drop between 50 an 100

[tutti confuso]

yesterday i visited the range to try out shockeys gold ffg for the 1st time... after loading a few rounds at 50 yrds with non adj able iron sites.. they all hit dead on center with a 3 - 4inch  group using a rest .. i cleaned the barrel an moved over to the 100 target an soon found out i wasn't hitting the target as it was shoot possible 18+inches low..
 is this normal for a 175 round ball with a charge of 90 grns of shockeys powder ?  using the same charge as the 50 yrd target..
before i had a chance to try a heavier charge or reall blk powder  i made a fatal error not paying attention i stuck a ball an patch down the tube .. u guest it no powder charge first... ended that day quick... anyways got it out at home with my air compressor.. no problem there.. but still wondering will a heavier powder charge help... i sure i need better sights, but in the mean time ?
it has a 32" barrel 1~62 twist .50 cal

[Semisane]

Hey TC.  I think you're probably getting lower velocities than what you are used to with 90 grains of powder - at least that was my experience with JSG FFG out of a Lyman Mustang .50 caliber in-line.   

I shot three five-shot groups over a chronograph, one with JSG FFG, one with Pyrodex RS, and one with T-7 FFFG.  All loads were with 90 grains volume powder and a 385 grain Hornady Great Plains bullet.  Here are the 5-shot average velocities for each group.

JSG = 1018 fps
Pyrodex RS = 1144 fps
T-7 FFFG = 1583 fps

However, the JSG produced the best 100 yard group (1 3/4"), followed by Pyrodex (4"), then T-7 (5 1/2").

[tutti confuso]

even so...  with the lower velocity you mention getting, i'm con fussed a bit with 176 grn ball weighing so much less then your 385 grn'er that it has so much of a drop [ 18+"] at a hundred yrds
 i would think the lighter bullet would have More velocity then the heavier... with that said.. my question topically is... how much more of a powder charge  can i / do i dare go to make up at least some of the velocity to get to the 100 yrds ?
 or do i give up on the this new powder shockey's gold ffg ? an move on....... 

[Semisane]

I can't figure it  TC.  If you're hitting dead on at 50 yards your velocity would have to be down around 700 fps to hit 18" low at 100.

I used the ballistic calculator at http://www.handloads.com/calc/ and plugged in the following data.

Velocity (See Below),  Bullet Wt. = 175,  Sight in at = 50 yds.,  Ball Coef. = 0.104,  Sight Ht. = .5,  Intervals = 25,  Mx Range = 100
       
With the zero "sight in at" set at 50 yards, it shows:

 -4.6" at 100 yards for 1600 fps
 -5.9" at 100 yards for 1400 fps
 -7.5" at 100 yards for 1200 fps
 -9.8" at 100 yards for 1000 fps

It doesn't make any difference what powder you use to get a certain muzzle velocity.  If 90 grains of T-7 starts the ball at 1500 fps and 120 grains of JSG starts it at 1500, the trajectory for those two loads would be about the same, although accuracy on target may be different.


   

[Idaho Ron]

Semisane,   The BC of a hornady .490 round ball is .067  The .495 is .070 
where did you come up with the .104?   Ron

[Semisane]

Thanks Ron. I didn't know the BC and used the calculator on that web site for a 175 grain .490 "round nose" bullet.  The BC it produced was higher than I expected and I figured it wasn't set up to work for RB.

Here's a recalculation with a BC of .067.

Velocity (See Below),  Bullet Wt. = 175,  Sight in at = 50 yds.,  Ball Coef. = 0.067,  Sight Ht. = .5,  Intervals = 25,  Mx Range = 100
       
With the zero "sight in at" set at 50 yards, it shows:

   -5.7" at 100 yards for 1600 fps
   -7.0" at 100 yards for 1400 fps
   -8.5" at 100 yards for 1200 fps
 -10.8" at 100 yards for 1000 fps

[Idaho Ron]

The PRB drops like a rock off a dump truck. While my big conicals drop a bunch they carry their energy WAY farther than a PRB.
The tests I did with a Chronograph and my rifles were interesting.  from my rifles The 410 gr 50 cal Hornady great plains bullet has the same energy at 175 yards as the PRB has a 25 yards.  Also the Hornady load in my gun has 1000 FPE past 200 yards.
Ron

[captchee]

Interesting . ? My point of aim with a .530 RB pushed with 80 grains of goex 3F is  the same stop at 100 as it is at 50 .
 In fact at  log gong shoots  which I have won a couple  at 250 and 300 , off hand with rb , using the same load  im only holding  maybe 12 inches high  from center ?.

 Have you seen this problem with other powders ?
 While some believe powder is powder , it is not . If the powder produces  its peak pressure  further down the barrel , it can produce a different our come .
IF however your  finding 1500 at the muzzle ? Then  the poster before me is correct .
A projectile doesn’t care what propels it to velocity , only that it get to a given velocity . Thus it would act the same  if fired with compressed air to 1500fps or  BP .

 I would say no its not normal for a 50 cal with that charge to have that much of a variance in trajectory  at that distance .

 Now I have seen barrels that would shoot something like a knuckle ball  trajectory .
 Infact I have one that has an iron barrel  that  it took  firing through paper gates to figure out what it was doing …
 Ironically that’s the rifle I use for long gong shooting .  At 25 yards it about 3 inches low , 35 ,,, 4  at 50 she starts to climb . Go figure ? I just accept it

[Idaho Ron]

captchee,  I chronographed a 177 gr PRB with 110 gr powder.  I got 1998 FPS with that load. When I plug that into my shooting software I don't see the same thing as you do. With a 100 yard zero  the PRB is 51 inches low at 250, and 91.98 inches low at 300. I wonder what the difference is?  While I have never shot that load at 300 yards I have shot it between 50 and 150. I have 12 inches of drop at 150 with a zero at 50.   Ron

[captchee]

 well ron i can only tell you  only what happens .
at those long distance events i lose more then i win . i can tell you i know no one that compensates that much for that distance .
 At  Seneca  this year I took first  at 300 yards , 5 out of 5  hitting a 3x3 target  at that distance I held   ¾ target , that’s what  what ?? 9 inches high ?? There abouts . Give or take a couple .
My spotter watching through a scope  from back on the hill was calling   5 low center  so that’s a drop of what  14 inches ?


 Yellow jacket this last  September I placed second  at 225  missing my 5th shot   with the target up hill .
 It was my fault  I aimed high  moving my POA to the top edge of the target  from where I was holding  at 200  which was ¾ . The consensus of those around was that I shot over  but center of the target .
 Now also understand that target on that range has a 8 inch hole in the center . Its not uncommon to  see folks clearly shoot center  on it

 I will also tell you this . The fella that cleans my clock  over and over again shoots a plains rifle Lyman  .
 We talked a number of time  as I try to figure out what it is im doing wrong . My max target range for a human size target   to consistently hit center mass  is right at about 275 to 300 depending on the range and the target . Now understand that’s center mass not  the 10 X ring .
 Normally if the top 4 or 5 shooters make the event , im left in the dust  and they move another 50 to 75 back before  deciding the outcome which normally comes down to , two individuals

 Tom uses  90 grains  of 3F as his load . He tells me his POA is  the same as mine .  His rifle he says is sighted in center for 100 . He says he  says he does not elevate above the target  tell about the 300 mark . That would be  no more then 18 inches  high at 300 . which also means he couldnt have more then 36 inches of drop  or he would hit low  and miss the target . cant say i have ever seen him do that . high yes low , no

Which is very much what  I am doing .However I can tell you  im hitting high , constantly
 that’s all I can say .
 As I said a lose more then I win  most times there are 20 to 25 folks entered  so I m in no way alone in this .
Also remember we are talking target shooting here not hunting . IMO one should never shoot over 100 with a RB  at big game .

[tutti confuso]

well it was back to the range today.. retested 176 ball an patch with shockey's gold ffg .. finally hit dead center at 100yrds with out any hold over...the final increased of the charge was 110 grns.that is where i ended up.. then with last bit  of Black Powder[ffg] i had left[ was like 15yrs old..]  i did the same 100yrds dead center with a load of only 88 - 90grns