Repeatability

I need a little help here.
I’m working up hunting loads for my 280. My last 4 shot group yesterday was 7/8” at 100 yards.
I left the rifle and the ammo outside in a shed all night to duplicate hunting conditions this morning.
My first 3 shot group was even smaller. I really thought I had my load.
I left rifle and ammo in the shade for an hour and shot another group. This one was 3 inches.
WTH – has this happened to anybody else?
The scope is a Leupold and is tight.
Any help would be appreciated.

It might be you. Just a thought.

I've had the same thought myself.

All jokes aside, try another scope.

My favorite load is about in the middle between min and max listings in my old Sierra manual. It consists of Remington cases, CCI 200 Primers, 51.0 grains of IMR 4350, and a 140 gr Sierra SPBT bullet. I've discovered that in my two rifles, reducing the OAL from the maximum listing of 2.330 to 2.225 reduces group sizes noticeably. I have a featherweight model 70 Winchester that shoots 3/4" 100 yard groups with it, and a custom mauser that will print one hole groups with the same load. If you don't mind sharing, what's yours?

I'm trying to work up the most accurate load so the combinations vary.
I had high hopes for 150 gr BTSP Sierra over 54.6 gr IMR 4350 with a CCI LR primer and R-P twice fired brass, neck sized. Theoretically this should give me 2900 FPS, good enough for Tennessee.

I have also tried 160 and 168 gr bullets and various powder charges. I stick with IMR 4350, having gotten good results from it in the past with various calibers.

After rechecking the scope mount and giving the rifle a thorough cleaning I reduced the powder charge to 52 gr IMR 4350 behind a 150 gr BTS Sierra. I shot six groups letting the barrel cool between groups.
The results at 100yds were:
2"
1-1/8"
1"
7/8"
1-1/4"
2" (this from an old box of reloads)
Good enough for hunting deer, but not good enough, consistent enough actually, to make me very happy.

Try adjusting your overall length. What kind of rifle are you shooting? Are your groups dispersed evenly, or are they strung out vertically or horizontally? Have you thoroughly cleaned your barrel lately? I'm sure you've thought of all of these, but once in a while you might let something obvious slip by. Many rifles simply don't shoot any better than that.

The rifle is an all weather Ruger Hawkeye. I bought it in Alaska for black bear hunting. ( I hunted poorly - no bear)
I was getting some vertical strings and a few vertical flyers before I gave the rifle a thorough cleaning with Hoppes. Now I get nice little, or not so little, triangles.
Although the book calls for 3.225 my OAL is 3.207 because the rifle is somewhat short chambered. I had trouble with my first handloads chambering until I seated them a little further into the case.

I'm pretty careful on the bench and hand weigh every powder charge.
The brass is R-P once fired, full length sized, trimmed to 2.530, deburred and chamfered, fired in this rifle then neck sized.

I have reduced the problem to three possible causes:

#1 My shooting - maybe you could come down here and shoot a few groups. You do pretty damn good, and that would take me out of the equation. (joking)

#2 The rifle itself, maybe that's as good as it gets for a Ruger Hawkeye.

#3 I haven't found the right bullet, powder, primer combination yet

Any ideas would be appreciated. I would be satisfied to keep a steady 1" group @ 100.

BTW - the twist is 1:9.5 RH.

greg, I may have found the problem.

I called Ruger technical department and asked what accuracy I could expect at 100 yds with a Hawkeye in 280 caliber.

The answer was "three inches or less".

All my groups are now 2" and under. It looks like that's all I get.