243 Win. barrel life question ?

[Bart B.]

Major Dave comments:

Some cartridges are extreme examples - for instance, 7X57 Mauser. Factory loads are only 46,000 CUP, 2,660 fps MV, with 139/140 grain bullets. Low recoil, long barrel life.

But, handload it to about 60,000 psi (same as 7mm Rem Mag), and you get 2,950 fps MV, noticeable recoil, and about half the barrel life.

What's the actual difference between 46,000 CUP and 60,000 PSI? That's two different pressure measuring systems that don't give the same numbers for equal pressure in the chamber. SAAMI specs for peak pressure in the 7mm Rem Mag's only about 13% higher than the 7x57 Mauser round.

Folks shooting the 7mm-08 in competition got 2 to 3 times the barrel life as the 7mm Rem Mags got. That round's within a couple percent of the same case volume as the 7x57. 7-08's standard SAAMI max pressure is the same as the 7mm Rem Mag; 61,000 PSI. At that peak pressure, 140's from a 7-08 leave at about 2840 fps in SAAMI spec'd chamber and bore/groove/length dimensions. A tighter bore and groove will both raise pressure as well as muzzle velocity; that's the way it is.

[Ridgerunner665]

Pressure has next to nothing to do with barrel life...its purely the amount of powder, gas, and residue being pushed through the throat that wears the barrel, or more correctly the throat...as it gets squeezed down to bore diameter.

Heat DOES speed up the process...we all know metal gets softer as it heats up...so shooting fast does increase barrel wear, shooting fast in a 308 may not make much of a difference, but if you compare fast vs. slow shooting with something like a 7mm Rem Mag...you'll notice the difference pretty quick.

Neck length and shoulder angle also come into play...

And yes, the 243 is a bit of a barrel burner, especially with heavy loads of slow burning powder such as Reloder 19.

[jimbob86]

That's looks pessimistic Bart B.

Maybe match barrels heat up more and wear faster.

Keep in mind that "accuracy gone to hell/shot out barrel" means completely different things to Benchresters or "top ranked competitor" target shooters than it does to more practically oriented shooters.

[Bart B.]

Jimbob86, exactly what is a "more practically oriented shooter?" Exactly how far in inches do you accept missing your point of aim at 100 yards? 300 yards? 500 yards?

Ridgerunner665, there are barrel makers who know pressure has lots to do with barrel life; they've prooved it beyond resonable doubt.

[PawPaw]

Originally Posted by Bart B.

exactly what is a "more practically oriented shooter?" Exactly how far in inches do you accept missing your point of aim at 100 yards? 300 yards? 500 yards?

First, we have to define point of aim. Lets say, for example, I'm aiming at a crow feeding on a newly planted field. He represents a target maybe 4" wide and 8" tall. I estimate his range at 200 yards. I settle the crosshairs, squeeze the trigger, and see him dissolve in a spray of feathers. I hit the target and that's all I care about.

Another example. I'm sitting in a tree overlooking a bean field. I see a whitetail deer step out of the forest, near a known 300 yard marker. I know that the deer's vital area is a target about 9" across. I settle the crosshairs, squeeze the trigger. The deer takes two steps, lays down, and stops moving. After watching him for 30 minutes, I surmise that he is dead.

In neither case did I miss my point of aim, although the target was quite large in both cases. Now, a benchrest guy might snort at that level of precision, which is really quite imprecise. I don't care where I hit in that 9" circle as long as the bullet collects heart/lungs on the way through.

So, when I'm practicing my marksmanship, for a final, field check, I use a 9" paper plate with no markings. I use that 9" paper plate when I'm shooting with the grandkids. They've got to be able to hit that 9" plate every time, on demand, from field positions. If we were shooting prairie dogs, I'd probably use something like a playing card, or a common 3X5 index card.

That's practical accuracy. The ability to hit a given target at an unknown distance from field positions. I wouldn't even attempt a shot at a whitetail deer from 500 yards. The animal deserves better than that.

[Bart B.]

Point of aim's where the scope's reticule center (or center of metallic/iron sight picture) is on the target when the round fires. It's a finite point, not an area of several square inches in size.

One may want to have the bullet strike no more than 1 inch from that point. Maybe 2, 3 or 4 inches; perhaps no more than 1/4 or 1/2 inch. Depends on their objectives.

[hooligan1]

I shoot alot from my daughters Mauser, hopefully not enough to burn it up, the handload I shoot from it mostly is a 100 grn Sierra Gameking over a 47.5 grain load of Winchester Supreme 780, it's really accurate and pretty mild also.

[WIN1886]

Man up , I'm going with a 243 cal rifle....I've been shooting my ole 45-70 rifles for so long its time I get me a bottlenecked mini bore speedster as well !

[jimbob86]

PawPaw said it better than I could. Acceptable accuracy is that which will accomplish the task at hand. For me, that a deer's vitals. We practice with gallon milk jugs......

Point of aim's where the scope's reticule center (or center of metallic/iron sight picture) is on the target when the round fires. It's a finite point, not an area of several square inches in size.

One may want to have the bullet strike no more than 1 inch from that point. Maybe 2, 3 or 4 inches; perhaps no more than 1/4 or 1/2 inch. Depends on their objectives.

But you want an exact answer, I see. A 1.5 inch group at 100 yards will still print well inside 8 inches at 450...... Abysmal by benchrest standards.... but will still kill bambi dead as a hammer. That's acceptable.

As for of point of aim...... I use the reticle as an aiming reference...... I know where the bullet will hit at various ranges in relation to that- anything under 250 and I'm actually holding under bambi's chest- I know that at 100, that'll take the top of his heart out, 200 the bullet will hit a bit higher... it's not until 300 that I actually make a center hold..... I 'm more concerned with ranging and shooting errors than I am with having a .5 MOA gun and load combination.

Practical accuracy depends much more on the shooter than the equipment: you have to be able to shoot, from field positions, to appreciate the difference between a .5 MOA tack driver and 4MOA AK-47..... someone who can shoot well can take that 4MOA "junker" and put all his shots in an 8 inch circle at 200 ...... someone who can not will be unable to do so with the tack driver.

[Metal god]

Im going to start with , I did not read all of the posts I read a bunch off them and somebody may have said this already . I did not see anybody talking about barrel material or how the barrels are made .

These numbers are general So please no slamming me on my this does that or my that does this .

For pure accuracy you want a stainless steel barrel with Precision Button Rifling and hand lapped. this type of barrel will shoot 1/4 to 1/2 MOA all day long .

Now you can get a pretty accurate rifle that has a hammer forged barrel This type of barrel will shoot 3/4 to 1 MOA all day long

The hammer forged barrel should and will shoot more rounds at it's MOA range then the stainless steel barrel will at it's MOA range .

There are many ways a barrel is made and they all effect accuracy and barrel life . Im sure you've heard that chrome lined barrels on a AR15 will last longer then Chrome moly vanadium . Imagine how long a hammer forged chrome lined barrel would last

I think thats what the competition shooters are saying . If your competition barrel goes from shooting 1/4 MOA to 3/4 MOA your not going to win any matchs . So by there own math that barrel is trashed .

Now by my math thats still a good/great barrel . I don't no about you but if I'm shooting 3 inch groups at 400 yards ,I'm pretty happy .

So the ? to you is how big is the vital zone on your target and how far away will you tend to be from it . Add ! MOA for evey 100 yards . Meaning If your not shooting any farther then 200 yards . A 1 MOA rifle only needs a 2" by 2" target .

[phil mcwilliam]

Unless you're shooting competitions, or handloading to maximum velocities, you shouldn't over worry about barrel life on a .243. I purchased a Sako 22-250 in 1980 & it took some 5,000 rounds over 30 years before accuracy dropped off & I had it rebarrelled. Groups had opened up to around 1 3/4 inches when I decided to rebarrel.
Note- the 22-250 is considered more of a "barrel burner" than a 243

[Bart B.]

Metal god comments:

I did not see anybody talking about barrel material or how the barrels are made .

That's probably because there's no difference in the accuracy different ways of making barrels as well as the types of steels used as long as the bore and groove dimensions are uniform throughout the barrel's length. Some methods are easier to do that others and some barrel makers pay more attention to detail than others. There's as many cut rifled barrels winning matches and setting records as their is button rifled ones these days. And those broach cut service rifle barrels in the early 1960's shot just as accurate as the best button and single point cut rifled barrels as used in competition in that era. Even Winchester's hammer forged 30 caliber match barrels were popular with folks using them in M1 and M1A match conditioned service rifles, but one had to use match bullets larger in diameter than .3085" and excellent accuracy was attained.

[PawPaw]

Originally Posted by Bart B.

Point of aim's where the scope's reticule center (or center of metallic/iron sight picture) is on the target when the round fires. It's a finite point, not an area of several square inches in size.

That depends, I guess, on the scope. I know (for example) that my Weaver K6 crosshairs cover a measured inch at 100 yards. On the other hand, the front bead on my Winchester 94 subtends (covers) almost 6" at 100 yards. My practice with irons has always been to have the bullet fall into the area that the front sight covers, so that it's "shooting into the front sight". I understand that it's done differently with post-type sights, so that the aiming point floats atop the sight. Still, I much prefer that front sight to have a bead.

But, we're nitpicking at this point, more of an intellectual exercise than a practical discussion. Interesting, nonetheless.

[coyota1]

the front bead on my Winchester 94 subtends (covers) almost 6" at 100 yards

.

This is why I have the target just above my open sight be it post or bead.

[JASmith]

Bart B. has it right for precision shooters. Many (most?) of us are not precision shooters, so our experience with barrel life is different.

Part of the confusion arises from the fact that a 1/4 MOA shooter gets really unhappy when the accuracy "degrades" to 3/8 MOA but the guy whose shooting skills make him happy with 3/4 MOA won't notice the change until the barrel degrades even further to say 1/2 MOA. This makes this second guy think his barrel life is longer.

It is indeed, even though the barrel is the same! Expectations and standards make a huge difference.

The additional confusing thing is that, even for the the 1/4 MOA shooter, barrel wear is a somewhat random process, much like the life of incandescent light bulbs. Some die at 1500 hours, other pop in as little as 700, and few die immediately.

[JASmith]

Coyota said:

This is why I have the target just above my open sight be it post or bead.

Amazingly enough, one can get groups as small as 2-3", sometimes better, by using that technique even with those large beads or posts!

[coyota1]

Most importantly you can see your target (quarry) instead of covering it.

[tobnpr]

But, we're nitpicking at this point, more of an intellectual exercise than a practical discussion. Interesting, nonetheless.

For minute of deer, yep. It's really not nitpicking, if you're developing precision handloads.

I'm in disbelief when I read posts from guys that are nit-picking their handloads to 1/4", when they're using a red-dot with a 4 minute dot, or a thick crosshair reticle.

There's no way to maintain an absolutely precise POA with something like that. As Bart said earlier, it's a finite point. Trying to eyeball the "center" of a 4 minute dot on a target is nothing but a guess.

[Metal god]

Really ! I mean really your going to say all barrels will shoot the same as long as there made to the same tolerances . Hum so a Pinto is just as fast and can coner as well as a Lamborghni . You know ,as long as there made to the same tolerances . Of coures the products will work the same if there made to the exact standards tolerances .One cost $5,000 and the other cost $300,000 . Thats because there not made to the same standards and tolerances .

I started the post with , this is a general coment . I just wanted to help the guy undrestand what compitition shooters mean when they say there barrel only last 1500 rounds . I was not trying to make a blanket statement that all SS barrels with button rifling are the best thing ever and all others should not apply . Thats why I said these numbers are general please don't slam me on them .

If you can afford and are buying the barrels or the guns that are setting the records and winning the matchs your talking about . your not worried about barrel life like the author of this post .

The thread is about barrel life and I believe my post is accurate .

[Bart B.]

Metal god, yes, all barrels made to the same bore, groove and rifling specs, as well as chamber specs, shoot the same bullets with equal accuracy.

And a Pinto with all of its parts made to zero tolerance will still be the same car with the same engine, drive train, suspension system, profile and weight. A Lamborghini's engine, drive train, suspension system, profile and weight, even with its parts tolerances on the sloppy side, is what makes it faster and corner better than a Pinto. It's not a parts fit issue, it's parts shape, size and function issue between a Pinto and Lamgorghini. Last I checked, there was a huge difference.

And barrels wear out regardless of how much their owner pays for them or worries about their life. Never known a barrel to care; either way.

[Metal god]

Your right . I totaly wrote that different then the way I ment it .

I was trying to say if there made exactly the same of course they will shoot the same . but there not all made the same

[Bart B.]

Metal god sez:

if there made exactly the same of course they will shoot the same . but there not all made the same

Yes, they're not all made the same. But even with several 10,000ths inch difference in bore and groove diameters as well as an inch or two in twist rates, I've watched a couple dozen folks along with me shoot the same handloaded .308 Win. ammo (new cases, metered charges 3/10ths grain spread) in as many different barrels all shooting 1/2 MOA at 600 yards. Most interesting to me was the fact that groove diameters in those barrels had quite a range; I asked them what their barrel specs were for data on how that new bullet performed. Groove diameters were from .3068 to .3080 inch and the 155-gr. bullets were .3084 inch. Bore diameters ranged from .2980 to .2995 inch.

The 7 or 8 Hart barrels I wore out shooting .308 Win. ammo all had the same 1:11 twist, bore, .2990" and .3078" groove diameters. There was probably a .00003" spread in the bore and groove, but that didn't seem to make any difference. I shot the same loads with different lots of bullets, powders and primers and they all had the same excellent accuracy level. So barrels can be made "all the same" for all practical purposes and they'll all shoot the same ammo very well.

I'm convinced that if you handed a rifle to 10 different folks who reload ammo asking each to develop a load for a given bullet for that rifle, there would be 10 different loads claimed to be the most accurate. No two receipies would have the same powder type/weight, bullet seating depth, case make and neck tension. There would be a lot more recipies if they could pick any bullet they wanted.

[JASmith]

from tobnpr:

...I'm in disbelief when I read posts from guys that are nit-picking their handloads to 1/4", when they're using a red-dot with a 4 minute dot, or a thick crosshair reticle.

There's no way to maintain an absolutely precise POA with something like that. As Bart said earlier, it's a finite point. Trying to eyeball the "center" of a 4 minute dot on a target is nothing but a guess.

Not sure what is meant by "nothing but a guess" but I can say unequivocably that I have done 1.5 moa and better with open sights on a rifle. I also know that many pistol shooters routinely turn in sub 2" groups when aiming at a 5" diameter bullseye at 25 and 50 yards. I used to be able to do that, but my eyes and muscle tone are no longer up to that task,

This is possible because one uses subtle references for assuring the sights are aligned and lined up with the target. In fact, the 'obviously large' target becomes effectively much smaller when these subtle references.

[Bart B.]

Here's a typical aperture front sight with a bubble level used on NRA match rifles in high power matches:


Here's the sight picture seen through a .040 inch (1.0 mm) aperture rear sight as the shooter focuses his eye on the front sight:


The front aperture can be changed to the size best suited for each person; some want more white around the bull than this one shows. Naturally, the better eyes one has the more easily they'll see a 1/4 MOA error in alignment.

The aiming bull subtends 6.5 MOA at 200 yards, 6.3 MOA at 300, 6.0 MOA at 600, 5.5 at 800, 4.9 at 900 and 4.4 MOA at 1000 yards.

Top classified competitors will call their shots within 1/3 MOA of where the bullet actually goes (in calm winds, perfect conditions ) with 1/2 MOA ammo and equipment. With a 16 to 25 power scope, within 3/16 to 1/4 MOA.

Below is a post front sight with a 6-o'clock hold on a bullseye. It shows qute accurate what the 600 yard NRA high power target bullseye looks like as seen through a .0595" aperture on a National Match rear sight used on M1 and M14 rifles with the shooter's eye focused on the front sight.


Top classified competitors will call their shots within 5/8 MOA of where the bullet strikes. Note the bullseye looks fuzzier and maybe a bit smaller than the one in the aperture front sight and smaller aperture rear sight. The same 36 inch bullseye is used with both front sight types.

Maybe I'll make some pictures showing a thick crosshair reticule in a scope as it appears on a 100 yard target. One will show perfect alignment of the reticule dead center on the target. The other showing what the sight picture looks like with a 1/4 or 1/3 MOA error.

[Metal god]

holy cow can this get anymore off topic . I read the original thead as asking , does a 243 barrel wear out faster then a 223 using standard factory loads .he/she did not say factory loads but I'd bet money thats what they meant .

Now dont you all start getting ultra techncal on us . ( well metal god do you mean hornady blah blah blah this, or do you mean remington blah blah blah that ) lets just for the sake of this thread use wikipedia's numbers so we can get an answer.

http://en.wikipedia.org/wiki/.243_Winchester