I didn't want to hijack the other 1/7 thread, so I started this.  I have read lots of opinions on both sides, that 1/7 is too fast for 55gr, and I've read it's fine.  But they're just that, opinions.  I'm not interested in the guy who thinks he knows, who is actually doing it and how does it work?  

I've shot WWB, Wolf and XM193 through my CMMG 14.5 1/7 upper. Seems to run fine for me?

every chance I get and not the first problem out to 300 yards

I've shot thousands of 55gr XM-193, Q3131A and Wolf from 1/7 barrels and they all shot just fine and I could not tell any difference from my 1/9 barrels.

I wonder who keeps spreading this BS about 1/7 barrels?  I heard the same thing several years ago when I was looking to purchase my first 1/7 barrel and it seemed to come from gunshop commandos who've never used a 1/7 barrel.

I've been on this board since the mid/late 90's and I never ever seen anyone complain about using 55gr ammo out of a 1/7.

Just fine here.

I have, in a FN A2 upper.  I haven't assaulted any paper target beyond 50 yards since the temp was above 80.  When deer season is over I'll push them out a little farther.  I haven't seen any difference between that and the 1/9" 14.5 Bushy I got.

I've fired probably 20k of 55 grn through my 1/7 barrels over the years.

Never any problem.  Accurate enough to do the job, function is fine.

If you want to shoot precision at distance, you're better off with heavyweight match quality bullets.

Shot my highest offhand score at 200 yds (194-8X) with cheap Federal 50 grain varmint stuff.  Barrel is a 1-7, Wylde chambered, stainless steel Wilson.

Ive shot 40gr WWB varmit loads from my 1/7

seemed to work ok

I've shot a lot of 55gr through a 1/7 16" and 1/7 14.5" with no problems.

- rem

just sighted in with 55gr.
-accurate enough for me, no keyholing or anything.

Who is shooting 55gr from 1/7?

Every chance I get.

Wonder why a lot of manufacturers use 1x9?

for over 15 years now

Nothing scientific, but my Bushmaster 1/9 and Colt 1/7 barrels actually do better with 55 grain stuff than the heavier stuff. After shooting many brands including MilSpec, commercial, and surplus, Winchester Q3131A 55 grain ammo seems to be the most accurate.

i have gotten reasonable groups out of my 1x7 recon bbl. with xm193 also never had a single problem with it

I have only 1/7" twist barrels at this point. my 1/7"s just keep "overstabilizing" those 55 grain bullets right into the bullseye. Proceed with confidence.

Quoted: Who is shooting 55gr from 1/7?   Every chance I get.

I'm with Stickman!

Quoted: Quoted: Who is shooting 55gr from 1/7?   Every chance I get. I'm with Stickman!

I'm with Stickman and Horik!

1/7 is only to "fast" for 55 fmj if that is all you plan on shooting.  1/12 is perfect for 55 fmj.

all your doing with 1/7 is spining a 55 more than it needs to be spun, beyond that no harm is done.

Quoted: Quoted: Quoted: Who is shooting 55gr from 1/7?   Every chance I get. I'm with Stickman! I'm with Stickman and Horik!

Don't leave me out

Question not answered by this thread or Ammo Oracle: Can a faster spin rate improve fragmentation on impact? And vice versa? It would seem logical that if a tire rotating at "50" rpm would come apart than a slower rotating tire at "10" rpm then a bullet would do the same thing.

Also, there is information that the lighter 40-45gr bullets come apart at/near the muzzel if shot in fast twist barrels.

Quoted: 1/7 is only to "fast" for 55 fmj if that is all you plan on shooting.  1/12 is perfect for 55 fmj. all your doing with 1/7 is spining a 55 more than it needs to be spun, beyond that no harm is done.

That's what I'm talking about, sailor!  1/7 should be BANNED!

Quoted: Question not answered by this thread or Ammo Oracle: Can a faster spin rate improve fragmentation on impact?

Yes that question IS answered in the Oracle - there are two Q&As that deal specificall with that issue:

Q. Didn't tightening the twist rate from 1:14 to 1:12 reduce the wounding potential of M193?

Q. If I increase spin or barrel twist, won't that decrease wounding by making a round more stable in tissue?

It is also answered in Dr. Fackler's paper "Wounding Patterns of Military Bullets" which can be found in a tacked thread at the top of the ammo forum.

The answer is 'no'.  Faster or slower spin rate's don't help.

Even the 45 grain JHPs work fine in my 1/7 barrels.

Quoted: Quoted: Question not answered by this thread or Ammo Oracle: Can a faster spin rate improve fragmentation on impact? Yes that question IS answered in the Oracle - there are two Q&As that deal specificall with that issue: Q. Didn't tightening the twist rate from 1:14 to 1:12 reduce the wounding potential of M193? Q. If I increase spin or barrel twist, won't that decrease wounding by making a round more stable in tissue? It is also answered in Dr. Fackler's paper "Wounding Patterns of Military Bullets" which can be found in a tacked thread at the top of the ammo forum. The answer is 'no'.  Faster or slower spin rate's don't help.

I did see the section on "yawing" and how spin rate relates to bullet stabilization or regaining stabilization, but I am not disputing the info shown. I still have a question that I don't think is answered by the articles. I may be splitting hairs here, but what I am saying is that the test in ballistics gelatin show bullet fragmentation without encountering any objects other than the gelatin.  Obviously, yaw has been induced, causing the bullet to fracture wherever jacket integrity is compromised in some way (cannelure, rifling striations, etc.). While the forward velocity of the projectile contributes to the depth of fragment penetration, it seems that the rotational speed of the projectile would contribute to the lateral velocity of the fragments moving away from the original path of the projectile.

An example of how I see this is a shotgun. Smooth bore (no choke), pellets disperse based on the disruption of their originally designated path by the combined effects of the surrounding air, surface defects in the pellets, and the "billiard" affect of contacting other pellets as they exit the bore.  Fire the same load in a rifled "slug" barrel and pellet dispersal is much more pronounced closer to the bore due to the imparted spin.

Just to beat the horse some more, a gyroscope with no forward velocity is spinning at "w" rpm and is absolutely stable up to "x" rpm.  But once it reaches "y" rpm, centrifugal force overcomes its structural integrity and it fragments.  Anyone in the vicinity of the lateral distribution of those fragments is in danger while those at the poles are not (no forward velocity).   If something were to affect the structural integrity of the gyroscope at either "x" or "y" rpm, fragments will still be released laterally, just without as much velocity. Still no danger at the poles.

I like to understand what I read and just like the 18 years of school (no I did NOT repeat any grades) and 40+ years of business management, I always tried to understand the answers and answer questions to the satisfaction of those asking.

And, yes, I am a hard head.

works well for me.

Several k's of  SA surplus 55.

fine & dandy

Works fine in mine and just ask any gulfwar vet from 90 91 because 55 grain was still in use back then.Or any one for that fact that carried an A2 from 84 for the marines and 86 for the army until 1992 or maybe 93 with somalia that the SS109 was in full use.

Quoted: for over 15 years now

What he says, though I might be 3yr longer...   Back in '87 when I bought my Sporter-II, it was a mix of A1 & A2, the barrel was A2 (1x7).... then I got the Gov't Model (all A2 except lower)...  

55gr ammo was all that was available at the time,  62gr on the free US market was unheard of.

Works for me.   Wasn't till early 90's the heavy match bullets came about (Hornady 68gr  and  Sierra 69gr, don't recall who came about first..)

All my ammo is still 55gr for the Gov't Model.

My 1/7 twist CAR-15 (early to mid 80's manufacture) shoots 55gr just as well as my AR-15A3 carbine(Bushmaster 2002 manufacture) with the exception of 300+ meters. This is the fault of the 11.5 inch barrel on the CAR and has little to nothing to do with the rate of twist. As the CAR is my dedicated CQB gun, Im not worried about it, plus they both love the XM-193 ammo, which is inexpensive & pleniful. I have even fired 40 and 45gr JHP out of the CAR with good accuracy out to 150m, and it prefoms great at CQB ranges, with the benefit of better wound ballistics/less penetration of walls.


Just my 2 cents,

John

"Im the 82nd Airborne, and this is as far as the bastards are going"