Best long distance airgun

[Smitty8141]

Voltar1,
Assuming I'm using the right BC, I show a POI of 278 inches, which is 23 feet. It's sounds close. Your shooting 30 more yards are your velocity is 20 ft/s slower than mine. It's showing a velocity of 366 ft/s at 264 with 13 ft.lb of energy.

It's amazing that these pellets seem to be staying relatively stable dropping from that distance.

[rsterne]

I have a BC of 0.040 (GA Model) for the .30 cal JSBs at 850 fps.... Sighted at 50 yards, ChairGun says 214.07" of drop (17.8') at 264 yds and 211.90" at 263 yards, so the pellet is dropping 2.17" in the last yard, or just 0.060" in the last inch of travel.... which works out to 3.44*.... The boreline at 264 yards is 40" above horizontal, making the total drop from boreline 254" (just over 21 feet).... 264 yards is 792 feet, or 9504 inches, so the angle is inv.sin(254/9504) = inv.sin(0.0267) = 1.53*.... If the bullet is still nose high, parallel to the boreline, it will be tearing though the paper at just under a 5* angle.... That would make the hole in the paper 0.033" taller than it is wide, for a pellet that is 0.38" long.... The pellet would be travelling 488 fps and still have 23.6 FPE of energy at 264 yards.... A 1 mph crosswind would drift the pellet 5.65"....

Bob

[Voltar1]

18 ft is right on then? Wow that is cool.
So the Bushy rangefinder must be accurate as well as the mildots of my scope. Coolbeans.

[rsterne]

Yup, looks like the BC is right on with your field results.... Using 0.039 it is slightly over 18 feet instead of slighty under (GA Model)....

Bob

[Rattus58]

I have a BC of 0.040 (GA Model) for the .30 cal JSBs at 850 fps.... Sighted at 50 yards, ChairGun says 214.07" of drop (17.8') at 264 yds and 211.90" at 263 yards, so the pellet is dropping 2.17" in the last yard, or just 0.060" in the last inch of travel.... which works out to 3.44*.... The boreline at 264 yards is 40" above horizontal, making the total drop from boreline 254" (just over 21 feet).... 264 yards is 792 feet, or 9504 inches, so the angle is inv.sin(254/9504) = inv.sin(0.0267) = 1.53*.... If the bullet is still nose high, parallel to the boreline, it will be tearing though the paper at just under a 5* angle.... That would make the hole in the paper 0.033" taller than it is wide, for a pellet that is 0.38" long.... The pellet would be travelling 488 fps and still have 23.6 FPE of energy at 264 yards.... A 1 mph crosswind would drift the pellet 5.65"....

Bob

Can't you just say that an over stabilized pellet will not follow trajectory (the nose leading the flight path) and is "dang" near key holing...

[rsterne]

What I'm saying is that the strange shaped holes in the target cannot be, IMO, from the bullet "dropping" into the target paper, there must be another reason.... Even if the nose of the bullet was still flying on the same angle above the horizon it was launched on, the hole in the target would only be 0.033" taller than it is wide.... "Overstabliized" to me, means that the bullet is spinning way faster than it needs to, so the nose is staying on the original course.... When it happens to artillery shells that are fired on a high angle, they don't land nose first, which is why the Military use Stability Factors between 1.5 and 2.5....

There may be some factor of Dynamic Instability involved that is causing the strange impact marks.... It might take high speed photos to find out exactly what is happening.... However, it can't be just the bullet dropping into the target, the angles just aren't great enough....

Bob

[Smitty8141]

Bob,

I can tell you that at 100 yards the holes are perfect. Unfortunately I don't have any way to put a target between 100 yards and 207 yards. I have a 100 yard range straight off my patio. To shoot farther I shoot across the mucky lake you see in the picture. Shortest is 207 yards, so far longest is 234. Also, the Boss has a smooth twist barrel. I would think the pellet is spinning slower, just a guess. Maybe that has something to do with the holes. BC for the .30 pellet in the FX is .035.

Kevin

[MicErs]

The 30cal BT65 that I built shooting at 264 yards put 5 JSB pellets into a 4 inch cluster.
Don't believe guys that discount long range pellet shooting.

One time...

[MicErs]

What I'm saying is that the strange shaped holes in the target cannot be, IMO, from the bullet "dropping" into the target paper, there must be another reason....

There may be some factor of Dynamic Instability involved that is causing the strange impact marks.... It might take high speed photos to find out exactly what is happening.... However, it can't be just the bullet dropping into the target, the angles just aren't great enough....

Bob

There is.  When the bullet gets significantly off line of travel drag further displaces it.  That is when you start to get key holeing with the tip of the bullet high due to stabilization.  The holes are oval because the bullets are hitting tip high.  The bullets are hitting tip high because of the effects of drag.  They were launched at nearly double the speed of impact.  They probably had a 50 foot rise to line of sight.  The math is non-linear, it would probably be modeled with a quadratic equation.  That bullet is right at the raged edge of turning backwards.

[MicErs]

W "Overstabliized" to me, means that the bullet is spinning way faster than it needs to, so the nose is staying on the original course.... When it happens to artillery shells that are fired on a high angle, they don't land nose first, which is why the Military use Stability Factors between 1.5 and 2.5....
Bob

Bob, I suppose that is true but what we are looking at here is probably what you are calling over stabilisation.  Who is building a barrel today that is intended to shoot to 200 yards at sub Mach I velocities with anything, let alone a .257 bullet?

I think the barrel is probably a one in ten maybe one in fourteen MAX.  We have this large, long, slow boolit, traveling down range subsonic.  End result is it is trying to flip over backwards, tip high.

Shoot it another 40 or 50 yards and see what you get.

Just my two and admittedly I did not bother with any math... so... SWAG  =)

[Smoketown]

Just my two and admittedly I did not bother with any math... so... SWAG  =)


I love Scientific Wild A** Guesses!   

Seeing as a slo-mo camera is a costly item, might I suggest a stack of scrap wallboard, block of clay/duct seal, stack of cardboard, or ballistic gelatin to catch the projectile at it's last attitude?

Having pulled many a target at the 800, 900 and 1000 yard lines, I have seen numerous .30 cal. holes in the 2"x4" target stands at rather steep/unusual angles.

I was also led to believe that airgun shooting at reduced distances was supposed to mimic this.

Cheers,
Smoketown

Edit - Spellun'

[Voltar1]

The 30cal BT65 that I built shooting at 264 yards put 5 JSB pellets into a 4 inch cluster.
Don't believe guys that discount long range pellet shooting.

One time...

Hope not :-)
BTW, how many times have you done 'it'?
Going to give it a go tomorrow. Weather should let up by then
Cheers

[Smitty8141]

W "Overstabliized" to me, means that the bullet is spinning way faster than it needs to, so the nose is staying on the original course.... When it happens to artillery shells that are fired on a high angle, they don't land nose first, which is why the Military use Stability Factors between 1.5 and 2.5....
Bob

Bob, I suppose that is true but what we are looking at here is probably what you are calling over stabilisation.  Who is building a barrel today that is intended to shoot to 200 yards at sub Mach I velocities with anything, let alone a .257 bullet?

Just to clarify. The target pictures were shot with a .30 pellet from an FX Boss with a smooth twist barrel. The target was at 234 yards.

Kevin

[rsterne]

As I said, the math for the pellet hitting on an angle due to excessive drop just doesn't add up.... On the other hand, since we're talking an FX with a smooth twist barrel, it is entirely possible that the pellet is understabilized, and on the verge of tumbling.... therefore hitting nose up, which would explain the smeared top and sharp, circular bottom (creating a pear shape) on some of the holes at 234 yards.... I saw one measurement of the spin rate on a pellet from an FX that showed the pellet was only rotating 1 turn in 13 FEET....

There are several very good programs for calculating the required twist, and the better ones deal with subsonic velocities just fine.... The .300 AAC Blackout shoots 200 gr. bullets at 1050 fps, and is very accurate out to 600 yards in an 8" twist.... so the technology certainly exists, and is pretty well known.... Several GTA members have produced spectacular results out to 400 yards, and bullets aren't tumbling as far out as 700.... but with bullets, not pellets, of course....

Bob

[Smitty8141]

Bob,
Tomorrow I'm going to run around the lake and pull some of the pellets out of the wood that the target sits on. I'll post pictures of them. Maybe we can see entry angle into the wood.

Kevin

[LDP]

The 30cal BT65 that I built shooting at 264 yards put 5 JSB pellets into a 4 inch cluster.
Don't believe guys that discount long range pellet shooting.

One time...

Hope not :-)
BTW, how many times have you done 'it'?
Going to give it a go tomorrow. Weather should let up by then
Cheers

Most likely it is a one time event or one in 100 groups. I dont think hes trying to get under your skin but its obvious that you are using one group at extended range to say dont discount long range pellet shooting and one group doesnt show anything. Try shooting 20 groups of 5 shots at 264 yards and see what the average group size turns out to be. I am not saying it cant happen but its unlikely you will retain a 4" average at that distance with pellets. Good luck and post the results.

Weather should let up by then

Why wait on weather? I think that would be the best way to prove you can get long range results with pellets. I almost never have calm conditions to shoot in and this is one reason people discount the long range ability of pellets. In real world conditions at ranges beyond their design pellets will have problems with even the slightest breeze. Chairgun says that a .22 JSB heavy that starts out at 835 fps will get pushed over 8" at 265 yards in a 1 mile an hour cross wind.

[Sfttailrdr46]

  Long range shooting with a pellet rifle is challenging at anything over 100 yards to date my best is 6 out of 10 shots at a 7" circular saw blade at 110 yards with my Daystate Huntsman Regal XL .25 and my Evanix RS II .22 5 hits out of ten on the same target. Funny thing is there was a guy doing it with a .177 RAW HM Target with a pro tune

PS He out shot me all day and even let me play with it for about 20 shots, the trigger was super light ~ 5 oz and he had a Leopold 4x12x ? not sure what the objective lens was 

[Voltar1]

This shooting I am telling about is the first attempt at that distance
I shot three hail mary shots then finally saw the dust kick. Reduced the power
to 8x so i could shoot and watch the hits. Took five shots at the chosen poa
Pleased as punch to watch them land. I expect this rifle to repeat that easy
when it is NOT just a five shot group selectively chosen to brag about. I woul
email pics to anyone handy at posting here.
Weather permitting......
I doubt any of you would be shooting for groups in the high mountains
in a driving rain storm on the verge of snow.
Today is much nicer but I cannot see the hits in the mud.
Cheers

[plinker81366]

 enjoy the pics, 204 yds , jsb 18 grns, 885 fps

[LDP]

This shooting I am telling about is the first attempt at that distance
I shot three hail mary shots then finally saw the dust kick. Reduced the power
to 8x so i could shoot and watch the hits. Took five shots at the chosen poa
Pleased as punch to watch them land. I expect this rifle to repeat that easy
when it is NOT just a five shot group selectively chosen to brag about. I woul
email pics to anyone handy at posting here.
Weather permitting......
I doubt any of you would be shooting for groups in the high mountains
in a driving rain storm on the verge of snow.
Today is much nicer but I cannot see the hits in the mud.
Cheers

I guess I dont understand that comment. Why do you need to see the hits in mud? Why do you even need to see the hits? It seems like it would be easy to put a target up at 264 yds and shoot some groups. You say that you can repeat the 4" 264 yd group easy so lets see it. As far as I am concerned thats a very bold statement to make so I need to see multiple groups on paper that show that. Like I said if you can and do make 4" consistent groups at 264 yds with pellets great shooting.