Hot barrel effect on accuracy?

Sporting Lad

Sporting Lad

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On a typical M-14 day at the range I'll shoot five groups of five rnds each (25 rnds total) with time out to reload mags between groups. The barrel does get warm, but IDK how much that effects my "accuracy".

My .308 Savage 14, on the other hand, seems to go astray after ~ten rnds have been fired. It's got a pencil-thin barrel. It's not a 'battle rifle' so much as a fine deer hunter. I think it's meant to be sighted in at the start of the hunting season, then fired once, maybe twice in the course of a typical hunting day. Barrel heating is never an issue when used for that purpose.

Now take a look at the "precision shooting" geek: He'll fire a 3 rnd group, then go for coffee or something while he waits for his barrel to cool off before he'll fire another 3 rnds. He gets nice tight groups (on a good day) and I can understand his passion/obsession/quest for that holy grail of 1 MOA.

But you can't be doing that in a fire fight. You can't be having a cease fire after every 3 rounds.
Come to think of it, that might not be a bad idea if we could get the other side to agree to it! :0 ]

But seriously, folks, how much is my M-14's accuracy being effected by shooting 25 rounds in ~30 minutes?
Maybe I ought to go out there and conduct my own testing, but I'm interested in what other members have been doing.
 
I have found that my Norinco 14S shoots much better groups if I don't let it cool off. First group of the day will be high andall over the place, first group after target change will also be high and not as good of a group as the rest.
Rodney
 
Hmmm, battle rifle eh. My XCR is the little 30, that count? ;)

Last weekend I shot 3 groups, testing barrel temp performance.
First group was 5 rounds, within 10 seconds. Results were ~2moa.
Second group was 90 rounds within 90 seconds. Results, ya right.
Third group was immediately after 2nd, 5 rounds, 10 seconds. My group was over 7moa.

I have it all on video, but it's a work in progress. :)
 
That is interesting stuff. So after 90 quick rounds your groups were still lethal.
Sure 7 MOA would do a "zombie" at 100 yds. Good enough standard for a typical fire fight.
I'm very keen to see the vid!

BTW-- Did that 90 seconds include your mag changes? 5 round mags??
 
rodauto said:
I have found that my Norinco 14S shoots much better groups if I don't let it cool off. First group of the day will be high andall over the place, first group after target change will also be high and not as good of a group as the rest.
Rodney
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This is also good stuff. I always call my first round a "fouling shot" (unless it's dead-on centre!).
Is it possible that you simply settle in and get serious after those early groups?
OTOH, I have seen a few shooters pack up and go home in disgust after getting that early group that's spread out.
Maybe they should stick around and get warmed up a bit?
 
rodauto said:
I have found that my Norinco 14S shoots much better groups if I don't let it cool off. First group of the day will be high andall over the place, first group after target change will also be high and not as good of a group as the rest.
Rodney
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Do you have a plastic stock?
 
I notice a more accurate trend when shooting with a cold barrel in winter. Whether this is due to barrel temp, or me being frozen into a solid shooting position is still up to debate :)

It makes sense to me that a hot barrel opens groups up, as materials (molecules) typically expand when heat is applied to them. Theoretically, the bore would expand ever so slightly too you would think....
 
Gleaned from FM 23-8 Department of the Army Field Manual:

(The following rates of fire can be maintained with-out danger to the firer or damage to the weapon.)
Semiautomatic:
1 minute _40 rounds
2 minutes _40 rpm ( 80 rd total)
5 minutes_30 rpm (150 rd total)
10 minutes _20 rpm (200 rd total)

This of course was in regard to U.S. Miltary M-14's. However, I would guess that this would work for the M305's as well.
 
Hmmm... Well, that's as may be for the US Army M-14s' durability under fire, but they don't mention anything about their accuracy during or after their shootin'fest... They may not have actually hit anything, but at least there's no danger or damage. 'And that's a Good Thing." :0 ]
 
Accuracy and the methods for attaining it are defined and determined by the mission of the rifle IMO. The three shot groups fired from cold barrels are the best way to go for a hunting rifle. That is the way they will operate during deer season. That rifle will sit around in camp, ride around on the quad, and if everything is done right - will only come out to make one shot. I accepted and used that for my hunting guns and have never been let down.

For the M14 I think you have the right of it: 5 shots, reload, 5 shots. The M14 will outshoot you all day long and with iron sights you probably won't be dwelling in the sub MOA range even with cold barrels. You will be the causal factor in determining accuracy. I shoot the M14 like a battle rifle - from formal and improvised positions. This is just my hot air - but I think the M14 was meant to be shot this way...with iron sights, slings, and skill.
 
One Lung Wonder said:
Accuracy and the methods for attaining it are defined and determined by the mission of the rifle IMO. The three shot groups fired from cold barrels are the best way to go for a hunting rifle. That is the way they will operate during deer season. That rifle will sit around in camp, ride around on the quad, and if everything is done right - will only come out to make one shot. I accepted and used that for my hunting guns and have never been let down.

For the M14 I think you have the right of it: 5 shots, reload, 5 shots. The M14 will outshoot you all day long and with iron sights you probably won't be dwelling in the sub MOA range even with cold barrels. You will be the causal factor in determining accuracy. I shoot the M14 like a battle rifle - from formal and improvised positions. This is just my hot air - but I think the M14 was meant to be shot this way...with iron sights, slings, and skill.
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X2. Well said. I wish for 18 year old eyes again.:(

My rifle has put 1400 rounds down range, all over irons and most unsupported prone and standing. Bench rest for zeroing different ammo makes, accuracy upgrade checks, or ammo head to head testing check only. And do this as far as you can shoot on your range. These rounds fly to 200 meters in a fraction of a second so stretch their legs and don't lead up the 50 or 100 yards backstops. I've said it before many times, these rifles give you the feel of a full size battle rifle over irons from days of yore at probably the most economical cost using surplus or bulk 762X51. I don't reload anymore, and at .303 prices,.. my No4 and No1 don't get shot alot anymore, so the nork fills the need for speed matched up with it's utterly reliable and not that bad shooting 762Norko ammo! 762NATO works okay too in the Asian gun!:cool:
 
"Philosophy of Use"...

RememberTheSomme said:
X2. Well said. I wish for 18 year old eyes again.:(
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Haha, yeah! I went thru Basic Training on the M-1 (Garand). My 18 year old eyes plus my boyhood rifle training, HS rifle team, etc, were good enough to earn my "Expert Rifleman" badge with the highest score in the company. When I arrived at my TO&E unit in Germany I was issued the M-14 (along with a number of other weapons). During our qualification trials there was nobody going around measuring groups with a micrometer. The standard for top honours was being able to drop a silhouette out to 350 meters with the USGI rifle. To "just qualify" you had to hit damn near everything that popped up from 25 to 250 meters or you got the green weenie. The 'main battle rifle' is made to strike a man-sized target in centre of mass at those ranges.
You peg an enemy there and he won't bother you anymore. That's what it was about. There was no time for turning of elevation knobs--we just had to know where to put the front site to score a hit on targets appearing in random order at various distances.

It's as Mr. Wonder said in his excellent post "...defined and determined by the mission of the rifle " or, as that "Nut'n Fancy" guy on YT is always discussing, "Philosophy of Use". Life is full of compromises and no one rifle will excel at every aspect of shooting (maybe that's why I have so many!).

Fast forward to 2014... Here I am now with my M305 still shooting iron sights and trying to figure out what happened to my 18 year old eyes. Peg off something at 350?? Hah! I can hardly even see anything at 350 now, even with my new shooting glasses... :)0 |
My Welsh game-keeper friend keeps telling me, "Nobody over the age of 50 ought to be using iron sights!" :^)

Well, I guess we digressed a bit from hot barrels, eh? That's OK with me--I like the turn we took a few posts back.
Cheers!
 
If you ever get into a fire fight, accuracy will be the least of your problems. Groups do not apply to fire fights anyway. Hitting the target, anywhere is the only thing you care about.
25 rounds in 30 minutes isn't terribly fast. DCRA F Class gives shooters 29 minutes for 20 rounds at 900 and 1,000 yards.
In any case, as a barrel gets hot, groups can open but it has multiple causes.
Rodauto, suspect you have a bedding issue. The barrel is most likely touching the stock somewhere when it gets hot.
 
sunray said:
If you ever get into a fire fight, accuracy will be the least of your problems. Groups do not apply to fire fights anyway. Hitting the target, anywhere is the only thing you care about.
25 rounds in 30 minutes isn't terribly fast. DCRA F Class gives shooters 29 minutes for 20 rounds at 900 and 1,000 yards.
In any case, as a barrel gets hot, groups can open but it has multiple causes.
Rodauto, suspect you have a bedding issue. The barrel is most likely touching the stock somewhere when it gets hot.
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Hi sunray,
Don't think it's a bedding issue rifle shoots very well after the first group.
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I think the thing to remember is that as your barrels heat up, steel does what it does best with changes in temperature, shrinks/expands, twists and contorts and not to mention that steels strength is lost as it heats up. If your barrel is heated up to much to often you may find that the stress on your barrel does damage to it that you may not notice at first.

A friend of mine who worked in an outdoors store here in town showed me a chunk 17 Remington barrel. A chunk about 4 inches long had been cut out of the center of the barrel, then cut in half lengthwise, what couldn't be seen before was that small sections of rifling had been torn out due to someone pouring to many rounds through it short periods of time and had been done many times.

That said, the US Army Marksmanship Training Unit, US Marines Scout Snipers and Marksmanship Training Units and National Guard Marksmanship Training Units were playing with M14's and seeing what was needed to make them even more accurate as early on as mid 1960 even though the first National Match where 7.62x51 Garands and M-14's were used was 1964. National Match M-14's used a standard receiver, though I have read that apparently there were a few that had tried welding a lug on and the forward section of the receiver to increase recoil surface (something that should NOT be tried as welding to a heat treated surface destroys the heat treatment and requires specialized welding techniques). Barrels were bought in standard, medium and heavy weights but not all were chrome lined (the chrome lining on Chinese Barrels is not as good as American/Canadian due to the fact that the Chinese barrels are not perfectly round on the inside due to high and low spots in the chroming process). The National Guard used 1:10 twist while the Marines used 1:12 Twist. The standard GI Flash suppressor/hider was reamed out with a #& taper reamer. Hand guards were trimmed so that they didn't touch the stock and the front tab was sometimes glued in place to it couldn't shift during firing. The standard weight Walnut stock was originally used but it was found to not be as reliable as a thicker and heavier stock. The forend of the stock had material removed so as to prevent the gas system from touching the stock. The ferrule contact points were polished so as to allow the smooth surfaces to properly reset under recoil. Gas systems were Unitized so as to keep a consistent barrel tension on the stock under firing. The Army/National Guard screwed theirs into place and staked them while the Marines TIG welded them into place. The triggers were honed and polished so as to give just over a 4.5 pound pull. And of course
NM Sights were used as well.

Making sure that there is no contact on the Op Rod, Gas System and Barrel are a major past of the M-14 accuracy along with a free floated barrel. Still, firing to many through this can cause over heating and accuracy problems. I had a CG-63 in 6.5x55, glass bedded and the CHANNEL that was there for the free floated barrel was something else, about 5/16 of an inch around the barrel to make it so nothing touched that barrel and to allow air flow around the barrel.

Also, it was found that the 173 Grain pointed boat tail bullet was most accurate at 2550 FPS~. while Federal Gold medal Match fires the 168 grain hollow point boat tail bullet at 2600 FPS~. Faster isn't always better.

I could add more, but I am tired and I am hungry and need a shower. If you want more info, say so, and I will dig through my books some more and add some more to this. Hope it helps.
 
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