Hey everyone, so after some advice I figured I would post the problems I’m having with my guns My main issue is spurt firing. It all seems related to the o ring breech. My guns are home made like many. I ended up finding a PDF document while researching on the combat forum. It was a great read different types of cannons and how to build them. So after all that I built 4 cannons mostly from scratch. I did have the original guns my boat came with I utilized what I could something to start with modified to fit . Anyway I will get to it. I listen for the distinct pop when firing my guns I aim at an alumni cans placed 5-6” away for a visual display. I know we are shooting at balsa and 2-3” of water. I figur if I can smash though a can I should have no problems. Listed below are my symptoms If the breach is to loose I get weak penetration no spurt fire cycle fine If the breach is to tight it’s a machine gun there no problem with going though 2 cans beast! If I get the breach close in the middle somewhere it will penetrate the can on one side and about every 6 -10 rounds the gun will spurt about 3bbs I’m having hell finding a happy medium that’s why I was considering purchasing a whole set of guns for quality and reliability Any advice much appreciated John z.
Have you ever heard that a picture is worth 1000 words? Sounds like you have issues with setting the piston correctly. What are you using for pistons and springs? Here is a general guide that might help if you have a standard setup Here are the parts, piston is the SS part, also spring, T fitting, and the cap for the bottom Height of piston in the 'down' position is set by screwing the cap in or out. In this picture it is to high and will stop BBs (gun would not fire). If it is too low, there can be spurting This is the correct height, just barely visible when looking in through the magazine port To adjust, I screw the cap 'up' all the way so the piston is set too high. I then put a BB in through the magazine port. Next I slowly back down the cap so the piston lowers, until the BB falls forward to directly above the piston When viewed from above, BB is now on the piston, ready to fire If you have a magnet, it can help by holding it up against the outside of the T as shown, it will pull the BB forward when height is correct Once you get the right height, use some CA glue to seal the threads between the T and the cap. It is best to 'tack' it first, then test fire a few times to make sure the height is right. Once you are satisfied, cover the complete circumference to prevent air leaks Hope this helps
Much appreciated. I’m going to post some pictures when I get back from the deer camp. Trying to keep myself productive while sitting in the stand. I’m using springs built by beaver on the forum also I’m using 316 stainless clevis pin as the piston and I do have a magnet fitted to the T. I’m also using stainless barrels
Ah yeah I had similar problems the past few times on the pond, and my club managed to help me tune them in, though not with as much finesse in explanation as Kevin's description. I'll have to try that magnet trick at some point. Speaking of magnets, are either of you attaching a magnet to the front of the Piston housing? I've removed mine, ans suspect that the magnets I used were too strong
I use magnets, but in general you should look at the gun components as an integrated package, something like magnets will help in some setups, and hurt in other setups. Variables that impact the ability to consistently fire 1 BB every time include piston size, piston height adjustment, spring, CO2 hose diameter and routing, magnets, piston being drilled or not, solenoids, operator rate of fire, etc. I have a setup that I have found to be very reliable, and give decent fps. When I briefly used the strike plastic pistons, there were a couple of guns that I could not get to stop spurting, I speculated that it was the length of the piston (too short). When I swapped them out for the SS rivets the issue was completely resolved. Magnets specifically can help with consistency, and remove concerns about mounting the T at the correct angle (otherwise the magazine should enter at a slight down angle to use gravity to ensure that BBs are on top of the piston). At Nate's battle I tried to help Kas get his triples to stop spurting (he didn't notice the issue, but he received several reminders during battle, you only get so many free-be's). He used magnets and the plastic pistons, and he was unsuccessful at fixing the issue, so I gave him some SS pistons to try out. Not sure if he fixed it or not
If it was his NC, then yeah, the problem's fixed. I was running half inch neodymium magnets on my guns but had a lot of issues, so I took them off, and am looking to put 1/4 magnets on there to see if that helps. Once I get my air compressor setup built for bench testing, I'll give it a shot
To follow up on what Kevin wrote earlier. You need to put a bend into the up-tube to allow gravity to feed into the T. Then a corresponding bend in your magazine .
Um, if it was my ship I'd shorten the "uppy tubeys" (as the new governor of my state would call them), and bring the mags up closer to the deck. Should help rate of fire and fps. Randy
so to fix spurt firing, you need to change the piston height by adjusting the cap at the bottom of the T. In the future you should use compression fittings to attach the brass to the T, to allow for easier disassembly and troubleshooting. You can follow my guide above, and the following: 1) Disconnect hose from magazine end so you can spin the cap. 2) Remove cap 3) remove Teflon tape 4) Check spring and piston for any issues, should be fine 5) Put spring and piston back in T, screw on cap all of the way 6) Put about 4-5 BB's into gun 7) hold gun level, slowly unscrew the cap until you hear the BB's slide forward to ontop of piston. This should be the correct height 8) Tack CA the cap in place 9) Hook up CO2, test fire 10) Consider small adjustments (1/8th of a turn or less) if you still have issues one way or another If gun wont feed (no BBs come out), then back the cap off more If spruting, screw cap on more Once you think it's good, tweak the gun down and run a few full magazines of BBs through. Vary up the shot rate (single shots, double, 5 in a row, etc). Once the piston height is set, seal threads with CA all the way around Hopefully that fixes your issue. Guns are pretty simple fortunately
