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Posted: 3/28/2017 4:17:10 PM EDT
[#1]
Generally 55gr will shoot just fine, beyond that you would need to test your bbl as each one will "like" different ammo.
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Posted: 3/28/2017 4:18:19 PM EDT
[#2]
It isn't about bullet weight as much as it is bullet length. A longer bullet typically requires a more frequent barrel twist. Notionally speaking, a "short" 69 grain bullet would be able to stabilize in a 1:9" or maybe even 1:12" twist barrel.
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Posted: 3/28/2017 6:10:11 PM EDT
[#3]
IMHO twist rate is the most
 thing with modern AR's
If your 1:7, 1:8, 1:9 twist barrels will not shoot 55-69 grain ammo well, you have a shitty barrel and twist rate has nothing to do with it. |
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Posted: 3/28/2017 6:36:53 PM EDT
[#4]
69 gr. Sierra's shot well in my previous 1:9 barrel. Now that all my 5.56mm AR15's are 1:7, I have tons of 50 to 55 gr. bullets that i may or may not try to reload for the newer rifles. I can always use them for my .220 swift. I also have a ton of 62 - 75 gr. bullets that will work fine, but I wanted to use 69 gr. + bullets for High Power Rifle matches, not for general target practice varmints or plinking.
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Posted: 3/28/2017 6:59:01 PM EDT
[#5]
I've tried 50gr, 55gr, 62gr, 69gr, 75gr, and 77gr, all performed fine in my 1:7 barreled AR's
In my SR15 Mod1, LW CL CHF barrel: American Eagle 50gr Varmint Tipped 223 ammo is 1MOA-1.25MOA at 100 yards, 10rd groups. Geco 55gr FMJ 5.56 ammo is 1.3MOA-1.5MOA at 100 yards, 10rd groups CBC 77gr OTM 5.56 ammo is 1MOA-1.25MOA at 100 yards, 10rd groups. You really have to try it out before making any judgement on it. |
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Posted: 3/28/2017 7:31:29 PM EDT
[#6]
Every 1:7 barrel I have shot 50g AE in has be stabilized fine. Excellent accuracy, close to MOA in most barrels.
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Posted: 3/28/2017 7:46:38 PM EDT
[#7]
Twist rate calculator hosted on Berger's website
Primary bullet stability factors are twist rate, bullet LENGTH not weight (although weight is generally an indicator of length which is why you've heard that), and muzzle velocity. |
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Posted: 3/28/2017 8:51:40 PM EDT
[#8]
Quote HistoryQuoted:
IMHO twist rate is the most thing with modern AR's
If your 1:7, 1:8, 1:9 twist barrels will not shoot 55-69 grain ammo well, you have a shitty barrel and twist rate has nothing to do with it. uh? not exactly. 1:7 will stabilize 55gr just fine, but 55gr will, typically, be more accurate with 1:9. If both are good barrels. There are clear differences in what each twist will shoot better. Some 1:9's will shoot 75gr, some wont. Some 1:7's will shoot 55gr great, some wont. But MOST of the time a 1:9 twist is better for 55gr and 1:7 better for 75gr. In between is a toss up. To OP: in most cases 1:7 is best with 68 to 77 grain. Maybe even 80 grain. Grab a box of decent 62gr, 68gr and 77gr from your local store. Shoot a few groups each at 100 yards. Your barrel will tell you which it likes. OR at the least, you will be able to interpolate what is best for your barrel from the data. |
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Posted: 3/28/2017 9:04:26 PM EDT
[#9]
Quote HistoryQuoted:
uh? not exactly. 1:7 will stabilize 55gr just fine, but 55gr will, typically, be more accurate with 1:9. If both are good barrels. There are clear differences in what each twist will shoot better. Some 1:9's will shoot 75gr, some wont. Some 1:7's will shoot 55gr great, some wont. But MOST of the time a 1:9 twist is better for 55gr and 1:7 better for 75gr. In between is a toss up. To OP: in most cases 1:7 is best with 68 to 77 grain. Maybe even 80 grain. Grab a box of decent 62gr, 68gr and 77gr from your local store. Shoot a few groups each at 100 yards. Your barrel will tell you which it likes. OR at the least, you will be able to interpolate what is best for your barrel from the data. Quote HistoryQuoted:
Quoted:
IMHO twist rate is the most thing with modern AR's
If your 1:7, 1:8, 1:9 twist barrels will not shoot 55-69 grain ammo well, you have a shitty barrel and twist rate has nothing to do with it. uh? not exactly. 1:7 will stabilize 55gr just fine, but 55gr will, typically, be more accurate with 1:9. If both are good barrels. There are clear differences in what each twist will shoot better. Some 1:9's will shoot 75gr, some wont. Some 1:7's will shoot 55gr great, some wont. But MOST of the time a 1:9 twist is better for 55gr and 1:7 better for 75gr. In between is a toss up. To OP: in most cases 1:7 is best with 68 to 77 grain. Maybe even 80 grain. Grab a box of decent 62gr, 68gr and 77gr from your local store. Shoot a few groups each at 100 yards. Your barrel will tell you which it likes. OR at the least, you will be able to interpolate what is best for your barrel from the data. |
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Posted: 3/28/2017 11:36:34 PM EDT
[#10]
Quote HistoryQuoted:
1/8 bbls are a great comprise |
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Posted: 3/29/2017 12:31:44 AM EDT
[#11]
To shoot 80 and 90 grain bullets.
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Posted: 3/29/2017 1:33:59 AM EDT
[#12]
Quote HistoryQuoted:
uh? not exactly. 1:7 will stabilize 55gr just fine, but 55gr will, typically, be more accurate with 1:9. If both are good barrels. There are clear differences in what each twist will shoot better. Some 1:9's will shoot 75gr, some wont. Some 1:7's will shoot 55gr great, some wont. But MOST of the time a 1:9 twist is better for 55gr and 1:7 better for 75gr. In between is a toss up. To OP: in most cases 1:7 is best with 68 to 77 grain. Maybe even 80 grain. Grab a box of decent 62gr, 68gr and 77gr from your local store. Shoot a few groups each at 100 yards. Your barrel will tell you which it likes. OR at the least, you will be able to interpolate what is best for your barrel from the data. OP- the majority of my reloads are 50 grain v-max. I buy them in bulk and have loaded thousands of them. The dozen or so 1-7 barrels I own and have shot with over the last few years have been perfect with the 50 grainers. Trust me, your 1-7 twist will shoot them exactly the same as an equal quality 1-9. |
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Posted: 3/29/2017 7:27:30 AM EDT
[#13]
Quote HistoryQuoted:
Why exactly would a 1-9 twist barrel shoot 55 grain ammo more accurately than a 1-7? Trust me, your 1-7 twist will shoot them exactly the same as an equal quality 1-9. Your AE XM193 may shoot better in a 1:9" twist barrel while my 55 grain Hornady VMAX may like something different. Even within the same ammo, 62 grain M855A1 was shown to have half the group size in 1-9" twist barrels that it did in 1-7" barrels. AMU appears to be using 1:8" twist barrels while they are shooting M855A1, FWIW... |
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Posted: 3/29/2017 7:50:18 AM EDT
[#14]
My 1:7's shoot 52gr HPBT match very accurately
the tightest 100 yard group I've ever shot was with 55gr VMAX LC brass, surplus WC846 / BLC-2 powder. did it with a 1:7 twist barrel. 1:7 is superior to 1:9 do not expect dime sized groups with either twist when you shoot shitty FMJ's and a k-mart leapers scope . |
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Posted: 3/29/2017 7:56:20 AM EDT
[#15]
Quote HistoryQuoted:
Dependant on bullet design and construction, different bullets like different twist rates. Your AE XM193 may shoot better in a 1:9" twist barrel while my 55 grain Hornady VMAX may like something different. Even within the same ammo, 62 grain M855A1 was shown to have half the group size in 1-9" twist barrels that it did in 1-7" barrels. AMU appears to be using 1:8" twist barrels while they are shooting M855A1, FWIW... 2) M855A1 is crappy to begin with, accuracy-wise. 3) The AMU used match grade rifles that happened to have 1-8 twist barrels versus rack-grade M16A2 with 1-7 twist barrels. To say that the twist was the sole cause of the reduced group size is incorrect, and highly misleading. |
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Posted: 3/29/2017 8:05:27 AM EDT
[#16]
Quoted:
What is the lightest bullet that will stabilize in a 1:7 twist barrel? I know that the 69 grain and higher weight bullets don't do well in slower twist barrels. 1:7 is a fast twist, it will stabilize 90gr down to the lightest bullet made. |
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Posted: 3/29/2017 8:08:17 AM EDT
[#17]
Quote HistoryQuoted:
Why exactly would a 1-9 twist barrel shoot 55 grain ammo more accurately than a 1-7? A fully stabilized bullet is a fully stabilized bullet, there is no 'over-stabilizing'. There is spinning a projectile so fast it comes apart or the jacket starts to separate, but 1-7 is not even close to causing that with 55 grain or 5p grain ammo. All bullets have imbalance, the faster you spin them the greater the dispersion from that imbalance. |
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Posted: 3/29/2017 9:09:28 AM EDT
[#18]
Quote HistoryQuoted:
1) Tight rifling twists rates only exacerbates the bullet's inherent inaccuracy (caused by the bullet's CG not being exactly on top of the geometric axis). Match quality bullets won't see any change, marginal bullets get slightly worst. 2) M855A1 is crappy to begin with, accuracy-wise. 3) The AMU used match grade rifles that happened to have 1-8 twist barrels versus rack-grade M16A2 with 1-7 twist barrels. To say that the twist was the sole cause of the reduced group size is incorrect, and highly misleading. Quote HistoryQuoted:
Quoted:
Dependant on bullet design and construction, different bullets like different twist rates. Your AE XM193 may shoot better in a 1:9" twist barrel while my 55 grain Hornady VMAX may like something different. Even within the same ammo, 62 grain M855A1 was shown to have half the group size in 1-9" twist barrels that it did in 1-7" barrels. AMU appears to be using 1:8" twist barrels while they are shooting M855A1, FWIW... 2) M855A1 is crappy to begin with, accuracy-wise. 3) The AMU used match grade rifles that happened to have 1-8 twist barrels versus rack-grade M16A2 with 1-7 twist barrels. To say that the twist was the sole cause of the reduced group size is incorrect, and highly misleading. Re: AMU using 1:8" as opposed to 1:7" or something else- that also supports my point that different bullets like different barrel characteristics. I apologize if that fact could be interpreted as misleading; I was only using it to show that one cannot say that bullet length (or weight) are the only determining factors in what barrel twist to select for bullets with similar lengths (or weights). |
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Posted: 3/29/2017 9:53:41 AM EDT
[#19]
Quote HistoryQuoted:
Why does Krieger only sell AR15 barrels with a compromise twist rate? |
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Posted: 3/29/2017 10:23:17 AM EDT
[#20]
Barrel twist rate mathematics look great on paper ( especially the light / fast twist ones ) .... but really leave out a ton of variables in the real world.
It does come down to the quality of the bullet ( match / perfect balanced v. mass produced bullets ) and the quality of the barrel... both those items are typically not included in most math models of twist rate v. bullet weight.... not to mention a bunch of other things. In the real world... you can safely fire very light bullets from an AR15. I believe, that the only way you can see if any ammo shoots good from your rifle is by actually testing it yourself. There are a few "magical" factory rounds that seem to have proven to be accurate from most everyone's barrels...but you can pretty much count those on your one hand ( maybe both hands ) . So I don't put much merit in light bullet / to fast of a twist mathematics. Also on a side note... the USGI spec 1n7 was made to stabilize those long 64gr Tracer rounds.... most factory heavy weights, 77gr specifically, came after the tracer rounds. Uncle Sugar has tested 1n9 twist , and if memory serves me, found the overall accuracy with 55gr and 62gr to be better then 1n7 twist... but again, the 1n9 would not stabilize the long 64gr tracers. So 1n7 was used... since it would produce "good enough" results with the 55gr, 62gr and 64gr Tracers. I have numerous 1n7 twist rifles ... all those shoot the Fed. 50gr Tipped varmint round better then my one 1n9 twist. |
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Posted: 3/29/2017 10:33:55 AM EDT
[#21]
As for Krieger and the AMU using specific twist rates... I am confident that the barrels used are of a very high quality, ie... nice sharp cut rifling and chambers etc.
Not to mention the QC used to make those twist rates and barrels are closely monitored.... no dull cutters allowed ! Those high quality barrels would have a much better chance of mimicking the mathematical formulas used for optimum twist rate compared to a bulk produced barrel. Bottom line here is... not all barrels are equal... regardless what the "written" specs claim. So back to the real world v. mathematical arena.... quality is rarely addressed by the formulas. |
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Posted: 3/29/2017 12:38:25 PM EDT
[#22]
Quote HistoryQuoted:
Also on a side note... the USGI spec 1n7 was made to stabilize those long 64gr Tracer rounds.... I wondered how long this thread would go before someone introduced this fact. |
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Posted: 3/29/2017 3:16:59 PM EDT
[#23]
Quote HistoryQuoted:
Why does Krieger only sell AR15 barrels with a compromise twist rate? Quote HistoryQuoted:
Quoted:
1/8 bbls are a great comprise |
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Posted: 3/29/2017 3:18:30 PM EDT
[#24]
Any given bullet requires a minimum RPM to be stable for the conditions.
Velocity and twist rate determine bullet RPM. Match bullets can be very uniform in makeup, but this is not the case for all bullets. The spinning of the bullet magnifies any imperfections. Obviously the faster the bullet is spun the more the imperfections affect group size. Some varmint type bullets have been reported to come apart midair. They were plenty stable, but could not withstand the centrifugal forces present with fast twists and high velocities. Aside from bench rest shooters this has been demonstrated with M855 ammo between 1:9” and 1:7” barrels. Usually with half decent ammo the difference is not enough to be significant for practical purposes in ARs. Bullet manufacturers publish recommended twist rates for their bullets. |
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Posted: 3/29/2017 3:48:56 PM EDT
[#25]
35 grns will stabilize just fine. If pushed fast enough, they will disintegrate before they reach the target.
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Posted: 3/29/2017 3:59:27 PM EDT
[#26]
Quote HistoryQuoted:
35 grns will stabilize just fine. If pushed fast enough, they will disintegrate before they reach the target. But, you are onto the secondary factor and that is jacket thickness and rpm. I shoot a 6mm Remington with 55 grain bullets at 4,100 fps. Some very thin jacketed varmint bullets do literally blow up from too much rpm before reaching a 100 yard target. This is a real issue. I don't know at which point, velocity wise, that the little Hornady 35 grain Superformance varmint bullets might shed their jacket. Being "stable" is meaningless if the bullet self-destructs before reaching the target. At the other extreme are super long for weight monolithic bullets, like Barnes TSX and TTSX hunting and tactical bullets. Because they are solid copper and not jacket lead core bullets, they have different twist requirements. A 70 grain jacketed lead core bullet will do just fine in a 1:9 twist. The same 70 grain weight Barnes TSX or TTSX is much longer. Attempting to shoot 70 grain TSX bullets from a 1:9 results in bad keyholing and groups so bad that some are completely off of the target. |
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Posted: 3/29/2017 4:04:57 PM EDT
[#27]
Don't get hung up on the twist. 1/9 is probably not the wisest one to get, but if you found yourself with one, that's OK too. I think the most limiting twist would be 1/12. Which barely anybody sells any more anyways. I've never seen an AR with a 1/10. And 1/8 is probably closer to the most optimum.
If you have a 1/9, see if the heavier stuff will work. Sometimes they stabilize 75/77s. Sometimes they don't. It would be a rare example if a 1/9 wouldn't stabilize a 69 grain bullet. I suppose it's possible but not likely. You could do far worse than a 1/9. But 1/8 and 1/7 are the better choices with no downside. Other than if you want to shoot the super duper light weight varmint bullets. like 35 - 40 grain. I've shot 45 grain UMC through my 1/7 20" gun with them shooting just fine. But those were hollow points and not varmint tipped. But as I understand it, the only reason 1/7 exists is to stabilize the super long tracer bullets in extremely cold environments. Arctic conditions. Which, you may find yourself doing. If you live in Wisconsin or Canada or something like that. I can't shoot tracers at my range. Booooooooooooo. |
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Posted: 3/29/2017 5:14:12 PM EDT
[#28]
Twist rate doesn't go both ways. There is no such thing as an over-stabilized bullet. With very thin jackets, and very light bullets, you supposedly can spin the jacket off a bullet with a fast twist barrel. This might be apocryphal. It seems whenever it comes up, it's second-hand or worse information. I've never run into problems with 50 grain V-Max out of a 1-7 twist barrel.
There are folks that hunt extreme accuracy that want the slowest twist they can get that will still stabilize the bullet. I'm skeptical about whether that matters. Like damn near everything else with shooting, you're not going to find any rigorous scientific testing of it. I think 1-8 is the best twist rate for an AR. |
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Posted: 3/29/2017 5:20:14 PM EDT
[#29]
Quote HistoryQuoted:
I am not really sure where we are in disagreement. My first point was that "dependent on bullet design and construction, different bullets like different twist rates" Re: AMU using 1:8" as opposed to 1:7" or something else- that also supports my point that different bullets like different barrel characteristics. I apologize if that fact could be interpreted as misleading; I was only using it to show that one cannot say that bullet length (or weight) are the only determining factors in what barrel twist to select for bullets with similar lengths (or weights). |
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Posted: 3/30/2017 1:23:45 AM EDT
[#30]
Quote HistoryQuoted:
Twist rate doesn't go both ways. There is no such thing as an over-stabilized bullet. With very thin jackets, and very light bullets, you supposedly can spin the jacket off a bullet with a fast twist barrel. This might be apocryphal. It seems whenever it comes up, it's second-hand or worse information. I've never run into problems with 50 grain V-Max out of a 1-7 twist barrel. There are folks that hunt extreme accuracy that want the slowest twist they can get that will still stabilize the bullet. I'm skeptical about whether that matters. Like damn near everything else with shooting, you're not going to find any rigorous scientific testing of it. I think 1-8 is the best twist rate for an AR. 
I could see the possibility of it. |
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Posted: 3/30/2017 8:46:17 AM EDT
[#31]
As I already posted I HAVE had this happen with one brand of 6mm 55 grain varmint bullet when pushed to 4,100 fps. The high rpm strips the thin jacket from the lead core. They either explode or what remains fly wide of the target. This is a real phenomenon with some very light jacketed bullets when pushed too fast.
That said, I've not see this yet with .223/5.56. Not yet. I do worry that the 35 grain Hornady NTX bullet in its Superformance varmint load might be vulnerable in a 1:7 twist, especially in a long enough barrel to maximize velocity. I did not have a problem shooting them in 1:8. |
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Posted: 3/30/2017 11:00:15 AM EDT
[#32]
Personally... I think a better way to describe "over-stabilizing" would be exceeding the design limits of the bullets jacket.
Very thin "explosive, varmint style" jacketed bullets could do this when the 1n7 twist first was marketed... the thin jacketed bullets were primarily designed to be used in the more common 1n12 twists in the popular bolt action rifles that were available.. After a few years the bullet manufacturers caught up... and designed the bullets to withstand the increased twist rate. Remember when Hornady's AMP jacketed bullets came out a few years ago and had issues ? Even a small nick in the bore could cause issues. Here is an example of a "nicked" bullets spewing its core... ( I don't recall the details... the image is only labled Sig MPX ) 
While not a great example....( apples to oranges ) I even had .22LR bullets go "poof" out of my brand new 20" 1n7 while using the Colt 22LR conversion unit... they would fire fine, and my buddy said he could see them disintegrate into a cloud of dust about 25ft from the muzzle. |
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Posted: 3/30/2017 12:13:47 PM EDT
[#33]
Quote HistoryQuoted:
As I already posted I HAVE had this happen with one brand of 6mm 55 grain varmint bullet when pushed to 4,100 fps. The high rpm strips the thin jacket from the lead core. They either explode or what remains fly wide of the target. This is a real phenomenon with some very light jacketed bullets when pushed too fast. That said, I've not see this yet with .223/5.56. Not yet. I do worry that the 35 grain Hornady NTX bullet in its Superformance varmint load might be vulnerable in a 1:7 twist, especially in a long enough barrel to maximize velocity. I did not have a problem shooting them in 1:8.  Green Mountain Experimental 18" 1/5 twist barrel test, 36gr Varmint Grenades |
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Posted: 3/30/2017 2:47:45 PM EDT
[#34]
50,55,62,6 will all shoot strait out of 1/7. 68 you should try yourself avoid 72,77
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Posted: 3/30/2017 3:35:58 PM EDT
[#35]
Quote HistoryQuoted:
Personally... I think a better way to describe "over-stabilizing" would be exceeding the design limits of the bullets jacket. Very thin "explosive, varmint style" jacketed bullets could do this when the 1n7 twist first was marketed... the thin jacketed bullets were primarily designed to be used in the more common 1n12 twists in the popular bolt action rifles that were available.. After a few years the bullet manufacturers caught up... and designed the bullets to withstand the increased twist rate. Remember when Hornady's AMP jacketed bullets came out a few years ago and had issues ? Even a small nick in the bore could cause issues. Here is an example of a "nicked" bullets spewing its core... ( I don't recall the details... the image is only labled Sig MPX ) https://scontent.fsnc1-2.fna.fbcdn.net/v/t1.0-9/17629682_1470673029620126_4292071762513303462_n.jpg?oh=e84bae0e53501852fa1e5c2819ad1b92&oe=59630343 While not a great example....( apples to oranges ) I even had .22LR bullets go "poof" out of my brand new 20" 1n7 while using the Colt 22LR conversion unit... they would fire fine, and my buddy said he could see them disintegrate into a cloud of dust about 25ft from the muzzle. |
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Posted: 3/30/2017 5:27:44 PM EDT
[#36]
Will an 80 or 90 grain cartridge even fit in an AR 15 magazine?
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Posted: 3/30/2017 5:30:37 PM EDT
[#37]
I have a 1-7, a few 1-8 (my preferred twist), and a pair of 1-9, and I regularly shoot everything from 40gr varmint to 80gr amax. Never had an issue with stabilization. I read all about the internet warriors saying 40gr will not work, they just separate jackets from cores with 1-7, bullspit. They work perfectly fine on ground hogs and whistle pigs. And I've read you can't shoot anything over 60gr out of a 1-9, another load of crap as my 77gr pet load shoots sub 1" even in 1-9 barrels. I load most of my rounds for specific rifles, but on occasion I do shoot ammo loaded for a specific gun out of a different one, and one thing I've found out: a good round shoots good out of any twist rate barrel.
It's like this, almost all kids like pizza, right? No matter the toppings or sauces, a pizza is pizza. If you find a kid that doesn't like pizza, it's pretty odd. I'm not saying "everyone" does but 99/100 do. Barrels are just like that. A good load will shoot good in a 1-7, 1-8, 1-9, hell probably even 1-11, just don't have one to verify. Twist rate is far less important that good shooting mechanics, repeatable positioning and breathing. |
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Posted: 3/30/2017 5:51:52 PM EDT
[#38]
Quote HistoryQuoted:
Will an 80 or 90 grain cartridge even fit in an AR 15 magazine? 
BUT... typical .223 /5.56 80gr SMK loads , are single load only with an extended OAL of 2.550ish... as an example, here is a factory Federal 80gr SMK image... ( don't think it is production any more ) 
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Posted: 3/30/2017 7:10:58 PM EDT
[#39]
Quote HistoryQuoted:
I have a 1-7, a few 1-8 (my preferred twist), and a pair of 1-9, and I regularly shoot everything from 40gr varmint to 80gr amax. Never had an issue with stabilization. I read all about the internet warriors saying 40gr will not work, they just separate jackets from cores with 1-7, bullspit. They work perfectly fine on ground hogs and whistle pigs. And I've read you can't shoot anything over 60gr out of a 1-9, another load of crap as my 77gr pet load shoots sub 1" even in 1-9 barrels. I load most of my rounds for specific rifles, but on occasion I do shoot ammo loaded for a specific gun out of a different one, and one thing I've found out: a good round shoots good out of any twist rate barrel. It's like this, almost all kids like pizza, right? No matter the toppings or sauces, a pizza is pizza. If you find a kid that doesn't like pizza, it's pretty odd. I'm not saying "everyone" does but 99/100 do. Barrels are just like that. A good load will shoot good in a 1-7, 1-8, 1-9, hell probably even 1-11, just don't have one to verify. Twist rate is far less important that good shooting mechanics, repeatable positioning and breathing. I can go a long way toward agreeing that you can't overstabilize light bullets with too tight a twist (if the jackets are not too thin and velocity too high), but you absolutely cannot stabilize really long bullets like a Barnes 70 TSX in 1:9. Hard laws of physics cannot be ignored. At some point slow twist cannot spin the bullet enough to stabilize it. Below are several representative .224 diameter bullets from my own loading bench. This photo illustrates how Barnes bullets of the same weight are significantly longer than their lead core counterparts. On the far right is the Barnes 70 TSX. To its immediate left is a 77 grain SMK. Note how much longer the lighter Barnes bullet is because of its all copper construction. On the far left is the common Hornady 55 FMJHP. Proceeding to the right is the Barnes 53 TXS; 55 TTSX, 62 TTSX, the 77 SMK and the Barnes 70 TSX. Everything up to and including the 62 TTSX stabilize nicely in 1:9. The 62 TSX is on the borderline. Its untipped version, the 62 TXS (not pictured as I am out) shoots MOA. The 77 SMK and the 70 Barnes TSX will not stabilize in 1:9. They shoot lights out, however with 1:8. 
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Posted: 3/30/2017 8:32:33 PM EDT
[#40]
Never shot the 70g Barnes tsx, too rich for my tastes. But now that I know they are so damn long, another reason to stay away lol.
In my 700 custom with bartlein 1-9tw I shoot 69-77s on the regular and have never had any issue. No keyholes, no weird grouping, nothing irregular. It shoots 70-73 vld's and 75 amax's great. Never shot them through my 1-9 ar though. But a 1-9 is a 1-9 no matter if it's a gas or bolt gun. I personally just find a load that shoots lights out and stick with it for that rig. I'm not really into spending a lot of time going thru different combos of bullets and powders. What kind of signs are you seeing to make you not wanna shoot the heavier pills? |
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Posted: 3/30/2017 9:15:36 PM EDT
[#41]
A 1:9 is not a 1:9 alone for stabilization purposes, as the other factor is velocity. Shooting a longer barreled bolt gun, 22" -24" or more, changes everything. Getting velocity up two hundred fps or more compared to a 16" AR greatly impacts stability, because it increases rpm.
Berger's twist calculator demonstrates this vividly. |
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Posted: 3/30/2017 11:06:55 PM EDT
[#42]
20" bartlein stainless, same length as a std m16. Although it is a 5r twist.
60-70fps chrono'd over my 18" mk12, same load. Guess it's just dumb luck I can shoot pills over 60g out of a 1-9t 
There's always going to be two sides to a scientific problem: theory and real world application. Not trying to stir anything up, but have you tried anything other than tsx bullets in that weight? |
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Posted: 3/31/2017 12:03:24 AM EDT
[#43]
Quote HistoryQuoted:
20" bartlein stainless, same length as a std m16. Although it is a 5r twist. 60-70fps chrono'd over my 18" mk12, same load. Guess it's just dumb luck I can shoot pills over 60g out of a 1-9t
There's always going to be two sides to a scientific problem: theory and real world application. Not trying to stir anything up, but have you tried anything other than tsx bullets in that weight? The extra four inches in barrel length of a 20" may let you get enough rpm to shoot 77 SMKs. I can't from a 16". |
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Posted: 3/31/2017 9:52:17 AM EDT
[#44]
Quote HistoryQuoted: 50,55,62,6 will all shoot strait out of 1/7. 68 you should try yourself avoid 72,77 |
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Posted: 3/31/2017 9:05:23 PM EDT
[#45]
Quote HistoryQuoted:
Indeed. Or Lilja or other custom match grade barrel makers? Quote HistoryQuoted:
Quoted:
Quoted:
1/8 bbls are a great comprise their target market is High Power and Service Rifle competitors |
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Posted: 3/31/2017 9:09:48 PM EDT
[#46]
Quote HistoryQuoted:
Will an 80 or 90 grain cartridge even fit in an AR 15 magazine? |
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