Grendel vs 308

[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.

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.

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.

[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.......

[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...

[NugginFutz]

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

Good dig, bigbear. I saw that the Amax is not there, but the smell test says it should be very close to the SST and perhaps a tad better. Now, where did I put my calibrated tad-o-meter?

[bigbear_98]

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...

Ted, I'm not sure what chart you're talking about? I posted a bunch. Mine were 175 vs 123. No one felt I was comparing apples to apples and since my Grendel data wasn't 100% trued, it really wasn't. I was running a higher bc for the Grendel.

[bigbear_98]

I just got the newest book. Taking the 2500-3000 fps number off of the top, the average comes out to .230 for the SST. I haven't been able to go to the range to test it yet.

The only problem I see is my velocity was 2528 averaged across 20 rounds the day I was playing with all of this. But when I enter all of the info into the calculator and try to make the poi match at different distances to what I tested in the field, the calculator changes my velocity to 2466.