but can start shooting all over the place. I've also tried predators but they don't fare any better than the CP's. I should add that I machined two brass spacers replacing the plastic ones in the breach assembly (I am hobby amateur home shop machinst). Will take another closer look to the muzzle crown tonight and see there is anything strange there. I had to recrown my mrod .22 to bring it to group, so maybe this is in order too for the np...
JSR:.
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I'd also give the H&N FTT a try, they shoot the best in my Trail NP.
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Thxs... will try them with my next batch purchase.
JSR:.
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the ftt pellets have a skirt diameter of 5.53 whch is about the largest around. they do great out of my 34p and the past owner of the tx200 ill have wed said they are the best for it. they dont get much talk but seem to be a great pellet and better yet, they are very affodable and come in 500 tins. i think its 12 or 13 per tin and i just got 2000 of them from PA on sat.