Accuracy Changes

[Jim1 AB]

I go down the bench yesterday for three things. First to check sight in and the 130 AB loads for the 6.5. Shoot a group of five, three shots cool down and shot two more. 3/4" and it is hitting 2 1/2" at 100 yards. Second and I'll post a new topic about this rifle later but to get a load for a friends 300 Win Mag. I got that put together. Third to check the loads and sight in for my Winchester 70 300 Win Mag. I had 30 180 e-tip loads made up. Last time I loaded four two bullet sets .5 grain differences. All printed close to the 3/4" mark, one was almost 1". I picked the heaviest load to load the 30 at. So I set down to sight it in. I checked with a three shot group and it's printing just over 1 3/4". What the hell. I had just clean the barrel but I usually don't need fouling shots with this rifle. I've seen this before a couple of times. Get a good group and then load up a bunch just to have it be the pits. I'll pull a few loads and check the charge weight today. You would almost think the digital scale was doing screwy things.

I'd appreciate your thoughts and suggestions.

Jim

 

[rick smith]

One group doesn't make a load, been there myself. I would vary the charge and get the best group, then play with seating depth and then different primers.Rick.

 

[barthowes]

I have found this myself on occasion. Variances in temp,wind, ect play a role in load development. Just like rick said one group doesn't make a load (good or bad). when I reload I vary in 0.5gr and load @ least 6 of each charge. Shoot a group with each load lowest to highest charge weight, then do it again to see if they are repeatable. then take the best group and play with seating depth +/-.005"

 

[Jim1 AB]

You would think with four sets and all good groups I'd get better accuracy than almost a two inch group after.

 

[Elkman]

If all of the components were exactly the same I would also guess environmental factors, or human factors. Lots of things like shadows, high humidity or really cold will change things.

 

[rick smith]

Could be a change in the rifle/scope/screw tension. Is the rifle bedded?Rick.

 

[Duncan]

if you have a factory stock on this rifle , this where your problems is. from my experience with a REM 700 factory stock I could not get consistency out of my loads due to the stock.

 

[Guest]

If you put any oil down the barrel after cleaning the gun it may take 3-fouling shots to burn it off. It does with my 300 Ultra Mag.
If you have a wooden Factory Stock check for the stock binding on the barrel if not free floated, this will change the POI too.
Different lots of Powder can change things in bullet grouping as well as seating depth. Tighten all screws in the stock as well as check the mounts and rings on the scope. Yes different climate changes could affect POI. Did you allow the barrel to cool in between shots?

Don

 

[Jim1 AB]

Well I'll have time today so the first thing I'm going to do is pull the bullets and check charge weights. The weather has been pretty much the same for the last few days so that wouldn't be high on my could be list. But hell who knows.

 

[Jim1 AB]

Pull three loads and charge weighs are within .1 grains on three loads pulled. Scrubbed the rifle a lot. I shot three rounds. A little better, 1 1/4" group. Adjusted the scope for center of the three shot group. One shot and center 1 3/4' high. Adjust again. 2 1/4" high and dead center. Now that's working. Needs the few foulers??? ..... by the looks of it.

 

[Jim1 AB]

I think the reason I get into issues I can't explain is I have had a lot of rifles that you find the load and it will always shoot that load. Example my Remington 700 BDL. a thousand years old. 180 grain Partitions Protected points. Same load year after year. 1" groups. My 358 STA is the same thing thing. Now I get into a couple that are a little more finicky and it kind of throws me.

Jim