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Longrange PD cartridge - Part II

 
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  #1  
Old 11-06-2003, 07:54 AM
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Longrange PD cartridge - Part II

Many of you have suggested that the 243 or 243AI with the 107gr SMK bullet would be the ideal longrange PD cartridge. My suggestion of the 22-243AI with a JLK 80gr did not seem to curry much support.

Here's my question:

Both the .224 80gr JLK and the .243 107gr Sierra bullets have very similar BC's, aprox .510 - .520. If the 22-243 can fire a high BC bullet @ 3,600 ft/sec and the 243(AI) can fire a bullet of similar BC @ aprox 3,000 ft/sec; how can the .234(AI) be a better longrange combination? The 22-243AI should shoot significantly flatter AND resist wind much better (similar BC and shorter flight time) than the 243(AI). The 22-243AI would also produce less recoil. As far as accuracy goes, I'm assuming that both cartridges are fired in quality rifles with the same potential for accuracy.

Am I missing something here?

VH
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  #2  
Old 11-06-2003, 08:22 AM
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Re: Longrange PD cartridge - Part II

sierra says .420 for the 80gn and .527 for the 107. [img]images/icons/confused.gif[/img]

also more weight=harder to move (80 v 107)
increased bore life
increased energy at longer range

those would be my reasons for the 243 ack.--also your gonna get more than 3000fps with a varmint length barrel in the 243 ack.

FWIW,
JB
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  #3  
Old 11-06-2003, 08:55 AM
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Re: Longrange PD cartridge - Part II

VH

The 6mm 107 gr MK has a .555 BC while the 105 JLK is higher then that.
The 80 gr barely breaks out of the .4 BC range and that is the difference in downrange flight.
Even "if" the 80 gr had a .500 BC it would not be a better choice then the 6mm for wind busting characteristics since it (6mm) has a .555 and higher BC rating.

Again, if the 80gr 224 bullet was so good, you would see it being used in 1000 yard matches, which you don't.
It's 6mm, 6.5 and 30 cals doing most of the winning with the 30s and 6.5 doing the best at some ranges and the 6mm and 30 cals at others.
I'm using the Williamsport and Montana ranges here for the cartridges/bullets used the most and also the records that have been broken.

I to have a 22/284 to make a good comparison and no way will the 80 gr 224 bullet do as well as the 105 or 107 gr 6mm bullet using the same length barrels and the same case size such as a 6/284 or the 243 case size.

The 80 gr bullet sheds it's velocity very quickly even though it starts out faster. This is because of the higher BC of the 107 and 105 gr 6mm Bullets.
Clearly a better choice for a longrange P-dog round out to 1000 yards or a bit further.

As the bullets diameter and weight increase the BC goes up in every instance as long as the bullets were designed as match type bullets to begin with. Even within the same diameter bullet, the higher weight is normally a higher BC if they are match bullets. A real good example of that is a 168 gr MK 30 cal compared to a 200 gr MK 30 cal.
A 224 BC is higher then a .17 Cal. a 6mm is higher then the .224, the 6.5 is higher then the 6mm, the 7mm is higher then the 6.5 and so on.
This is true in most every bullet made.

The true test of any bullet is actual fire and I have done it.
There will be less drop to get from point A to point B (1000 and 1100 yards) using the 6mm 105 and 107 gr bullets then my 80 gr 22/284 which does come out of the end of my barrel faster to start with then the 6mm.

For that original poster concerning this topic, lets look at throat erosion to. Running an 80 gr bullet in a smaller diameter barrel at 3500 to 3600FPS will create much more wear then the 243 or 6/284 will using a higher BC bullet and going a bit slower.

I like my barrels to last a bit longer.

Later
DC
As an add on here---The 6/284 is moving that 105 and 107 gr MUCH faster then 3000 FPS.
The 243 in a good 8 twist 30" long barrel is also.
Comparing energy levels--Hands down, goes in favor of the 105 or 107 gr 6mm bullets.

[ 11-06-2003: Message edited by: Darryl Cassel ]
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  #4  
Old 11-06-2003, 11:25 AM
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Re: Longrange PD cartridge - Part II

My Sierra manual lists the .243, 107gr MK @ a BC of .526. The JLK 80gr .224 was listed at .510. That is a fairly small difference in BC, especially when the launch speed of the .224 bullet is 500+ ft/sec faster.

Yes, the Sierra 80gr has a relatively low BC, which is why I do not prefer it when varminting at long range.

Another question:

If a .224 bullet and a .243 bullet had the same BC and were fired at the same MV, wouldn't they both have the same bullet drop and wind resistance?

I am not in disagreement with the results that you have seen on paper, but am having a hard time in understanding why this would be. I think I'll take another look at the ballistic calculator.

VH
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  #5  
Old 11-06-2003, 11:39 AM
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Re: Longrange PD cartridge - Part II

Just got done with the ballistic calculator and here is what I got when comparing the two. I also increased the speed of the 107 Sierra to 3,100 ft/sec.

Both were calculated with a 100yd zero.

22-243AI 80gr @ 3,600 drop @ 1,000yd -189.3"
10mph wind + 61.4"

243AI 107gr @ 3,100 drop @ 1,000yd - 263.5"
10mph wind +73.4"

It sure seems like the 22-243AI has the 243AI beat in this comparison. Opinions [img]images/icons/rolleyes.gif[/img]

VH

[ 11-06-2003: Message edited by: Varmint Hunter ]
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  #6  
Old 11-06-2003, 04:54 PM
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Re: Longrange PD cartridge - Part II

VH,
My cousin and I have expermented with the 22/284 we were having problems with the 80 JLK and the 80 SMK at 3500-3800fps+ they were exploding 20 yards right out the barrel. We also shot this gun at several 1000 yard matches our best groop was a 9 inch 5 shot groop at the Ohio club. If there was any wind at all the bullet would blow two targets down. we had a very hard time competing and even keeping it on paper.
Also at the high velocity we only shot 500 rounds through the barrel before it was shot out. Needless to say we rebarreled it to a 6.5/284 and have been very successful.
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  #7  
Old 11-06-2003, 06:21 PM
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Re: Longrange PD cartridge - Part II

I didn't think it was possible to disintegrate a Sierra 80gr SMK with its heavy jacket. There must have been something awful going on in that barrel.

Many shooters have experienced this problem with the 75gr A-Max bullet and fast twist barrels, but the Sierra and JLK bullets normally hold up pretty well.

My favorite long range varmint load shoots the 75gr A-Max @ 3,668 ft/sec. I have never had a single bullet fail to get to its target intact. I attribute this to a smooooth Hart barrel, moly coated bullets and ammo that is loaded about .006" into the rifling. The 75gr A-Max is a devastating bullet on Pa groundhogs.

It is interesting to hear that you guys have had problems with these bullets in the wind. The ballistic programs would indicate otherwise. I have never had the opportunity to shoot this cartridge @ 1,000 yds (except in the field) so will rely on your input.

For the record, I also shoot varmints with a custom rig in 6mmAI but have really become fond of the 22-243AI. It has produced many of my longest kills.

VH
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