7.62 FGMM Clone Load Question

[Infinity]

I realize that I can load better for my rifle than cloning FGMM. That said, I am amidst load development to match 7.62 x 51 FGMM using 175 SMKs, Federal Brass, Reloader 15, and F210 Primers. I've found a bit of a sweet spot a hair over 43.4 grains of RL-15 loaded to mag length (same ogive measurement, approximate OAL of 2.807-2.813").

I chronoed the FGMM @ ~2515 fps out of my 20" LAR-8. My hand load is almost exactly the same velocity (within 5 fps). FGMM and my hand load shoot to the same elevation, and shoot darn good groups (best 5-shot group for the day was sub .5" with my hand load).

My Question: POI for my hand load is approximately 1/3 MOA (I mean MOA, hair over 1/3") to the left of my FGMM zero. Is there anything I can do to shift my POI to the right or should I just shift my windage one click (.1 MOA adjustments) and call it a day when I shoot hand loads? Is this odd considering almost identical velocities and components?

Thanks all for your time,
Adam

 

[ChrisGarrett]

Use the knobs, bro, use the knobs. You pay for them, so you might as well use them.

Why you have a difference in POI, I can't say, nor does it ultimately matter.

You sure that your clicks are .1 MOA, or .1 mil, as .1 mil is pretty common these days.

Either way, just get your bullets hitting at you crosshairs and you'll be golden.

Chris

 

[Infinity]

Thank you for keeping me honest, it's late and I mis-typed. They are .1 mil.

 

[FLIGHT762]

Yes!! One click left and call it macaroni! Have a drink to celebrate you've found a load to duplicate your 175 GMM ammo. You're done. Good work.

*Edit* I got in 40 minutes ago from the range (open at night) and had a good night. Sighted in a Sig 516 With a new Bushnell Elite 1-6.5
scope and shot some 308 175's with 40.0 of AR comp that shot very well. I'm having a dirty Martini W/ 3 garlic stuffed olives. I like this hobby!

 

[Infinity]

Chris, Thanks. I assumed as much but I figured you gurus might have some magic for me. Simple = magic I guess.

In that case, good load development day! Mongo happy. Cheers,
Adam

 

[Warbone]

Every FGMM i have tested all have a OAL of about 2.800, maybe play with your seating depth a little i know this can change PoI.

 

[2clicks]

I put it on the burn rate pressure curve body reaction when that kind of stuff happens to me. It's the only way I can justify those little shifts right or wrong. Of course it could inconsistency behind the rifle too but I'm near perfect so that can't possibly be it.

 

[Infinity]

Flight, I did not see your post when I first replied. Congrats on a good day's work. I'm also a big fan. Now I just have to figure out how to balance fishing and shooting/reloading.

Warbone, that's interesting. All of my FGMM has OALs measuring from 2.805 to 2.814 (ask me how I know). Could it have something to do with mine being 7.62 and maybe yours being 308? Just a thought. Either way, good thinking, I'll tweak a bit on the seating depth to see if I can make the click unnecessary. If it doesn't work on the first try, I'm calling it and click it is.

 

[Infinity]

...just poked around a little more...perhaps I should pull out a couple different boxes and measure a bit. You see what you did? ;D

 

[Infinity]

I shot a bit more this evening. Conditions were perfect so I assumed tight groups would be easy. They were, but I identified a major leak in my shooting form. This time, my group, with FGMM was about .3" right of my zero. Apparently my prone body position needs some work. I'm assuming this accounts for the R/L difference in my hand load and FGMM. I share this as I feel it might help someone having similar issues. Hope it helps,
Adam

 

[M40_A1]

LOL! To regulate windage on a fixed-sighted Colt Single Action Army, it is best to turn the barrel in/out to cant the front sight as needed (except 3rd generation). I learned pretty quickly to NOT make any changes until I had fired the revolver for several outings before making the decision which way and how much to turn the barrel (a major PITA). Of course, more consistency narrows the range of variation eventually. As well, invisible and unknown wind patterns between you and the target can make the difference, too, for intermadiate and long range tests. Shoot, shoot, shoot!

 

[Infinity]

Warbone, I measured another box. Is it possible just the 168s are 2.800"? All of the box I measured of 175s measured 2.811-2.814".

2Clicks, not sure how I missed your post. Ha, it couldn't possibly be us. Must be isolated down wind gusts. Ya, that's it.

 

[Warbone]

I went back and checked my notebook, checked 2 boxes and all where between 2.798 and 2.805, and they where the 308 box not the 7.62 x 51mm box(notes are about 2 years old). Info i found was that the 308 box is suppose to have higher standard for accuracy than the 7.62. I believe it was on this websight i read.
That being said i have done alot of load developent the past 3 years and i can say for sure in the 2 308 rifle i have, changing the seating depth does change the PoI, i also know that going from prone to benchrest also changes the PoI, was from a article i read on 6mmbr i think.
Using the same seating depth (2.800) i was able to set up 3 loads, 168g smk, 175g smk, and 178g amax all with the same PoI . If i changed the seating depth on any of them it would throw PoI off as much as 1.5 inch.
It kinda funny i can take 5 round of these loads in any combination and get under 1 MOA with my tikka t3 scout.

 

[Infinity]

Warbone, that's very interesting about the lengths varying. I know my micrometer is accurate. Thank you for info regarding changes in seating depth. Was it a left/right poi difference? I'm pretty sure it was my form at this point. I'll let you know after I shoot a bit more, I think tomorrow. Thanks again,
Adam