Need help with 2285 yard shot.

[groper]

topshot,

i shot 3 different loads with these, 96-98grns AR2217, no dramas at all. Next outing ill shoot the 99-100gr loads.

ive played with my numbers a bit more and adjusted the zero range to an estimated 280yds for the calculations. Using a BC of .82, 3250fps works for the actual required drop @ 700yds i was shooting them which is a more realistic velocity i feel until i actually shoot them thru the chrony.

BTW, he has made a typo on his website, the new bullets i have measure 44.8mm long - not 47.8mm. you should check yours...

If the BC is true, they will stay supersonic at 2000+yds, however we will have to do the leg work on testing the BC of these - i doubt anyone else has much data on them.

 

[Topshot]

topshot,

i shot 3 different loads with these, 96-98grns AR2217, no dramas at all. Next outing ill shoot the 99-100gr loads.

ive played with my numbers a bit more and adjusted the zero range to an estimated 280yds for the calculations. Using a BC of .82, 3250fps works for the actual required drop @ 700yds i was shooting them which is a more realistic velocity i feel until i actually shoot them thru the chrony.

BTW, he has made a typo on his website, the new bullets i have measure 44.8mm long - not 47.8mm. you should check yours...

If the BC is true, they will stay supersonic at 2000+yds, however we will have to do the leg work on testing the BC of these - i doubt anyone else has much data on them.

Groper,
I put three of them over the chronograph today. Load was 97gn H1000 with CCI 250 primer, results were 3034fps, 3039fps and 3067fps. POI at 100 yards was right on the money, which is unreal seeing as there is 65 grains difference in bullet weight and about 200fps difference in velocity compared to the 300gn SMK.
As I said the seating depth of these loads varied heaps, so that would not have helped the E.S. OAL was about 4.00" give or take 0.020"
I can't see how the B.C. could be .82 all the way out past 2000yds but who knows till its tried.

 

[Topshot]

Well I tried the Hornady 250 grain BTHP Match projectile this morning at the 2285 yard target with much better results. I even hit the target!
Although I could not spot every impact, it was obvious that these bullets were grouping much better than the 300 gn SMK.

I did a quick velocity test of two loads yesterday, 98 and 99 grains of H1000. Velocity readings were 3044, 3048 for the 98gn load and 3087, 3144 for the 99 grain load. My chronograph is not that reliable so I was not too worried about the spread. Pressure was OK, and average POI @ 100 yards was 1.5" high.
I used the 99 grain load and weight sorted some new brass as I wanted to use this shoot to fire form some brass. I also weight sorted the bullets and picked out 12 that weighed 249 grains.

Calculating a drop for this shot the night before, I used a nominal velocity of 3100 fps, pressure 992 mb, temp 14*C and humidity 70%. Drop using Litz data on JBM with these conditions worked out at 111.5 MOA.
Actual conditions this morning were 998 mb and 15*C. There was no wind at ground level but up above the trees where the bullet would be flying, there was a slight breeze left to right.

With the scope set on 8 power each division on the R1 reticle was worth 2.75 MOA so I dialled up 60 on the elevation turret and held on the second last division. The first shot was low and 6 MOA right windage. So I dialled left 6 MOA and held a bit higher. The next three shot group, landed in line but again low so I held a bit higher again and fired off another three shots. I repeated this process till I had fired off the remaining shots. The estimated dial up that I needed to hit the target was 115 MOA. and room in the scope was running out. There also seems to be a bit of parallax right at the edge of the scope lens which doesn't help.

I packed up and went to check out the results. And yes I did hit the target once, but of more interest to me was that just about all bullet impact points on the ground were in line with the target and in a much more consistent pattern than the 300 gn SMK. All of the shots except the one that hit the target were low with quite a few right at the base of the target so If I had a spotter to help me I am sure that I would have got the elevation worked out better and got more hits on the target. The bullet that hit the target made a nice round hole so given this and the tight pattern of impact points, I would say that this Hornady bullet has retained its stability into the sub sonic zone quite well. I also recovered a bullet and it did not show any deformation or expansion at all, just like the SMK.

 

[cavtrooper94]

Congrats on the shot

 

[3fingervic]

That was great to hear. Congrats!

 

[7mm Eclipse]

Topshot,

Congratulations on the shot!!! Awesome shooting.

Mike

 

[theodore]

Awesome! Does any one have access to the new 338 VLDs? It would be sweet to see those bullet results here.

 

[groper]

interesting topshot... congrats on the shot gun)

my rifle does seem to shoot slightly faster than most for some reason, it does have a very long barrel (30-31" not sure where to measure from lol) and long brake after that. My POI changed dramatically with the predator pills VS the 300SMK, but i zero @ 218yds (200m) so the difference is more pronounced than at 100...

If my velocity was actually closer to yours, rather than my estimated 3250fps.... Then i must be achieving an even higher BC than .82??? in fact to get the calc to match the trajectory i need to use a G1 value in excess of 1.0 which is very unrealistic. So i think my velocity has to be somewhere around 3200fps or more???

When you gonna shoot the predators way out?

ill do alot more shooting with them when i get from back from OS... holidays here we come

 

[MontanaRifleman]

Topshot, great results and very interesting.

I wonder that with your 10 twist barrel, if the SMK's were "barely" stabalized and that with the 250 Hornady's they were "more" stabalized?

I wonder what the results would be with the 300 SMKs out of a 9 or 8 twist barrel?

Keep it up and you might be able to land a military consulting contract

 

[liltank]

It's interesting that it took a 250grn HP Hornady (BC=.675 vs. .768) to hit a target that far with some dissemblance of accuracy over the 300grn SMK. I guess the Secant will always whip the Tangent ogive at long distance every time.

Tank

 

[MontanaRifleman]

It's interesting that it took a 250grn HP Hornady (BC=.675 vs. .768) to hit a target that far with some dissemblance of accuracy over the 300grn SMK. I guess the Secant will always whip the Tangent ogive at long distance every time.

Tank

Was it the ogive or was the stability factor?

 

[liltank]

Was it the ogive or was the stability factor?

Well this is my only theory. We all know that the 168SMK will destabilize at 1000yrds. This is due to speed loss and having a tangent ogive. Using another bullet of same weight with a secant ogive, can penetrate through the sonic barrier to subsonic and maintain stability. We also know that JLK, Hornady, and Berger use the Secant ogive, respectively, on their A-Max and VLD bullets. This leads me to believe that the 250grn BTHP by Hornady would be designed with the secant ogive. Without knowing the exact specs of the bullet it is difficult to say, but looking at pictures of said bullets in question, you can see a much longer taper on the Hornady over the Sierra.

The other factor is once again our dear friend velocity. The high BC for and the the design, plus the increased velocity over the 300grn SMK helped to push it through and maintain trajectory. However any bullet at this time is going to be very susceptible to any minor wind change. However from Topshot's notes we can see that all the bullets impacted in line and on the same level as his previous shots. We can also deduce that the SMK could not handle that transition. A few would go high, some would go low. Therefore we see by this demonstration that a 250grn Secant ogive pushed hard enough can transition in such a way that a 300grn SMK Tangent ogive can not.

Watson, get me my pipe! I feel like a stroll to Scotland Yard. Oh... it was the maid with the candle stick holder in the pool house.

Tank

 

[Topshot]

Well this is my only theory. We all know that the 168SMK will destabilize at 1000yrds. This is due to speed loss and having a tangent ogive. Using another bullet of same weight with a secant ogive, can penetrate through the sonic barrier to subsonic and maintain stability. We also know that JLK, Hornady, and Berger use the Secant ogive, respectively, on their A-Max and VLD bullets. This leads me to believe that the 250grn BTHP by Hornady would be designed with the secant ogive. Without knowing the exact specs of the bullet it is difficult to say, but looking at pictures of said bullets in question, you can see a much longer taper on the Hornady over the Sierra.

The other factor is once again our dear friend velocity. The high BC for and the the design, plus the increased velocity over the 300grn SMK helped to push it through and maintain trajectory. However any bullet at this time is going to be very susceptible to any minor wind change. However from Topshot's notes we can see that all the bullets impacted in line and on the same level as his previous shots. We can also deduce that the SMK could not handle that transition. A few would go high, some would go low. Therefore we see by this demonstration that a 250grn Secant ogive pushed hard enough can transition in such a way that a 300grn SMK Tangent ogive can not.

Watson, get me my pipe! I feel like a stroll to Scotland Yard. Oh... it was the maid with the candle stick holder in the pool house.

Tank

Well Sherlock, you may be onto something there!

Those new secant ogive .338 calibre Bergers may need to get a run over this distance when I get hold of some.

Below is a photo of both the recovered projectiles. Hornady left and the Sierra right. You can see the shape of the bullets although the Hornady has its secant ogive ground down a bit by gravel rash. The Hornady was found laying on top of the ground at the base of the target while I had to dig out the Sierra.

One problem that I didn't mention with shooting at this range was with adjusting for elevation. Looking at the impact point from 2285 yards the impact may appear 2 MOA low in the scope. But the actual impact point may be 10 yards in front of the target. As the bullet is coming down at a very steep angle, the true point where the bullet would pass directly under the target, might actually be 5 MOA low.

This is why I had a lot of trouble adjusting for elevation. I would adjust up 2 MOA and the apparent point of impact would not appear to change by that amount. The next three shots would land closer to the target but still be low. I did not think about this effect until after but it is something that I sure will take into account, next time I do any extreme range shooting.

 

[yama49]

keep sharing your progress, very interesting.... thx