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Posted: 9/12/2010 7:20:49 AM EDT
Can the 77 grain sierra BTHP be shot through the 1/9 twist barrel of my AR15? I'm looking at it for a deer round.
Link Posted: 9/12/2010 7:25:26 AM EDT
Shoots good to 300 yards in my 20" AR Standard 1 in 9. I would look at the 55gr or the 65gr Sierra Game King for Deer.
Link Posted: 9/12/2010 7:33:30 AM EDT
Wouldn't a longer barrel in a lower twist work the same as a short barrel with a tight twist? Or does the bullet spin 1:1 with the barrel?

I would say that with a longer barrel, you should be okay, but in the 16-20" range, you probably want to have a 1:7 or 1:8 to shoot heavy rounds accurately.
Link Posted: 9/12/2010 8:02:11 AM EDT
ah I forgot to mention my ar is a 16'
Link Posted: 9/12/2010 8:03:39 AM EDT
Originally Posted By M60forever:
ah I forgot to mention my ar is a 16'


I would say stick to 65gr's as being your largest round in that case. Your gun doesn't have the physics to really make use of a 77gr.
Link Posted: 9/12/2010 8:07:31 AM EDT
Not to hijack, but can the 77grn be loaded to mag length?
Link Posted: 9/12/2010 8:10:39 AM EDT
Originally Posted By Claybrook:
Not to hijack, but can the 77grn be loaded to mag length?


Yes, you can seat it to 2.260". It's the 80gr that is too long.
Link Posted: 9/12/2010 8:10:47 AM EDT
[Last Edit: 9/12/2010 8:10:59 AM EDT by Boosted98gsx]
Originally Posted By Claybrook:
Not to hijack, but can the 77grn be loaded to mag length?


Yes, it's the heaviest round capable of being seated to 2.26" OAL.
Link Posted: 9/12/2010 8:17:17 AM EDT
Originally Posted By Boosted98gsx:
Originally Posted By M60forever:
ah I forgot to mention my ar is a 16'


I would say stick to 65gr's as being your largest round in that case. Your gun doesn't have the physics to really make use of a 77gr.


The 1/9 is pretty much for the 65gr's. Correct?
Link Posted: 9/12/2010 8:34:28 AM EDT
Originally Posted By M60forever:
Originally Posted By Boosted98gsx:
Originally Posted By M60forever:
ah I forgot to mention my ar is a 16'


I would say stick to 65gr's as being your largest round in that case. Your gun doesn't have the physics to really make use of a 77gr.


The 1/9 is pretty much for the 65gr's. Correct?


I believe so.

They even make a 1:6 twist for 90 gr rounds (yes, sierra makes a 90 gr round for .223).
Link Posted: 9/12/2010 8:48:47 AM EDT
Originally Posted By Boosted98gsx:
Originally Posted By M60forever:
Originally Posted By Boosted98gsx:
Originally Posted By M60forever:
ah I forgot to mention my ar is a 16'


I would say stick to 65gr's as being your largest round in that case. Your gun doesn't have the physics to really make use of a 77gr.


The 1/9 is pretty much for the 65gr's. Correct?


I believe so.

They even make a 1:6 twist for 90 gr rounds (yes, sierra makes a 90 gr round for .223).


Damn.
Link Posted: 9/12/2010 9:00:52 AM EDT
What you need is the 62gr Barnes TSX if you want something that will stabalize in a 1:9 twist and kill deer, Hog's, and anything else you plan to shoot.

I have them in 53gr, 55gr, 62gr, & 70gr TSX for the .223 and the 70 is my favorite but I have a 1:8 twist which is just enough for the long 70gr TSX, the 62gr is just as awesome but can be loaded to mag length(as can the 70) and shot from a 1:9 twist.

The 22-250 shooters usually have a 1:12 or slower twist so they use the 55 & 53gr TSX and they kill deer with the light 53gr all the time plus anything but very large game included.
Link Posted: 9/12/2010 9:04:23 AM EDT
Originally Posted By M60forever:
Originally Posted By Boosted98gsx:

I believe so.

They even make a 1:6 twist for 90 gr rounds (yes, sierra makes a 90 gr round for .223).


Damn.


https://www.sierrabullets.com/index.cfm?section=store&page=item&stock_num=9290
Link Posted: 9/12/2010 10:02:10 AM EDT
While I agree with Boosted that a 1/9 barrel probably wouldn't stabilize a 77gr bullet (which can be loaded to magazine length), it has nothing to with barrel length. Either a barrel with stabilize a bullet or it won't. That is twist vs bullet weight/construction. It has nothing to with shorter barrel vs twist etc.
You could try, load 100 and see but I would say that it probably won't work.
Link Posted: 9/12/2010 10:23:43 AM EDT
Other factors are involved. I have a 1/9 twist Winchester HB Varmint rifle with a 26" barrel. It will stabilize 75/77 grain bullets, at least out to 200 yards. I tried to measure the twist rate with a cleaning rod and find that it's actually closer to 1/8.75". So that helps too.

Shorter barrels need more twist than a longer barrel needs, but this only applies when you are pushing the extremes. My 26" barrel combined with the slightly faster than 1/9 twist combine to make that rifle work. A lot of rifle's won't.

The only way you are going to discover the truth about your rifle is to try some 77's. It's probably a 50/50 chance that it will just make the cut. You will be on the borderline any way you look at it. It may work fine in hot weather and fail below 40 degrees. Many people have discovered that their rifle will shoot them, just as many find out otherwise. There is no way to know in advance.

We tried to shoot 69 grain SMK's from a friends 24" Browning A-Bolt and and could barely keep the rounds on the 4'x4' backer at 100 yards. Every one of the rounds impacted sideways. Know this in advance, you are responsible for where the fired rounds finally end up. He didn't know what his twist rate was, I imagine 1/12, maybe even 1/14.

Good luck.
Link Posted: 9/12/2010 10:33:00 AM EDT
Sierra will tell you, as they have told me. They have concerns with their 69 grain SMK HPBT stabilizing in a 16" 1in9 twist barrel. They don't say it can't be done. Sierra, 660-827-6300.
Link Posted: 9/12/2010 10:47:23 AM EDT
The .223 heavies 75, 77, etc. will work in mag length OAL, only for the OTMs with truncated meplat. The plastic tipped heavies above about 70 gn like the AMAXs will not work well with mag. length OAL config.
Link Posted: 9/12/2010 11:20:33 AM EDT
i have i 1/9 upper that shoots 77 smk well and 1 that wont. of all my ars my 1/8 wilson stainless upper groups the best with them. It will just depend on your barrel some 1/9 barrels lean more toward 1/10 others toward 1/8 some straight up 1/9 it all depends on the manufacturers quality control is like.
Link Posted: 9/12/2010 11:41:10 AM EDT
The short answer is: your 1/9 barrel may work fine with 69 or even 77 gr. bullets. Or it may not.

Whether or not a bullet will stabilize is not simply a matter of twist vs. weight. Many factors come into play, but the short of it is bullet length vs. bullet RPMs. A bullet of a given length and weight must have a minimum number of RPMs to be stable.

If you have a bullet that is stable in a 1 in 9 twist 24" barrel at say 2700 fps, it will be spinning at 216,000 rpms. If you shoot that same bullet out of a 16" barrel, the muzzle velocity will drop to the neighborhood of 2550 fps, and down to 204,000 rpms. The bullet will slow as it travels. As the velocity and RPMs are reduced, at some point the bullet will become unstable.

For a bullet to be stable, the bullet length is more critical than the simple weight. A long bullet with a high BC requires more spin than a short, fat bullet. And it's not the barrel length so much as it is the bullet velocity / RPMs. Higher velocity gives a higher spin rate than a low velocity from the same twist.

Bottom line: my nephew's 1/9 16" DPMS shoots 77s fine out to 300 yards. Beyond that, we can't keep them on paper. The only way that you will know if your rifle will work with 69s or 77s is to try them.

For deer, my recommendation is toward the heavier end of the spectrum. Use as heavy a bullet as your rifle will stabilize, something like the Swift 75 gr. or the Barnes 70 gr. TSX. IF your rifle will stabilize them.

Good luck.


Link Posted: 9/12/2010 5:53:12 PM EDT
Stick with the 65gr Gamekings as the Matchkings do not make for goof hunting bullets.
Link Posted: 9/12/2010 7:23:00 PM EDT
Link Posted: 9/12/2010 7:26:18 PM EDT

Originally Posted By dryflash3:
My 16" 1 in 9 shoots the 69 gr Sierra very well.

Tried a few Hornady 75 gr OTM's, no tumbling at 100 yds.

You just have to load some and see.

Mine too...it shoots 75gr just as good as 69gr.

You'll have to try some to see if yours will do it, but 69gr shouldn't be a problem at all.
Link Posted: 9/12/2010 7:28:50 PM EDT
[Last Edit: 9/12/2010 7:31:59 PM EDT by AeroE]
Link Posted: 9/12/2010 7:30:16 PM EDT
Link Posted: 9/12/2010 7:44:38 PM EDT
[Last Edit: 9/12/2010 7:58:58 PM EDT by TGH456E]
Ok, i'll ask and hijack this thread from the OP.
I agree on several things that have been brought up in this thread- 77's may or not work- TRY IT, at end of it's flight the muzzle velocity (and retained velocity) come into play as far as stabilizing the bullet and since we are getting into specifics here and not a general answer to the OP, that the bullets BC plays into all this.
But my question is this, if I understand some of the responses, how does the barrel length have anything to do with stabilizing or not a given bullet, instead simply put either the twist is sufficient to stabilize a given bullet or it isn't?
A Colt 1911 45 ACP has a 5" or less barrel and a twist of 1/16" (looking in my Sierra reloader guide) and it stabilizes up to 230gr bullets. The 80gr SMK I shoot thru my AR are stable because I have a 1/7.7 barrel, and still are at 600yds, despite losing all that velocity. ANY projectile will eventually lose it's energy, become unstable (though I would include going subsonic here-with rifle cartridges) and then fall to the ground. What keeps it stable during it's useful flight time is the barrel twist providing it the stability by imparting the spin needed to do that. That is why a particular twist will stabilize a range of bullet weights and likewise no AR manufacturer that I know of uses a faster twist if they shorten the length of the barrel. You get, for example, a 1/7 twist or whatever in a 20"or 16" or 14" barrel and not say a 1/6" in a 14" barrel. I agree that shortening the barrel will reduce the muzzle velocity and then the range at which the bullet is accurate but that isn't the same thing as saying it won't be stable during it's flight, prior to losing it's energy.

To the OP: Try it and see. Let us know.
Link Posted: 9/12/2010 7:58:09 PM EDT

Originally Posted By 1911smith:
Sierra will tell you, as they have told me. They have concerns with their 69 grain SMK HPBT stabilizing in a 16" 1in9 twist barrel. They don't say it can't be done. Sierra, 660-827-6300.

I agree with them. I used to have a Bushmaster Patrolman's Carbine with a 1/9 barrel & it didn't like the 69gr SMKs at all.
Link Posted: 9/12/2010 9:00:18 PM EDT
I have 3 AR's with a 1-9 twist.

2 of them will shoot the 77gn

1 will keyhole.

I am only going off the stamp on the BBL.



Pick up a box of pills and load them to find out. One way to be sure
Link Posted: 9/12/2010 9:03:20 PM EDT
The 75 grn TAP bullet is a better round for deer. One of my 1-9s will stabalize, 1 will not.
Link Posted: 9/12/2010 9:45:56 PM EDT
Originally Posted By Gone_Shootin:

Originally Posted By 1911smith:
Sierra will tell you, as they have told me. They have concerns with their 69 grain SMK HPBT stabilizing in a 16" 1in9 twist barrel. They don't say it can't be done. Sierra, 660-827-6300.

I agree with them. I used to have a Bushmaster Patrolman's Carbine with a 1/9 barrel & it didn't like the 69gr SMKs at all.


Sierra prefers that bullet if shot with AR to be 1in7

Link Posted: 9/13/2010 7:56:42 AM EDT
I think the problem here is you are violating Sierra's basic premise - don't use MatchKings for hunting. They are very clear on this topic, it is all over their reloading manual. Use a different bullet, a hunting bullet, for hunting.

Just for reference, because everyone else is discussing stabilization, I had a 1/12 barrel that would stabilize everything up to and including the Hornady 75 gr HPBT-M bullet. It could not stabilize the 80 SMK.
Link Posted: 9/13/2010 9:17:23 AM EDT
Originally Posted By Mike_Mills:
I think the problem here is you are violating Sierra's basic premise - don't use MatchKings for hunting. They are very clear on this topic, it is all over their reloading manual. Use a different bullet, a hunting bullet, for hunting.

Just for reference, because everyone else is discussing stabilization, I had a 1/12 barrel that would stabilize everything up to and including the Hornady 75 gr HPBT-M bullet. It could not stabilize the 80 SMK.


Has anyone tested what matchkings do to ballistics gelatin?
Link Posted: 9/13/2010 9:46:04 AM EDT
Link Posted: 9/13/2010 11:12:58 AM EDT
I just talked to ER SHAW b/c that is the type of barrel I have.

He said:

The 1 in 9 twist in the AR15/M16 bbl was designed for a 62 grain to 69 grain bullet.
Link Posted: 9/13/2010 12:26:30 PM EDT
Link Posted: 9/13/2010 12:46:21 PM EDT
Originally Posted By M60forever:
I just talked to ER SHAW b/c that is the type of barrel I have.

He said:

The 1 in 9 twist in the AR15/M16 bbl was designed for a 62 grain to 69 grain bullet.


Who did you talk to ?? 62, yes. 69, no. Not a 16" AR barrel, maybe a 20".

Anywho. I have no dog in this fight. If you need a heavy bullet, then use a heavier gun. If its deer hunting your wanting it for. Best of luck. I keep my hunt restricted to my butcher's meat case. Black Angus tastes a lot better than deer on any day when served on my plate.

Link Posted: 9/13/2010 1:26:57 PM EDT
Link Posted: 9/13/2010 2:51:21 PM EDT
M60Forever:
Well, the easiest thing to do would be follow the manufacturers advice and pick a hunting bullet in that range then.
If you want try them- but it may or may not work. Good luck!


Eric802:
+1 to what you said (experienced)! I don't understand this idea that some are putting out that the length of the barrel has something to do with it stabilizing the bullet??
As I posted earlier, why then is a 1911 pistol with no more than a 5" barrel and a 1/16" twist able to do it?
Link Posted: 9/13/2010 3:48:22 PM EDT
Originally Posted By Eric802:
They do just fine in gel, but that's not the point. It's a fragmenting round, so unless you like picking copper and lead out of your venison, it's better to go with an actual hunting bullet like a Winchester PowerPoint or the Barnes TSX. The SMK will likely kill a deer dead, but it's really not the right tool for the job, and the 64gr PowerPoint or the 62gr TSX will almost certainly stabilize in a 1/9 twist.


It affects a very small portion of meat its not like lead flies off in all directions, any lead bullet will leave bits in your deer.
Link Posted: 9/13/2010 3:50:00 PM EDT
Originally Posted By 1911smith:
Originally Posted By M60forever:
I just talked to ER SHAW b/c that is the type of barrel I have.

He said:

The 1 in 9 twist in the AR15/M16 bbl was designed for a 62 grain to 69 grain bullet.


Who did you talk to ?? 62, yes. 69, no. Not a 16" AR barrel, maybe a 20".

Anywho. I have no dog in this fight. If you need a heavy bullet, then use a heavier gun. If its deer hunting your wanting it for. Best of luck. I keep my hunt restricted to my butcher's meat case. Black Angus tastes a lot better than deer on any day when served on my plate.



bullet twist is determined in the first inch or two of the barrel, the longer barrel wont make it stabalize if the shorter one didnt. I shoot 69 grn SMKS fine in both of my 1-9 ARs a 16" and a 20"
Link Posted: 9/13/2010 6:04:58 PM EDT
Originally Posted By MTNmyMag:
bullet twist is determined in the first inch or two of the barrel, the longer barrel wont make it stabalize if the shorter one didnt. I shoot 69 grn SMKS fine in both of my 1-9 ARs a 16" and a 20"

Not directly anyway. But a longer barrel should end up with a higher velocity which means higher RPMs which may barely stabilize a bullet that a shorter barrel can't shoot.
Link Posted: 9/13/2010 7:03:56 PM EDT
Link Posted: 9/13/2010 7:22:13 PM EDT
You will also get a sermon from the ballisticians at Hornady over using AMAXs for hunting instead of their SSTs or Interbonds. Hey, they look the same on the outside. Who was to know?
Link Posted: 9/13/2010 7:29:57 PM EDT
Tripletdad:
I agree that a longer barrel may end up with higher velocity but either the twist will stabilize a given bullet or it won't. All that increased velocity does is increase, in effect, the distance that that bullet remains stable. But if that bullet isn't stable coming out of the barrel, no amount of increased velocity will stabilize it.
Link Posted: 9/13/2010 8:22:35 PM EDT
[Last Edit: 9/13/2010 8:23:07 PM EDT by glorifiedG]
Right idea (heavier) ...wrong bullet
Don't buy an F-150 to tow your 5th wheel
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