GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: Novagun on July 22, 2022, 07:23:10 PM
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The delivery of the pellet in any air gun depends on the barrel so it had better be good. I think it is not unreasonable to expect a decent barrel from any high end air rifle and even from the second tier guns. Cardew recommends in his book that a springer barrel should be about 11 inches long. Anything longer just adds friction drag to the pellet. I believe the AA Prosport actually has a barrel about 9 inches long and the rest of just a tube. Indeed with a couple of my rifles the performance improved by shortening the barrel. So why do springer manufacturers make them so long. See Diana 340. A tube, maybe incorporating air vents could be used to get the leverage needed for comfortable cocking effort. Removable so the crown can be inspected. Both break barrel and underlever.
If we could, and often we can't, maybe we should test the barrel before buying a gun by pushing a pellet through. Just a check to see that the barrel is consistent throughout its length. Not tight and lose spots. Hector says that the choke at the end is the important bit. How long should that restriction be. 15 mms or 30. and how tight, very or just a nip. The reality is that we make the best of what we have got, defects that we don't know about.
Next comes cleaning. We will all agree that a new barrel needs attention to get any manufacturing swarf out and to clean out the varnish or antirust oil out. Patches and solvent. I use turpentine poured into the barrel to soften up the dirt. Take care because turpentine residue goes bang. Bayman talks about scrubbing the barrel. He really means the use of copious numbers of patches and some solvent. He and I shun the use of brushes, usually metal. Air gun barrel steel, especially Gamo is pretty soft. I note though that my Hoppes .177 cleaning kit includes a brush that looks like copper but is in fact plastic. Maybe the copper colour is just colour or some copper additive.
The brush seems to me to be a good idea because I can not see that a patch through a barrel can get into the corners of the rifling to scrape out dirt that must be there. Of course, does it really matter? I always wonder after I have cleaned my barrel if I have done a good enough job. More patches and more solvent might get more dirt out.
I have never used any polishing paste on my barrels probably because I have never seen it in shops here. Should I use it and is there any point in it after shooting say 1000 pellets?
Despite reading about the things that I can do to a barrel I still do not have any standard operating procedure to rely on and if I did would I follow it. So what am I getting at?
Just a long winded way of expressing unease. Maybe I should do better.
PS, I do change the oil and filters in my engines regularly. Sometimes I wonder why.
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way i see it dirt matters less than 'roughness' of the metal .. lead fouling and dirt actually smooths a rough barrel over and cleaning it to squeaky clean, although it might make a rough barrel consistent, it will pretty much be not so good consistently lol .. yes, polish out a rough barrel especially at the choke .. likely it will 'relax' the sharpness of the crown, which likely was pretty crapy to start with, but it should be a crisp straight and even crown .. the goal is you want 'no' drag or crown irregularities messing with the pellet at the end, tipping it, etc ..
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Since I was mentioned I want to clarify my feelings on a couple things.
First the only airguns I own and work on are Weihrauchs and the one Diana so far.
I now clean the barrels of new guns as described with several tight patches wet with hoppes 9 to clean out the corrosion protectant. Then a couple of patches to dry it out.
I have not cleaned any of my barrels since switching them to only soft lead pellets. When I was occasionally using hard lead pellets I would eventually have to clean out the hard lead build up because it would degrade the accuracy. To do so required a good scrubbing with one piece carbon fiber rod and a bronze brush. Usually dipped in Hoppes 9.
The Weihrauch barrels seem to be fine with the bronze brush. I can't speak about other manufacturers. I have no qualms about bronze brushing a Weihrauch barrel when done right. Most of my guns have had it done and they all shoot very well.
When I work on other people's guns if the accuracy isn't good I brush them out and polish them up with JB bore paste and start from scratch. Now that we're at a bare metal fresh barrel it may take a couple hundred shots before the accuracy comes around. It's not uncommon for me to run a tin or more through a gun during testing.
JB bore paste is a good product. I've had good luck cleaning and polishing up barrels with it. It's improved the accuracy on a few guns for me. It's less aggressive than bronze brushing and seems to be nearly as effective at cleaning albeit slower. It also polishes out minor irregularities and smooths the bore. Perhaps something to consider if you are questioning the condition or quality of your barrel. Just remember that you will have to reseason the barrel and the accuracy may initially be worse than before you cleaned it. It will come around in a few hundred shots. If you stay with soft lead pellets you may never have to clean it again. I bet my Hw30s have 30k shots or more since their last cleaning.
Be well Ron
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I'm very familiar with the Cardew book, and have read it cover to cover. While I often consider their book "the bible", I don't think that you can really use that 11 inches with modern springers. Their acceleration vs. barrel length chart (pg. 82) goes up to 440 fps with a .22 pellet. That's about a 6 FPE gun!! Most modern guns are at least 2-3 times that power. That means that they are pushing way more air than the Cardew test rig, and would therefore need a considerably longer barrel. I wouldn't go chopping barrels to 10 inches.
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I'm very familiar with the Cardew book, and have read it cover to cover.
Doug, did you mean to post your quoted reply to this thread: https://www.gatewaytoairguns.org/GTA/index.php?topic=201294.msg156350426#msg156350426 (https://www.gatewaytoairguns.org/GTA/index.php?topic=201294.msg156350426#msg156350426) ?
My posts above about barrel length were intended for that thread. When I saw your length reference, I made an assumption, without paying proper attention. I have reported my own posts to move them to that thread. I hope the mods are willing and able to do that. I did not suggest your post be moved. That is for you to determine.
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Its obvious to me from firsthand experience, Cardew's research, and even simple common sense that optimum barrel length has a pretty strong relationship with pellet velocity.
11" would be too short for a lot of modern springers. And it would be too long for others.
Air Arms makes a couple rifles with a 9.5" barrel. In both 177 and 22. These are not screamers, compared to the most popular selling rifles, today. And even at low to mid 800's, the 177 version might be too short?
What I've read about them, the minimum pellet weight most people recommend in the 177 is 8.5 grains. A 7.5 grain pellet should still be only flirting with the low 900's, so it's not anything to do with going supersonic. (And 7.5 to 7.9 grain pellets are way cheaper and more available to those of us in the US).
These rifles are also known for a modification called short-stroking. Dunno what the chrony numbers are, but I suspect the velocity can only go down by doing this mod. If this is the case, and velocity comes down, it would make sense that it might shoot more accurately out of that short 9.5" barrel.
Of my higher power springers, I have only found it necessary to significantly shorten my 22. That one shoots mid 700's (faster than an AA TX200/Prosport, I believe). The fliers went away at 12.5". And believe it when I tried everything else I could think of, first. I even discovered the fliers mostly went away when I sorted pellets by headsize. The ones that passed through my DIY headsize go/no-go gauge would mostly shoot right. The ones that didn't slide though would have a ton of fliers. Most normal people would just pay for a high quality JSB in the right head size (an in Europe it is apparently easy and cheap to buy pellets in various headsizes to the hundred of a millimeter). I rather make my gun shoot Crosmans accurately, even if it involved a hacksaw.
I have 2 177s that shoot in the 900's+, and they are fine how they came out of the box, when shooting ligher weight pellets. It I wanted to shoot 10.5's? Well, those cost a lot, so I don't really know. I can already shoot accurately out to 50+ yards with my .22, using 1 cent pellets. (I shoot a lot; my last 2 orders of pellets were more $$ than the average cost of my springer rifles).
ALL 3 of my sub 600 fps rifles have been vastly improved in accuracy by significant shortening. 2 were completely useless to begin with, other than entertaining someone who doesn't know what airguns are supposed to be able to do. Barrels lengths from 6.5" to 10" on these rifles. I think a 22 Prosport shoot in the low 600's? 9.5" barrel would be right in line with what I'm seeing with my slower rifles, even though it's my slower 177s vs a 22. I think the velocity is the closest indicator you need to go by, when considering barrel length.