Which load to chase ?

[JimSC]

The one with the smallest ES/SD or the one with the smallest CTC measurement ? Or maybe just load up ten rounds @ 41.5 and ten rounds @42.4 then shoot four groups of 5 shot groups round robin? This is just a fun gun for plinking/practice a .308 set up in a MDT chassis and shot from a Harris style bipod and a squeeze bag on the rear. 175 gn Match Burner bullets and TAC powder

 

[RegionRat]

I guess that depends on how far you plan to run the load.

Since there is lots of risk in banking on just three shots, I could see taking the next tests out to full distance and then deciding.

If the velocity stats on the 42.5 load are really what they are, a larger sample may get even worse and the load won’t look pretty at distance. The 41.5 might close up with a little seating depth change, and with luck and the speed stats hold together, might be the ticket out at distance… The only way to find out is to do a little more testing and let the target do the talking…

In for the range report.

 

[JimSC]

. The 41.5 might close up with a little seating depth change, and with luck and the speed stats hold together, might be the ticket out at distance… The only way to find out is to do a little more testing and let the target do the talking…

In for the range report.

850 will be max distance and yeah that was what I was thinking, just looking for confirmation. Odd thing today was the POI dropped about 5 inches between 41.0 and 41.3 then held steady through the rest of the test

 

[RegionRat]

Wow. That is a really big shift depending on the distance.

Dropped 5 inches at what range?

 

[JimSC]

Sorry was actually 2 1/2 inches at 100. It was between 41.1 and 41.3. My POA on 41.3 was the upper left square and the. POI was lower left square. I did a 2.5 MOA adjustment on the scope before the next group.It makes me want to check my scope to see if it is tight and reshoot those last six loads

 

[DaveTooley]

In 40 years I have never tuned a rifle using a chronograph. It will lead you down the wrong path. Won many a match with an accurate rifle and unknown SD's. If you reversed that I doubt the results would be the same.

 

[flintcreek6412]

Since it's a plinker I'd say 42.4. You might be in the middle of node based upon the average vertical location of the loads around it and you may have also stumbled into the correct seating depth already based upon good group. The question is if you can duplicate it.

 

[JimSC]

I want to keep the COAL at 2.8 for magazine loading. I am leaning heavily toward loading a bunch up between 42.4 and 42.7 and running the range out to 300 and seeing what happens. I have plenty of those components and it is just for entertainment and practice

 

[PigButtons]

I want to keep the COAL at 2.8 for magazine loading. I am leaning heavily toward loading a bunch up between 42.4 and 42.7 and running the range out to 300 and seeing what happens. I have plenty of those components and it is just for entertainment and practice

Any reason to go to the range is good enough for me. Have fun and let us know what you find.

 

[BigWyoming]

To me, it looks like the 42.1 and 42.4 areas (42.2 and 42.3) might require some more exploration - close to a velocity node. Then, start working back from that 2.8 COAL to find accuracy.

 

[JimSC]

Just a quick update for anyone interested. I took it out to 850 today and shot 3 five round groups with each charge. The 41.5 charge gave me horizontal stringing , the 42.4 vertical. It was a fun little practice session however. I had a 5 - 10 mph wind fishtailing from 6 o'clock. The 42.4 made a beautiful 3 inch wide ribbon, 12 inches tall lol. I am planning on bringing it back to 600 yards and working the seating depth in to see if I can get the groups to round out. If not I have other powders, primers and bullets to play with. This gun will never be shot in any sort of competition, but it is great training for recoil management and wind reading

 

[NorCalMikie]

Looks like the 42.4 is the winner. Not much tweaking needed there. I go for groups.
IMHO, If it won't group, no matter what the numbers say, it's a waste of time.
Never seen a target or game animal bitch about speed.

 

[Laguna Freak]

Just a quick update for anyone interested. I took it out to 850 today and shot 3 five round groups with each charge. The 41.5 charge gave me horizontal stringing , the 42.4 vertical. It was a fun little practice session however. I had a 5 - 10 mph wind fishtailing from 6 o'clock. The 42.4 made a beautiful 3 inch wide ribbon, 12 inches tall lol. I am planning on bringing it back to 600 yards and working the seating depth in to see if I can get the groups to round out. If not I have other powders, primers and bullets to play with. This gun will never be shot in any sort of competition, but it is great training for recoil management and wind reading

The 41.5 and 41.3 pics look promising to me. If your horizontal stringing at 850 is within 1.5 moa, I would work seating depth to see if PoI tightens up and yields triangular or diamond shape. I would load 41.3, 41.4, 41.5, 41.6 and go both sides of current CBTO in 0.002” or 0.003” increments as next step.

 

[JimSC]

. I would load 41.3, 41.4, 41.5, 41.6 and go both sides of current CBTO in 0.002” or 0.003” increments as next step.

trying to stay with magazine length so shorter is the only option length wise, but thanks for the advice. That progression you suggested might just be the ticket

Also next trip I think I will use the IDPA target on the shotmarker and see if I can put 10 rounds in center mass at 850. The rifle itself is just a fun toy to work on recoil control and long range wind reading with. Stevens 200 receiver I rescued for 75 bucks years ago. I have reconfigured it now at least a half dozen times, Savage/Stevens is the Jeep of rifles. Over the years it has had a .204, a 223, .243, 260, 6BR, and two different .308 barrels, 4 or 5 scopes, 3 stocks.

Currently it has a Rifle Basix trigger, Shilen barrel, MDT chassis. Magpull rear stock and bipod. 20 power $400 scope with a German #4 reticle and a sand filled sock for a rear bag

 

[karrarararararar]

How wide was the horizontal stringing? It doesn't take much of a wind change for a 308 to get blown around at 850. I'd work whichever load holds vertical and 12" of vertical at 850 isn't that great IMO.

 

[JimSC]

I'll see if I can DL the Shotmarker targets but none was worth a darn really. I had some ammo that I had loaded for my AR10 that I used to zero on the steel that shot better. 168 SMK's and Varget. After some thought I think the TAC with 175's and Rem primers is a waste of time to pursue. I have some other combos I think I want to try.

 

[RegionRat]

If you own the Shot Marker, you can always wait till you are home to process target images or pull your data in the CSV file.to use your spreadsheet.

If you are on a borrowed eTarget, you can always screen grab the target right away using your tablet or smart phone. It would also be the time to pull that CSV file so you can just cut/paste the columns for spreadsheet processing. No matter what target you use, you can project an MOA or MIL grid over the whole thing.

The main point is keeping notes even on poor performance is worth the trouble since time can add fog to the specifics and there is as much to learn from what doesn't work as there is in what does.

Almost any time I have been in a situation where I am not comfortable or being rushed, and then decided to postpone taking notes or labeling data, becomes a risk that I will regret it later when specific details are lost.

In school we hear about the psychology of collecting too much data and not using it. It is a common fault in many corporations. However, being in development I have come to the conclusion it is better to have the tapes running during the chaos, and then throw the data away if it isn't valuable, than to wish you had captured the data and didn't have it....

 

[D-4297]

Jim ; I've been shooting Berger 185 Jugg Targets , IMR 4064 , and Heaven forbid , Rem 7 1/2BR primers for a couple years now . Got me to a Masters rating , and pushing at that elusive HM in TR . If you stay inside 700 , you can get away with using the 168's but anything beyond is a total loser with that bullet , in my opinion . Just to unstable beyond 650 - 700 . I do shoot the 185's to 1,000 in Comp , rather than the 200.20x , only because it's easier on my barrel , not trying to push the mid-heavy to the good velocity required .