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View Full Version : 1x9 vs. 1x7 advice please


shopkeep
01-08-2006, 2:41 AM
Thanks for the advice on the co-witness setup, I'm going to try with just a flat-top fixed sight and if that gives me problems I'll swap out the gas block with Yankee Hill's flipsight.

I'm going to use a 16 inch barrel config, which should I use... 1 x 9 or 1 x 7? What are the advantages and drawbacks of each? I can't wait to get pics up of the fixed mag build when it's done :)!

blacklisted
01-08-2006, 3:02 AM
I'm considering the RRA Varmint A4 20 or 24" upper half, which comes with a 1:8 twist rate. Will this basically do it all (55-77gr)?

pieeater
01-08-2006, 9:00 AM
Lots of good info in here http://www.ammo-oracle.com/

delloro
01-08-2006, 9:29 AM
go with the fastest twist available.

BigAL
01-08-2006, 9:32 AM
55 grain is the lightest bullet I shoot. And I have recently got around to trying out the heavier 75 grain match loads so 1x7 is all I buy now.

TonyM
01-08-2006, 9:51 AM
55 grain is the lightest bullet I shoot. And I have recently got around to trying out the heavier 75 grain match loads so 1x7 is all I buy now.

Same here.

I stick to 1 in 7. Works great for XM193/Q3131A and M855, and When I decide to get a Dillon Conversion kit to reload .223 I can load up and shoot some heavy weight match loads. Buying 1 in 9 really only limits you since 1 in 7 shoots the 55gr loads just fine. I don't ever see myself shooting lighter loads than that.

As fo the Varminter question:

Those are usually designed to shoot lighter loads, you don't need 62gr bullets to kill a P.D. or ghopher. I've been thinking about building a longer barrel upper, but because of the twists available I have decided I'll get a custom barrel in 1 in 7 made. You can checkout www.ar15barrels.com (http://www.ar15barrels.com).

elmo
01-09-2006, 10:15 AM
most upper models will be 1-9 as it goes with the popular grain bullets out there in .223 etc. I'd stick with that, not many 1-7 16" barrels out there compared to 1-9

bu-bye
01-09-2006, 10:40 AM
My 1-9 twist DPMS bull barrel will shot everything from 40gr to 69gr under an inch. The trick is finding the load that has the smallest groups out of that range. My gun seems to like the 40gr v-max and other lighter bullets then the 55gr and up bullets. They will all shoot sub MOA with the right powder and charge. I like 1-9 and maybe 1-8 but I just feel that 1-7 is to tight for me. I like the lighter loads but then again I'm a bench shooter and not a Zombie killer so you pick what ever setup you like. 1-7 will work great with heavy loads but remember heavy is not always better. 2700-2600fps is the magic number that makes the 223 so deadly and a heavy 77gr bullet will slow down to that speed faster then a 55 gr.

BigAL
01-09-2006, 10:47 AM
2700-2600fps is the magic number that makes the 223 so deadly and a heavy 77gr bullet will slow down to that speed faster then a 55 gr.

The heavy 75-77 grain stuff actually has a much lower frag velocity than the regular stuff. Around 2300 fps not 2700. So all things equal the heavy stuff actually has a farther frag range than XM193 even though it is traveling slower.

triaged
01-09-2006, 1:06 PM
Some notes from my research...correct me if I am wrong.

-The heavier bullets work better at LONG range (600-1000yd)
-Faster twist rates wear out faster
-Chrome lined will last longer but be less accurate
-16" barrel is short for LONG range (600-1000yd)
-Most of the local ranges don't go out past 300yd

I have decided on a 16" mid-length barrel in 1:9 twist. I will decide on chrome or not after looking at price but will most likely skip it.

BigAL
01-09-2006, 1:15 PM
Some notes from my research...correct me if I am wrong.

-The heavier bullets work better at LONG range (600-1000yd)
-Faster twist rates wear out faster
-Chrome lined will last longer but be less accurate
-16" barrel is short for LONG range (600-1000yd)
-Most of the local ranges don't go out past 300yd

I have decided on a 16" mid-length barrel in 1:9 twist. I will decide on chrome or not after looking at price but will most likely skip it.

Depends on what your desired end use is. Chrome lining is something I would like on a defensive weapon. I mean were not talking something like you add chrome and the groups suddenly open way up. Chrome barrels are still more than enough to get the job done in a defsive situation. And as to wearing out a barrel faster if you can afford enough ammo to actually wear out a barrel then buying a new one won't be a problem. Besides, it's the throat that will likely wear out before the rifling does and this has nothing to do with twist.

delloro
01-09-2006, 2:41 PM
Some notes from my research...correct me if I am wrong.

-The heavier bullets work better at LONG range (600-1000yd)
-Faster twist rates wear out faster
-Chrome lined will last longer but be less accurate
-16" barrel is short for LONG range (600-1000yd)
-Most of the local ranges don't go out past 300yd

I have decided on a 16" mid-length barrel in 1:9 twist. I will decide on chrome or not after looking at price but will most likely skip it.

velocity is everything with 5.56 terminal perdormance. why give away velocity by going with a shorter barrel?

triaged
01-09-2006, 2:58 PM
velocity is everything with 5.56 terminal perdormance. why give away velocity by going with a shorter barrel?
I'm not too worried about terminal performance...16" is as short as we are allowed. 14.5" would be my first choice. I think having a 14.5" barrel with a permanently attached long muzzle device on it is just stupid...so 16" mid-length it is (mid so I can use a bayonet if I want).

zenthemighty
01-09-2006, 3:51 PM
Depends on what your desired end use is. Chrome lining is something I would like on a defensive weapon. I mean were not talking something like you add chrome and the groups suddenly open way up. Chrome barrels are still more than enough to get the job done in a defsive situation. And as to wearing out a barrel faster if you can afford enough ammo to actually wear out a barrel then buying a new one won't be a problem. Besides, it's the throat that will likely wear out before the rifling does and this has nothing to do with twist.

In a defensive situation, I'm grabbing something other than a mousegun anyways. To me, the 223 platform is an excellent one for young/new shooters to cut their teeth on.

BigAL
01-09-2006, 5:15 PM
In a defensive situation, I'm grabbing something other than a mousegun anyways. To me, the 223 platform is an excellent one for young/new shooters to cut their teeth on.

Yes we all know .223 and 9mm are for pansies/women/children and will only bounce off the bad guys while .308 and .45 will one shot stop everyone they come into contact with.:rolleyes:

BigAL
01-09-2006, 5:17 PM
velocity is everything with 5.56 terminal perdormance. why give away velocity by going with a shorter barrel?

Maneuverability and weight. Why carry a 20" when you won't be shooting past 100 yds (and likely even closer in than that)?

TonyM
01-09-2006, 5:39 PM
velocity is everything with 5.56 terminal perdormance. why give away velocity by going with a shorter barrel?


Well, near the end of November M855 out of my 14.5" barrel (with perm. attached Phantom to increase to over 16") flew through my Chronograph at over 2700 feet per second. Seems like plenty of velocity for me.

BigAL
01-09-2006, 6:14 PM
XM193 will just break 3000 fps at the muzzle on my 14.5", which gives it a frag range out to 90-100 yds. Heavy OTMs will increase that range a bit and make the fragmentation itself more violent. I've decided this is adequate for my purposes.

delloro
01-09-2006, 6:14 PM
well, it's not you that needs to be impressed; it's the BG. ;o)

there is a velocity under which fragmentation does not reliably occurr, I forget what it is. I am sure it's under 2700 fps, but the more velocity I have the better I like it.

Shoot-it
01-11-2006, 7:48 PM
Lots of good info in here http://www.ammo-oracle.com/

You got it pieeater thats the site i found when i used the (search button) . I learned so much on that site.twist rate to what ammo to use since i read that i know what you guys are talking about and it helped me to decide that i wanted a 1-9 twist for 40-69 grain i believe.They also talk about vietnam and what happened with the m16 and how the first twist 1-14 was to slow too stabelize the 70 grain loads. check it out you wont be sorry....:D

bobfried
01-12-2006, 12:08 PM
Golden Rule - .223 barrel should be between 11" and 16" anything less and you have problems, any more is a complete waste of metal as you do not gain any velocity.

Put it this way, USSOCOM uses 14.5" 1x7 barrel for general purpose rifle (SPR and RECCE are different). Do you know more than them?

delloro
01-12-2006, 1:04 PM
...Do you know more than them?
I know that what's best for special forces is not always best for everybody.
I know that most of the military uses a 20".
I know I'm not SF. Are you?

delloro
01-12-2006, 1:06 PM
Golden Rule - .223 barrel should be between 11" and 16" ... any more is a complete waste of metal as you do not gain any velocity.

wanna bet?

Matt-man
01-12-2006, 1:49 PM
Yeah, a complete waste of metal.

BigAL
01-12-2006, 2:36 PM
Not only does a 20" give more velocity but it also gives you the extra "smoothness" of the 20" gas system.

bobfried
01-12-2006, 3:10 PM
Wow 100fps......whatever would I do without that much velocity.

I don't own anything other than midlengths so that smoothness in the 20" isn't something I miss. Even with the carbine gas system an H2+ or a 9mm buffer will smooth thing out just fine.

I've spent enough time wielding and shooting a 20" A2 to know it is far from being any better than a 14.5" M4 I was issued when I became an NCO. The only thing I missed from that switch was the heavy and monstrously long barrel and the horrid whale *** they called a rifle stock. I've owned a few dozen M16/M4/AR in my lifetime to know what works and what does not. If you have never shot a 16" or less AR than your missing out on alot more versatility.

My latest upper built: Noveske Afghan 14.5" (pinned and welded FH) on an LMT upper with midlength handguards. It will shoot as good or better than anything out there and is damn handy. If only I could own an SBR like Arizona I'd be all over a 11.5".

delloro
01-12-2006, 4:43 PM
Wow 100fps......whatever would I do without that much velocity?

not frag a BG at distance? :D

BigAL
01-12-2006, 5:05 PM
Wow 100fps......whatever would I do without that much velocity.


Well the guy did claim NO increase in muzzle velocity from 16" to 20". 100 fps is a lot more than 0 fps. But I also prefer the shorter 14.5" or 16" barrels myself. Lighter weight, more mobility, and will still frag out to the distances I see myself shooting at.

bobfried
01-12-2006, 5:16 PM
not frag a BG at distance? :D

Now we all know that's what the FAL and M1A are for. :D