Quote from: ER00z on July 18, 2021, 01:56:55 AMAfter everyone in the house settled I spent the last hour to hour and a half reading about the Nitro Piston/B19 barrel pivot/alive jam (chisel detent and rod/lock up) situation. I'm more lost now than before. Haha.1- It seems there were some design changes over the years, especially to the "alive jam". I've never seen a double chisel design, so I won't go there. BUT...2- How important is the chisel detent tension?3- If weak, will it cause vertical stringing? Then the pivot set up...4- Does the pivot bolt squeeze the forks together?...Or does the bolt only draw tension on the washers/barrel block to the threaded fork? (This would imply the bolt head only "nests" in the fork, mainly relying on washer fitment between forks to stabilize barrel and securing everything to the threaded fork)5- How important is the pivot bolt fitment through the barrel block? If loose or worn would this cause vertical stringing or is this not really important, relying on pivot washers and chisel detent?More importantly...6- As far as I can figure, the barrel stability relies on 80-90% of the pivot washers, the other 10-20% on the chisel detent and rod (alive jam). Is this about right? All I can say is... somehow this Prowler NP is fairly accurate with the plastic pivot washers. Luckily no detectable side to side play in the barrel and lock up seems solid. But after diving in deeply into the general pivot set up of the B19, it's apparent why other designs can stack pellets while these struggle to do so. Not saying it can't be done, but generally with MY Prowler, my groups tend to run twice as large than what I normally expect, especially from a fixed barrel springer. I'd still do pesting with this gun, but standing firm on limiting myself to 30 yards or so.1- I know of two ''chisel lock'' designs on the B19 platform: one uses a double-chisel arrangement, the other have a cross pin pressed into the comp. tube. Additionally, the breech blocks are not quite the same, you must use the correct design one if you swap barrels. See attached picture.2- Very important: it maintain a good seal between the tube and barrel, and prevent the barrel from moving vertically when shooting.3- Yes it can, and it can cause the breech seal to leak.4- On the B19 platform, yes. This is why it's a good idea to use highly wear-resistant (brass, or better yet, bronze - not the same ) pivot washers.5- Very important. It must be a snug fit, so you can easily fit the bolt into the hole but there must not be any play. A worn bolt or pivot hole has the same effects as a loose chisel lock (alive jam).6- Well the most important thing to remember I think is to not have any play in any part, but yet they work smoothly together. I have some very accurate (3/8'' groups @ 25 yds) Crosman B19 guns that still has the plastic pivot washers. If the barrel has no side play with them, leave'em alone till they wear out . The chisel lock can be ''tuned'' to be very efficient. You need to remove the pivot block bushing, this part holds the chisel into its bore. Put a rag on the chisel to catch it and gently knock the bushing out. Clean off all old grease and then you can use gradually finer sandpaper wrapped around a 1/4'' wooden rod to polish the chisel bore. You'll also want to polish the chisel sides and the chisel faces. Often there will be sharp edges on the chisel faces and the actual edge, you want that mirror polished. The chisel edge (s) can be lightly rounded. If your gun also has the pressed-in cross pin, polish the pin as well. Then use your favorite EP lube in the bore and on the chisel spring, on the chisel faces and cross pin if applicable. When this light tune is done, your barrel block will close with a solid and comforting ''CLICK'', and if you needed to ''tap'' your barrel to open it, you may not need to do that anymore.Sorry for being late to the party. HTH .
After everyone in the house settled I spent the last hour to hour and a half reading about the Nitro Piston/B19 barrel pivot/alive jam (chisel detent and rod/lock up) situation. I'm more lost now than before. Haha.1- It seems there were some design changes over the years, especially to the "alive jam". I've never seen a double chisel design, so I won't go there. BUT...2- How important is the chisel detent tension?3- If weak, will it cause vertical stringing? Then the pivot set up...4- Does the pivot bolt squeeze the forks together?...Or does the bolt only draw tension on the washers/barrel block to the threaded fork? (This would imply the bolt head only "nests" in the fork, mainly relying on washer fitment between forks to stabilize barrel and securing everything to the threaded fork)5- How important is the pivot bolt fitment through the barrel block? If loose or worn would this cause vertical stringing or is this not really important, relying on pivot washers and chisel detent?More importantly...6- As far as I can figure, the barrel stability relies on 80-90% of the pivot washers, the other 10-20% on the chisel detent and rod (alive jam). Is this about right? All I can say is... somehow this Prowler NP is fairly accurate with the plastic pivot washers. Luckily no detectable side to side play in the barrel and lock up seems solid. But after diving in deeply into the general pivot set up of the B19, it's apparent why other designs can stack pellets while these struggle to do so. Not saying it can't be done, but generally with MY Prowler, my groups tend to run twice as large than what I normally expect, especially from a fixed barrel springer. I'd still do pesting with this gun, but standing firm on limiting myself to 30 yards or so.
HAH....i could write a BOOK about what i went through with the Benjamin GPNP .22 pictured in my avatar.....yup you read that correctly that airgun started out as a Benji gpnp....from being the crash dummy that Oletomcat taught me to do intial "lube tune" work on all the way to barrel honing, soft bedding and a stock swap packed a pound and a half of duct seal.....you name it, everything except piston buttons...on it's best day it was hitting a 2" square swinging target at a measured 100 yards at one of Oletomcat's South Carolina Fun Shoots....i have wonder what he thought of the monster he created when he saw that!
I used to have a. 177 Venom Dusk. Kinda wish I'd never let it go. It was literally pellet on pellet, with Crosman 10.5 domes. Very easy to shoot, just couldn't use an "artillery " hold. It liked to be held like a .22. EROOz, you might want to try a firmer hold. What I found, that works on every springer / rammer I've had, is to put your thumb & forefinger in the screw cups on the forearm, and rest the cocking slot in the center of the heel on your hand. With the trigger hand, lay your thumb on top of the stock, ( unless you have a thumbhole, then it's impossible), and draw the gun into your shoulder with the remaining 3 fingers of your trigger hand. All this is done with a light to moderate grip.
Quote from: HYspd on July 22, 2021, 07:47:55 PMHAH....i could write a BOOK about what i went through with the Benjamin GPNP .22 pictured in my avatar.....yup you read that correctly that airgun started out as a Benji gpnp....from being the crash dummy that Oletomcat taught me to do intial "lube tune" work on all the way to barrel honing, soft bedding and a stock swap packed a pound and a half of duct seal.....you name it, everything except piston buttons...on it's best day it was hitting a 2" square swinging target at a measured 100 yards at one of Oletomcat's South Carolina Fun Shoots....i have wonder what he thought of the monster he created when he saw that!What kind of stock is it in now, Chuck
Hi Zack.I shot another group with the Np Crosman Redtail today.It was 12 shots at 25 yards.I was seated on a 3 leg camp stool and shooting semi off-hand with my outstretched for-stock hand braced on an upright door jam.I let the rifle rest in a V formed between my fingers and thumb.The shooting was a little difficult as I was shooting into the sun.. somewhat. I was shooting 14.3 gr 22 cal Crosman Hollow point pellets.Best Wishes - Tom