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Long range barrel profile

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Unread 02-25-2006, 12:46 PM
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Re: Long range barrel profile

Lerch says: “Well then explain to me how a large, heavy, bull barrel that is so much stiffer would be less accurate than a barrel that is skinnier than a willow branch???”

If both have the same bore, groove, twist and chamber dimensions as well as the same ammo used, I don’t think there would be any difference in accuracy. People who have measured (not guessed) how a barrel whips vertically when fired know there is only one whip. It’s much like the wave in a bull whip when it’s flung out across a male bovine’s backside. As long as the bullet leaves the barrel at about the same place in that single whip, it will go to the same small cluster of shots previously fired.

Lerch also says: “Not to mention that all of the benchrest shooters and extreme range enthusiasts shoot barrels that look like sewer pipes!!”

That’s not quite true albeit a popular belief among rifle shooters. If one checks out the barrel dimensions of folks on Palma teams around the world as well as folks in the USA shooting prone rifles in 600 and 1000 yard matches, they’ll learn those barrels are skinnier and more whippy than the ‘sewer pipes’ used in bench rest matches. Yet the accuracy they attain when fired under equal conditions are all equal.

Bill Bailey says: “I think the whole key here is CAN BE as accurate. With out a doubt there are skinny bbls out there that have shot some great groups. The problem is the load has to be precisely tuned to the bbl. The skinny bbl WILL NOT shoot as good, day in and day out under varying temps and atmospheric conditions using the same load. Could you tune the load for every condition? Sure you could, but who wants to have ump-teen different loads when you could just have a heavier bbl that will vibrate w/a much lower magnitude that will shoot the SAME LOAD into respectable groups under most all conditions. Now you still may have to have a summer and winter load, but 20-30 degrees won't make much difference.”

The above is a very common (popular) belief. Consider what happened in 1991. The US Palma Team Captain asked in late 1990 if I and several other former Palma team members would help develop the ammo to be used for the 1992 World Long Range and Palma Championships. As this match was to be held at the NRA range at Raton, New Mexico, all the ammo had to be supplied by the USA; everybody would shoot the same stuff. The host country always supplies the ammo.

Our criteria was simple, use new .308 Win. cases, Federal 210M primers, metered (not weighed) powder charges of several powder makes and types, then seat Sierra Bullet’s then a prototype .3084-in. diameter 155-gr. Palma bullet to an OAL of 2.80 inches. We all used various powders including RE15, AA2520, IMR4895, IMR4320, WW748 and a couple others I now forget. These loads were tested in several Palma rifles with different actions but all had 5- to 6-pound 30-inch barrels with tapers much like those I mentioned earlier about 1.2 inches at the back and about .800 at the muzzle. Bore diameters ranged from .2980- to .2995-in., groove diameters from .3065- to .3075-in. Mine was .2980 and .3070. Bullet runout on our development loads was mostly in the .001- to .003-in. range. We shot our ammo at 1000 yards with both aperture and scope sights. After each of us had shot a few 20-shot strings with each load, it was easy to tell which ones shot great and which ones didn’t. The load selected was 45.3 grains of IMR4895.

Winchester said they would make the cases but our ammo master said he wanted to go to their plant and check tolerances before the production run was made for a few hundred thousand cases. The plant had to change their case forming dies and setup three or four times to get body and neck wall thickness tolerances down where we wanted them. But the results were worth it. Those cases were probably the most uniform made since the famous WCC58 and WCC60 stuff Western Cartridge Company made for the US Olympic Team’s free rifles.

Two Dillon 1050 progressive machines made the ammo. One resized just the necks so bullet grip would be uniform and seated the 210M primers. The other 1050 metered powder and seated bullets. While our ammo man’s two sons were busy cranking out ammo, he randomly grabbed 22 rounds one day then took them to his local 600 yard range to test them. He clamped his Winchester 70 Palma rifle in a machine rest, fired two shots to center the group on a target, then fired 20 consecutive shots in about 15 minutes. That 20-shot group was shown in a 1991 issue of Handloader Magazine; it measured about 2.7 inches between widest centers. Not too shabby for ammo with powder charges having a 3/10ths grain spread and bullet runout up to .004-in. And the first time that barrel had shot that ammo.

Samples of all our test loads were sent to a ballistics lab. The ammo with the lowest muzzle velocity spread, smallest charge weight spread and most uniform chamber pressures used AA2520 ball powder. That load was also the worst for accuracy in all the test rifles. Only average spreads in muzzle velocity, charge weight and peak pressure happened in the selected load using IMR4895. But it was the most accurate.

In the summer of 1991 at a big long range match at the NRA Whittington Center south of Raton, NM, several thousand rounds of that load were made available to rifle shooters to compete in an “International” category. In addition to 30 or so of the USA’s top long range shooters, about 60 to 70 top long range shooters from around the world were also there to check out Sierra’s prototype Palma bullet. We shot that load at 600, 800, 900 and 1000 yards over a five day period. Temperatures ranged from the 50's in early morning to the low 90's in mid afternoon. Each person fired 170 record shots. An Australian won the International Palma match aggregate fired at 800 through 1000 yards for each of 3 days. I won the International 600 and 1000 yard aggregates fired over 2 days. I also had the high combined International aggregate for all 5 days beating that Australian by only two points. I though that was a pretty good thing for both me and Sierra’s then new Palma bullet.

I asked many top scoring shooters how that ammo shot at its worst in their rifles. They all said it did about 3 to 4 inches at 600 yards and about 7 to 8 inches at 1000 yards. All the folks from overseas said it was the most accurate ammo they had ever shot. Considering that all sorts of light to medium weight 30-inch barrel profiles and internal dimensions were used in temperatures ranging from the 50's to the 90's, that load had to do very, very well regardless of what barrel whip issues existed. The International Palma Committee met soon afterwards and decided that from then on, only the Sierra 155-gr. Palma bullet would be allowed in international matches.

And everybody at the 1992 World Championships loved that ammo. I didn’t make the US team that year but one of their top shooters borrowed my rifle and did well with it.

When I got a new Palma rifle built in 1993, I loaded 22 rounds of that stuff but used WCC60 cases full-length sized to new case dimensions. Arriving at the local 1000-yard range about 5 AM one Tuesday morning, I put up a foam board target at 800 yards, laid down slung up prone and looked through the Weaver T20 scope I’d mounted on the rifle as I fired two shots to center my group on target. Then I fired 20 shots each about 30 seconds apart. A picture of that 3.2-inch group was sent to John Krieger (great barrel maker) and he used it in a 1997 issue of Precision Shooting magazine to advertise his great barrels.

When with the US team in South Africa in 1998 for their national matches, they had loaded Sierra 155's at some arsenal for us to use. We shot that stuff for over a week in our various whippy barrels. I came in second for one of the daily aggregates. It was as good as any “perfect” handload any of us had put together. In talking with several folks from around the world about their ammo some said it was as good as the stuff they shot in 1991 at Raton, NM.

Form any conclusions you want about the same load not performing well in a variety of barrels and atmospheric conditions. I’m just sharing some realities of what’s possible for best accuracy. I can only conclude that each rifle must have had its bullets leave its barrel at close to the same point it its single whip and it didn’t matter very much where that point was.
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Unread 02-25-2006, 01:46 PM
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Re: Long range barrel profile

UncleB says: “I see that you have a new computer program,while I'm sure that it is a significant upgrade over your previous Inspector Gadget Lab. it is still no better than the information fed into it.”

You made a wrong assumption. My computer is not an ‘Inspector Gadget Lab.’ I think it’s a ‘Barbie Doll Boolean Darling’ and I affectionatley call it my 'BDBD' or 'Beady-Beady.' I’ll have to find the box of Cracker Jack it came out of and re-read the advertisement on it. The darned thing is too cheap to have any nameplate on it. But it seems to work OK. I think it’s worth the 79 cents I paid WalMart for that box of Cracker Jack.

UncleB says this, too: “it is obvious that you are very good talking with your computer but not so good feeding it correct information ,you are playing cyber gun guru but have you ever shot a real rifle (other than the Daisy Red Ryder you dand near put your eye out with last christmas).”

No, I don't shoot reel rifles; that's too fishy. I just put on my $725 Kurt Thune prone jacket (made in Finland and popular with Olympic shooters), lay down on my belly and hold a bullet between my extended left hand's thumb and forefinger like some 5-year-old holding his 'Shooter' marble at the edge of a circled string around a nest of cat's eye's, then flick that bullet down range such that it spins fast enough to stabilize it. (Excuse me while I turn my reality switch back the 'on' position.)

I really did laugh out loud when I read this one’s comment about the Daisy Red Ryder. Fact is, a friend of mine has done almost that very thing and I came close to doing it myself. He took a 17 caliber barrel, rechambered it for a wildcat case with a large rifle primer pocket then screwed it into an old action. After priming the case, a pellet or a BB would be put in the case mouth then shot through a chronograph. Hot or magnum primers would produce higher velocity than milder ones. Primers shooting that BB or pellet out with the lowest velocity also produced the best long range accuracy. One could also tell which primers were most uniform ignition wise ‘cause their velocities had the lowest spread. Sometimes primers with the lowest spread in BB velocity didn’t shoot as accurate in normal handloads as primers having the lowest BB average velocity but just average in velocity spread. But the guy whose underground 100-yard range I helped him build had to move back east so I didn’t get my BB gun to shoot my eye out for any Christmas.

UncleB continues with: “Most of your idea's if not all have zero merit in the real world. I would love to see your remmy with a 6 foot barrel along with the target and 6 foot group on it but I'm sure I wont because it's all just BS.”

Whatever you think about my ideas is fine with me. That was a concept statement; not reality. I think most folks figured that out.

And UncleB next says: “just out of curiosity just what numbers did you put into your computer to come up with a model70 being 3 times stronger eeerrr stiffer (don’t want to mis quote you)than a remington. and how do you do your static and dynamic measureing on your computer game.”

I put Arabic numbers into my BDBD computer when I need to, you know 0, 1, 2...and so forth all the way up to 9. There aren’t any Roman numerals on the keyboard’s numeric keypad.

I didn’t use my computer software to check out receiver stiffness; I don't have any software to do that. It’s easier, more meaningful and simpler to do the dynamic method; measuring how much a receiver bends with a 40-pound weight hung on it. Take a barreled action placed horizontally on a benchtop resting on the bottom of its recoil lug with the receiver out over the edge, then anchor its barrel down solid. Mount a dial indicator atop the front receiver ring, place its measuring plunger midpoint on the receiver bridge then zero it. Hang a 40 pound weight on the receiver’s tang then note how much the dial indicated the receiver bent. Compare as many receivers as you want as long as the weight and dial indicator is placed in the same position on all receivers. I tested only bending in the vertical axis as that’s the axis the barrel whips in. Folks I’ve convinced to do this are usually amazed at which receivers bend most and least. The nice thing about this method is it’s very good, realistic and doesn’t require any math or computer skills.

The static method involves math using fourth order mathematical equations. You may well be better at math than I am so go check out “modulus of elasticity” on your web search engine and do your own stuff. It’s the same stuff used to calculate how stiff fluted and plain barrels are. Harold Vaughn’s old book “Bolt Action Rifles” (I think that’s the title) has a section on receiver stiffness. Besides Remington 700 and Winchester 70 models, others are listed along with the math formulas he used to make the calculations. It’s this reference that lists the Winchester to be 2.7 (?) times stiffer than a Remington receiver of the same type. This information compares favorably with my static methods of measuring receiver stiffness.
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Unread 02-25-2006, 07:01 PM
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Re: Long range barrel profile

I tested only bending in the vertical axis as that’s the axis the barrel whips in. Folks I’ve convinced to do this are usually amazed at which receivers bend most and least.

[/ QUOTE ]
Have you tested any with and without a one piece base bolted on?
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Unread 02-25-2006, 10:39 PM
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Re: Long range barrel profile

Bart, it's obvious you have very little knowledge or experience in these matters! [img]/ubbthreads/images/graemlins/grin.gif[/img]
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Unread 02-25-2006, 11:18 PM
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Re: Long range barrel profile

Have you tested any with and without a one piece base bolted on?

[/ QUOTE ]

No, I've not done that. I've got Medesha 20 minute aluminum bases for post-'64 Win. 70 long actions but they are too thick at the front for my dial indicator to fit on when they're installed.

Come to think of this, I could do it optically. Clamp two low power scopes with a ring just behind their objective lens bell then mount one at each end of the base facing each other. Look through the back one into the front one then adjust the reticule until they both align. Next, hang the weight on the receiver and look through the rear scope. As the receiver and base will bend, the rear scope will now be aimed higher relative to the front scope's reticule. Click the rear scope down in elevation until both reticules coincide and I'll know the angle the darned thing bent.

Of course, one could do this without a one-piece base, too by using the existing holes atop the receiver ring and bridge.

The based receiver would bend less; how much depends on how tight the base screws were torqued and what material the base was made of. Mine are aluminum.
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Unread 02-26-2006, 07:54 AM
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Re: Long range barrel profile

My comments about not being too good at math caught up with me again. I mentioned searching the web for “modulus of elasticity” but I forgot to also mention "moment of inertia." One needs to use both in order to get the complete picture.

Sorry 'bout that.
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Unread 02-26-2006, 09:36 AM
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Re: Long range barrel profile

Bart B,

To say a barrel only flexes vertically is a bit strange to me. How a bullet being forced to rotate as it is driven down a bore only produces vertical forces on the barrel does not make any sense to me personally.

I am not sure what you were referring to as far as the flexibilty of a heavy barrel compared to lighter barrel but if you are saying they both flex the same amount or have the potential to flex the same amount you are sorely mistaken.

As a gunsmith, I have the somewhat unique ability to mount barrels up in the lathe all the time. My chambering techniques is to hole the muzzle in the chuck and support the breech end with steady rest while chambering.

While setting up a barrel this way I can leave the barrels unsupported only being held by the muzzle. A light contour barrel will flex DRAMATICALLY more then a heavy contour. In fact, with a barrel length of 28 to 30" you will see these lighter contour barrels "droop" under their own weight until supported by the steady rest.

The heavier contours flex very little in comparision and once you reach around a #7 contour there is very little if any flexing that is noticable.

This is the same if the barrel is reversed as well for fitting a muzzle brake.

Now I am not sure you are referring to this in your post as I did not wish to read that far into it but if your talking about barrel rigidity you are incorrect.

I am not speaking with clinical laboratory test experience, just real life, in the shop and on the range experience which I often find much more useful and valuable then what is printed from laboratory testing!!

You must consider many variable that you are not when determining how a barrel will flex, whip or vibrate under live fire testing. Here is a short list that I hope you are including in your test data or your results will be flawed:

-Receiver thread diameter
-Receiver thread length
-Receiver thread fit
-Receiver thread taper amount if any(should not be)
-Receiver thread squareness
-Recoil lug squareness if present
-Barrel thread fit
-Barrel thread diameter
-Barrel thread length
-Barrel thread squareness
-Barrel shoulder squareness
-Chamber axial alignment
-Bore axial alignment
-Bullet run out
-Bullet velocity
-Bullet weight
-Bullet concentricity
-Bullet contruction

Ya see these reasons are why a custom rifle will often out shoot a factory rifle by a huge margin. There is alot more to accuracy then barrel stiffness you are correct in that, BUT, with all things equal, a heavy barrel will consistantly out perform a light barreled rifle over a string of shots over a given period of time.

Certainly there are exceptions to this rule but on average, the results are very easy to see.

If all of these aspects are not perfectly tuned for each of the test barrels you will not get consistant accurate data of what a barrel does when a bullet is driven down the barrel.

If you say that this is just a practical test to show the basic harmoinic patterns in a barrel, I can then say that putting bullets on target will do the exact same thing but in the case of a rifle shooter, the data corrected on target is much more valuable then how one engineering test tells you which barrel will vibrate compared to another.

Simply put, go to a local BR match and see what they are using for barrels. Generally for 100 and 200 yard BR matches you will see very heavy, very short(20-22" barrel lengths) barrels chambered for very low intenstity rounds shooting relatively light weight bullets. All in an attempt to limit as much barrel vibration as possible from shot to shot. They get groups in the .1s which is not practical with lighter, longer barrels with heavier bullets at higher velocities, why? The reason is obvious!!

Good Shooting!!

Kirby Allen(50)
Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

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