My Perfect 45/70 load gone South!

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ACES&8S

ACES&8S

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This past year I went nuts with 45/70 & got a T/C Encore & an 1895 Marlin with 22" BBL &
worked relentlessly on a common accurate load for both & came up with IMR3031 at 1850 FPS,
only 50 FPS below book max using a Hornady 300 grain HP #4500.
During all the testing with other powders & various volumes I saw a repeating result that I have
heard of but never encountered before. The impacts would --string-- up or down almost in a straight
line.
Finally both rifles settled perfectly into the load mentioned. They stayed there with no problems
& I don't just guess at it, I made 20 more & fired 10 in each rifle for confirmation.
Now it is near deer season & I get my Marlin out. It shoots a perfect -string- straight up at 100
yards with the same original set up I had on it. Leupold scope & all. Now I think it's the scope
& swap it to a Nikon 3x9 BDC which has always been reliable & get the same results.
Any thoughts?
 
I don’t know the answer but my 444 swings wildly vertical with some loads. Have you tried shooting over a chrono to see if there is a correlation to velocity shooting high or low? Mabey it just needs a magnum primer
 
I have a chronograph but I usually believe the book stuff as to FPS but with such a large caliber you may be right.
& the Mag primer is worth consideration as well, thanks.
 
Question for you... When you worked up the load prior, how did you rest the rifle (assuming you benched it.) ...and how are you doing it now? The others are also correct... differences in temperatures will affect your handload, but different temperatures and humidity might be playing games with the forearm/barrel contact.
 
Tube fed lever guns can be prone to vertical stringing. Barrel harmonics as the magazine empties do change. A few thoughts.

How does it shoot if loaded singly?
Are you resting the barrel or fore end on the front rest? If so, try resting the receiver, just in front of the trigger, on the rest.

I shoot obviously a very similar hunting load out of my H&R single shot, and my nephew shoots the same load out of his Marlin 1895. IMR 3031, Winchester Large Rifle primers, and the Hornady 300 grain hollow point, but mine average right at 1800 FPS. The Marlin will verticle string, but not if loaded singly. And it strings less if the magazine is loaded and the rifle is rested on the receiver.

The first shot is high, with the shots getting progressively lower as the magazine empties. To see how it does hunting, fire 3 shots at 100 yards, then let the barrel cool. The 1895 will put all 3 in a group about 3 inches at 100 yards, not too shabby for pigs and deer.
 
Slow down.
Shooting quickly heats up the barrel, causing stringing.
My protocol for shooting l/a’s is three shot groups, minimum 1min between shots, min 5min between strings. I usually take several guns to range to swap out while others cool down.
 
Charlie98 said:
Question for you... When you worked up the load prior, how did you rest the rifle (assuming you benched it.) ...and how are you doing it now? The others are also correct... differences in temperatures will affect your handload, but different temperatures and humidity might be playing games with the forearm/barrel contact.
Click to expand...

Lead sled every time.
Did the load work thru June & July which will cause a difference in temp & humidity causing impacts
to move but not to this extreme would it.
 
greg_r said:
Large Rifle primers, and the Hornady 300 grain hollow point, but mine average right at 1800 FPS. The Marlin will verticle string, but not if loaded singly. And it strings less if the magazine is loaded and the rifle is rested on the receiver.
Click to expand...

I always load one at a time.
I load lots of rifle calibers & have never had one string like this caliber, there has to be a reason
for it.
 
GooseGestapo said:
Shooting quickly heats up the barrel, causing stringing.
My protocol for shooting l/a’s is three shot groups, minimum 1min between shots, min 5min between strings. I usually take several guns to range to swap out while others cool down.
Click to expand...

That is how I shoot all the time, slow enough to keep it cool, sometimes 5 minutes between shots. I have a 300 yard
range out my back window which makes it easy to take my time, even during testing I will make a round then shoot it
& look at the results,make another while it cools a bit, never shoot them hot.
 
My Savage 99 will string shots vertically when I shoot it too fast, the 99 doesn’t even have the burden of the magazine tube, either.
 
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