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Old December 11, 2010, 08:14 PM   #1
lwakefie
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.243 Hornady A Max 105 gr

I am having trouble with accuracy with these bullets in my Ruger Mk II(1/9 twist rate). I have MOA luck loading 80-100 gr spitzers to 2.70" OAL. With the A max I load 2.70 OAL over 40 gr of H4350. 100Yd grps are 6 inches. Also with 35.5-37 gr IMR 4895 set 2.84 and 2.785 oal I get 2-3" grps. This seems way long but I thought to try it given the long ogive of these blts.
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Old December 11, 2010, 09:03 PM   #2
GP100man
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My SWMBO had bought a model seven & it will not shoot anything over 90 grs !!! Wish it was a 1-in-10 twist !!!
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Old December 11, 2010, 09:34 PM   #3
Hog Buster
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I also have a Ruger Mk II in .243. Mine seems to like 95 grain Hornady SST’s with a load of 37.5 grains of IMR 4895, groups about an inch. This is my deer hunting load. I haven’t had the time to experiment with lighter bullets, but when deer season is over I will.

I did a bit of testing with the A-Max bullets in a 30/06 and got somewhat poor results. Switched to the SST’s with the same load and accuracy improved.
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Old December 13, 2010, 01:58 PM   #4
Chinny33
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twist rate?

I do know that for the heavier .243win round you do need a faster twist rate.

People who benchrest for accuracy and for competition use faster twist rates for the heavy 6mm bullets such as Sierra 107gr matchking bullets. They recommend a 1x8 twist or FASTER to stabilize the weight of the bullet.

The accuracy load they recommend is 39.6 gr of IMR-4350. 2800fps.

good luck.

Also make sure if you are going for an accurate load, IMHO use a higher quality brass, such as nosler, weatherby, lapua.
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Old December 14, 2010, 10:38 PM   #5
kdog70
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I was told you need a 1 in 8 twist barrel to shoot the 100+grain bullets. I had a 1 in 7.5 cut in 243AI for the 115DTAC/115 Berger bullet. I then got a 1 in 8 twist for my other gun for shooting the 105 Amax, SMK, Berger.

I run 4350 for powder it gets me the best velocity, but Varget and H4831SC work great but just not the velocity I wanted.

The best thing about the Amax you do not have to chase the lands. I have shot them in 243,243AI, 260AI, 7WSM, and 300 win mag with excellent success. If you get the to shoot, buy every box you can get your hands on because they can be hard to get at times.
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Old December 17, 2010, 10:25 PM   #6
castnblast
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That powder is too fast for that bullet which is probably the issue you are having. Try H4831 or H4350, or the IMR versions. Should fix your problem.
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Old December 18, 2010, 01:54 AM   #7
T. O'Heir
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A 1 in 9 twist is fine for 105's.
"...over 40 gr of H4350..." That's 2.5 grains over max for a 105.
"...2.84 and 2.785 oal..." Too long. 2.710" is the max OAL.
Did you work up the load or just pick a few and hope? You must work up the load using data from a manual. Are you shooting off a solid bench rest? Had a trigger job done?
Mind you, A-Max bullets are rumoured not to be as accurate as they should be for a match grade bullet(not made for hunting anything but varmints).
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Old December 19, 2010, 06:01 PM   #8
kdog70
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You can change the Max OAL of a cartridge as long as you are single loading other than that you are held to magazine length. If you have a long throat and chasing the lands then you can go a ways out of the neck/case junction.

Maybe he worked up to over max. All my guns I am at max or over max but I carefully worked up to that point. I chase the higher accuracy node a couple extra FPS makes a difference at 1000-1700 yards.

Although the amax is designated as a target bullet many people have used them for light skinned animals and have had great results. I have taken 10 deer with the amax bullet but they do not hold up well at close range. They do make an excellent predator bullet.

As for accuracy I do not shoot competition but I have had great accuracy out past a mile. Under 1.5 MOA for me at least which is great for me.
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Old December 30, 2010, 07:12 PM   #9
243LR
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In my experience 1 in 9 twist was not enough for the 105gr A-max
1 in 9 will work great with Sierra 100gr Game Kings
My old gun measured at 1 in 9 and the groups suffered when I switched from Game Kings to the 105 A-max. (GKs were MOA or better, 105A-max were 4 MOA)
My solution was to build a new gun, to shoot 105-107s
Just as a point of reference it says 8 twist on the box
Basic calculations will show you where you need to be on twist rate with regard to bullet diameter bullet length and velocity. When I run the numbers, it looks like an 8.5 twist is the minimum rate to stabilize the A-max and the Sierra Match King needs even a bit more. So an 8 twist is most likely where you need to be.
OAL for a 243 is not cut and dried “2.710” unless you are reading it from a reloading book. It has more to do with your chamber and you action… I load 0.005 off the lands and my OAL is 2.760” with no feeding issues. The rest of the recipe Lapua brass, fire formed neck sized only, 40grs IMR 4350 (middle of the road by my book) not the same a H4350
And as far as anyone saying “the A-max is not as accurate as it should be”??? Tell that to all the 6mm BR guys.
IMHO The A-max, in the right gun with the correct twist, is about as good as you can get.
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Old January 4, 2011, 09:23 PM   #10
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Got real nice groups with my 1:10 on Speer 100 gr BTSP's. Powder is the Hodgdon Hybrid V100. Charge was 42.5 gr. .5" group @ 100yds w/ Howa 1500. Killed two hogs w/ 1 shot using that round this weekend.
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Old January 4, 2011, 10:16 PM   #11
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When I worked my .308 168 gr. A-max's up in my weatherby I found that it liked VIHT N-150 at 42.2 gr. best. Which is supposedly 2400fps.(haven't used my chrono to test) I could have pushed it to 2600fps using 46.1 gr. but my shot groups opened up when I went that fast. So you might want to test some different powder loads if you haven't yet. I make 5 rounds of each step up as I go to test my loads with 5 shot groups. I don't trust 3 round groups as much.
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Old June 21, 2012, 01:08 PM   #12
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100 gr Hdy, 1:10 twist

I've tried the 100gr Hdy BTSPs out of a 1:10 twist Xbolt, and they shoot great! At the OAL I tried, light loads running out at about 2700fps with 32.0 gr Varget are very accurate. .25 - .75 MOA, and at 300 yards sub 1" groups are not uncommon. They seem to buck the wind a little better at 300 yrds than the 85 gr Sierra GK HPBT bullets I shoot, which are also very accurate at 3040fps.

I have thought about switching to a slower powder than Varget to see if I can keep the accuracy while increasing velocity on the 100s. Federal 100gr factory loads are very accurate and they go out at about 2900fps, but of course we don't know their formula.

I want to know if anyone has tried a Berger 105VLD in a 1:10 twist barrel.
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Old June 21, 2012, 04:00 PM   #13
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Quote:
I have thought about switching to a slower powder than Varget to see if I can keep the accuracy while increasing velocity on the 100s.
I like Reloder 22 in the .243 for heavy bullets. My current load uses 100 grain Hornady soft points with Reloder 22 for 3100 fps. Very accurate load.



My rifle is a standard Savage 10 with a 1:9.25 twist sporter barrel. It's very prone to vertical stringing if the barrel gets hot, you can watch the shots walk up the paper. Keep the rifle cool and it's a shooter.
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Old June 22, 2012, 02:16 PM   #14
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I gave up on the 105's, I have a 1:10 twist.
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Old June 22, 2012, 07:14 PM   #15
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Some guns just don't like some bullets , and that's a fact ! I have a Model 7 that likes the Speer 105 FB and Win.-760 .
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Old June 27, 2012, 09:53 PM   #16
chucknbach
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Tried lighter bullets in my daughters .243 Ruger compact 1:9 twist. Couldn't get good groups till I switched to the 105 Amax over H4895.
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Old June 28, 2012, 09:26 AM   #17
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Tried lighter bullets in my daughters .243 Ruger compact 1:9 twist. Couldn't get good groups till I switched to the 105 Amax over H4895.


Did you try different powders with those lighter bullets?
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Old June 29, 2012, 10:33 PM   #18
chucknbach
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Quote:
Did you try different powders with those lighter bullets?
Yes. Quite a few.
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Old October 22, 2012, 03:04 PM   #19
kilotanker22
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I had some trouble at first with the amax in 243. Try to measure the throat of the rifle then set your seating depth to about 50 thousandths off of the lands. I have found best results with 38.5 grains of h4350 with fire formed and neck sized cases.

By the way my rifle is a rem 700sps varmint with a 1-9 1/8 twist.
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