Service Rifle Accuracy. - M14 Forum

M14 Forum


Service Rifle Accuracy.

This is a discussion on Service Rifle Accuracy. within the The M14 forums, part of the M14 M1A Forum category; I have found one of the unfortunate things about the internet is there is information given without any reference to the source. This leads to ...


Go Back   M14 Forum > M14 M1A Forum > The M14

8Thanks
Reply
 
LinkBack Moderator Tools Display Modes

Old November 19th, 2015, 09:26 PM   #1
Old Salt
 
lysander's Avatar
 
Join Date: Apr 2015
Location: North Carolina
Posts: 1,755
Service Rifle Accuracy.

I have found one of the unfortunate things about the internet is there is information given without any reference to the source. This leads to problems as sometimes opinion is given as fact and sometimes questionable information is given. I have run across this little nugget several places:

Quote:
1. acceptance accuracy for 1903 Springfield was 3" at 100 yards.
2. acceptance accuracy for M1 Garand was 5" at 100 yards.
3. acceptance accuracy for M14 was 5.5" at 100 yards and was waivered continually as it could not meet that.
4. acceptance accuracy for M16 series is 4.5" at 100 yards.
I would ask the author of this, where did this information come from? Some is incomplete, thus very misleading, and some is just wrong.

I have researched the specified acceptance accuracy of several US small arms from the published military specifications, (most are available on-line) and this is what I have found:

M1903
I cannot find any authoritative documents on the M1903, M1903A3 or M1903A4. If someone can provide a reference to the acceptance requirements, it would be greatly appreciated.

M1 Garand
REF: Army Specification 52-1-21 and MIL-R-3285

Quote:
3.9 Accuracy.-The accuracy of each rifle shall be such that five successive shots fired at 100 yards shall fall on the target so as to group within or be cut by the size circle specified in 4.9.
.
.
.
.
4.8 Targeting firing tests.

4.8.1 Rifle M1 - At a range of 100 yards and using a fixed or muzzle and elbow rest, each rifle of a lot shall be fired one series of five rounds of caliber .30 ball ammunition of known accuracy, at a 5-inch bull’s eye or a "T" target.

4.8.1.1 With the rear sight set at zero windage, the aperture elevated eight clicks from the lowest position and the sights aligned at 6 o’clock on-the target, all shots shall come within or cut the edge of the bull’s eye (or a centrally located 5-inch circle if a “T” target is used) or it shall be possible to move the group within the bull’s eye (or circle) with not more than six clicks of adjustment, either up or down, right or left, or both.
.
.
4.9 Accuracy firing test.

4.9.3. Rifle, M1.

4.9.1.1 Ninety-toot range option. - At the option of the contractor, each rifle may be fired at least one series of 5 rounds of caliber .30 standard service ball ammunition of known accuracy, using a fixed or a muzzle-and-elbow rest, at a range of not less than 90 feet, The accuracy shall be such as to meet the corresponding requirements of the above paragraphs. If rifles are fired at a 90 foot range, then 1 percent of all rifles shall also be fired at a 100 yard range as specified in 4.8.1.
M14
REF: MIL-R-45012

Quote:
3.3.24.2 Accuracy.

3.3.24.2.1 Process qualification rifles. The accuracy of process qualification rifles shall be such that when fired 10-shot targets at a range of 100 yards, the average figure of merit (FM) shall not be more than 3.2 inches and the standard deviation shall not be more than 0,6 inch when tested as specified in 4.5.7.1 and 4.5.7.4 using selected lots of ammunition (see 4.4.4.2).

3.3.24.2.2 Individual rifle acceptance. The accuracy of individual rifles shall be such that when fired 10-shot targets at a range of 100 yards, the figure of merit (FM) shall be not more than 3.2 inches when tested as specified in 4.5.7.2 and 4.5.7.4, using selected lots of ammunition (see 4.4.4.2). When using unselected lots of ammunition (see 4.4.4.2), the accuracy of individual rifles shall be in accordance with the acceptance criteria established by firing the ammunition to be used for testing in the process qualification rifles (see 4.4.3.4, 4.5.7.2 and 4.5.7.4).
.
.
.
4.5.7.1.3 Target measuring and calculations. The following data shall be obtained:

(a) The figure of merit, the extreme horizontal (EH) plus extreme vertical (EV) divided by two [(EH+EV)/2] shall be measures and recorded for each 10-shot target. Measuring of targets shall be to the nearest tenth of an inch using the center of the bullet holes as a reference points.
.
.
.
4.5.7.2 Individual rifle acceptance. When using selected lots of ammunition (see 4.4.4.2), individual rifles shall be fired 10-shot targets for accuracy using the procedure specified in 4.5.7.1.2, and the targets measured as specified in 4.5.7.1.3 (see 3.3.24.2.2). When using unselected lots of ammunition (see 4.4.4.2), individual rifles
shall be fired 10-shot targets for accuracy using the procedure specified in 4.5.7.1.2 and the specific sequential test plan and acceptance criteria (see 3.3.24.2.2 and figures 1 through 5) determined for each lot of ammunition used.
[NOTE: “4.4.4.2 Ammunition. The M60 high pressure test cartridge shall be used for the high pressure resistance test, selected lots of M80 ball cartridge which gave an average mean radius of 4 inches or less in 600 yard ammunition acceptance tests shall be used in the targeting and accuracy tests and unselected lots of M80 ball cartridge shall be used in the functioning and reliability tests.”]

M16 and M16A1
REF: MIL-R-45587

Quote:
3.3.2.0 Targeting and accuracy. A series of 10 rounds fired from each rifle at 91.4 or 45.7 meters shall be within the extreme spread and targeting area (heavy outline) specified in Figure 1. when front and rear sights are set as follows and when tested as specified in 4.8.6. The normal rear sight peep (sight rotated fully rearward) shall be used with the rear sight set centrally in the slot for windage within plus or minus two (2) clicks. The top edge of the front sight post flange shall be set flush to .030 inch below the bottom surface of the front sight slot. Maximum utilization shall be made of the 91.4 meter range. Ammunition shall be Government standard M193, 5.56mm ball cartridges conforming to MIL-C-9963, and shall have been certified by the Government to be of a quality that will group within a mean radius of 1.2 to 1.4 inches at 200 yards as measured in accordance with MIL-C-9963.


(to be continued)

Thanks from unkola
lysander is offline  
Remove Ads
Old November 19th, 2015, 09:28 PM   #2
Old Salt
 
lysander's Avatar
 
Join Date: Apr 2015
Location: North Carolina
Posts: 1,755
M16A2
REF: MIL-R-63997 - Same as M16A1, until Rev C, then this Figure 1 was used (note the allowable EV and EH have increased to 5.0 inches):



XM4
REF: MIL-C-70599

Quote:
3.4.6 Targeting and accuracy. A series of 10 rounds fired from each carbine at a range of either 91.4 meters or 45.7 meters shall be within the extreme spread and targeting area (heavy outline) specified in Figure 1 when front and rear sights are set as follows. The normal rear sight peep (sight rotated fully rearward) shall be used with the rear sight set centrally in the slot for windage with in plus or minus five (5) clicks. The top edge of the front sight post flange shall be set flush to .030 inch below the bottom surface of the front sight slot. Maximum utilization shall be made of the 91.4 meter range. Ammunition shall be Government standard M855, 5.56mm ball cartridges conforming to Drawing 9342868, and shall have been certified by t h e Government to be of a quality that will have an average horizontal and vertical standard deviation of 3.4 to 4.0 inches at 600 yards as measured in accordance with MIL-C-9963. Testing shall be as specified in 4.5.3.1, TABLE III.


M4
REF: Same as above just REV A

The M4 changed this slightly:

Quote:
3.4.6 Targeting and accuracy. A series of 10 rounds fired from each carbine at a range of 91.4 meters shall be within the extreme spread and targeting area (heavy outline) specified in Figure 1 when the front and rear sights are set as follows. The normal rear sight peep (sight rotated fully rearward) shall be used with the rear sight set centrally in the slot for windage within plus or minus five (5) clicks. The top edge of the front sight post flange shall be set flush to .030 inch below the bottom surface of the front sight slot. Ammunition shall be Government standard M855, 5.56mm ball cartridges conforming to Drawing 9342868 and shall have been certified by the Government to be of a quality that will have an average horizontal and vertical standard deviation of 3.4 inches to 4.0 inches a t 600 yards as measured in accordance with MIL-C-63989.


Then with REV B, Figure 1 changed again, now it is this, (EV and EH are now 5.6 inches):



M4A1
The M4A1 (REF: MIL-C-71186) is the same as the M4.

[NOTE: The requirements for windage were later dropped. After 2009, all M16/M4 series weapons used this paragraph for targeting and accuracy:

“Ten (10) rounds shall be fired from each weapon at a target, the heavy outline specified in Figure 1, located at 100 yards. The extreme spread shall be in accordance with Figure 1. The M855, 5.56mm ball cartridges shall be in accordance with drawing 9342868 and shall have an average vertical and horizontal standard deviation between 3.4 inches and 4.0 inches at 600 yards. For each weapon, the target and accuracy measurement shall be taken using rounds number 5 thru 15 of the function firing semi-automatic (see 3.6.4.1) verification.”

The various Figure 1s remained the same as the ones shown above.]

For comparison purposes (I am not going to transcribe the paragraphs):

Carbine M2 and M3 (JAN-C-691) - 5 out 7 shots shall cut a 5 inch circle at 100 yards, using unselected lots of ammunition.

M240 Machine Gun (MIL-M-63314): With the weapon in a vise, a ten round belt shall be fired in one pull of the trigger with the gas plug in position #1. The extreme spread shall not be greater than 30 cm. The spare barrel will also be tested to the same criteria; the mean point of impact for the two barrels shall not differ by more than 28.3 cm, with selected ammunition lots.

(to be continued)

Thanks from 2336USMC and unkola

Last edited by lysander; November 19th, 2015 at 09:49 PM.
lysander is offline  
Old November 19th, 2015, 09:30 PM   #3
Old Salt
 
lysander's Avatar
 
Join Date: Apr 2015
Location: North Carolina
Posts: 1,755
Now, why can the initial quote be misleading?

Well, at first glance, the M16/M16A1 seems to have tighter accuracy standards than an M1 Garand, after all, 4.8 inches is smaller than 5 inches. But, it isn’t, necessarily.

The M1 Garand was required to put five shot inside or cut a 5 inch circle, the M16/M16A1 was require to have a maximum extreme spread of 4.8 inches. It’s a Granny Smith apple to Macintosh apple comparison, it seems to be the same, but it is slightly different.

To demonstrate, here is a nice group that passes the M16/M16A1 requirements:



It fits comfortably inside the 4.8 inch window:





But, when you drop it on the M1 Garand 5 inch circle, it fails:



Anything in the corners of the 4.8 inch extreme spread requirement will be outside the 5 inch circle. But, then again, the M1 requirement allows the bullet to cut the 5 inch circle, so the all the shots must be inside a 5.6 inch circle, but there will still be open corners that preclude certain M16 groups from passing the M1 requirements, but so too, will there be groups that pass the M1 requirement that fail the M16. Further, the M1 was fired by hand, off a rest, the M16 - from a vise, so operator error must be accounted for with the M1. (There is also the statistical confidence of a 5 round group versus a 10 round group . . .)

So, which was required to be more accurate? Good question. You could do some statistical analysis and find what size mean radius (MR) gets six sigma of the shots inside the respective targets, and then compare the two MRs . . .

But, I will leave that exercise to the reader if he/she so wished. I will go out on a limb and offer that the two requirements are for practical purposes - equal.

However, the M4 series now has a 5.6 inch extreme spread, which is directly comparable to the M16/M16A1’s requirement. The current production M4 series is not required to be as accurate as the M16 was . . .

(The M16A2 requirement was opened up to 5.0 inches, but that was done in 2009, I don’t think we have bought any M16A2s since that time. I don’t have access to the M16A3 or A4 specifications, but I would guess they are similar to the M16A2.)

Now, I am sure someone out there is going to say:

1) “But, the M4 series is a carbine and the others are rifles, so that’s not a fair comparison . . . ”
2) “It’s the sight radius of the M4 . . .”
3) “It’s the shorter barrel . . .”

My answers:

1) The M4A1 is the primary individual weapon of the infantryman in both the Army and the Marine Corps, as was the M1, M14 and M16, it is immaterial if it is classed as a rifle or a carbine.
2) The accuracy test is from a vise and there is no shot-to-shot re-aiming of the weapon. Tens rounds are shot at a 16 x 22 piece of paper, as long as there are ten holes on the paper they can calculate the extreme spreads, so sight radius plays no part in this.
3) A quick google search will turn up a few good quality experiments that show shorter barrels are not inherently less accurate.

In conclusion, from the information available, I feel it is safe to say that the M1 Garand, M14 and M16A1/M16A2 were required to be of comparable accuracy. Which makes sense, to make an automatic rifle more accurate, requires greater care in manufacture and assembly, and therefore it comes with a higher price tag. If the Army requires that a rifle be able to hit a man sized target 200 yards away 99.9% of the time, why should they require, and pay, for something that exceeds that requirement?

P.S. Why did they reduce the accuracy requirement for the M4? I have no idea, and I do find it somewhat disturbing. Unless they feel the ‘system accuracy’ is the same with an optical sight, as the loss of weapon accuracy is compensated for by a reduction in aiming error, but that is an expensive way to do that as I cannot imagine that an M4 that is required to hold a 4.8 inch ES (or even a 5 inch ES) is $500 more expensive than one that is an inch worse.

P.P.S. Again, if someone has primary documentation of the accuracy requirements of the M1903, it would be interesting to read.

lysander is offline  
 
Old November 20th, 2015, 12:40 AM   #4
Old Salt
 
rwilli's Avatar
 
Join Date: Jan 2013
Location: New Mexico
Posts: 1,270

Awards Showcase

That was an informative and interesting read, Thanks Lysander.

rwilli is online now  
Old November 20th, 2015, 02:06 AM   #5
Grunt
 
subscriber's Avatar
 
Join Date: Mar 2015
Location: California
Posts: 101
This site measures the drop off in accuracy and velocity over 10,000 rounds of steel VS brass cased ammo using AR-15 rifles. Some of the steel cased ammo uses steel jacketed bullets: http://www.luckygunner.com/labs/bras...el-cased-ammo/

It is interesting that the test starts at about 3.5 MOA for all three ammo types. The cheap ammo chews the barrels out after less than 5000 rounds, while the expensive ammo performs much more consistently all the way to 10,000 rounds.

My guess is that the true degradation follows more of a curve, rather than a step; and that the shape of the graph is due to an overly large sampling interval.

Not exactly the main-line of the is thread; but it answers the question; will steel bullets wear out my barrel faster?

Note that the "test" was done at firing rates that clearly overheated the barrels, so shooing a more modest pace would probably increase barrel life significantly.







From this at 50 yards:





To this, with the cheap ammo:



Last edited by subscriber; November 20th, 2015 at 03:58 AM.
subscriber is offline  
Old November 20th, 2015, 03:26 AM   #6
Lifer
 
Join Date: Jun 2012
Location: South Charleston, WV
Posts: 2,405
Good to see factual research on questions/statements coming from the internet, good read and appreciate it, thanks.

Instructor is offline  
Old November 20th, 2015, 04:23 AM   #7
Automatic Rifleman
 
tlturbo's Avatar
 
Join Date: May 2014
Location: West Palm area, Florida
Posts: 151
I wouldn't call that CHEAP Ammo, more like CRAP ammo. Am I seeing right that almost all shots keyholed? What ammo was this?

Thanks from USN14
tlturbo is offline  
Old November 20th, 2015, 04:39 AM   #8
Grunt
 
subscriber's Avatar
 
Join Date: Mar 2015
Location: California
Posts: 101
Quote:
Originally Posted by tlturbo View Post
I wouldn't call that CHEAP Ammo, more like CRAP ammo. Am I seeing right that almost all shots keyholed? What ammo was this?
It was either Brown Bear of Wolf that keyholed. Both resulted in substantially smoothbore AR barrels by the time 10,000 rounds were fired.

Quote:
For the test, 10,000 rounds each of Federal, Brown Bear, Wolf, and Tula ammunition in caliber .223 Remington were used. Each brand of ammunition used a 55 grain full metal jacketed bullet with a lead core. The Federal 55gr .223 ammunition featured a solid copper jacket and a brass case, while the other three brands used a bimetal (steel and copper) jacket and a steel case. The Brown Bear ammo’s steel case was coated in a green “lacquer,” while the Tula and Wolf cases were coated with a gray polymer.


Last edited by subscriber; November 20th, 2015 at 09:45 AM.
subscriber is offline  
Old November 20th, 2015, 06:43 AM   #9
Doc
Lifer
 
Doc's Avatar
 
Join Date: Dec 2011
Location: MS
Posts: 3,387
Great read - thanks for posting

Doc is offline  
Old November 20th, 2015, 06:57 AM   #10
Grunt
 
Join Date: Sep 2015
Location: USA
Posts: 95
Great info, thanks.

And I'm not buying any more Wolf for my AR...

ABTOMAT is offline  
Old November 20th, 2015, 07:12 AM   #11
Lifer
 
JayKosta's Avatar
 
Join Date: Mar 2009
Location: Endwell NY
Posts: 2,189
Quote:
Originally Posted by lysander View Post
...
But, when you drop it on the M1 Garand 5 inch circle, it fails:


...
-------------
Just very minor 'nit picking' -

The '5 inch circle' test would be satisfied if the center of the circle is moved so the edge of the circle 'cuts the bullet holes' that are located at the 7 o'clock and 8 o'clock positions.

I have not tried to determine if some other arrangement of bullet holes would not pass the 5 inch test, but do pass the 4.8 inch test.

Thanks for the information about the various testing and acceptance procedures.

Jay Kosta
Endwell NY USA

JayKosta is offline  
Old November 20th, 2015, 08:23 AM   #12
Old Salt
 
lysander's Avatar
 
Join Date: Apr 2015
Location: North Carolina
Posts: 1,755
Quote:
Originally Posted by JayKosta View Post
-------------
Just very minor 'nit picking' -

The '5 inch circle' test would be satisfied if the center of the circle is moved so the edge of the circle 'cuts the bullet holes' that are located at the 7 o'clock and 8 o'clock positions.

I have not tried to determine if some other arrangement of bullet holes would not pass the 5 inch test, but do pass the 4.8 inch test.

Thanks for the information about the various testing and acceptance procedures.

Jay Kosta
Endwell NY USA
That group might pass, but if you move the upper right hole further to the right, say another .6 inch, it will not pass.

One group that will always pass the 4.8 ES test but never pass the 5 inch circle: one with the maximum allowable EH and EV in the corners.

But, you get the point there are some groups that meet the 4.8 ES, but fail the 5 inch test . . .


Last edited by lysander; November 20th, 2015 at 08:40 AM.
lysander is offline  
Old November 20th, 2015, 04:45 PM   #13
Old Salt
 
lysander's Avatar
 
Join Date: Apr 2015
Location: North Carolina
Posts: 1,755
Quote:
Originally Posted by JayKosta View Post
-------------
Just very minor 'nit picking' -

The '5 inch circle' test would be satisfied if the center of the circle is moved so the edge of the circle 'cuts the bullet holes' that are located at the 7 o'clock and 8 o'clock positions.

I have not tried to determine if some other arrangement of bullet holes would not pass the 5 inch test, but do pass the 4.8 inch test. [there are theoretically and infinite number of groups that fit this situation, all those with holes in opposite corners, both outside the 5.6 radius, and those with one hole in a corner and with the extreme vertical and extreme horizontal at the maximum value.]

Thanks for the information about the various testing and acceptance procedures.

Jay Kosta
Endwell NY USA
Here is a group that passes the 4.8 inch ES but unambiguously fails the 5.0/5.6 inch maximum group size:


lysander is offline  
Old November 20th, 2015, 05:30 PM   #14
Old Salt
 
Douglas Haig's Avatar
 
Join Date: Dec 2008
Location: Southeast
Posts: 1,945
Thanks, Lysander, for a well thought out and documented post.

However, It won't matter too much for the readers as all the modern commercial M1A rifles especially those scouts and socoms all print under one or two MOA or so the forum reads.

I wonder what the Government's Springfield Armory (Not commercial SAI), TRW, International Harvestor, Colt, Winchester, Harrington&Richardson and all the subcontractors were doing so wrong that they produced such sloppy 5" grouping weapons. :)


Last edited by Douglas Haig; November 20th, 2015 at 05:54 PM. Reason: Speling
Douglas Haig is offline  
Old November 20th, 2015, 06:19 PM   #15
Grunt
 
subscriber's Avatar
 
Join Date: Mar 2015
Location: California
Posts: 101
Quote:
Originally Posted by Douglas Haig View Post
I wonder what the Government's Springfield Armory (Not commercial SAI), TRW, International Harvestor, Colt, Winchester, Harrington&Richardson and all the subcontractors were doing so wrong that they produced such sloppy 5" grouping weapons. :)
As you know, there is a difference between an acceptance threshold, and the expected performance of the population.

It is quite possible that the average performance of the population could be twice as good as the minimum acceptable grouping capability. If this were not so, then it would mean that many service rifles would need to be rejected and reworked before being issued...

subscriber is offline  
Reply

  M14 Forum > M14 M1A Forum > The M14


Search tags for this page

1903 100yd accuracy

,

m-14 rifle accuracy

,

m14 accurracy requirement

,

m1a service rifle

,

service rifle competition m14 accuracy

,

service rifle lead m14

Click on a term to search for related topics.

Moderator Tools
Display Modes


Similar M14 Forum Discussions
Thread Thread Starter Forum Replies Last Post
Record of Texas M1A Rifles Different Devine M1A 108 June 14th, 2017 11:04 AM
How long will an M14 stock stay tight with or without glass bedding? Gus Fisher Gus Fisher 22 March 14th, 2013 09:35 AM
NRA Rules for Service Rifle Equip and Ammo XXIV Corps Rifle Competition 0 April 25th, 2012 10:18 AM
Data base - M1A under sn 004600 Different Devine M1A 15 September 15th, 2007 10:00 AM



Top Gun Sites Top Sites List