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Old September 20, 2006, 06:19 PM   #1
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.243 accuracy problem

Well, I was shooting the boy's .243 Rem m7 today.

I started shooting at 30 yards, to get it on paper.

I am concerned about two things.

First. It seem to hate 55 gr balistic tips. They string from left to right, moving 1/2" progressively, and vary in altitude slightly.

Secondly, with 100gr winchester, which it seems to shoot more was still stringing a little.

Both rounds were shooting a 4-6" group at 100, albiet at different heights.

I loaded these rounds with the same powder and primer...imr 4895.

Could another powder give me different results?

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Old September 21, 2006, 04:34 AM   #2
Smokey Joe
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Loading for the .243Win

Depending on whom you ask, .243's are very finicky as to their load. Or very accepting of almost any load.

You want to check yr cases for excessive length, and trim any that are longer than SAAMI spec. If you're really going for accuracy, trim 'em all to the same length. Then the trimmed ones need neck chamfering inside and out. Over-length cases can cause awful flaws in accuracy, besides mebbe generating excessive pressure.

While you're at it, are yr cases sorted by manufacturer? In trying for an accuracy load, you should be using cases as alike as possible.

And of course you're using all the same brand and type of primer. Hand-seating is more uniform than doing it on yr loading press.

Anyhow, before trying different powders, I'd make up a series of loads with your IMR 4895 since that's what you've started with. Vary each load by, say, 0.3 grains and make 5 rounds of each load. DO NOT exceed the maximum load stated in yr manual!!!

Then shoot all the loads, taking care that the rifle doesn't get too hot nor too dirty. You will probably find that one load shoots better than most of them.

Then you load up another series, bracketing the best performer, but varying by only 0.1 grains, 5 of each, or 10 of each if you don't mind doing the extra shooting.

You will probably isolate the "best" load with that rifle and that bullet and that case and that primer, with the IMR 4895.

Is all this putzy enough for you? Now, if yr IMR 4895 gets acceptable results, fine. If not, try IMR 4350--that is the "classic .243Win powder." And you just started all over again.

But that's part of what reloading is all about.

Enjoy. Remember, as always, the journey is part of the destination.
God Bless America

--Smokey Joe
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Old September 21, 2006, 08:24 AM   #3
Ben Shepherd
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Are the action screws torqued correctly?

Do you have any pressure on the barrel from the fore end of the stock?
From my cold dead hands.........

NRA certified rifle, pistol and shotgun instructor.
Hunter education instructor
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Old September 21, 2006, 09:18 AM   #4
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Smokey Joe: Bought all new winchester brass, all were shorter than they had to be. I hand seat all my primers.

Ben: Yes they are, the action is glass bedded, and the bbl floated.
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Old September 21, 2006, 10:12 AM   #5
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Buy some factory varmint loads; I like Remington.

Buy some factory varmint loads; I like Remington. Fiddle with the rifle until the factory loads shoot small round groups. Save the brass.

FREX especially if the glass bedding was done outside the factory then indicate on the action while turning the screws in and out and look for shifting or bending in the action to show a defect in bedding. Look at the rifle crown under some magnification to check for damage or defects. Check the bore with a borescope - may have to pay a gunsmith to do that - or otherwise be sure the bore is clean to start - an Outer's Foul Out does a good job as do lots of other techniques.

Once the rifle and the shooter technique have been demonstrated good then apply known accuracy techniqes including checking the handloaded ammunition for run out. Although many people are quite satisfied with the 55 grain bullets there is a possibility your rifle won't shoot them well. Notice that ever since the .243/6mm issue of shooting heavier bullets the twist has been chosen for heavier rather than lighter bullets. I like Redding dies but fine ammunition can be loaded with any of the brands, assuming unworn and undamaged, by applying techniques such as raising the press handle half way then back down and rotating the case to minimize run out. Check distance to the lands and start say .050 off the lands - assuming a good throat as checked by borescope if necessary. Buy some of the loading technique books out of Precision Shooting magazine or by Fred Sinclair or what have you.

Again, try some good factory loads first and demonstrate small round groups before going wild with reloading techniques.
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Old September 21, 2006, 04:36 PM   #6
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Thanks Clark, I'll try that.
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Old September 25, 2006, 07:04 PM   #7
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If you have some other powders around, you might try that as well. Generally when you have a group that size, switching powder is probably more likely to show you a change than altering the amount of the type of powder you're using.
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Old September 25, 2006, 11:52 PM   #8
T. O'Heir
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55 grain bullets are likely too light for the rifling. .243 rifles usually have 1 in 10 rifling. Although the M7 comes in 1 in 9.25 too. You need to figure out which you have. Put a patch on a jag and run it through the barrel. Mark the rod and pull it out until the mark turns one complete revolution. Mark the rod again. Then measure the distance between the two marks. That'll tell you what the twist is. Then use a bullet weight for that twist.
Then try IMR4320 or IMR4350 or IMR4064 with 90 or 100 grain bullets. Mine likes 90 grain bullets with IMR4350.
However, you must work up a load for that rifle. Just picking a load from your manual doesn't work. My old Lyman manual gives IMR4320 and IMR4350 for the accuracy load powders.
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Old September 26, 2006, 12:51 AM   #9
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although imr4350 imr4064 works well you mite want to try Varget / Sierras 85gr MK / GM Fed. primer , since you already have Win.cases

6mm/.243 8" Special for VLD bullets over 100 gr.

10" For bullets up to 120 gr. and VLD under 100 gr.

12" For bullets up to 85 gr.

13"* For bullets up to 75 gr.

14"* For bullets up to 70 gr.

15"* Special for bullets up to 70 gr.
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