Note that the swept volume in the second chart (84.8 cc) is the correct value.... That still places it ahead of any of the others in the list, however....Bob
Hi tarheel! what about the torpedo 155 underlever, is it the same powerplant as the 125 or the 135, or is it all together diffrent? Also is the 155 more accurate because its a underlever and because its a underlever is it still a good candidate for a nitro ram conversion? just some questions i had that maybe some1 can answer.About the accuracy though my r9 is more accurate than me so if the 125 135 are that good i would rather have a breakbarrel anyways. Thoughts?
Dave, THANKS for sharing your info bro !!! Mike
Thanks mag man and dave i am having a really hard time trying to figure out what to get the 135 or the torpedo. and is the torpedo a good fit for nitro conversion, i dont know how the setup is on this underlever.
Very few springers have enough swept volume to produce more power in .25 cal than in .22 cal.... The B-28 (350 clone) is a perfect example, it produces more FPE in .22 than in .25 cal.... and it's 70 cc.... Now it's just possible that is because the transfer port is optimized for .22 cal, I dunno.... If any springer has the chance to be a good .25 cal gun, the Hatsan 135 would be the most likely candidate....Bob
I think swept volume DOES make a difference on which caliber is better.... It's just that very few springers actually deliver more FPE in .25 cal, and those that do are certainly in the BIG range.... There are so many variables to optimize a springer for lighter or heavier pellets.... and I'm not really the one to comment, other than from what I've read and what logic tells me.... From what I understand, the following things favour heavier pellets within a given caliber (ie greater SD)....More swept volumeHeavier piston (moving mass)Higher spring forceLarger transfer portWhat I mean is, when you change things in the above direction, you are more likely to find the gun works better with heavier pellets.... I would think that the same things would help in a larger caliber as well, with the swept volume being needed because the bore is larger, and hence more volume is needed to propel the larger pellet.... When a high powered springer was a BSF S60 or equivalent, then .177 was favoured, but as springers got bigger, the .22s came into their own.... and now as the search for power continues, the guns are getting even bigger so that the .25 cal will work properly....Bob
Scotchmo knows a lot about gas-ram conversions.... IIRC he had some ideas about how increases in swept volume affected FPE levels.... Maybe shoot him a PM and ask him to leave some comments in this thread....How to you plan on increasing the stroke that extra 5mm?.... Don't forget, you need a small amount of preload on the gas-ram (2-3mm IIRC).... so you may only be able to get 122-123mm maximum anyway....Bob
A couple of comments:The large swept volume of the 135 makes it more suitable for larger calibers. On my experiments with rifles of smaller chamber volume, I decided that 100psi was the cutoff point where barrel friction overrides any FPE gain from the the remaining air pressure in the barrel. I verified it by doing a progressive chop of a .177 barrel from 18>15>12>11>9 inches. I now use 100psi to estimate the best barrel length for maximum power in a .177 spring gun. A Hatsan 135 in .177 caliber would need a barrel that was over 30 inches long before it used up all the available energy in the air. You can make the barrel shorter and it will work fine, but you are wasting some of that large chamber volume. For comparison, a .25 has 100psi remaining with a 15 inch barrel. Friction relative to bore area is not the same for a .177 and .25 so it may not be a direct comparison. But it is useful data. .25 is probably the best caliber for a rifle with the chamber volume of the Hatsan 135.For gas spring conversions, I try to leave at least 2mm of preload AND 2mm of extra travel. You do not want to bottom out the spring or let it top out. It is good to use a gas spring with a total stroke that is 4-5mm longer than the rifle stroke. The less allowance that you give yourself, the more critical the spacer dimensions used when installing the spring.I estimate that 85cc of air could make use of 100 ft-lbs of spring energy. That is about what the MF19-125 YW gas spring can produce. The Hatsan 135 looks like a good match for that spring. I usually recommend the RD (132 bar) gas spring for conversions, but that may be a little weak for the Hatsan 135. If I was doing a gas spring conversion on a 135, I would use the MF19-125 YW (177 bar) gas spring. If you want more than that, you would have to go with the MF25-125. What is the inside dimension of the Hatsan 135 piston?