What are the pros and cons of building a rifle with 1/7 or a 1/9 twist. I don't see the advantage of going to a 1/7 because 99% of what I shoot is 55gr. Is there something I am missing? Any input would help
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What are the pros and cons of building a rifle with 1/7 or a 1/9 twist. I don't see the advantage of going to a 1/7 because 99% of what I shoot is 55gr. Is there something I am missing? Any input would help
If you only shoot is 55 grain there would be no advantage to a 1/7 over a 1/9.
I chose 1:7 so I could use any ammo out there in case the SHTF and ammo is hard to come by. I am a pessimist by nature.
There's no advantage to a 1/9 twist
1/7 will fire 50-80 just fine, and it's been my experience that even 45gr fires perfectly fine.
You realize the m16/m4 are 1/7, right? m193, the most-fired cartridge in the Army, is 55gr... shoots as accurately as any twist can shoot it.
The only evidence that I've seen of 1/7 having any limitations whatsoever is an occasional person saying that it's possible 1/7 wont stabilize <50gr ammo- possible. i've never seen it, i've never heard anyone else say they've seen it, never read anyone post here that they've seen it, nor read any specific instances published. I've never even heard lame-ass gunshow dealers pawning 1/9s give any specific examples- guys who are known for lying.
1/9, on the other hand, has very well documented and widely known limitations...
why would anyone ever get a 1/9? 1/7 is the only twist i use. my 5 current guns are 1/7, two of which have fired cheap underpowered PMC 45 .223 ~1.25 MOA- without trying very hard. aside from 75gr training TAP, i fire xm193 pretty much exlusively. no problems whatsoever.
What is going to be your purpose/use for this gun?
That might give some answers for others to go by.
But BKB0000 gave you a good reason for 1/7 which were the same ones I based my decision on.
1/7 got my vote for those reasons.
Thereis no advantage to shooting a 1/9 even if you think you will only ever shoot 55 grn.
Why limit yourself on ammo selection. Who say tha one day you find a "too good to pass up" deal on a case or two of 75 grn ammo.
"Damn I would love to buy that but my barrel won't shoot it........"
why do many manufacturers even still use 1/9 as their primary twist for their barrels?
their line is that "1/9 doesn't wear as fast as 1/7".
but these manufacturers KNOW that 99% of their customers are likely to never shoot out one of their barrels regardless of the twist rate.
i just don't get it.
is it because its just cheaper for them, because the customers who buy the varmint type ARs want 1/9, therefore they save money if they make all their ARs with the same twist rate?
that's probably it. the same reason they try to sell us chrome lined 16" HBARs :rolleyes: because the profit margin is higher.
What about 1/8 twist rate? I believe that is what the S&W 5.45 barrels have, why not in a 5.56 barrel?
I still vote for 1/7 though; it's blue on "the chart" for a reason.
One advantage that I can see is that a 1/7" will more than likely be HP/MPI tested and inspected and a 1/9" more than likely not. In addition though some 1/9" will shoot the heavier bullets there is no guarantee the one you get will. A 1/7" most likely will and shooting 55gr. is no problem. Seems like the 1/7" is the smarter choice.