Site Notices
11/27/2014 12:14:39 AM
  Previous Page
Page:  / 3
Author
Message
arowneragain
Jesus Saves!
Offline
Posts: 25973
Feedback: 100% (20)
Posted: 4/4/2009 10:09:25 AM EST
[Last Edit: 4/4/2009 10:26:08 AM EST by arowneragain]
With all the new AR buyers here, it seems that the question frequently pops up as to whether a rifle with a 1-7" twist will shoot light (55 grain) ammo well.


I was bored today, so I decided to do a short, non-scientific test. I frankly wasn't in the mood to set up my chronograph and wasn't in the mood to shoot 10-shoot groups with current ammo prices. Yes, I'd rather use 10-shot groups.

I went to the local sporting goods place - the ONLY .223 load they had in stock (they used to have pallets of wolf) was hornady's 55-grain v-max load. This load has a reputation for decent accuracy, so I bought a box. I also had 10 rounds left out of a box of Prvi 75-grain match.

I took my Oly lower (it has an A2 stock and the best trigger of all my AR's) and my LT-104 scope mount with Swarovski 4-16x50, and grabbed two uppers:

First was my LMT 14.5" m4gery, with permanently attached Gemtech FH and a YHM free-float railed forend.

Second was my CMMG 16" lightweight midlength with a set of carbine handguards (non-FF) and a phantom 5C2 FH.

All shooting was at 100 yards.

With the LMT upper, 5 rounds of Prvi 75-grain match went into 2.375". That's really about what I expected from this rifle - its first 500 rounds were as a full-auto demo upper, and since then I've put about 1500 rounds through it, getting it quite hot a few times. The bore hasn't been cleaned beyond a patch with CLP since I've owned it - it is NOT a 'match' gun.

Then I shot 5 rounds of the hornady 55-grain v-max load. 5 rounds went into 1.5". That's GREAT accuracy from a worn 14.5" chrome-lined upper, and demonstrates that 1-7" twist service-grade barrels can shoot 55-grain ammo well enough.

As a side note, of those 5 rounds, I had TWO blown primers. Both resulted in stoppages, and both demonstrated why .223 varmint ammo loaded for use in bolt guns, even at .223 pressures, is NOT the best choice for defense ammo, bullet performance notwithstanding. Even if the v-max was a SD bullet, or even if you placed one perfectly onto a perfect-case target, it's useless if the primer blows and causes a stoppage in mid-fight. Crimped primers and case necks, for defensive ammo, ALWAYS.

Ok, moving on, I took the scope/mount and lower and put them on my CMMG upper.

Between the light barrel and non-FF handguards, I wasn't expecting much here.

5 rounds of PRVI went into 2.2". That's not bad - and the group was strung vertically, which suggests an inconsistent hold on my part. The group was only 7/8" wide - who knows what this rifle would do with a FF handguard or a more consistent hold on the sandbags?

I then shot 5 rounds of the hornady 55-grain v-max load. 5 shots went into 1.2". I was pleasantly surprised.

As a control, I took out my Tikka 595 in .223 and shot 5 rounds of the hornady 55-grain v-max load. This rifle is about 13 years old and over the years it's been a laser-beam, shooting several factory loads sub-moa, some well under sub-0.5 MOA, and one handload 'in the teens' - and all of this not just at 100 yards but also at 200 and 300.

So, anyway, I shot 5 rounds of the 55-grain hornady v-max load. They went right where they were supposed to (the rifle was sighted-in 2.5" high at 100 with another 55-grain load, but hasn't been shot in several years), 5 shots centered 2.5" high in a nice, round group of 0.81".

Disclaimer: 5-shot groups are statistically worth very little. However, this is enough to demonstrate that GOOD 55-grain ammo can group quite well in a barrel with 1-7" twist, even in chrome-lined 'service grade' barrels such as LMT or CMMG. These aren't match barrels; these are barrels I'd go into a fight with.

Further, I wouldn't look at any of these groups as being substandard - it's been over a year since I did any bench shooting, I'm out of practice, half my sandbags were still sitting in deer stands, so I wasn't in a comfortable shooting position (especially with the bolt gun) and it was a bit breezy today - light gusts from right to left.


Lessons learned:

55-grain ammo is NO PROBLEM for 1-7" twist barrels.
Varmint loads are NOT suitable for fighting carbines, no matter how cool they perform on varmints.
As O_P says, shooting stuff is fun.


...But his word was in mine heart as a burning fire shut up in my bones, and I was weary with forbearing, and I could not stay...All my familiars watched for my halting...But the LORD is with me as a mighty terrible one...

Jeremiah 20 9-11
smithc6
Offline
Posts: 443
Feedback: 100% (47)
Link To This Post
Posted: 4/4/2009 10:22:20 AM EST
nice!
bearfan620
Offline
Posts: 15
Feedback: 0% (0)
Link To This Post
Posted: 4/4/2009 10:24:18 AM EST
[Last Edit: 4/4/2009 10:56:33 AM EST by bearfan620]
Nice work...thanks for taking your time to post and clear up some of the rumor mill. I shoot 55 grain Remington UMC in my 1:7 DD M4 and it's accurate enough for me! I'm not a match gunner, and for SHTF purposes, if I can empty my mag on man sized targets....errrr zombies..... at 100 and 200 yards then I'm OK, because that's why I bought this rifle. And realistically, I should hope I'm not engaging targets at even 100 yards for HD or else there are some bigger problems.
DSRV
Offline
Posts: 90
Feedback: 0% (0)
Link To This Post
Posted: 4/4/2009 10:25:20 AM EST
Great info.

Thanks!

SSN_Doc
Member
Offline
Posts: 2699
Feedback: 100% (2)
Link To This Post
Posted: 4/4/2009 11:09:27 AM EST
The nly strange thing is getting blown primers from .223 ammo. The only blown primers I've experienced have been using 5.56 ammo in a .223 chamber, and never teh other way around. You might want to let Hornady know about the problem and include the lot number, their a pretty good company, and would likely want to improve their QC and do some checks on that lot for safety/liability reasons.

You're right though, it wouldn't be a problem in a bolt action rifle, but some LEOs practice with this ammo.
nhsport
Team Member
Offline
Posts: 3948
Feedback: 100% (1)
Link To This Post
Posted: 4/4/2009 11:24:07 AM EST
With all the jaw flapping that goes on around here it is good when OP or someone else takes the time to actually try and shoot something and then report to us.
Thanks.

Yes I realise that to be a scientific and statistical test one needs to shoot boxes and boxes of ammo in precisely controlled conditions but thanks for your effort - we do get what you were going for.
us-kiwi
Member
Offline
Posts: 530
Feedback: 100% (1)
Link To This Post
Posted: 4/4/2009 11:34:10 AM EST
Great report - cleared up a lot of stuff for me.
Many Thanks for your effort.

on me!!
Motor Racing, Mountain Climbing and Bullfighting are the only true sports. All the others are simply children's games played by adults. - Ernest Hemingway
AZ-AR15
BAMCIS!!!
Offline
Posts: 3525
Feedback: 100% (8)
Link To This Post
Posted: 4/4/2009 11:40:45 AM EST
good post. Hopefully this stays at the top for a while so ppl can see it.
Celer, Silens, Mortalis
Derek45
Diligentia, Vis, Celeritas
Online
Posts: 4724
Feedback: 100% (9)
Link To This Post
Posted: 4/4/2009 11:44:47 AM EST
1:7 chromed lined COLT barrel. cut to 18" by randall at ar15barrels.com

hornady 55gr. VMAX
LC once fired.
surplus WC846(BLC-2) powder.
loaded on my DILLON XL650

100yrds. group.

NRA Life Member
USPSA-IPSC


"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."

- Benjamin Franklin
arowneragain
Jesus Saves!
Offline
Posts: 25976
Feedback: 100% (20)
Link To This Post
Posted: 4/5/2009 9:56:01 AM EST
Originally Posted By SSN_Doc:
The nly strange thing is getting blown primers from .223 ammo. The only blown primers I've experienced have been using 5.56 ammo in a .223 chamber, and never teh other way around. You might want to let Hornady know about the problem and include the lot number, their a pretty good company, and would likely want to improve their QC and do some checks on that lot for safety/liability reasons.

You're right though, it wouldn't be a problem in a bolt action rifle, but some LEOs practice with this ammo.



I may grab the lot # and send them a link to this thread. I, too, would never have expected excessive pressure signs from this ammo in that barrel. Cases fired in my .223 showed no signs of undure pressure (I realize that case observations aren't a perfect way to measure pressure, of course) but the cases from the LMT string all showed flattened primers and prominent ejector marks. The rifle's chamber was relatively clean - dirty, yes, but not obstructed or anything. Further, the hornady load was shot after the PRVI load, so any excess oil in the chamber would have been removed by then. This is the first time I've ever noticed anything like this out of any factory ammo in any chamber of known quality, and I frankly don't know what to make of it - I just know now that a bolt won't close with a spent primer in it's way.

Maybe it was just a matter of a handful of cases that were overly soft for some reason?


As a side note, I later went home and re-mounted my Eotech and BUIS to the LMT upper, and remounted my aimpoint to the CMMG upper. I re-zeroed at 50 yards, and the eotech returned to within 1/4" of zero. The BUIS needed 3 clicks (IIRC, that's about 2 moa) of windage to zero, and the aimpoint (in an old M68 mount) needed 3 moa of adjustment to return to zero. Both rifles shot 2-MOA 5-shot groups with PRVI M193 at 50 yards. That's honestly the very limit of my ability to shoot with no magnification. One day I may have to run another test with these rifles with some M193 and a good scope.
...But his word was in mine heart as a burning fire shut up in my bones, and I was weary with forbearing, and I could not stay...All my familiars watched for my halting...But the LORD is with me as a mighty terrible one...

Jeremiah 20 9-11
Hero
Life, Liberty, and the Pursuit of Happiness
Offline
Posts: 3924
Feedback: 100% (137)
Link To This Post
Posted: 4/5/2009 10:26:19 AM EST
Nice report, thanks!
"Government big enough to supply everything you need is big enough to take everything you have ... The course of history shows that as a government grows, liberty decreases." ~ Thomas Jefferson
Cold
AR Variants Mod and Juris Doctor (in training)!
Offline
Posts: 9710
Feedback: 100% (152)
Link To This Post
Posted: 4/5/2009 10:38:02 AM EST
Originally Posted By Derek45:
1:7 chromed lined COLT barrel. cut to 18" by randall at ar15barrels.com

hornady 55gr. VMAX
LC once fired.
surplus WC846(BLC-2) powder.
loaded on my DILLON XL650

100yrds. group.

http://img.photobucket.com/albums/v488/derek45/AR/IMGP6003.jpg



Is that the load you shoot for 3 gun ? What 69's or 75s do you shoot? Load wise?
When there's lead in the air... there's hope in the heart.

www.68Forums.com
Oh, how the ghost of you clings...
www.458SOCOMforums.com
Derek45
Diligentia, Vis, Celeritas
Online
Posts: 4730
Feedback: 100% (9)
Link To This Post
Posted: 4/5/2009 11:16:21 AM EST
69 & 77 get VARGET.

....but at 100yrds., these 55gr. VMAX shoot really well in this barrel.
NRA Life Member
USPSA-IPSC


"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."

- Benjamin Franklin
Conqueror
Offline
Posts: 394
Feedback: 0% (0)
Link To This Post
Posted: 4/5/2009 3:04:43 PM EST
Were people really doubting this? I don't think I've ever seen someone claiming 55gr ammo wouldn't shoot from a 7-twist barrel. It's generally the other way around, people pointing out that heavy ammo won't be stable from slow-twist tubes.

My 26" upper has printed a 0.3" group with 45gr JHPs.
Geohans
Member
Offline
Posts: 1249
Feedback: 99% (110)
Link To This Post
Posted: 4/5/2009 3:35:23 PM EST
Yes, but at 100yds the bullet is still rising in relation to the line of sight. The real test is how it performs as it descends. Try several weights out of the same 1/7 twist at 200 and 300, and see what happens.

The reason this discussion persists is due to a thread once called the ammo oracle; don't know if it's still around. It showed how a light bullet with a high spin rate would keep its nose up as it descends, rather than tracking down. This leads to turbulence, which affects accuracy.

Not that your test is invalid; some folks seem to think the jacket will spin off, or you'll keyhole.
Molon
All hail Jeanne Assam!
Offline
Posts: 4169
Feedback: 100% (289)
Link To This Post
Posted: 4/5/2009 5:01:56 PM EST
[Last Edit: 4/5/2009 5:22:36 PM EST by Molon]
Originally Posted By Geohans:
Yes, but at 100yds the bullet is still rising in relation to the line of sight. The real test is how it performs as it descends. Try several weights out of the same 1/7 twist at 200 and 300, and see what happens.

The reason this discussion persists is due to a thread once called the ammo oracle; don't know if it's still around. It showed how a light bullet with a high spin rate would keep its nose up as it descends, rather than tracking down. This leads to turbulence, which affects accuracy.

Not that your test is invalid; some folks seem to think the jacket will spin off, or you'll keyhole.



Testing performed by C.E. Harris at Aberdeen Proving Ground and later at Sturm-Ruger has shown that the above statement is false. The testing showed that “overspinning” quality light-weight bullets from a fast twist barrel does not become an issue unless you have a gyroscopic stability factor greater than 5.0 (which would require something along the lines of a 1:6” twist barrel launching a 55 grain bullet at over 3500 fps) or unless firing at an angle greater than 85 degrees.

After the U.S. Military adopted the 1:7” twist for the M16A2, C.E. Harris did extensive testing comparing the accuracy of light-weight bullets fired from 1:10” twist barrels and 1:7” twist barrels using 52 grain Sierra MatchKings. The accuracy testing was done from 200 yards, well into the downward slope of the trajectory, and the accuracy results from the two different twist barrels were nearly identical.

Contrary to what has been posted on the Internet, quality 55 grain bullets can shoot superbly from fast twist barrels. The 10-shot group pictured below was fired from a Krieger barreled AR-15 with a 1:7.7” twist using 55 grain BlitzKings.

Also, I've launched Hornady 40 grain V-MAX bullets at over 3,600 fps from chrome lined, NATO chambered barrels with 1:7" twists with no ill effects.







Member of the General Population
chapperjoe
GIANTS 31 patriots 24
Offline
Posts: 27151
Feedback: 100% (346)
Link To This Post
Posted: 4/5/2009 5:06:04 PM EST
[Last Edit: 4/5/2009 5:07:57 PM EST by chapperjoe]
the question i have ... does M193spec ammo produce 55gr vmax accuracy?

when most people think of running (or speak against running) 55gr through a 1/7, I don't think they mean vmax...

There is but one truth in the world and it is all yours. If you are not sure of it stay at home; but if you are sure don't look back and it will be your way.

Honored to be a "Proud Member of Ranstad's Militia"
JJREA
Member
Offline
Posts: 12208
Feedback: 100% (6)
Link To This Post
Posted: 4/5/2009 5:10:54 PM EST
Somehow, I'm skeptical that this will stop:

A. the question about 1/7 twist for 55 grainers

And

B. All the supposed experts who say a 1/7 isn't good for 55 grainers. Heck, I even here some people that know a thing or two say it's not ideal. Or that you'll lose like 10% accuracy. Well, I don't agree because what you have just shown and because any 1/7 I've had has shot 52's very very well. Better than even some heavier loadings in that barrel. I have a 1/7 that absolutely hates the 69's. Go figure.


EVERY BARREL IS PREJUDICED
Jesus came to comfort the afflicted and afflict the comfortable. - My Pastor
JJREA
Member
Offline
Posts: 12209
Feedback: 100% (6)
Link To This Post
Posted: 4/5/2009 5:12:20 PM EST
Originally Posted By chapperjoe:
the question i have ... does M193spec ammo produce 55gr vmax accuracy?

when most people think of running (or speak against running) 55gr through a 1/7, I don't think they mean vmax...



It doesn't matter. That has nothing to do with twist and everything to do with that ammo and barrel combo. You should know better than that. If you don't, you haven't shot enough. IMHO. Sorry, but this subject gets to me. Time for me to stop posting over here. I'll probably start saying things I regret.
Jesus came to comfort the afflicted and afflict the comfortable. - My Pastor
myitinaw
Men for Others
Offline
Posts: 7359
Feedback: 100% (17)
Link To This Post
Posted: 4/5/2009 5:18:36 PM EST
This is a "ful of win" post, thanks for your efforts!

A socialist may indeed be academically superior, And yet, most certainly, emotionally retarded…
myitinaw 2006
SB_Matt
Home of the Hard Blue barrel.
Offline
Posts: 152
Feedback: 0% (0)
Link To This Post
Posted: 4/5/2009 5:23:27 PM EST
Decent write up. I think a video is better. While I did not shoot at 100 yards. I show that well made, quality barrels will shoot light bullets accurately. There has always been a debate about this in some form or fashion. I shot 40 grain bullets at 300 yards with good accuracy.

CLICK HERE
www.superiorbarrels.com
Every good man deserves a good rifle. That starts with a Superior Barrel.
No other barrel lasts longer and shoots tighter than a Hard Blue barrel.
JJREA
Member
Offline
Posts: 12211
Feedback: 100% (6)
Link To This Post
Posted: 4/5/2009 5:29:05 PM EST
Originally Posted By SB_Matt:
Decent write up. I think a video is better. While I did not shoot at 100 yards. I show that well made, quality barrels will shoot light bullets accurately. There has always been a debate about this in some form or fashion. I shot 40 grain bullets at 300 yards with good accuracy.

CLICK HERE


That's IMPOSSIBLE THEY SUPPOSEDLY BLOW UP RIGHT AFTER THEY LEAVE THE MUZZLE. THIS CAN'T BE.

Maybe this thread will get tacked, because that is one thing "they" almost ALWAYS point to. The 40 grain bullets. Which I could see how sometimes maybe it is problematic, but it is on the extreme light side. And it is usually brought when people are asking specifically about the 55 grainers. Anyways, good post.
Jesus came to comfort the afflicted and afflict the comfortable. - My Pastor
vicious_cb
Offline
Posts: 1203
Feedback: 100% (1)
Link To This Post
Posted: 4/5/2009 5:36:11 PM EST
[Last Edit: 4/5/2009 5:36:40 PM EST by vicious_cb]
I really dont get the point of shooting really lightweight varmint bullets anyway. Whats the point in shooting 36gr or 40gr bullets? Just so you can watch the little ground hogs explode into a dozen pieces? A heavy grain bullet will kill varmints just as dead. I have no need for a 1:9 or even a 1:8 for that matter.
SB_Matt
Home of the Hard Blue barrel.
Offline
Posts: 155
Feedback: 0% (0)
Link To This Post
Posted: 4/5/2009 5:49:16 PM EST
Originally Posted By vicious_cb:
I really dont get the point of shooting really lightweight varmint bullets anyway. Whats the point in shooting 36gr or 40gr bullets? Just so you can watch the little ground hogs explode into a dozen pieces? A heavy grain bullet will kill varmints just as dead. I have no need for a 1:9 or even a 1:8 for that matter.


We usually don't shoot light bullets either but yes that is why you shoot light bullets.

I did this to show people that you can reliably shoot light bullets from a well made quality barrel that is 1:7 twist. People I talked to would doubt that you could shoot anything lighter than a 55 grain bullet in a 7 twist. So I figured I would show the lightest bullet that held together with a compressed load and demonstrate how it performed. This happened to be a 40 grainer.

I hope you enjoyed the video.

www.superiorbarrels.com
Every good man deserves a good rifle. That starts with a Superior Barrel.
No other barrel lasts longer and shoots tighter than a Hard Blue barrel.
mercdank
Offline
Posts: 989
Feedback: 100% (166)
Link To This Post
Posted: 4/5/2009 6:01:05 PM EST
my 1/9 twist barrel stabalizes 75gr. bullets well, even out to 300 yards. every barrel is different, theres no way to make a blanket statment about this, too many variables.
cobrasks
Offline
Posts: 2480
Feedback: 100% (1)
Link To This Post
Posted: 4/5/2009 6:20:20 PM EST
Very interesting ,and good to hear .

Since this big run on ammo started ,I've been using mostly 55 grain in my Colt 6920 . (That's a 1/7 twist carbine as well )

I honestly would like to see a series of tests that include 50 yards,100 yards ,150 yards,and 200 yards with
55 grain,62,and 77 in a 16 inch barrel with a 1/7 twist .
Especially using a dot sight sighted in for 50 yards like so many of us have .

Preferably from an average Joe just wanting to see for themselves instead of some gun mag writer trying
to prove their point of view .
  Previous Page
Page:  / 3