What does VTR stand for?
Has anybody tried either of the Seneca .25 Cal, 35.8 gr or 43.2 gr pellets? Do these pellets have enough spin to be stable and not tumble out of this rifle? What Group size at 35-50 yards do they yield? The .117 equivelent pellet weights are 9.0 gr and 10.9 gr that have the same Hydrodynamic back pressure effects profile on the Piston, if the barrel is changed to .177.
The question was, are the heaver pellets going to be spinning fast enough to be stable? For a refernce about this, check out the Greenhill Formula in _Hatcher's Notebook_ . It is available on line in PDF for free at _archive.org_ . Look in the last chapter on external ballistics. He also goes over the drag functions for different projectile shapes. There are graphs showing different drag functions. The drag goes up by almost an order of magnitude passing through the trans sonic region (+/- 20% of the speed of sound). To avoid this instability keep velocities below about 880 FPS. Also, another must have freebie is _Hawke ChairGun_ . It goes through ALL the number crushing on external ballistics you need to be a successful Airgunner in graph and table form . Just google it.
Further down the page in response to the JSB 33.95 FPE question, Steve "got an average of 605 FPS with the 33.95 JSB pellet." That is 27.6 FPE. Piston air guns are at first approximation a transformerized Newton's Cradle. The transfer function coupling the mass of the pellet to the mass of the piston goes as the fourth power of the bore vs. the piston diameters. If all that we do is change the barrel we don't need to know the piston mass or cylinder size since it hasn't been changed. Going from .177 to .25 gives a hydrodynamic factor 3.98x. Thus the JSB 33.98 gr. gives an equivalent weight of 8.53 gr for the .177. There are secondary factors like the residual (air)spring pressure adding more remaining pressure further down the barrel. Also the .177 barrel is equivalently half the expansion ratio of the .25, Also the extreme temperature (over 1,300F peak) from compressing the cylinder air enough to generate the pressure needed with a high compression ratio results in a larger loss than friction. For the .177 equivalent 8.53 gr. with 27.6 FPE gives an equivalent velocity of 1,207 FPS, essentially twice the .25/33.95 @605FPS. The actual .177 energies are lower due to other velocity loss problems. The popular 10.5 gr. .177 pellet is equivalent to a 41.8 gr. .25 pellet. Of course the 725 FPS at 28 FPE needs a 24 gr pellet. For the .177 with the 5.1 gr. Gamo PBA @ 1,500 FPS has 24 FPE.
Heavier pellets don't work well in springers. You can try it typically the 20-25gr will make the most power, then at some point, likely ~30gr, power will start to taper off. At some point later power will nose dive hard. It's hard to predict when these happen because there are lots of factors involved, but even if it didn't lose much power your velocity will be rather low, like 550 or less would be my guess. The rifling is likely ~17 +-1 so you're good there. Accuracy cannot be estimated with chinese guns, the bore quality varies far too much. What you're missing on the pressure is other factors, like the time pressure is available to use, stiction and friction of the pellet. The 30+gr pells are generally pcp ammo. If you change that gun to 177 using a Trail XL barrel you will lose a ton of power and the JSB 13.43 pellets, maybe the 16gr, will be the only ammo to choose from. Why is too much to explain here but there's a lot of factors involved. In short, it's a delicate balance of parts and weights, similar to a car and its engine and gearing. Throw one off, like camshaft choice or gearing, and you're screwed. If you do try them, and have a Crony, please post the #'s because this is a common question and many assume it'll shoot any wt pellet at 725fps. Fyi you should get this guy; Piston Seal, Fits Walther Falcon... which will net you some free power. Well, by free I mean no drawbacks. It should be worth 5-10% more power.
There used to be H&N Excite Coppa-Spitzkugel Pellets, .25 Cal, 24.54 listed here . Does the Copper coating reduce barrel resistance over lead? And will these pellets ever be available again? If you want to see the Pyramyd Air listing for this pellet just google it for a link.
Pointed pellets look cool but they actually have poor BC. The copper is kinda neat too, but kinda pointless. I suggest the JSB 25.39 round nose. If you want to reduce barrel friction you need to sand the bore. I know how that sounds but there's a reason for it, which is low chinese quality, and it must be done a certain way. I have detailed instructions if you/anyone wants; chevota at hotmail. Just tell me what gun. Fyi, the point of sanding is accuracy, byproducts are less friction, less blowby and more power.
The copper coating did nothing for velocity. It was really just to reduce lead contact. We do not carry them. They did not sell.
What muzzle Energy does this .25" magnum air-piston rifle produce with Lead pellets that people are going to actually use? In the 25gr to 31gr range?
Normally 30 is about the max, but I've had a few people say they hit 32. This was for the Trail XL btw, and this should be the exact same power plant and barrel. More often I hear ~28ftlbs, so the 32, if I recall correctly, was tuned.
What pellet and chronograph conditions gave _You_ (Mark) 34 FPE for 725 VTR .25? Also was there smoke coming out of it?
I had the Hatsan 30 caliber break barrel do you think the Remington has as much knock down power
The Hatsan 130 is .30 caliber. I did choose Remington VTR725. More practical ammo choices. Chronographed a 5 shot group of Predator GTO 16.54 grain, averaging 887.6 fps. Low of 885, high of 891 fps, in 57 degrees. Get a chronograph. Woodys World.
The Remington is rated at 30 ftlbs. The Hatsan 130 is rated at 34 ftlbs. Very close.
900 fps on a .25 cal?? will buy one if it is correct...
You could hit 900, but as others mentioned you need the lightest pellets and those usually suck and are expensive. Using a realistic JSB 25gr round nose, which I consider ideal for this gun, expect 700 to 725. If you open it up for a little tuning the 725 should be guaranteed and you might even hit 750. Note, you can buy the Trail XL barrel in .22, which is imo a better choice and can hit 900 using std lead pellets. Mine, which I tuned, shoots 14.35 at 940. So a little less power than .25 but the velocity is perfect. Plus .22 pells are cheaper and way more to choose from. Oh, last I checked that barrel was $20 total delivered, direct from Crosman. Ideally you need a little more info to swap it out; chevota at hotmail and I'll give it + the tuning stuff
On 3/2/2020 I conducted another chronograph 5 shot test, shooting the Predator GTO Lead-Free 16.54 grain lead pellets temperature was 57 degrees, 25 feet above sea level altitude, in 41% humidity. Results were: 890, 883, 891, 889, & 885 fps. Average was 887.6 fps. Get a chronograph. Woodys World.
On 1/27/2020, I dis shoot (5) Predator GTO Pellets across my Competition Electronics ProChrono Digital. Temperature was 45 degrees, humidity was 57%, 25 feet above sea level. Results were: 872, 881, 876, 883, and 879 fps, Averaging 878.2 fps. That categorizes this as meeting the up to 900 fps. Weather temperature has a lot to do with velocities. I have done nothing extra to this air rifle, in the two months I have had it, only lubricated it with silicone oil, thats it. I recommend this air rifle. Get a chronograph. Woodys World
I recommend this air rifle. Woodys World.
I got 850 fps with the 16.54 Predator GTO using my ProChronoDLX
Only the .25 caliber pellets with the lightest grain weight will achieve or come close to that velocity, that should be a no-brainer. The 16.54 grain Predator GTO is the lightest that I know of. Also consider altitude above sea level, weather, and temperature. There are not a lot different .25 caliber pellets available. Get a chronograph. Woodys World.
They don't tell you what weight pellet they use to achieve that velocity though
What would the fpe be on the 25 caliber with 33.95 grain jsb pellets..
The power drops as pelle wt goes up. Generally peak power will be in the 20-25gr range, but you shouldn't lose too much at 30, or maybe even 33. The guns themselves will likely vary in power more than the difference between 25 and 33, so only one way to find out. The #'s Steve gave sound right, so his gun no doubt makes 29-30 with 25gr. Maybe he can post various #'s so people can get a feel for what happens as wt changes.
Easy formula to determine FPE. Velocity x Velocity x weight in grains /450240
I got an average of 605 fps with the 33.95 JSB pellet. Using the online PyramydAir Airgun Calculator, it came out to 27.6 fpe.
The fpe will depend on the actual fps velocity that this .25 caliber, 33.95 grain pellet will be shot. You can not figure it out only on the fact it is a 33.95 grain .25 calibers. You also have to have the actual fps velocity the pellet is moving to get the FPE. Get a chronograph. Woodys World.
I guess I'm wondering how just a front sling attachment works since I've never had a rifle with one? It's always been either two or none....but never just one. How exactly do you attach a sling? Do you just loop it around the grip? I'd be inclined to suggest just adding the stud to the shoulder stock would have been a good idea but maybe I'm missing something.
The gun is basically the same as the Trail XL, which has said mount. So you can buy the mount $1.15, then mod your barrel block to accept it. I have the how-to if you want; chevota at hotmail
it doesn't come with a sling mount because there's no normal place to mount a swivel on a break barrel!! This is a break barrel gun not a centerfire rifle, break barrels have to bend in half to cock, that leaves NO room for a swivel unless you want to ruin the stock & place it on the outside of the gun like Hatsan does(Stupid & Ugly).... best bet is to buy that cheap Buddy sling, it attches without swivels... Good luck
Some shooters dont want or install the second stud mounted on the lower standard end in the usual position. Some attach that stud further forward on the stock, like near the trigger guard or near there. They do that because of how they want to sling the rifle on their shooting side according to how it would hang or be slung on his body easier and It would allow for them to easily bring the barrel up to a cocking, loading, and shooting position, if not already cocked and loaded, getting a shot off faster with less movement, instead of slung on the shoulder the standard/old fashion way. That may be why it does not come with that second attached sling mount and sling. Plus you would pay more for the air rifle if it came with a sling. Firearms do not come with slings, so why should air rifles. But, it should be an option. I would rather mount the sling my self, in the manner I explained herein. Get a chronograph. Woodys World.