I think I found the sweet spot

Ike666 · January 23, 2011, 05:23 PM

Cold day at the range today, very cold. But I'm very happy. I've been working up some .308 loads for 168 gn SMKs, experimenting with Varget. I decided on a load of 41.4 gns after testing multiple combinations from late last summer up through the fall. Today I took a box of fifty rounds to try out.

The rifle is a Winchester M70 Stealth with new glass I just mounted and zeroed earlier this week. The target below was my zero-check 5-rnd group (barrel already warmed) at 100 yards (scope zeroed for 200 yards, down 2.25 MOA).

I think I found the sweet spot.

DiscoRacing · January 23, 2011, 05:25 PM

Quote:

I think I found the sweet spot

It would almost appear that way....

... to the untrained eye

Miata Mike · January 23, 2011, 09:06 PM

I would say sweet!

armoredman · January 23, 2011, 11:16 PM

I think I would concur - NICE!

tkofoid · January 24, 2011, 03:39 PM

if that was one of my groups,,the one at 6:00 out of the group would be my fifth shot. most of the time when I get four in a bughole,I try to get the fifth off too quickly. I refer to my fifth shot as 'operator headspace'. NICE SHOOTING!

Doodlebugger45 · January 24, 2011, 03:54 PM

Yep.

I have been known to mess up some pretty good groups with that 5th shot also. I'm not a serious target shooter so I just don't have thousands of targets behind me for experience. Several times I have fired 3 or 4 rounds at a target like normal. But then I just can't stand it anymore and I will take a peek through the spotting scope to dee how it's going. If I see a real tight group developing, almost invariably, it messes with my head and I overthink that last shot. I try extra hard to force it in there and end up screwing it up. I have learned now to either avoid the temptation to peek at the target with the spotting scope, or in a few cases I just quit at 3 or 4 shots if I want something to show my buddies the next day.

**Unclenick** · January 24, 2011, 03:55 PM

Heh, heh, heh! Operator Headspace. I just may have to steal that sometime.

Nice shooting Ike66!

Ike666 · January 25, 2011, 12:30 PM

We used to call it "operator headspace and timing" -from the old M2 Browning

I wish I could lay claim to the one at 6 being the fifth shot - however it was the fourth. I felt it slip when I sent it downrange, I could have had the stock tighter in my shoulder pocket, but as you all said I rushed the shot. I'm using a variable scope at 15X and could see the group shaping up. I just got too amped up on that fourth shot. I almost quit after three but told myself to stick with a 5-shot group. I actually had an internal debate whether or not to send the fifth round down after letting the fourth fly. I'm glad I stuck with it. In a curious way it served as proof-of-concept for the load.

Now, I need to see how the performance will change when the weather warms up again. I'm also going to put a lighter spring in the M.O.A. trigger from Ernie the Gunsmith. I'd love to be able to do that consistently.

Clay · January 25, 2011, 01:34 PM

Yours is almost identical to what I found for mine, 41.6. My lowly Savage Stevens 200 can't group quite as well, but my DPMS LR-308 looked even tighter than your group. Both liked the 41.6 load the best. Those were with the 165gr Sierra exposed tips, whatever they're called. I'm ordering up some Hornady A-Max's this week, can't wait to try them out!

Doodlebugger45 · January 25, 2011, 04:15 PM

I especially love to hear about these kinds of results when they are from very light loads. It seems like I'm always hearing folks wanting to load beyond the max published loads. The load here this thread is a little bit below the suggested starting load, but the accuracy is just fine.

TATER · January 25, 2011, 06:45 PM

Maybe somewhere around 2425-2450 FPS ??? I guessing...
Definitely not taxing anything, Brass should just about last forever..(Big Grin)
Good Shooting.. Have you actually reached out to 200 Yet?? Just curious if
up 2.25 is getting you back to the 200 mark.

Ike666 · January 26, 2011, 10:19 PM

Sorry, I should have mentioned that I used the load to zero at 200. No groups as good as the 100 yd one, but most were sub-MOA in the 1.75- 2.0 inch range.

I have a new scope with an MOA reticle (NP-R1) AND MOA knobs and fired the 100 yard target just to see how well my tables worked. I actually used a table for 2600 fps built from external ballistic data (168 SMK) out of the Sierra manual. My range book is downstairs and I'm too lazy to get it tonight, but I'm getting MVs not too far from that (2550-2600) with this load.

The table calls for -2.16 MOA (bullet-down) on the knob and I've got 1/4 MOA clicks so moved 2.25 MOA down (9 clicks).

SMK 168gn @ 2600 fps
Range Drop MOA HoldOver Clicks
Muzzle -1.5 0
50 1.07 0.5235998 -2.0435455 -8.174181885
100 2.26 1.0471996 -2.1581368 -8.632547224
200 0 2.0943992 0.0000000 0
300 -9.33 3.1415988 2.9698254 11.87930171
400 -27.04 4.1887984 6.4553119 25.82124745
500 -54.81 5.235998 10.4679184 41.87167375
600 -94.73 6.2831976 15.0767183 60.30687305
1000 -437.06 10.471996 41.7360740 166.944296

tkofoid · January 27, 2011, 08:02 AM

Here is an example of what happens to me on my 5th shot

TATER · January 27, 2011, 11:39 AM

Ike666,
I would not have thought that you were generating
that much velocity. I am shooting almost the same
Rig in .308 it sounds like...Although, I’m shoot’en 20” tube.

**Unclenick** · January 27, 2011, 02:40 PM

Tater,

He's got a 26" barrel with the Stealth. Using a QuickLOAD Varget powder model I modified based on the last time I measured Varget performance in my own rifles, I will estimate that if he uses the same cases and primer you do, if you average about 2438 fps from your 20" barrel, he's at about 2583 fps.

Ike666,

I used Bryan Litz'z measured G7 BC for the 168 gr SMK and that 2583 fps MV I estimated and a scope 1.5" above the bore (getting that accurate matters to these tables) and got the following:

Code:

Range		Velocity	Total Drop	Trajectory in.	Trajectory MOA	  Holdover	Nearest ¼ moa	  TOF
  0. yds	2583 fps	  0.0 in	  -1.50 in	  1.50 in	   inches	 correction	0.0000 s
 50. yds	2482 fps	  0.7 in	   1.11 in	  2.12 moa	 -1.11 in	-8 clicks	0.0593 s
100. yds	2382 fps	  2.7 in	   2.32 in	  2.22 moa	 -2.32 in	-9 clicks	0.1209 s
200. yds	2191 fps	 11.6 in	   0.00 in	  0.00 moa	  0.00 in	0 clicks	0.1399 s
300. yds	2009 fps	 27.8 in	  -9.57 in	 -3.05 moa	  9.57 in	12 clicks	0.3952 s
400. yds	1835 fps	 52.5 in	 -27.78 in	 -6.63 moa	 27.78 in	27 clicks	0.5515 s
500. yds	1669 fps	 87.6 in	 -56.33 in	-10.76 moa	 56.33 in	43 clicks	0.7229 s
600. yds	1509 fps	135.3 in	 -97.41 in	-15.50 moa	 97.41 in	62 clicks	0.9119 s
700. yds	1356 fps	198.2 in	-153.81 in	-20.98 moa	153.81 in	84 clicks	1.1216 s

I stopped the table at 700 yards because the 168 grain MatchKing, uniquely, with its odd boattail shape becomes unstable in the transonic velocity range (about 1000 fps-1400 fps at sea level), so there is no point in trying to shoot further with it. It's great to 600, but I don't trust it beyond that for target score.

Litz mentions this problem and, indeed, I've seen it twice myself. Once was tumbling and whizzing off all around a 748 yard popper at Gunsite. The other was keyholing on 800 yard targets at the Long Range Firing School at Camp Perry (lots of people had the problem up and down the line there). Using the 175 grains SMK instead solves the problem. It doesn't have this issue and remains stable through the whole transonic range.

TATER · January 27, 2011, 04:05 PM

Unclenick,
Ahhhhh, I was thinking 24”
To be honest, I don’t think I ever broke the 2400 threshold till I
Got to “42. Something” with Varget, I will have to look tonight..
I have played with a bunch of combinations with this rifle. Heck, even Now.

January 23, 2011, 05:23 PM	#1
Ike666 Senior Member Join Date: October 10, 2009 Location: SW VA Posts: 491	I think I found the sweet spot Cold day at the range today, very cold. But I'm very happy. I've been working up some .308 loads for 168 gn SMKs, experimenting with Varget. I decided on a load of 41.4 gns after testing multiple combinations from late last summer up through the fall. Today I took a box of fifty rounds to try out. The rifle is a Winchester M70 Stealth with new glass I just mounted and zeroed earlier this week. The target below was my zero-check 5-rnd group (barrel already warmed) at 100 yards (scope zeroed for 200 yards, down 2.25 MOA). I think I found the sweet spot. __________________ ___________________ "I'm your huckleberry."

January 24, 2011, 03:55 PM	#7
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Heh, heh, heh! Operator Headspace. I just may have to steal that sometime. Nice shooting Ike66! __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 25, 2011, 12:30 PM	#8
Ike666 Senior Member Join Date: October 10, 2009 Location: SW VA Posts: 491	We used to call it "operator headspace and timing" -from the old M2 Browning I wish I could lay claim to the one at 6 being the fifth shot - however it was the fourth. I felt it slip when I sent it downrange, I could have had the stock tighter in my shoulder pocket, but as you all said I rushed the shot. I'm using a variable scope at 15X and could see the group shaping up. I just got too amped up on that fourth shot. I almost quit after three but told myself to stick with a 5-shot group. I actually had an internal debate whether or not to send the fifth round down after letting the fourth fly. I'm glad I stuck with it. In a curious way it served as proof-of-concept for the load. Now, I need to see how the performance will change when the weather warms up again. I'm also going to put a lighter spring in the M.O.A. trigger from Ernie the Gunsmith. I'd love to be able to do that consistently. __________________ ___________________ "I'm your huckleberry."

January 26, 2011, 10:19 PM	#12
Ike666 Senior Member Join Date: October 10, 2009 Location: SW VA Posts: 491	Sorry, I should have mentioned that I used the load to zero at 200. No groups as good as the 100 yd one, but most were sub-MOA in the 1.75- 2.0 inch range. I have a new scope with an MOA reticle (NP-R1) AND MOA knobs and fired the 100 yard target just to see how well my tables worked. I actually used a table for 2600 fps built from external ballistic data (168 SMK) out of the Sierra manual. My range book is downstairs and I'm too lazy to get it tonight, but I'm getting MVs not too far from that (2550-2600) with this load. The table calls for -2.16 MOA (bullet-down) on the knob and I've got 1/4 MOA clicks so moved 2.25 MOA down (9 clicks). SMK 168gn @ 2600 fps Range Drop MOA HoldOver Clicks Muzzle -1.5 0 50 1.07 0.5235998 -2.0435455 -8.174181885 100 2.26 1.0471996 -2.1581368 -8.632547224 200 0 2.0943992 0.0000000 0 300 -9.33 3.1415988 2.9698254 11.87930171 400 -27.04 4.1887984 6.4553119 25.82124745 500 -54.81 5.235998 10.4679184 41.87167375 600 -94.73 6.2831976 15.0767183 60.30687305 1000 -437.06 10.471996 41.7360740 166.944296 __________________ ___________________ "I'm your huckleberry."

January 27, 2011, 02:40 PM	#15
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Tater, He's got a 26" barrel with the Stealth. Using a QuickLOAD Varget powder model I modified based on the last time I measured Varget performance in my own rifles, I will estimate that if he uses the same cases and primer you do, if you average about 2438 fps from your 20" barrel, he's at about 2583 fps. Ike666, I used Bryan Litz'z measured G7 BC for the 168 gr SMK and that 2583 fps MV I estimated and a scope 1.5" above the bore (getting that accurate matters to these tables) and got the following: Code: Range Velocity Total Drop Trajectory in. Trajectory MOA Holdover Nearest ¼ moa TOF 0. yds 2583 fps 0.0 in -1.50 in 1.50 in inches correction 0.0000 s 50. yds 2482 fps 0.7 in 1.11 in 2.12 moa -1.11 in -8 clicks 0.0593 s 100. yds 2382 fps 2.7 in 2.32 in 2.22 moa -2.32 in -9 clicks 0.1209 s 200. yds 2191 fps 11.6 in 0.00 in 0.00 moa 0.00 in 0 clicks 0.1399 s 300. yds 2009 fps 27.8 in -9.57 in -3.05 moa 9.57 in 12 clicks 0.3952 s 400. yds 1835 fps 52.5 in -27.78 in -6.63 moa 27.78 in 27 clicks 0.5515 s 500. yds 1669 fps 87.6 in -56.33 in -10.76 moa 56.33 in 43 clicks 0.7229 s 600. yds 1509 fps 135.3 in -97.41 in -15.50 moa 97.41 in 62 clicks 0.9119 s 700. yds 1356 fps 198.2 in -153.81 in -20.98 moa 153.81 in 84 clicks 1.1216 s I stopped the table at 700 yards because the 168 grain MatchKing, uniquely, with its odd boattail shape becomes unstable in the transonic velocity range (about 1000 fps-1400 fps at sea level), so there is no point in trying to shoot further with it. It's great to 600, but I don't trust it beyond that for target score. Litz mentions this problem and, indeed, I've seen it twice myself. Once was tumbling and whizzing off all around a 748 yard popper at Gunsite. The other was keyholing on 800 yard targets at the Long Range Firing School at Camp Perry (lots of people had the problem up and down the line there). Using the 175 grains SMK instead solves the problem. It doesn't have this issue and remains stable through the whole transonic range. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 23, 2011, 09:06 PM	#3
Miata Mike Senior Member Join Date: May 22, 2010 Location: North East WI Posts: 418	I would say sweet!

January 23, 2011, 11:16 PM	#4
armoredman Senior Member Join Date: May 22, 2007 Location: Arizona Posts: 5,299	I think I would concur - NICE!

January 24, 2011, 03:39 PM	#5
tkofoid Senior Member Join Date: October 10, 2008 Location: N. D. Posts: 149	if that was one of my groups,,the one at 6:00 out of the group would be my fifth shot. most of the time when I get four in a bughole,I try to get the fifth off too quickly. I refer to my fifth shot as 'operator headspace'. NICE SHOOTING!

January 24, 2011, 03:54 PM	#6
Doodlebugger45 Senior Member Join Date: April 15, 2009 Location: Wyoming Posts: 1,717	Yep. I have been known to mess up some pretty good groups with that 5th shot also. I'm not a serious target shooter so I just don't have thousands of targets behind me for experience. Several times I have fired 3 or 4 rounds at a target like normal. But then I just can't stand it anymore and I will take a peek through the spotting scope to dee how it's going. If I see a real tight group developing, almost invariably, it messes with my head and I overthink that last shot. I try extra hard to force it in there and end up screwing it up. I have learned now to either avoid the temptation to peek at the target with the spotting scope, or in a few cases I just quit at 3 or 4 shots if I want something to show my buddies the next day.

January 25, 2011, 01:34 PM	#9
Clay Senior Member Join Date: November 11, 2009 Posts: 166	Yours is almost identical to what I found for mine, 41.6. My lowly Savage Stevens 200 can't group quite as well, but my DPMS LR-308 looked even tighter than your group. Both liked the 41.6 load the best. Those were with the 165gr Sierra exposed tips, whatever they're called. I'm ordering up some Hornady A-Max's this week, can't wait to try them out!

January 25, 2011, 04:15 PM	#10
Doodlebugger45 Senior Member Join Date: April 15, 2009 Location: Wyoming Posts: 1,717	I especially love to hear about these kinds of results when they are from very light loads. It seems like I'm always hearing folks wanting to load beyond the max published loads. The load here this thread is a little bit below the suggested starting load, but the accuracy is just fine.

January 25, 2011, 06:45 PM	#11
TATER Senior Member Join Date: November 19, 2002 Location: Mississippi Posts: 963	Maybe somewhere around 2425-2450 FPS ??? I guessing... Definitely not taxing anything, Brass should just about last forever..(Big Grin) Good Shooting.. Have you actually reached out to 200 Yet?? Just curious if up 2.25 is getting you back to the 200 mark.

January 27, 2011, 11:39 AM	#14
TATER Senior Member Join Date: November 19, 2002 Location: Mississippi Posts: 963	Ike666, I would not have thought that you were generating that much velocity. I am shooting almost the same Rig in .308 it sounds like...Although, I’m shoot’en 20” tube.

January 27, 2011, 04:05 PM	#16
TATER Senior Member Join Date: November 19, 2002 Location: Mississippi Posts: 963	Unclenick, Ahhhhh, I was thinking 24” To be honest, I don’t think I ever broke the 2400 threshold till I Got to “42. Something” with Varget, I will have to look tonight.. I have played with a bunch of combinations with this rifle. Heck, even Now.