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Posted: 6/18/2007 4:17:44 AM EDT
Hello, before anyone replies I want to tell you that I KNOW this is theoretically too heavy for a 1:9 twist barrel, but I have heard that it will work from multiple people. So I was wondering if any of you have actually tried it, and if so, what have the results been. I am looking for first hand info really, not so much theoretical or anecdotal evidence.

Also, what effect do you think molly coatings would have on this combo? I have the feeling that it would cause the bullets to twist even slower, and stabilize less. Thoughts?
Link Posted: 6/18/2007 4:41:37 AM EDT

Originally Posted By Reckoning9-11:
Hello, before anyone replies I want to tell you that I KNOW this is theoretically too heavy for a 1:9 twist barrel, but I have heard that it will work from multiple people. So I was wondering if any of you have actually tried it, and if so, what have the results been. I am looking for first hand info really, not so much theoretical or anecdotal evidence.

Also, what effect do you think molly coatings would have on this combo? I have the feeling that it would cause the bullets to twist even slower, and stabilize less. Thoughts?


go to bushmaster's website and read their review.
Link Posted: 6/18/2007 6:22:25 AM EDT
I have already seen it, it really dosen't say anything about accuracy, just velocity and penetration. I wanted to know if any of you here on AR-15 have actually tried it.
Link Posted: 6/18/2007 6:22:54 AM EDT

Originally Posted By Reckoning9-11:
Hello, before anyone replies I want to tell you that I KNOW this is theoretically too heavy for a 1:9 twist barrel, but I have heard that it will work from multiple people. So I was wondering if any of you have actually tried it, and if so, what have the results been. I am looking for first hand info really, not so much theoretical or anecdotal evidence.

Also, what effect do you think molly coatings would have on this combo? I have the feeling that it would cause the bullets to twist even slower, and stabilize less. Thoughts?


You're not too far off your accuracy sweet spot of 69grns for a 1:9 twist. Will 75 grns shoot....work ?? Yes though, at least theoretically, your accuracy will not be maximized.

I don't believe moly coating would have much affect.

T

Technical evidence has been presented as well as opinion.
Link Posted: 6/18/2007 6:37:33 AM EDT
Link Posted: 6/18/2007 7:18:25 AM EDT
[Last Edit: 6/18/2007 7:39:19 AM EDT by Reckoning9-11]
Nice, but what length barrel was the 1:7? If it was a 20 inch, that could explain the accuracy difference.
Link Posted: 6/18/2007 7:30:37 AM EDT
Someone needs to come up with a 72 Grain BTHP round...
Link Posted: 6/18/2007 10:54:59 AM EDT
[Last Edit: 6/18/2007 10:57:17 AM EDT by DevL]

Originally Posted By Reckoning9-11:
Nice, but what length barrel was the 1:7? If it was a 20 inch, that could explain the accuracy difference.
How so? Longer barrels are not more accurate they are less accurate all things being equal.
Link Posted: 6/18/2007 10:55:37 AM EDT

Originally Posted By Reckoning9-11:
Someone needs to come up with a 72 Grain BTHP round...


Why the 75 works just fine? You seem to be full of misconceptions today.
Link Posted: 6/18/2007 10:59:02 AM EDT

Originally Posted By Reckoning9-11:
Hello, before anyone replies I want to tell you that I KNOW this is theoretically too heavy for a 1:9 twist barrel, but I have heard that it will work from multiple people. So I was wondering if any of you have actually tried it, and if so, what have the results been. I am looking for first hand info really, not so much theoretical or anecdotal evidence.

Also, what effect do you think molly coatings would have on this combo? I have the feeling that it would cause the bullets to twist even slower, and stabilize less. Thoughts?


The only way moly would cause the bullets to twist slower woul dbe if you moly coated a bullet and did not compensate for the reduced velocity by adding more powder. Surely you do not think the moly has any effect on the bullet engaging the rifling do you?
Link Posted: 6/18/2007 11:05:28 AM EDT
height=8
Originally Posted By DevL:
height=8
Originally Posted By Reckoning9-11:
Hello, before anyone replies I want to tell you that I KNOW this is theoretically too heavy for a 1:9 twist barrel, but I have heard that it will work from multiple people. So I was wondering if any of you have actually tried it, and if so, what have the results been. I am looking for first hand info really, not so much theoretical or anecdotal evidence.

Also, what effect do you think molly coatings would have on this combo? I have the feeling that it would cause the bullets to twist even slower, and stabilize less. Thoughts?


The only way moly would cause the bullets to twist slower woul dbe if you moly coated a bullet and did not compensate for the reduced velocity by adding more powder. Surely you do not think the moly has any effect on the bullet engaging the rifling do you?


No I just thought that the decreased pressure and velocity would decrease the RPM.

Also Molon sates in his test, "As before, 30-round composite targets were compiled to compare the mean radii. The mean radius from the 1:9” twist barrel measured 0.54” while the mean radius from the 1:7” twist barrel measured 0.46”. Again we see an increase in group size for the rounds fired from the 1:9” twist barrel. (Keep in mind that the control group from the 1:9” twist barrel was right on par with the control groups from the 1:7” twist barrel.)"

So the 1:9 might be fine, but its not as good as 1:7 for 75gr. I thought 72gain would be better stabalized in 1:9.

And since when are shorter barrels more accurate?
Link Posted: 6/18/2007 11:18:16 AM EDT
Link Posted: 6/18/2007 11:29:23 AM EDT
I have no problem with the 75s in my RRA 16in 1-9 twist bbl. In fact it works quite well.
Also, Hornady specifically makes and advertises that the 75s work well in 1-9 twist bbls.
Each bbl is different.
Link Posted: 6/18/2007 11:36:02 AM EDT

Originally Posted By Reckoning9-11:
[

And since when are shorter barrels more accurate?


The only accuracy advantage (usually) of a longer barrel is longer sight radius. A longer barrel does not equal better accuracy. Many weapons, of all types, with shorter barrels are quite capable of great accuracy. Velocity, on the other hand, is another issue.

Sarge
Link Posted: 6/19/2007 6:25:11 AM EDT
I just found out that berger makes a 73gr. that is perfect for 1:9 twist. I think I am just going to use that and add my own cannelure.
Link Posted: 6/19/2007 6:43:31 AM EDT
Link Posted: 6/19/2007 7:02:42 AM EDT
Link Posted: 6/19/2007 7:04:38 AM EDT
Link Posted: 6/19/2007 7:31:48 AM EDT

Originally Posted By Reckoning9-11:
And since when are shorter barrels more accurate?


Given equal quality, shorter barrels have always been more accurate. Longer barrels only give more velocity.

A shorter barrel will be stiffer than a longer barrel of the same diameter, which means less barrel whip when the shot is fired. This results in better accuracy and consistency from shot-to-shot.
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