JSB Exact Beast Diabolo .177 Cal 16.20 Grains Pellets

[josixpack]

Well, I got the JSB Exact Beast Diabolo .177 Cal Pellets, 16.20 Grains pellets yesterday and man to they seem to pack a wallop!
 
So far I only used them in the Beeman P17 I also got but compared to the Crosman .177 Hollow Point 7.9gr Premier Pellets they produce considerable more damage.  On soda cans the dents from impact and exit hole are much bigger and they sound like they hit with some serious authority.   Accuracy from 15 to 30 feet was very good from the P17. Although, I’m not sure if the P17 would hold up if I shot them all the time.  I’ll give them a try in my rifle this weekend at longer distances to see how the preform.  They may not be very accurate at distances farther then 30 feet.  However, they look down right scary, just like the JSB Match Diabolo Exact Jumbo Monster .22 Cal, 25.39 Grains pellets.

[playa]

Man that is a beast of a pellet.  I'm new to AG's, what's the perceived benefit of such a heavy pellet in .177 
Seems you give up so much velocity, the other part of the FPE equation that it would offset the increased mass? 

Is it more intended for "Magnum" guns with 1200+ fps?

[josixpack]

Man that is a beast of a pellet.  I'm new to AG's, what's the perceived benefit of such a heavy pellet in .177 
Seems you give up so much velocity, the other part of the FPE equation that it would offset the increased mass? 

Is it more intended for "Magnum" guns with 1200+ fps?

Well, there's obviously some physics here that are beyond me and a heavier pellet will slow FPS but may give you more FPE or knock down power down range.  Not sure what is more important but I think too many air gunners get caught up in the FPS thing.   

I don't' use the heavy pellets all the time just for plunking, but love the intimidating size compared to smaller pellets and the way they smack things around.

[Charles Outdoors]

I would think they would be best suited for pcp's. If you could push that pellet around 1000 fps accurately it should be a nice flat shooting round.

[K.O.]

I have all the parts to build a MK1377 pumper and I think these will be perfect for it I even have 3 different twist rate barrels for it Crosman ,Daisy and L.W.

The same powerplant and a 16" barrel has already hit 900+ fps with 7.9g CPHP( over 1020fps when I cheated with a 130*f valve)...

Hoping for a 50+ yard .5" group pumper...

[Motorhead]

Generally HEAVY weight pellets like this are PCP food and just too darn heavy to be efficient or practical in much else.
Monster is right !! 

[rsterne]

If your gun is less than about 25 FPE, stick with the 13 gr. Monsters.... This is fodder for .177 PCPs that shoot around 25-35 FPE, and they are rare....

Bob

[K.O.]

I am currently at 21 fpe as a .22 with Ruger 16g and the 21g Barracudas are accurate to the  30 yards I have ( have not checked fps with them)... I think I can get another .02+ c.i. of valve volume ( currently at .242c.i.)  and edge to 22-23 fpe...

I think it just might work worth the $10 next month to find out... it would be at the bottom edge of fpe enough though.

[rsterne]

You do realize we are talking about a 16 gr. pellet in .177 here, right?.... huge difference between that and .22 cal. in terms of the type of rifle to put them to good use.... There is nearly a 50% difference in the SD, and therefore in the effective pressure needed to achieve the same velocity....

Bob

[K.O.]

I was thinking about like 1/3 harder/more energy needed : since I am at 805 fps with 14.3g(558 w/26g so I am over ported for the 14g-16 pellets) and think I can get to 830-850 fps with 14.3g

22 is~ .038 in²
.177 is ~.025 in²

.038 x.66 = .025 so yep I guess I am down about 4-6 fpe (not the full 1/3 (7-8 fpe) because the air in the .177 stays a bit ahead on pressure/velocity longer

if starting at 1600 psi @ barrel port 5" into the barrel the .177 has a 165 psi advantage at 1061 psi so lets just say 10% more energy, at 24" into the barrel the .177 has a 130psi advantage at 465 so lets call it 30% and yes now it is wasted but it shows the .177 does make up a bit in the barrel because its smaller bore...

so 16g .177 at 18 fpe+ (711+)fps does seem do-able

Holes in my logic...  ?

[K.O.]

If necessary can add a 1" valve extension...

[grauhanen]

Well, I got the JSB Exact Beast Diabolo .177 Cal Pellets, 16.20 Grains pellets yesterday and man to they seem to pack a wallop!
 
So far I only used them in the Beeman P17 I also got but compared to the Crosman .177 Hollow Point 7.9gr Premier Pellets they produce considerable more damage.  On soda cans the dents from impact and exit hole are much bigger and they sound like they hit with some serious authority.

With a Beeman P17 you must be able to see the pellet throughout its flight.  That's a very heavy pellet in a very low-powered air pistol.

[rsterne]

I didn't follow the logic, but if shooting a heavy pellet at 700 fps (or 500, or 300) turns your crank, there is nothing wrong with it.... I prefer not the be able to see my pellets head downrange.... When my pellets get over 900 fps, then I think about trying something heavier, and with a 13 gr. pellet that is 23 FPE, so unless I had a .177 shooting over 25 FPE, or I couldn't get accuracy with a lighter pellet, I wouldn't be looking at a 16 gr.... That was my only point, YMMV....

To push a given SD to a given velocity takes a given combination of pressure and barrel length.... Keep the velocity and barrel length constant, if you increase the SD 50%, you need 50% more pressure, it's simple physics.... For the same weight pellet, the SD in .177 is 50% higher than in .22 cal.... so what you can do at 2000 psi in .22 cal takes 3000 psi in .177.... Once you launch it, however, the .177 should have a 50% higher BC than a .22 cal of the same weight....

Bob

[josixpack]

Well, I got the JSB Exact Beast Diabolo .177 Cal Pellets, 16.20 Grains pellets yesterday and man to they seem to pack a wallop!
 
So far I only used them in the Beeman P17 I also got but compared to the Crosman .177 Hollow Point 7.9gr Premier Pellets they produce considerable more damage.  On soda cans the dents from impact and exit hole are much bigger and they sound like they hit with some serious authority.

With a Beeman P17 you must be able to see the pellet throughout its flight.  That's a very heavy pellet in a very low-powered air pistol.

Well, not really but maybe... it seems like I can see the pellets from my Discos R Us Discovery .22 in the right light conditions. 

[rgb1]

Would like to add my experience with these heavyweights. They were checked for BC with
muzzle velocities from 790 to 890 using an old benchrest gun (LW barrel) and two chronographs.
The value I calculated is .047 (corrected to 29.92 and 59) with a corresponding Cd of .37 ........which
will certainly help with wind drift. An old post on one of the Russian forums (guns.ru) had them
at .048. Groups at 39 yd and 885 f/s were quite acceptable........typically 6-8 shots in .25 c-c and
one "flyer" that opened it up to .4-.5 . However, at 65 yd this performance seemed to disappear.
The norm at this distance was on the order of .8 and holes in the target paper suggest larger
than normal yaw. If and when time permits, I'll set up the high speed camera to investigate.

                                                                                                           Ron

[K.O.]

I didn't follow the logic, but if shooting a heavy pellet at 700 fps (or 500, or 300) turns your crank, there is nothing wrong with it.... I prefer not the be able to see my pellets head downrange.... When my pellets get over 900 fps, then I think about trying something heavier, and with a 13 gr. pellet that is 23 FPE, so unless I had a .177 shooting over 25 FPE, or I couldn't get accuracy with a lighter pellet, I wouldn't be looking at a 16 gr.... That was my only point, YMMV....

To push a given SD to a given velocity takes a given combination of pressure and barrel length.... Keep the velocity and barrel length constant, if you increase the SD 50%, you need 50% more pressure, it's simple physics.... For the same weight pellet, the SD in .177 is 50% higher than in .22 cal.... so what you can do at 2000 psi in .22 cal takes 3000 psi in .177.... Once you launch it, however, the .177 should have a 50% higher BC than a .22 cal of the same weight....

Bob

.177 is only  about 1/3 less area that is pushed on, and drag in the barrel is about the same slightly more contact at the .22s head and skirt.

Area pushed on by psi to me is the simple physics...

 In external ballistics it (SD) corrects  with a form factor... and in terminal ballistics it just says all else being equal the skinnier the better for penetration...So like before I still think it is off for internal ballistics on an air rifle. Sure Sd can be used but the form factor will be an internal ballistic form factor not the same as the ballistic FF...

I do think 800+ fps is better (whatever speed is most accurate with harmonics and all other considerations) but it is just another option and the 13g is likely to be a better option...
Heck my 2289 clone is only 650fps with 14.3 grains but on a calm day hitting a quarter at 30 yards is a done deal...

In the interest of flatter shooting yep a larger valve  and a bit more pressure will help, but even at 700+fps it will perform better than the 2289 clone.

But like I said I can add 1" of valve, it would have an internal diameter of .4" so valve volume would be ~ .37 c.i. your disco pumper in the 5.5cc(.335 c.i.) configuration got about 25 fpe at 1500 psi with 25g .25 pellets while retaining air... at .37 c.i. (6.1cc) you got about 30fpe...

http://www.gatewaytoairguns.org/GTA/index.php?topic=37401.0


And yep It might take me 35 pumps with the smaller swept volume but the build would only take one custom part... and not need the more expensive disco tube and steroid linkage...(I still prefer the disco pumper carbine  )

I see the pumping as the price of it being a very simple budget build ~$140...

[K.O.]

Would like to add my experience with these heavyweights. They were checked for BC with
muzzle velocities from 790 to 890 using an old benchrest gun (LW barrel) and two chronographs.
The value I calculated is .047 (corrected to 29.92 and 59) with a corresponding Cd of .37 ........which
will certainly help with wind drift. An old post on one of the Russian forums (guns.ru) had them
at .048. Groups at 39 yd and 885 f/s were quite acceptable........typically 6-8 shots in .25 c-c and
one "flyer" that opened it up to .4-.5 . However, at 65 yd this performance seemed to disappear.
The norm at this distance was on the order of .8 and holes in the target paper suggest larger
than normal yaw. If and when time permits, I'll set up the high speed camera to investigate.

                                                                                                           Ron

I picked up a Daisy 953 1:15 twist barrel because I suspected it might need a faster twist and I just wanted to see how it does out of a 19"-20"

Crosman, Daisy &  L.W. barrels ( the special on the Airforce 20$  L.W. barrels was just in time)

I  am dreaming of a good long range cheap pumper and having fun seeing what I get... I suspect the L.W. barrel with Monsters will kick butt on the Daisy barrel on the Beasts...  But...

[rsterne]

.177 area = 0.0246 sq.in. x 3000 psi = 73.8 lbs. force to accelerate the pellet....
.22 area = 0.037 sq.in. x 2000 psi = 73.9 lbs. force to accelerate the pellet....
50% more pressure required in the .177 to reach the same velocity in the same barrel length....

Bob

[K.O.]

.177 area = 0.0246 sq.in. x 3000 psi = 73.8 lbs. force to accelerate the pellet....
.22 area = 0.037 sq.in. x 2000 psi = 73.9 lbs. force to accelerate the pellet....
50% more pressure required in the .177 to reach the same velocity in the same barrel length....

Bob

Bob it is just a semantics issue  2000 is 2/3 ~.66 of 3000... so yes 1000psi is 50% of  2000 so yes you can say it takes 50% more psi

but since the barrels eat psi at differing rates... and it is abut the force felt I chose to say the difference felt at the same psi is that the .177 feels .66  the force of the .22...

so  1500 psi

.037 x 1500 = 55.5,       55.5 x .66 =36.63

.0246 x 1500 = 36.9

So you are saying it take 50% more energy to accelerate the .177 at the same rate

and I am saying the .177 accelerates at 66%  the rate of the .22 at the same energy level...

[rsterne]

Yep, 33% discount = 50% markup in any Economics course.... Same math, different starting point....

Bob