GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: Gibsonvair on February 27, 2023, 03:09:15 PM
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Just a random thought, and I know there are those with the knowledge on this forum. Could a slight choke be formed by using a die and a hydraulic press to compress an area near the end of the barrel. My HW 95 has a choke near the end of the barrel and shoots a little more accurately than my Crosman 1322's. The HW barrel is only 12" long and produces more power and is more accurate. I can afford to experiment since the Crosman barrels are so cheap. My Crosman barrels are from Pyramyd Air and are the 14.5" variety. I love the lack of vibration after pulling the trigger the 1322's have compared to the springer.
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I am open to the fact that the accuracy may be something else besides the barrel, but I cant seem to reach it with the Crosmans so far. The 1701 style trigger and hammer assembly is going to be my first experiment as soon as I get the funds.
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Crosman barrels benefit from a minor deburring, and a brass screw crown job, I would push a pellet through the barrel and feel if there is not already a choke. I am one that rather not have a choke and find the perfect fitting pellet.
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Here is a good thread on barrels by nervoustrigger https://www.gatewaytoairguns.org/GTA/index.php?topic=130555.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=130555.0)
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Crosman barrels benefit from a minor deburring, and a brass screw crown job, I would push a pellet through the barrel and feel if there is not already a choke. I am one that rather not have a choke and find the perfect fitting pellet.
Just the kind of advice I was looking for. I was rushed to assemble the gun and just gave the barrel a cursory look over. The crown looked good and I didn't push a pellet down the bore and inspect the rifling marks on the pellet or for a choke. I probably wouldn't be here if I had just inspected first.
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What are the diameters of the barrels? Is the HW95 a .177, or .22? A thicker, heavier barrel would be more stable/vibration resistant than a thinner barrel.
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A subtle choke is a very effective method for counteracting the usual dimensional variations of inexpensively manufactured barrels, and generally result in a barrel that will shot a broader range of pellets well. However it is a tricky thing to get right. I can’t point you toward a step-by-step but plenty has been written on the topic if you run a search.
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There is a well reputed tuner on this forum who chokes his barrels by heating the muzzle and as I recall, quenching it immediately. Perhaps he will chime in (I have not done it, but intend to someday).
Heating and quenching sounds to me to be the simplist and most controlled method of choking. I do not remember how hot he got it (dull red, cherry red, etc.., or if he quenched in oil or water..
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Thank you to both responses. I am tearing down the 1322 carbine today. I did some baseline tests today with my three air guns. A 1322 with 10.5" barrel (pistol), a 1322 with a 14.5" barrel (carbine). and my hw 95 WITH A 12" barrel. Interestingly when I shot through layers of compressed cardboard, the 10.5" barreled Crosman didn't show much difference between 10 and 15 pumps, but the 14.5" barrel really improved layers of penetration wit 15 pumps. I also felt a puff of air, only once, when I fired the pistol. 10.5" barrel average of 19 layers 10 pumps , average 22 layers at 15 pumps. !4.5" average 21 layers at 10 pumps and average 30 layers at 15 pumps. For reference , the HW penetrated an average of 38 layers. I am ordering a chronograph and getting some baseline readings before doing any modifications. I want to get the best power from a 14.3 grain Crosman domed pellet at 15 pumps. I have learned to take only headshots (Fox squirrels) with the lower power, but I hope to be able to take more body (shoulder area) shots as I do with my Weihrauch.
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There is a well reputed tuner on this forum who chokes his barrels by heating the muzzle and as I recall, quenching it immediately. Perhaps he will chime in (I have not done it, but intend to someday).
Heating and quenching sounds to me to be the simplist and most controlled method of choking. I do not remember how hot he got it (dull red, cherry red, etc.., or if he quenched in oil or water..
I plan on checking for a choke in my barrel. I am holding off, of course, on immediate action, but I really like learning and getting pointed in the right direction. I am going to assume that a higher velocity will be achieved with no choke and the right pellet. This forum seems to contain the most knowledge and I do try searches many times. My plan is to try and use the 14.3 grain Crosman Premier domed, because they are cheap and have done well for me in the past and I have already stocked a few thousand.
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There is a well reputed tuner on this forum who chokes his barrels by heating the muzzle and as I recall, quenching it immediately. Perhaps he will chime in (I have not done it, but intend to someday).
Heating and quenching sounds to me to be the simplist and most controlled method of choking. I do not remember how hot he got it (dull red, cherry red, etc.., or if he quenched in oil or water..
I have done this. I heat the last inch or so of the muzzle to a dull red, then roll it on a block of ice, let it cool, rod a pellet to check for a choke, and repeat if necessary.
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Thanks for that contribution Jim. Gotta give it a shot in the near future on a couple of my Chicom's.
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Thanks for that contribution Jim. Gotta give it a shot in the near future on a couple of my Chicom's.
I should add, Richard, that it's something I would only consider as a last resort to save an otherwise scrap barrel.
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Does it ruin the bluing around the muzzle?
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Just a random thought, and I know there are those with the knowledge on this forum. Could a slight choke be formed by using a die and a hydraulic press to compress an area near the end of the barrel. My HW 95 has a choke near the end of the barrel and shoots a little more accurately than my Crosman 1322's. The HW barrel is only 12" long and produces more power and is more accurate. I can afford to experiment since the Crosman barrels are so cheap. My Crosman barrels are from Pyramyd Air and are the 14.5" variety. I love the lack of vibration after pulling the trigger the 1322's have compared to the springer.
I choked a couple .177 HW barrels years ago when living in West Virginia (one was a home chopped & choked .177 R1 barrel) using a home fabricated "choke clamp" made from the head of a 1 1/8" grade hex bolt and a rather heavy 5" cast iron vise. While compressing the "choke clamp" over the end of the R! barrel after cutting I determined the amount of choke by pushing a series of new dome pellets through the bore past the created choke after each compression. The only purpose of the "home choke" was to guarantee that the smallest constriction in the HW barrel was at the last 1/2" at the muzzle. When pushing a new pellet through the bore I would determine that the amount of choke by the resistance of "pellet push". If there was a tighter constriction in the bore before the pellet was pushed past the "muzzle constriction" the vise was loosened, the barrel rotated about 45 degrees in the "choke clamp", then more pressure was applied to the vise handle to add a bit more choke. "So on and so forth" till the tightest constriction in the bore was at about 1/2" from the crown.........
(https://i.imgur.com/pyLIXaE.jpg) (https://i.imgur.com/UlVj0qA.jpg) (https://i.imgur.com/E5xGWWO.jpg)
Here is a target I shot with my Beeman R9 sporting the home chopped and choked .177 R1 barrel. The targets were shot "bucket and sticks style" with the first group dropping about 3 1/2" below the aim point. I was surprised by the nice group because I never had a HW springer that shot Beeman FTS pellets accurately so I decided to zero the gun at 50 yards and shoot another 5 shot group sittin' on a bucket restin' the gun on cross sticks after "walking the poi" up the target to aim "dead on" at 50 yards and shooting the second group. Anywhoo, the home chop and choke didn't hurt the R9 "bucket and sticks" accuracy at all!...........
(https://i.imgur.com/daG1cT8.jpg)
Another way I home choked a .177 HW barrel was to use a modified rather heavy pipe cutter after removing the cutting wheels and replacing them with home turned O1 tool steel rollers. The modified pipe cutter did provide enough pressure to swage the muzzle forming a choke however the rollers also upset the barrel finish and crown............
(https://i.imgur.com/X0sReKd.jpg) (https://i.imgur.com/plO7MWF.jpg)
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What are the diameters of the barrels? Is the HW95 a .177, or .22? A thicker, heavier barrel would be more stable/vibration resistant than a thinner barrel.
The Crosman barrels are .22 caliber, and about 7/16" (.4351") and the Weihrauch is .22 caliber with an O.D. of .6214. Yeah, the thicker shorter barrel performs remakably well and makes a nice cocking lever.
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Just a random thought, and I know there are those with the knowledge on this forum. Could a slight choke be formed by using a die and a hydraulic press to compress an area near the end of the barrel. My HW 95 has a choke near the end of the barrel and shoots a little more accurately than my Crosman 1322's. The HW barrel is only 12" long and produces more power and is more accurate. I can afford to experiment since the Crosman barrels are so cheap. My Crosman barrels are from Pyramyd Air and are the 14.5" variety. I love the lack of vibration after pulling the trigger the 1322's have compared to the springer.
Not much 'squish' is needed at the muzzle to make an effective choke. Once the muzzle crown is deburred and polished, you can heat the last couple of inches red hot with a torch then quench it. The subsequent contraction from cooling will cause a few thousands constriction in the bore.
I've done this to a few project guns and it does work. You can test the muzzle before and after by pushing a pellet through. Or, machine up a gauge pin before and then test afterwards. The pin will not go afterwards or require tapping in. Don't tap the pin in! The lands will get fouled. The best method is by feel, pushing a pellet through.
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Just a random thought, and I know there are those with the knowledge on this forum. Could a slight choke be formed by using a die and a hydraulic press to compress an area near the end of the barrel. My HW 95 has a choke near the end of the barrel and shoots a little more accurately than my Crosman 1322's. The HW barrel is only 12" long and produces more power and is more accurate. I can afford to experiment since the Crosman barrels are so cheap. My Crosman barrels are from Pyramyd Air and are the 14.5" variety. I love the lack of vibration after pulling the trigger the 1322's have compared to the springer.
Not much 'squish' is needed at the muzzle to make an effective choke. Once the muzzle crown is deburred and polished, you can heat the last couple of inches red hot with a torch then quench it. The subsequent contraction from cooling will cause a few thousands constriction in the bore.
I've done this to a few project guns and it does work. You can test the muzzle before and after by pushing a pellet through. Or, machine up a gauge pin before and then test afterwards. The pin will not go afterwards or require tapping in. Don't tap the pin in! The lands will get fouled. The best method is by feel, pushing a pellet through.
"Not much 'squish' is needed at the muzzle to make an effective choke."
I found that only about one half the force was needed to push a new pellet past my "home choke" compared to the factory .177 HW95 choke even though my "home choke" was indeed the tightest constriction in the bore.