75 grain Hornady from 1:9 twist 16"

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[ARCHIVED THREAD] - 75 grain Hornady from 1:9 twist 16"

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?

Posted: 6/18/2007 4:41:37 AM EDT

[#1]

Quoted:
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.

Posted: 6/18/2007 6:22:25 AM EDT

[#2]

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.

Posted: 6/18/2007 6:22:54 AM EDT

[#3]

Quoted:
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.

Posted: 6/18/2007 6:37:33 AM EDT

[#4]

Accuracy Testing of Hornady 75 grain loads from a 16" barrel with a 1:9" twist.

Posted: 6/18/2007 7:18:25 AM EDT

[#5]

Nice, but what length barrel was the 1:7? If it was a 20 inch, that could explain the accuracy difference.

Posted: 6/18/2007 7:30:37 AM EDT

[#6]

Someone needs to come up with a 72 Grain BTHP round...

Posted: 6/18/2007 10:54:59 AM EDT

[#7]

Quoted:
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.

Posted: 6/18/2007 10:55:37 AM EDT

[#8]

Quoted:
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.

Posted: 6/18/2007 10:59:02 AM EDT

[#9]

Quoted:
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?

Posted: 6/18/2007 11:05:28 AM EDT

[#10]

height=8

Quoted:
height=8

Quoted:
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?

Posted: 6/18/2007 11:18:16 AM EDT

[#11]

Quoted:
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?

CLE 16" 1/9 HBAR middie gas system does not throw 75 Gr TAP for shit. Was keyholing them at 50 yards, and was shooting about 8" group at 25 yards. SHooting 55 gr Redbox BH with a 4-12 burris on top of it, the owner has put 5 round clover leafs out there repeatedly, so it is not that the gun is inaccurate.

Posted: 6/18/2007 11:29:23 AM EDT

[#12]

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.

Posted: 6/18/2007 11:36:02 AM EDT

[#13]

Quoted:
[

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

Posted: 6/19/2007 6:25:11 AM EDT

[#14]

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.

Posted: 6/19/2007 6:43:31 AM EDT

[#15]

Quoted:
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.

Yup, kind of funny we have been building firearms for over 4 centuries now and there is still a little bit of the alchemical uncertainty about what will work for your personal weapon. Which is why you might end up like me with several half boxes of ammo sitting around with notes about which gun it shoots well in and what guns it does not shoot well in.

Posted: 6/19/2007 7:02:42 AM EDT

[#16]

Quoted:
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.

4 out 4 of my 16" (and shorter) 1:9 twist barrels would shoot it acceptabley. One of my 14.5" barrels required a good copper removal scrubbing to shoot it (once clean it shot fine). Best group was 1.75" @100y, with the worst group of the 4 being at 4". The other 2 were around 2" groups.

BTW I ran a poll on this a couple of years ago in the Rifle section. Results were that over half the 1:9 twist barrels would produce 'acceptable' results with 75gr for their owners. Acceptable beind defined by each owner.

Posted: 6/19/2007 7:04:38 AM EDT

[#17]

Quoted:
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.

Get a Lee Factory Crimp Die - cannalure not required.

Posted: 6/19/2007 7:31:48 AM EDT

[#18]

Quoted:
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.

[ARCHIVED THREAD] - 75 grain Hornady from 1:9 twist 16"

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