Author Topic: Slightly new topic.  (Read 376 times)

Alan

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Slightly new topic.
« on: April 18, 2019, 01:58:24 PM »
As I read yours and other comments about SSG and TSS adjustments, I begin to wonder if either system is really necessary? This said, when I installed a TSS (to replace an SSG) in my Marauder, it did increase the number of shots, and those shots were a tad faster too (I replaced the transfer port. Now .162). I wouldn't argue about adjustments of these devices, other than to say the TSS was easier to get correct. Fast forwarding a bit, my WAR Cobra doesn't have either device. Both airguns are .25 caliber, both are regulated (1,900 for the Marauder, and 1,825 for the Cobra). The Cobra will shoot twice as many shots before falling off the regulator (both ≈875 fps). Again, adjustments aside, I can't improve the Marauder's shot count, no mater what I do. I'm almost tempted to go back to stock spring and hammer with the Marauder. Comments Mr. Sterne?


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Alan

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rsterne

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Re: Slightly new topic.
« Reply #1 on: April 18, 2019, 04:10:23 PM »
I can't comment on the specific SSG from WAR as I have never used, or even seen one.... and I have never used a TSS.... Many try and fit an SSG into the stock space available in the gun, and this limits them to using a stock spring and preloading it.... which increases the cocking force.... The SSG is intended to use a longer, softer spring, but with preload and a gap to the hammer.... This will often require a new, longer end cap to obtain the additional length required.... It will result in using less air, and with a lighter cocking force, than a conventional, preloaded hammer spring, in every gun I have tried it on....

It often happens that products are made differently to the original idea, and because of contraints in either the design, or the desire to have to replace as few parts as possible, compromises are made.... I have never used a TSS as it doesn't make sense to me, and the SSGs I make work the way I want, so I never bothered to even try one.... For a given hammer energy, a properly designed and built SSG will have less hammer bounce, and an easier cocking force.... but some guns just do not lend themselves to an easy SSG design....

The Cobra valve is quite different, and uses what amounts to an adjustable "air spring" which provides a progressive valve spring effect.... It is great for high shot count, but requires more hammer strike, so increased cocking force.... If that isn't an issue, and you are getting the power you require, then it's a great setup.... I have never been able to achieve good results with a Cobra styled valve at the high FPE levels I am usually trying to achieve.... so again, I'm no expert in setting them up, or their advantages in that situation....

Bob
« Last Edit: April 18, 2019, 04:13:59 PM by rsterne »
  • Coalmont, BC

Alan

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Re: Slightly new topic.
« Reply #2 on: April 19, 2019, 04:58:57 AM »
Very well stated. However, you bring up another topic, and that is generating highest power vs. air use requirements—if I may be so bold.

In my case, I have the .25 caliber Cobra shooting 25.39 grain pellets (JSB Exacts) at 875 fps. That's about 43 fpe. I can easily turn it up higher, but besides using more air, the accuracy diminishes. This is especially true at velocities over about 950 give or take (3,500' asl, ≥90° ambient). And this brings up another issue—terminal ballistics. I suspect 43 fps is adequate for the game I shoot (primarily pigeons and trash birds), as the pellets always exit even at ranges out to 125 yards (that as far as I have checked). The issue here is, when is the developed energy enough? I can't answer that question to be sure!
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

rsterne

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Re: Slightly new topic.
« Reply #3 on: April 19, 2019, 08:25:39 AM »
I don't use above about 960 fps either, because the drag is increasing so fast the wind drift increases quickly, and the pellet looses a lot of its velocity in just the first few yards.... Some pellets/bullets are still accurate over that, but I still wouldn't push above that with a pellet, and not above about 1060 for a bullet (which loses less velocity right after the muzzle)....

Terminal ballistics is another matter.... The volume of the wound cavity is roughly proportional to the FPE (in a consistent medium)…. while the penetration is roughly proportional to the velocity times the sectional density (which means heavy pellets in a given caliber penetrate more for the same FPE)…. Light and fast means a shallow and wide wound channel, whereas heavy and slow (but same FPE) means a longer, thinner channel.... Which is best for your target depends on what it is.... For birds, you need enough penetration to make it through their feathered armour, but if you aren't after the flesh to eat, having the pellet blow up would be the most effective.... may as well expend that energy within the critter, if possible....

Since I try and tune all my guns in the 900s, I vary the weight to achieve that.... For major changes in FPE, then I vary the caliber.... While you can, in theory, kill humanely with 1 FPE per lb. of body weight on big game, that formula falls apart as the target shrinks dramatically.... I find more effectiveness in anchoring Grouse at 20 FPE than at 15 FPE, even though both pellets exit the bird.... The "hole" is larger, and the bird has less tendency to fly away, and a greater chance of being knocked off its feet by the impact of a heavier pellet.... transfer of momentum, as it were....

Bob
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Alan

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Re: Slightly new topic.
« Reply #4 on: April 19, 2019, 11:01:10 AM »
I don't disagree with any of your data. However, your comment (in a consistent medium) is telltale. Wouldn't it be nice if we could duplicate the exact impact spot, each and every time? Since we can't, I tend to use John Schaefer's scenario, in that two holes are better than one! That is, clean through—two holes to bleed out—with enough wound channel to inflict damage to the tissue that does bleed.

Sooner or later, JSB is coming out with a .25 caliber Hades pellets. I certainly will try them, in an effort to see if blowing up inside the target is as good as a pass through. But for now, the 25.39 grain Exacts do a fantastic job at downing game.
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

rsterne

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Re: Slightly new topic.
« Reply #5 on: April 19, 2019, 01:36:21 PM »
By "consistent medium" I am referring to a uniform density and harness throughout.... ie not feathers, skin, bone, muscle and various organs, which all have a different reaction to the penetration of a pellet or bullet.... To compare how various projectiles perform, you have to "set" the parameters, otherwise you can get results that at totally unpredictable....

Most of our small critter and bird shooting is pass-through, unless you are using a gun that is marginal for the quarry, IMO.... After that it's a matter of how big are the holes you punch and how much energy is expended inside the target.... The Hades pellets are apparently available, HAM just tested the 15.9 gr. in .22 cal.... It will be interesting to see how their accuracy and BC compares to the Exacts....

Bob



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Alan

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Re: Slightly new topic.
« Reply #6 on: April 19, 2019, 02:17:38 PM »
Excuse the pun, Exactly.

My experience with PolyMags, for example, have been dismal at best. Past about 40 yards, they just don't fly well.

Rick had good luck with the Hades at 50 yards, and I'll have to ask him how his 100 yard groups look. We shall see.
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

rsterne

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Re: Slightly new topic.
« Reply #7 on: April 19, 2019, 04:29:39 PM »
I have never found a gun that liked the Polymags either.... I hope the Hades are better....

Bob
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