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3/20/2017 5:03:23 PM
Posted: 3/17/2009 4:36:48 PM EDT
i am looking to try and 77 grain bullet for my AR with a 1/9 twist, any thoughts for which is best bullet and load ? or pros and cons on this idea.
TY
Link Posted: 3/17/2009 4:44:31 PM EDT
I havent heard of anyone having any luck stabilizing the 77's with a 1 in 9". I have only loaded up to 69's with a 1 in 9" and I load 77's for my 1 in 7". Call Sierra Bullets
Link Posted: 3/17/2009 5:32:57 PM EDT
[Last Edit: 3/17/2009 5:34:16 PM EDT by 308Sako]

Originally Posted By nozzleman671:
I havent heard of anyone having any luck stabilizing the 77's with a 1 in 9". I have only loaded up to 69's with a 1 in 9" and I load 77's for my 1 in 7". Call Sierra Bullets

As you say, you have only loaded up to the 69 grain weight in your rifle, good for you and I hope they shot better than your expectations.

That said: With all due respect PLEASE SPEAK from EXPERIENCE.



The above target was shot with 77 Sierra's and TAC powder... witnessed by 2 AR15.com members, range 405 yards. Rifle, Colt CR6724, 1 in 9 twist 24" barrel 5.56 chamber.


Sierra 77's, Hornady 75 A-Max, Nosler 77 Custom Competitions all stabalize in my Colt 1 in 9 twist rifles. I have posted results with some amazing targets numerous times over the past year. I should add that the witnesses to the above target also shoot 1 in 9 twist RRA, and LaRue rifles with no problem shooting 77 grain Sierra bullets, clear on that?


Link Posted: 3/17/2009 6:03:22 PM EDT
[Last Edit: 3/17/2009 6:07:41 PM EDT by nozzleman671]
I was speaking from experience. As I said Ive never shot 77's from a 1 in 9". The only 1 in 9" I ever owned was a a rifle I got a deal on. Otherwise I stick to 1 in 7"s. It appears they did stabilize in your rifle however Sierra recommends a 1 in 8" or faster. * These bullets require special barrel twist rates: 69 grain #1380: 1x7" to 1x10" twist. 77 grain #9377: 1x7" to 1x8" twist. 80 grain #9390: 1x7" to 1x8" twist. This comes directly from the Sierra manual. Also The technician I frequently talk to does not recommend them in anything slower than 1 in 8". Call Sierra at 1-800-223-8799. Realize every barrel has its likes and dislikes and they can be off on their twist rate by a half inch so you may have a 1 in 9" but it actually may be a 1 in 8.5" or even a 1 in 9.5". Try them and check for key holing on paper.
Link Posted: 3/17/2009 6:10:31 PM EDT
I've shot 77's in my rifles with varying success. My Savage 10FP shoots BH 77gr SMK loads into less than an inch, and has been known to throw a sub 1' group at 200 yards. My 20" 1/9 SPRish clone, on the other hand, doesn't seem to like anything I am feeding it right now (including 55-77gr loads). Of course, that rifle is being fickle, while my Savage seems to shoot anything I load in to it.

As far as the debate on whether 1/9" will stabilize a 77gr bullet, I have yet to see one that wouldn't. Of course, YMMV...
Link Posted: 3/17/2009 7:16:19 PM EDT
I have loaded them in a 1 in 9 rifle and it is not worth the money you waste trying to make it work . Get a 1-7 or chose another bullet .
Link Posted: 3/17/2009 7:39:09 PM EDT
I load 77 gr smk with 24.0 grs of Varget, which is standard fodder for match shooting with my nm service rifle that has a 1-8 twist. Just for kicks I ran a few 77 grain loads through my RRA 20" with a 1-9 twist, and they shot under moa.

Although the 69 gr would be my choice for a 1-9 barrel, some may stabilize a 77 gr bullet, and you will not know until you experiment with it.
Link Posted: 3/17/2009 7:42:33 PM EDT
[Last Edit: 3/17/2009 7:45:25 PM EDT by 308Sako]
delete

Link Posted: 3/17/2009 7:45:53 PM EDT
[Last Edit: 3/17/2009 7:46:28 PM EDT by innocent_bystander]
75 grain Hornady BTHPs shoot into 4-5 inch five shot groups at 100 yards in my 16 inch 1x9 barrels.

Same loads are sub 1 inch out of my 1x8 and 1x7 barrels.
Link Posted: 3/17/2009 7:51:11 PM EDT
Link Posted: 3/18/2009 4:32:36 AM EDT
Someone correct me if I'm wrong, as I'm no *expert*.
I believe Sierra's 77gr has quite a short "ogive" for the weight of the bullet.
This is likely a beneficial factor when shooting them out of a 1:9 twist barrel – it should help to stabilize it in SOME barrels.

Just what I’ve heard from several people…
Comments, anyone?
Link Posted: 3/18/2009 5:48:50 AM EDT
Originally Posted By liaisons:
Someone correct me if I'm wrong, as I'm no *expert*.
I believe Sierra's 77gr has quite a short "ogive" for the weight of the bullet.
This is likely a beneficial factor when shooting them out of a 1:9 twist barrel – it should help to stabilize it in SOME barrels.

Just what I’ve heard from several people…
Comments, anyone?


Yes the ogive on the smk 77is a tangent ogive and is the same as the 69 gr, so the extra length and weight is in the shank, or bearing surface of the 77. The 80 gr smk has a secant ogive and for weighing only 3 more grains, the ogive is cosiderabley longer which gives a better bc, but requires more spin to stabilize.
Link Posted: 3/18/2009 6:19:25 AM EDT
Originally Posted By 308Sako:

Originally Posted By nozzleman671:
I havent heard of anyone having any luck stabilizing the 77's with a 1 in 9". I have only loaded up to 69's with a 1 in 9" and I load 77's for my 1 in 7". Call Sierra Bullets

As you say, you have only loaded up to the 69 grain weight in your rifle, good for you and I hope they shot better than your expectations.

That said: With all due respect PLEASE SPEAK from EXPERIENCE.

With all due respect, he DID speak from experience. In his experience, which included exchanging information with other people, he hadn't heard of anyone being able to properly stabilize 77 gr. rounds from a 1:9 barrel. He didn't claim it couldn't be done. Just that he wasn't aware of anyone being able to do so.
Link Posted: 3/18/2009 7:17:48 AM EDT
If they are only used at high elevation, on hot, humid days, they MIGHT be stabilized in a 1:9" This makes for a thin atmosphere, reducing the drag which sets the need for gyroscopic stability a bit lower.

The 69s are the largest bullet that can be stabilized in a 1:9" on every range at any condition.
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