starting loads group best?

[headednorth]

A while back I worked up a load for my Garand. Started @ 44gr of imr4895 for a 150gr fmjbt. I worked up to the max load in maybe 4 or 5 jumps and the starting load of 44gr ended up grouping the best so I went with it.

The other day, I worked up loads for a 55gr fmjbt .223 and a 230 lrn in 45 colt. Started the 223 with 20.5 grains of H335. Again, the starting load grouped best. Moved to the pistol side of the range to try the 45 colt and the starting load of Trailboss (forget what the charge was) showed the smallest group.

This got me to thinking if there was something more to this rather than these particular loads working out the best. Like the barrel heating up as I progress opening up the groups, or maybe me not taking my time so much causing groups to open up as I work through to the max load. Just seemed odd that the starting load for 3 consecutive work-ups seemed to shoot best.

Anything to this, or am I just putting too much thought into it?

 

[EddieCoyle]

I generally find the complete opposite to be true, but then again, there are usually serveal accuracy nodes throughout the charge weight range, and I (correctly) look for the fastest one.

 

[mac1911]

I generally find the complete opposite to be true, but then again, there are usually serveal accuracy nodes throughout the charge weight range, and I (correctly) look for the fastest one.

Can you explain why you look for the fastest one?
Curious as many of my loads especially for the M1 come at the lower side of the powder charges. For my match M1 the "node" where I get the least amount of POI change and tightest groups ( 1.25"@100us) is in the 44.8-45.5 grain charge.
As for my AR 55gn FMJ with H335 and Varget are at the top end. Same rifle likes nosler 77s at mid weights.

As my skills and equipment improved over the past few years I found taking the time to do the OCW system to really help finding loads that shoot consistently. I have one load using 80 grain 223 that will get me sub moa for 3-5 shots then throws out a far left foul! Then took the time to do the OCW method and found that a grain less group opened up to moa and slightly larger but no more flyers?

It's all fun and finding a good load that works well will keep you from wondering ammo/gun or me.

 

[akma]

When testing multiple loads during the same session it is good to shoot round robin to help average out fatigue and the effects of the barrel heating up.

 

[Mountain]

Done any work on the Garand lately? Had the trigger group out? Mine might shoot a decent group then throw some flyers before it settles in. Takes 30 shots or so. After that back to really nice groups. 168 SMK's, 46.5 gr Varget.

 

[EddieCoyle]

Can you explain why you look for the fastest one?

A faster bullet has a flatter trajectory, so head/tail winds and errors in distance estimation result in less vertical dispersion.

 

[headednorth]

-The higher velocity=flatter trajectory idea makes sense to me. Fwiw, two of my other loads using Varget and a couple different bullets grouped best at max or near-max.

-Round robin meaning say if I am testing 5 different charges, I'd load a round of each charge in the same mag and keep track of which is which rather than ten of starting load, then ten of the next highest load, etc?

-Havent had the Garand apart in a while. Ive heard constant detailed strips arent necessary and cause excessive wear.

- Really I just figured it was weird to have three loads in a row come in at the starting charge. Started to think there was something more to it. (like I said, barrel heating up or whatever)

 

[mac1911]

-The higher velocity=flatter trajectory idea makes sense to me. Fwiw, two of my other loads using Varget and a couple different bullets grouped best at max or near-max.

-Round robin meaning say if I am testing 5 different charges, I'd load a round of each charge in the same mag and keep track of which is which rather than ten of starting load, then ten of the next highest load, etc?

-Havent had the Garand apart in a while. Ive heard constant detailed strips arent necessary and cause excessive wear.

- Really I just figured it was weird to have three loads in a row come in at the starting charge. Started to think there was something more to it. (like I said, barrel heating up or whatever)

I know M1s can do all sorts of fun things as they warm up or cool down.
My 1942 M1 SA which is darn close to correct will actual start to cork screw after 20 rounds. You will be dead on 1-6 then 8-12 might shift a little to the right then it starts 13-20 will be higher but dead center then it just spirals clock wise out to the 7/8 ring area. It wont do this in middle of Jan when it's 15' F though....ahh the fun with that rifle.