Grendel vs 308

[bigbear_98]

The bullet I am shooting is the SST. Ballistic AE is the app. My barrel shoots well. I am not getting wild groups or flyers. I sat two chronos up at 200 yards and shot through them to get the numbers I have.

I understand that this information combined with the comparison to my 308 seems as if I am trying to tear the round down. I have spent a lot of money on my rifle, and a lot of time shooting. Enough that I want this round to be successful.

I shouldn't have posted the 308/ Grendel I suppose. I just don't own a shorter 308, or longer Grendel to compare.

[bigbear_98]

Here is a comparison between the two. Notice how little difference there is until you get to close to 1000. This is where I was confused until I shot little things from far and measured them. Would you be able to see the difference by just measuring the group in the scope?


Edited to clean up the thread. The numbers are posted in post #44

[NugginFutz]

Something wrong with the data vs. column information alignment, in this last post. Short one column of data, it appears. Time values are zeroed, as well as going negative. (Inverse time? Bullets arrive prior to being fired?)

Perhaps when LRRPF52 reformatted the data, it got lost in translation.

[bigbear_98]

This is only showing the difference in drop between the two charts. The complete ballistic charts are in previous post.

[NugginFutz]

Thanks for clearing that up. Still a little tired from the week's festivities.

[LRRPF52]

From the shooter perspective in my case in the same shooting area and almost identical conditions, I have made similar shots with both the .308 22" bolt gun spitting 175gr SMK's (1118yds), and 123gr A-MAX from my 16" AR15 carbine (1200yds).

Bryan Litz put out an extensive series of articles, as well as two excellent books on long range applied ballistics, and he valued the G7 model for the 175gr SMK at .243

iSnipe lists the 123gr A-MAX at .256

Atmospherics and temps are the same for the following comparisons, basically sea level at 59 F. .308 will almost always have an energy advantage if comparing bullets with similar BC's shot at the same speeds. Hornady's 9th shows 2500fps as max for a 22" bolt gun .308 with 178gr, and 2500fps with the 123gr 6.5mm from an 18" Grendel, considering that the 120gr GMX limited them in the speeds due to start pressure of a solid and its longer bearing surface.

What I get out of this is that my supersonic reach is a bit farther, my powder consumption is significantly less, recoil is around half, and the Grendel works out of an AR15, purpose-built for an AR15. When I was shooting .308, I only hand-loaded since I was shooting gas guns, and the 168gr sucks as a long range bullet, whereas the 175gr loads are optimized for bolt guns with no gas system.

6.5 Grendel 123gr A-MAX at 2500fps mv

       Range    Velocity    Energy     Trajectory         TOF          Drift
      (yards)     (fps)     (ft-lb)       (MILS)         (sec)         (MILS)
          0      2500        1707           0.00         0.0000         0.00
         50      2414        1592          -0.00         0.0611        -0.10
        100      2330        1483           0.00         0.1243        -0.21
        150      2247        1379          -0.30         0.1898        -0.32
        200      2167        1282          -0.68         0.2578        -0.44
        250      2088        1190          -1.12         0.3283        -0.56
        300      2010        1103          -1.60         0.4015        -0.68
        350      1934        1022          -2.11         0.4776        -0.81
        400      1860         944          -2.65         0.5567        -0.94
        450      1786         871          -3.23         0.6390        -1.08
        [B]500      1715         803          -3.85         0.7247        -1.22[/B]
        550      1644         738          -4.50         0.8140        -1.37
        600      1575         677          -5.19         0.9072        -1.53
        650      1507         620          -5.93         1.0046        -1.69
        700      1440         567          -6.71         1.1064        -1.86
        750      1375         517          -7.54         1.2130        -2.04
        [B]800      1312         470          -8.43         1.3247        -2.23[/B]
        850      1250         427          -9.38         1.4419        -2.43
        900      1190         387         -10.40         1.5649        -2.64
        [B]950      1134         351         -11.48         1.6941        -2.85[/B]
       1000      1087         323         -12.65         1.8294        -3.08
       1050      1056         305         -13.90         1.9697        -3.31
       1100      1032         291         -15.24         2.1135        -3.53
       1150      1012         280         -16.65         2.2604        -3.75
       1200       994         270         -18.15         2.4102        -3.96

.308 175gr SMK at 2500fps mv

       Range    Velocity    Energy     Trajectory         TOF          Drift
      (yards)     (fps)     (ft-lb)       (MILS)         (sec)         (MILS)
          0      2500        2429           0.00         0.0000         0.00
         50      2410        2256          -0.00         0.0611        -0.11
        100      2321        2093          -0.00         0.1245        -0.22
        150      2234        1940          -0.30         0.1904        -0.34
        200      2150        1795          -0.69         0.2588        -0.46
        250      2067        1660          -1.13         0.3300        -0.59
        300      1986        1532          -1.62         0.4040        -0.72
        350      1906        1412          -2.14         0.4811        -0.86
        400      1828        1298          -2.69         0.5615        -1.00
        450      1752        1192          -3.29         0.6453        -1.15
        [B]500      1677        1092          -3.92         0.7328        -1.30[/B]
        550      1603         999          -4.59         0.8243        -1.46
        600      1531         911          -5.31         0.9200        -1.63
        650      1460         829          -6.08         1.0204        -1.81
        700      1391         752          -6.90         1.1256        -2.00
        750      1324         681          -7.77         1.2361        -2.19
        [B]800      1259         616          -8.71         1.3523        -2.40[/B]
        850      1196         555          -9.72         1.4746        -2.62
        [B]900      1136         501         -10.80         1.6034        -2.85[/B]
        950      1086         458         -11.97         1.7387        -3.08
       1000      1054         432         -13.22         1.8791        -3.32
       1050      1029         412         -14.56         2.0232        -3.56
       1100      1009         395         -15.99         2.1706        -3.78
       1150       990         381         -17.50         2.3209        -4.00
       1200       972         367         -19.09         2.4740        -4.22

[cory]

The bullet I am shooting is the SST. Ballistic AE is the app. My barrel shoots well. I am not getting wild groups or flyers. I sat two chronos up at 200 yards and shot through them to get the numbers I have.

I understand that this information combined with the comparison to my 308 seems as if I am trying to tear the round down. I have spent a lot of money on my rifle, and a lot of time shooting. Enough that I want this round to be successful.

I shouldn't have posted the 308/ Grendel I suppose. I just don't own a shorter 308, or longer Grendel to compare.

I'm happy to eat crow here. Now let's figure out what's going on, and get you squared away.

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

[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

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

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

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...!