Reload testing question

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jerrya

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I am new to reloading this year. I worked up loads for my 270 winchester and came up with a load for it relatively easily that shoots great consistently. I now am working on a 270 wsm. I am having a problem getting any consistency out of my reloads. The question I have is if you are at or close to maximum powder charge for a particular rifle other than the obvious signs of pressure on the case or sticky bolt would inconsistent grouping be a sign of too much powder?
I worked up to 69 grains of magpro (69.5) listed as max in Nosler guide) and got a good grouping. I loaded some more of that charge the next day and the grouping went to hell. I don't have a chrono yet.
 
What is went to hell?

.5" group to 12" ??

Could be your powder. Could be you seating depth, could be many things. Barrel fouling....barrel not fouled enough.

Think you need to give more details.
 
Went from a 1 1/4" group on my first try with that load. Next time out 4 1/2" group with no change in coal. I start with clean barrel, a couple of fouling shots. I shot a few other loads each time also alternating between loads.Each time the fouling should have been very close to the same. I am using Magpro powder as it was listed in the Nosler guide as most accurate.
I am going to the range this morning to try again, I also loaded other groups with a change in coal to try. This all has been using 140 gr. accubonds seated .024" from lands.
 
1 1/4 to 4 1/2 With the same load?

That's on you.

"Too much powder" will not affect accuracy. It will start to affect all those other things at a certain point.

If you load 5 rounds in 1/4 to half grain increments you will see something call "nodes". Your groups will open up then start to close up again and then open again.

Find the tightest grouping at as close to max velocity (no crono then max powder) and then load 5 round groups in .1 grain increments.
 
jerrya said:
Went from a 1 1/4" group on my first try with that load. Next time out 4 1/2" group with no change in coal. I start with clean barrel, a couple of fouling shots. I shot a few other loads each time also alternating between loads.Each time the fouling should have been very close to the same. I am using Magpro powder as it was listed in the Nosler guide as most accurate.
I am going to the range this morning to try again, I also loaded other groups with a change in coal to try. This all has been using 140 gr. accubonds seated .024" from lands.
Click to expand...

That was the most accurate load for the equipment (action, barrel length....) that they used to test with. Does not necessarily mean that it will be the most accurate for you. It can be a place to start but you may need to try other powders. I don't load for that cartridge so can't give any advise on powder selection, others here do and will.
 
With the 140 grain load for your 270 WSM, the most accurate powder was MagPro but the most accurate load was 67.5 grains.
Sierra also runs to 69.5 grains but their hunting accuracy loads with the 140 grain bullets are:

Accuracy Load: RE-19/ 63.1grs. 3050fps/ 2892ft. lbs.
Hunting Load: RE-22/ 64.9grs. 3100fps/ 2988ft. lbs.

Both manuals are excellent starting points but they both used different rifles.
 
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