Grendel vs 308

[bigbear_98]

Have you tested your current scope to make sure it's tracking true?

Yeah it's pretty true through 20 moa. This was at 100 yards shooting groups anyway.

I may have time tomorrow to go try it again and refine the test a little more.

[LRRPF52]

When I first looked at the 123gr SST, I suspected a BC difference from the 123gr A-MAX, since the SST has more of a tangent ogive. It seems that your results are reflecting a lower BC value for it. I have not done the type of accurate distance shooting with the SST yet, other than 600yds.

One way to check would be to load the same charges and other components, and alternate SST/A-MAX to see if there is a vertical dispersion. My suspicion is that there will be one.

Just using G1 data had me almost dead-on at 1200yds with the 123gr A-MAX, after chronographing it and using morning atmospheric data in the afternoon. I was 14.4 Mils at 1200yds.

I think the 123gr SST is a great hunting and target bullet, and it is nice to see some real world data for it at 1000yds, with BC truing featured software. So what G7 BC is working for you with the 123gr SST again, .224 was it?

[bigbear_98]

So what G7 BC is working for you with the 123gr SST again, .224 was it?

.224. Please verify. I would love someone else's results.

I have some of both projectiles. I will try to put some together matching all variables except the bullet, and compare.

[bigbear_98]

I spent a little time in Excel and cleaned up the data. Hopefully it is easier to understand now.

Notice how little difference there is until you get close to 1000

Code:

0.224 G7 123gr 2489 YRD Drop in Drop MOA Velocity 100 0 0 2318 150 -1.06 -0.68 2232 200 -3.86 -1.84 2149 250 -8.54 -3.26 2067 300 -15.24 -4.85 1987 350 -24.13 -6.58 1909 400 -35.39 -8.45 1832 450 -49.24 -10.45 1756 500 -65.88 -12.58 1682 550 -85.59 -14.86 1610 600 -108.63 -17.29 1538 650 -135.33 -19.88 1468 700 -166.04 -22.65 1400 750 -201.15 -25.61 1333 800 -241.13 -28.78 1269 850 -286.48 -32.19 1206 900 -337.78 -35.84 1146 950 -395.65 -39.77 1096 1000 -460.7 -43.99 1063 1050 -533.4 -48.51 1039 1100 -614.11 -53.31 1019 1150 -703.15 -58.39 1001 1200 -800.85 -63.73 983

Code:

0.260 G7 123gr 2432 YRD Drop in Drop MOA Velocity 100 0 0 2286 150 -1.06 -0.68 2213 200 -3.89 -1.86 2141 250 -8.61 -3.29 2071 300 -15.34 -4.88 2002 350 -24.24 -6.61 1934 400 -35.44 -8.46 1867 450 -49.13 -10.43 1801 500 -65.48 -12.51 1737 550 -84.71 -14.71 1673 600 -107.01 -17.03 1611 650 -132.66 -19.49 1549 700 -161.9 -22.09 1489 750 -195.05 -24.83 1429 800 -232.43 -27.74 1371 850 -274.4 -30.83 1314 900 -321.38 -34.1 1259 950 -373.82 -37.58 1205 1000 -432.2 -41.27 1154 1050 -497.08 -45.21 1107 1100 -569 -49.4 1075 1150 -648.4 -53.84 1052 1200 -735.63 -58.54 1033

Code:

Comparison YRD Drop in Drop MOA Velocity 100 0 0 32 150 0 0 19 200 0.03 0.02 8 250 0.07 0.03 -4 300 0.1 0.03 -15 350 0.11 0.03 -25 400 0.05 0.01 -35 450 -0.11 -0.02 -45 500 -0.4 -0.07 -55 550 -0.88 -0.15 -63 600 -1.62 -0.26 -73 650 -2.67 -0.39 -81 700 -4.14 -0.56 -89 750 -6.1 -0.78 -96 800 -8.7 -1.04 -102 850 -12.08 -1.36 -108 900 -16.4 -1.74 -113 950 -21.83 -2.19 -109 1000 -28.5 -2.72 -91 1050 -36.32 -3.3 -68 1100 -45.11 -3.91 -56 1150 -54.75 -4.55 -51 1200 -65.22 -5.19 -50

[bigbear_98]

Has anyone had time to compare their number to my theory? I am anxious to see if anyone gets similar results.

I don't have anymore factory ammo and haven't had time to load any rounds yet hence the reason I haven't posted recent scope tracking on my Vortex PST. I did however do a tracking test on my Nightforce/308 to 40moa last weekend. I was very pleased with the results. I will post pictures of the two as soon as I get them.

Here is a couple of previous tests I ran on the Vortex/Grendel Combo.

15.75 MOA (anymore ran off of the target backer and into the framing boards)


10 MOA

[bigbear_98]

Nightforce/308 combo just because I was so happy with the results

[BluntForceTrauma]

Very cool, and good on Nightforce, huh?

[bigbear_98]

Very cool, and good on Nightforce, huh?

Yeah I was pretty excited. I haven't had the nightforce long. Having one makes me want to get more...!

[bigbear_98]

Anyone had a chance to test my theory?

[bigbear_98]

Cabelas had some factory sst. I also found one box of the stuff I had. Two different lot numbers and the cabelas stuff was faster. I checked the tracking on my scope at 100 yards up to 35 Moa. That's as much as I could get on paper.

To add more confusion I got a new chrono. At 10' it read 2528 for the old load and 2566 for the new.

I don't know what else I can test to prove my theory. Any ideas?
I guess maybe I can video the targets at distance?

[bigbear_98]

So check this out. I dropped the bc to .215bc (G7) in the calculator and bumped up the velocity to the 2525 averaged by the new chrono. Then compared it to the chart I verified the other day at the range. See below. Thoughts?

[bigbear_98]

Here is a relative drop chart. I don't believe there is enough difference to easily measure on the reticle of the scope.

Code:

yrd inches moa fps 100 0.08 0.07 28 110 0.09 0.08 27 120 0.11 0.09 26 130 0.13 0.1 25 140 0.15 0.1 24 150 0.17 0.11 23 160 0.2 0.12 23 170 0.22 0.13 22 180 0.25 0.13 21 190 0.28 0.14 20 200 0.31 0.15 19 210 0.34 0.15 19 220 0.37 0.16 18 230 0.4 0.17 17 240 0.44 0.17 16 250 0.47 0.18 15 260 0.51 0.19 15 270 0.55 0.19 14 280 0.58 0.2 13 290 0.62 0.21 13 300 0.67 0.21 12 310 0.71 0.22 11 320 0.75 0.22 10 330 0.8 0.23 10 340 0.84 0.24 9 350 0.89 0.24 8 360 0.93 0.25 8 370 0.98 0.25 7 380 1.03 0.26 6 390 1.08 0.26 6 400 1.13 0.27 5 410 1.18 0.27 4 420 1.23 0.28 4 430 1.28 0.28 3 440 1.33 0.29 2 450 1.38 0.29 2 460 1.44 0.3 1 470 1.49 0.3 1 480 1.54 0.31 0 490 1.59 0.31 -1 500 1.65 0.31 -1 510 1.7 0.32 -2 520 1.75 0.32 -3 530 1.8 0.32 -3 540 1.85 0.33 -4 550 1.9 0.33 -4 560 1.95 0.33 -5 570 2 0.34 -5 580 2.05 0.34 -6 590 2.09 0.34 -7 600 2.14 0.34 -7 610 2.18 0.34 -8 620 2.23 0.34 -8 630 2.27 0.34 -9 640 2.31 0.34 -9 650 2.34 0.34 -10 660 2.38 0.34 -10 670 2.41 0.34 -11 680 2.44 0.34 -12 690 2.47 0.34 -12 700 2.49 0.34 -13 710 2.52 0.34 -13 720 2.53 0.34 -14 730 2.55 0.33 -14 740 2.56 0.33 -14 750 2.56 0.33 -15 760 2.57 0.32 -15 770 2.56 0.32 -16 780 2.55 0.31 -16 790 2.54 0.31 -17 800 2.52 0.3 -17 810 2.5 0.29 -18 820 2.47 0.29 -18 830 2.43 0.28 -18 840 2.39 0.27 -19 850 2.33 0.26 -19 860 2.28 0.25 -19 870 2.21 0.24 -20 880 2.13 0.23 -20 890 2.05 0.22 -20 900 1.95 0.21 -20 910 1.85 0.19 -19 920 1.74 0.18 -18 930 1.62 0.17 -17 940 1.49 0.15 -16 950 1.35 0.14 -15 960 1.2 0.12 -14 970 1.05 0.1 -13 980 0.89 0.09 -12 990 0.72 0.07 -11 1000 0.55 0.05 -11 1010 0.37 0.03 -11 1020 0.18 0.02 -11 1030 -0.02 0 -10 1040 -0.22 -0.02 -10 1050 -0.42 -0.04 -10 1060 -0.63 -0.06 -10 1070 -0.85 -0.08 -10 1080 -1.08 -0.1 -10 1090 -1.31 -0.11 -10 1100 -1.55 -0.13 -10 1110 -1.79 -0.15 -10 1120 -2.04 -0.17 -10 1130 -2.3 -0.19 -10 1140 -2.57 -0.21 -10 1150 -2.84 -0.24 -10 1155 -3 -0.25 -10 1160 -3.12 -0.26 -10 1170 -3.4 -0.28 -10 1180 -3.69 -0.3 -10 1190 -3.99 -0.32 -10 1200 -4.3 -0.34 -10

[bigbear_98]

I was able to go the range today and verify again. Here is some video.

Shots 2 and 3 of the day were at 500 yards. Put one on the plate to verify elevation. Then I shot at the clay. The wind was bouncing a little and I'm not good at reading it yet. I only had the one box left from the stuff I bought at Cabela's so I didn't get to spend a lot of time behind the Grendel.
[video=youtube;cJq6mtTLZkc]http://www.youtube.com/watch?v=cJq6mtTLZkc&feature=youtu.be[/video]

First 3 shots at 750. You can hear me dial the scope from 500. I Verified I was there on the plate, then tried to shoot the tennis ball. I didn't hit it, but you can see the elevation is there.
[video=youtube;7NBdR4ZPl68]http://www.youtube.com/watch?v=7NBdR4ZPl68&feature=youtu.be[/video]

[LRRPF52]

Nice videos. You can see where the wind switched on you if you watch the streamers and the mirage. When it switched, you started impacting right. Reading and calling the wind is much more fun for me than shooting because I get to be in control mostly of what kind of performance will be result, as well as being able to watch it all happen.

I especially like getting new shooters on the guns and having them make 1st-round hits as far out as we can go, and rapid 2nd round corrections.

[bigbear_98]

Nice videos. You can see where the wind switched on you if you watch the streamers and the mirage. When it switched, you started impacting right.

Heh, I was actually trying to hit the little tennis ball on the stick on the last two shots. There are also golf balls hanging from strings there as well. One calm day I was able to hit one of the golf balls with the 65 and my 308.

I can usually read wind close enough to get on the plates but those little targets are a bear to hit.

ETA: What I should mention is how easy it is to watch the impact and make a follow up shot with my Grendel. I don't really even have to readjust position much.

[bigbear_98]

So it looks like Bryan Litz's new book Ballistic Performance of Rifle Bullets has the 123 SST data. We will soon find out I suppose.

[NugginFutz]

Yeah, I saw that too. Be interesting to see how the G7 estimates among our better informed members compare.

[bigbear_98]

I would like to go on record saying that I think the G7 for the 123 gr SST is ~.213.......:p

[bigbear_98]

Weeeelllllll..... If you go onto the Ballistics calculator on Applied ballistic web site, it is .236 G7 and .462 G1.


When I run that BC it changes the muzzle velocity down to 2450

[Tedward]

Can you print and post that chart? I don't know all of the in's and out's of setting those charts up but really want to see it. Anyone can change the perameters to make anything look better and this one has been bugging me. I would like to see apples to apples, not one using a factory 123gr bullets (Grendel) and the 308 getting an advantage with light weight bullet, it should be average 168gr. I shot my buddies AR-10 308 the other day and my sholder was not use to that and it was a light 147 gr PMC factory ammo. It was very accurate but shure made me want to go back to the Grendel in a hurry. Shoulder felt it for a few hour...