What are my targets telling me?

[Jevyod]

I know some of you guys are way better at looking at data and targets, and figuring out where to go from there. Me, not so much. I decided I would post a picture of the target and give you all the data, and see what advice you could give me. The load data was as follows: 1x fired starline brass, CCI 200 primers, IMR 3031 powder, and Noe 360-232 bullet. The bullet was cast on the soft side, 12 bhn. It had a gas check installed, powdercoated, and sized to .360. I ran everything over the chronograph, and the data from there looked good, but the groups, not so much.

I put all the targets together on one, to see if I can see patterns.
Group 1 is Blue. 37 grain charge. 2040 fps, ES 34, SD 18. 2 3/4 inch group
Group 2 is Red. 37.8 Grain charge. 2132 fps, ES 62, SD 27. 2 inch group
Group 3 is Black. 38.6 grain charge. 2161 fps. ES 53, SD 23. 4 3/4 inch group
Group 4 is green. 39.4 grain charge. 2221 fps. ES 41, SD 18. 3 inch group
All were shot at 100 yards off of sand bags. I just don't know what to make of this. Wrong powder? Something else? Rifle is a custom with a 1:14 Lothar Walther barrel. Reason I was pursuing these velocities was to increase range. Maybe I am just pushing too hard, but with PC should be fine in these velocity ranges. Here is the picture. I am open to critique and constructive criticism.

[Scott.M]

No idea what cartridge, but rifles are like wives, they don't always like what we want them to like.

[MrWolf]

I never liked three and four shot groups. Pick a few loads you like and try increasing to maybe ten shots then decide. Good luck

[Jevyod]

No idea what cartridge, but rifles are like wives, they don't always like what we want them to like.

Sorry, missed that! 358 Winchester

[725]

? scoped rifle ? ~ check the mounts and rings to ensure they are tight.
OAL ? changing the OAL can change impact and tighten up groups. Lever action? Bolt action?
Sand bag technique? Resting on a bag can induce a "jump". Can vary if the rifle / bag contact is different from shot to shot. Best to use the bag support on the back of the weak hand as the weak hand grips the rifle as shooting from the field.
Black & blue seem best, so slower might be the answer.
What are the grid measurements? 1" sq, 1/2" sq., etc?

[swheeler]

Put some jacketed through it to get yourself an accuracy base, they also will help clean up the throat and break the barrel in. One 50 rd box of 200 gr 358 bullets fired with near max loads will give you some perfect once fired brass to work with, then don't mess it up by running it right back through your FL sizer, neck sizing works great. I also agree with MrWolf 3 and 4 shot groups just don't do it for me, 10 shot give much better idea of accuracy potential.

[Jevyod]

? scoped rifle ? ~ check the mounts and rings to ensure they are tight.
OAL ? changing the OAL can change impact and tighten up groups. Lever action? Bolt action?
Sand bag technique? Resting on a bag can induce a "jump". Can vary if the rifle / bag contact is different from shot to shot. Best to use the bag support on the back of the weak hand as the weak hand grips the rifle as shooting from the field.
Black & blue seem best, so slower might be the answer.
What are the grid measurements? 1" sq, 1/2" sq., etc?

Mauser bolt action rifle with Swarovski z3. Will recheck the tightness of the scope. OAL was 3.440 which is just kissing the rifling. I got it to shoot pretty well with the 160 grain and the 200 grain cast I loaded seating them like that. Grids are 1/2 inch. I have shot other bullets with the rifle, and know it is far more capable than this. 200 grain RCBS shot at right around an inch. The 160 grain bullets are pictured below. That is 30 shots at 50 yards, so usually the rifle shoots well. Jacketed groups (200 grain) hover between an inch and an inch and a half. So again, the rifle is very capable.

[dverna]

10 shot groups are ideal, but not too practical for me. Three reasons....It takes a long time if you doing a load work up (barrel cool down), it is difficult for me to stay "sharp" for 60+ shots, and it wastes resources.

I use 5 shot groups. If the first three shots are not acceptable, I move to the next load. That leaves me only two rounds to breakdown.

I will take the best 5 shot groups and work from there.

My initial seating length is .020" away from the rifling for all loads. It is a good starting point...at least for jacketed loads. I do not shoot HV cast.

From what I have read on this site, bullet quality, size, alloy, lube, and powder are the key to good cast rifle accuracy.

I would start with bullet quality. Visual inspection...it needs to be perfect. Then weight sorting and only use bullets at the top end of the weight distribution. Lighter bullets that all weigh the same have a defect of some sort that you cannot see...IMHO.

If "good" bullets give poor groups, my next kick at the cat would be a slower powder. You have a lube that should work...PC...and if your bullets are .002" oversize that should be OK. As to the lube, you can try a traditional lube as, in general, it seems to give better results for some...but there are good groups being shot with PC too.

Good luck!!!

[fredj338]

Even with a gc, I think you need a bit harder alloy going over 2000fps.

[725]

Jevyod ~ nice group. Just have to keep tinkering. You certainly have the shooting skills down pat.

[charlie b]

Slower groups are better than faster groups. Alloy is a bit on the soft side for wanting higher velocities.

How good is your quality control? Weight sorted to at least 1gn? No surface or base defects. GC's seated square and coaxial with the bullet. When you try for higher speeds the little things matter more.

[Winger Ed.]

I'd go with a harder alloy at those speeds, and sort out the boolits by weight.

I've had some pretty dramatic weight differences in a batch just from not stirring the pot very often.
I'd don't know for sure if the alloy stratifies like muddy water does when it sits, but it sure acted like it.

If they weigh differently, I'd count on them flying differently too.

[Land Owner]

Somewhere between the BLUE charge and BLACK are probably several "relative minimum" groups. Try 3-shot groups each 0.10 grain above the former and reshoot. From that data pick the best and then try increasing seating depth (jump to lands) to tighten it up. If that does not satisfy, change powder and start over. Imo, 0.80 grain powder increments are too far apart. 0.50 grain is the coarsest increment I use. YMMV

[Jevyod]

Slower groups are better than faster groups. Alloy is a bit on the soft side for wanting higher velocities.

How good is your quality control? Weight sorted to at least 1gn? No surface or base defects. GC's seated square and coaxial with the bullet. When you try for higher speeds the little things matter more.

I think this is where I am going to start. I think my quality control on brass prep seems to be pretty good (according to the chrono). But i tend to cast, do a quick lookover, coat, load, and shoot. And at lower velocity i can get by with it. But as you mentioned, higher speeds means I need to focus on the little things on my bullets.

[Land Owner]

Here are several typical (100 yard non-selective caliber or bullet) powder charge vs. group size graphs at 1.00 grain and 0.50 grain increments, and their overlay for one rifle.

In the first graph, powder loads are 1.00 grain increments plotted against group size (in inches). These results look "FINAL" and point to a "best accuracy" of about 1.75". Meh, these results are not too impressive and the decision could be made that it may not be worth the time or money to accurize this rifle. Move on maybe...





In the next graph (the SAME RIFLE), loads are 0.50 grain increments plotted against group size (in inches). These results (looking only slightly like the former graph) SUGGEST there could be a better accuracy between 37.5 and 38 grains.





In the third graph, the former graphs are plotted together on one chart. It is CLEAR that smaller initial powder increments exposed the greater potential for this rifle. The red dotted lines suggest where the relative minimum SHOULD BE. More testing proved the point.



Consider the numbers:
5 shots for each group for graph 1 ===> 30 shots. Maybe quit here (and MISS IT).
3 shots for each group for graph 2 ===> 48 shots. Too many you say searching for a MOA rifle?

Increasing 0.10 grains per charge between 37.5 and 38 grains, shooting 3-shot groups, the BEST relative minimum was found (0.65" FINAL group and BELOW the predicted curve), added another 12 shots, and produced VERY HIGH CONFIDENCE in that combination. Load and shoot 10 shots at 37.7 grains (this example) and after that SHOOT 'EM TILL YOU'RE HAPPY.

If the initial powder increment is too large, you may be missing the POTENTIAL of the rifle in hand.

[Larry Gibson]

Your target is telling you that alloy is too soft for the load used in the twist of that rifle.

[Silvercreek Farmer]

Here are some 100 yard groups from a 1 in 12 Ruger American with the Lee 200 cast from 50/50/2, air cooled, and powder coated with ebay clear. I didn't log velocities, but if I recall properly, they were in the 2200 fps range. ESs were a bit high, some dacron might tighten groups up a bit.

[white eagle]

What are my targets telling me?

you need to shoot the same colored boolits

[GregLaROCHE]

Five shot groups have worked well for me. Three is not enough.

[charlie b]

Three shot groups may tell you which loads are bad, but, may give a 'false' good group, ie, 1" 3shot group may end up being a 2" 5shot group.

I like doing a lot of casting/loading/shooting so I use 5 shot groups to get me close (0.2gn increments) and then a few 10 shot groups to get the final load. I also shoot at 200yd so 'small' differences in group size show up better.