Help with understanding these results please

[GEEKMEDIC]

I shot this load test today. This is IMR 4064 with SMK 175's. I am not a novice shooter, but am new to precision rifle. While I am not new to reloading I am new to precision reloads. I shot this from a front rest and rear bag. Obviously my lack of shooting skill has something to do with these results, but I felt like I shot reasonably well and didn't yank any shots during the test. If anyone can help me understand these results I would appreciate it. I did not see any signs of pressure with any of the cases. I have tried searching for an explanation as I know I've seen one before but can't find a thread that explains it well. I know they exist but my Google Fu must be off today. If someone can post a link to a thread I would really appreciate it.

[0321jarhead]

What rifle were you using, a Schmidt-Ruben K31 perhaps? Also at what distance were you shooting?

[JTROKS]

That looks like what my Remmy 700 PSS in 308 did last time I shot it. Playing with the action screw torque for now. This rifle shot very decent groups in the .75 MOA at 100 yards. I'll post once I shoot some test loads.

[trailtundra]

Seems like you're trying to do an Optimal Charge Weight test. Have you seen/read these instructions? They are very detailed.

http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134

I'm attempting the same thing, and I think for the same reason. 3/22.

From how I understand it, you want to triangulate each grouping to locate the center of each three shot group. Then measure how far away from the POA those centers are. You'll get an idea of how each load is shifting the POI. When a set of test loads have a similar POI (regardless of group size), you should be able to select a middle load in that series of loads that should produce a level of precision with some leeway, high or low, on the charge weight/pressures (or temps too?).

The instructions in the link above calls for finer test loads but I think you can still learn from your target. I did one at 0.3gn apart.

This video was also very helpful for me learning about OCW tests (I did not want to attempt ladder tests!).

***I am a novice at this but it seems like we're in the same boat so I thought I'd share what I have learned. I am sure some of the more experienced shooters/loaders will have more to add.

[gigante]

What rifle were you using, a Schmidt-Ruben K31 perhaps? Also at what distance were you shooting?

^^^ This

Geek, I'm a lot like you when it comes to shooting/reloading experience vs precision shooting/reloading experience. Other precision loaders/shooters will chime in with greater advice than mine, but I will share what has helped me to progress.

You're using SMKs, so I'm going to assume you are not developing a hunting round, but I'm not sure if you are shooting these out of a hunting rifle. Yours look a lot like mine when I began a hunting load- triangles, or 2 touching and one off to the side. If you are shooting these from a hunting rifle, these make some sense to me. If they were shot from a bench rifle, then i think shooter influence is playng a bigger part.

Since I'm far from an expert, I bought a sled to use for load development to help take myself out of the accuracy component of the development. For me I found that it was more efficient-less wasted components and time developing an accurate load, so I use the sled for load testing and don't use it when I'm just shooting.

Besides rifle and distance, also provide the diameter of the circles you drew. Need some kind of reference.

[GEEKMEDIC]

Thanks for your responses everyone. This was shot with an FNH SPR A2 with a 24" 1:12 barrel @ 100 yards. I used a high quality micro adjustable front rest that is normally used for bench rest. I have certainly shot more consistently with factory match ammo than any of these groups. I have shot a good bit of small bore benchrest, and I think my technique there is OK but not great. If the third round would have hit where the first two did I would have liked the results at either 42.5 or 44.5. Even though I didn't see signs of pressure I don't think I'd want to consistently load anything above 43.0gr based on the chronograph readings. The numbers at 43.0 were 2713, 2700, 2721. The greatest ES for any of the groups was 40, the least was 7 @ 40.5.

[707electrician]

43.5 looks best to me

[Pete1979]

OP, shooting at 100yds you will get bigger gains from adjusting the seating depth than you will from charge weight. Try sticking with 42.5 and move the bullet closer to the lands. My remington 700 20" 1/12 barrel shoots it's best with a middle of the road charge weight and the bullet touching but not jammed.


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[Pete1979]

Also how many firings on the cases? Neck tension needs to be consistent so you need to pay attention when drawing the cases back out of the die. If a case takes an abnormal amount of effort or squeaks coming down, set it aside or toss it.


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[Fjold]

It looks like they are tightening up as you work up at 44 and 44.5 grains. Try 0.2 grain increments going up from 44 grains until you see signs of pressure or don't feel comfortable and then start playing with seating depth.

[GEEKMEDIC]

It looks like they are tightening up as you work up at 44 and 44.5 grains. Try 0.2 grain increments going up from 44 grains until you see signs of pressure or don't feel comfortable and then start playing with seating depth.

This is the second firing for these cases. I don't mind going up as long as I don't see signs of pressure. The one concern I have is velocity. The three rounds at 44.5 were 2798, 2782, 2819. What does that do for barrel life? At what point does velocity start to wear on a barrel? Also, I was pretty conservative on seating depth. I have these .015 off the lands. I can seat them another ~.008 closer and still be within length for the magazine.

[Fordtrucks]

I wouldn't worry about velocity vs barrel life. If ur not above 3500fps ur not gonna see much extra degradation, case life might drop but oh well. Just shoot worry about barrel life later.

[GEEKMEDIC]

Oh, and the dots on the target were ~.5" to 1". I had a nicely done target all made up with bright dots placed neatly spaced on the paper and then forgot it at home. So out came the sharpie. Improvise, adapt, overcome.

[rm1911]

I'm not an expert but I look at 40.5-41.5 gr as your best loading range. The group sizes for that range yielded the smallest groups. Other weights got similar group sizes but they were in between wider spreads. Of course, there could be a lot of variables in there, something simple as using a dot versus a crosshair target can change aiming point and throw off results. However, I go back to group size. That range seemed to provide most consistent group sizes. Try 41, weigh each charge and get it as close as possible to 41. Then go .2 in either direction to verify and fine tune.

[Pete1979]

You also may want to try a 168. The advantages of the 175 don't come into play until 500-600yds. Clean and uniform primer pockets and if you have the tool, debur the flash holes.


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