Long range barrel profile

[Bart B]

Centre Punch, increasing sight radius between front sight (or fore sight) and rear sight (or back sight) doesn't help aiming. The shooter sees the same angular error between line of sight and line to target for a given angular displacement regardless of the distance between the two sights. Increasing sight radius reduces the amount of impact change per click on the back sight and makes it easier to see for eyes that have degraded somewhat; that's all.

OK, now that I've said that, dozens, hundreds or thousands of folks will say I'm wrong. But if each one of these naysayers looks into an aperture rear sight through twelve front aperture sights all aligned in a straight line and 3 inches apart (the furthest one being 36 inches in front of the rear sight; typical of Palma rifles), they will notice that for a given amount of misalignment with the downrange target, each one of those twelve front sights have the same angular error relative to the target's bullseye and they'll all stay aligned with each other.

The reason people who compete in Palma matches have long 30-inch or so barrels is to get muzzle velocity high enough (at least 2900 fps) with a 147- to 155-gr. bullet from a .308 Win. to stay supersonic through 1000 yards at sea level. In the USA, Palma rifles could use any weight bullet and 190- and 200-gr. bullets worked well in 26-inch barrels. Since 1992 the Sierra 155-gr. bullet has become the world standard and it bucks the wind better at 3000 fps from a 30-inch barrel than a 190 leaving a 26-inch barrel at 2550 fps.

 

[Bart B]

[ QUOTE ]
Goodgrouper and UncleB, maybe you know something I don't know. What's the typical 20-shot group accuracy you think someone could attain at 800 yards with one of those whippy, 30-inch long Palma barrels that's only about .800-inch at the muzzle weighing about 5 pounds?

Benchrest competition rifles shoot aggregates of several 5- or 10-shot groups that average about 1/2 moa at 600 yards and about 7/10ths moa at 1000 yards with their stiff barrels. And yes, these rifles sometimes shoot a single group that's smaller. How do you think a whippy, less stiff Palma barrel would compare?

[/ QUOTE ]
Well, Goodgrouper and UncleB, I guess you two have chose not to cross the "line in the sand" so I'll give you some facts.

In the late 1960s, a 13 pound .308 Win. on a Win. 70 action was tested at 600 yards. 40 consecutive shots went into 1.9 inches.

In 1971, tests were made with a 13-pound rifle using a Winchester 70 action with a medium weight whippy 26-inch barrel at 600 yards shooting the .308 Win. Several 10-shot groups were fired and they ranged from 1.5 inches down to 0.8 inches.

In 1991, another test with a rifle using a Winchester 70 action was made at 600 yards with .308 Win. ammo using new cases charged with metered (not weighed) powder was made. It had a long, whippy 30-inch Palma barrel and put 20 consecutive shots into 2.7 inches.

In 1993, another .308 Win. Palma rifle based on a Paramount action was tested at 800 yards and it put 20 consecutive shots into 3.2 inches.

Over a period of 15 years, a .30-.338 Win. Mag. on a Winchester 70 action was tested 6 times at 1000 yards; twice with each of three barrels. It's 28-inch long whippy medium weight barrels were able to have all of those 15-shot test groups under 7 inches. Some of the 5-shot strings were under 2 inches.

All of the humongus benchrest rifles with extremely stiff barrels used today are no more accurate than those using the whippy barrels mentioned above. If you're not aware of this, you must not be hangin' out in the shooting discipline where there are people that know about it.

 

[goodgrouper]

[ QUOTE ]
Well, Goodgrouper and UncleB, I guess you two have chose not to cross the "line in the sand"

[/ QUOTE ]


Well I don't know exactly what this means, but if you mean we didn't want to start the old pot stirring then you are correct. I, for one, am not interested in expending energy to dispell all the so called "facts" you rattled off. I have been answering questions and disqualifying myths for many years and quite frankly, one more guy going against all known basic principles and general common knowledge related to firearms just to stir crap up and confuse people really doesn't concern me at this point. If you want to keep on believing that pillars are not needed in a bedding job, and there is no such thing as overweighting a receiver, or to say a pencil barrel is as accurate as a bull barrel, then by all means go right ahead. It makes no difference to me. I have stacks and stacks of actual published literature directly contradictory to your statements (as well as many others here surely do) but that means nothing unless you want it to. I only fear that beginners are getting mixed signals as to what to do when they build rifles or bed a stock. It is for them that I step up and get a little non-diplomatic when Bart B starts typing. Ask any of the knowledgeable gunsmiths here if they believe skinny barrels are better or more accurate than heavier barrels. They probably would have already answered but they are in a position on here where they have to be more diplomatic. I'm not. I try to be patient and try to be polite and if that means ignoring someone or not stepping over a line in the sand, then that is what I generally try to do.

Your above example means nothing. It is not detailed enough, does not have controlled conditions, and has no author. For all we know, the barrel may not have been a #9 contour, but it may have been a #5 and was more accurate than a #3. Who knows. Without more context, nothing can be derived from it. HOwever, you can pick up a copy of Precision shooting magazine, or a copy of "Understanding firearm ballistics" by Robert Rinker. They will enlighten you.

I will comment on this one last thing before I end this coverstation just because I have had a dozen people email me and ask what is right or wrong in this thread this week.
Anyone who has ever developed a precision reload sequence for a pencil barrel along side a heavy barrel will immediately notice a difference in the two. The heavy barrel is much more tolerant of a variety of loads and is more consistently accurate from day to day. This is old hat. YOu ain't foolin me buddy. It is much harder to get the bulllet to leave the skinny barrel in the exact same point in the oscillation because <font color="red">THE SKINNY BARREL ABSOLUTELY OSCILLATES WITH HIGHER FREQUENCY AND GREATER MAGNITUDE THAN THE STIFFER (HEAVIER) BARREL! </font>

Have a nice day. /ubbthreads/images/graemlins/smile.gif

 

[Bart B]

Gee, what a rant, Goodgrouper. If I was a judge grading your rant (including the shouting in red typeface), I would thumb through my cards numbered 1 through 10 then hold up the one labeled 3.

You still didn't answer my questions. But now I know why: your ignorance just got unveiled.

 

[goodgrouper]

A little bit of advice for you Bart:

If you want to debate and argue basic points of firearms, go to accurate reloadings website.

If you want to get nasty and uncivil, take it offline. My email address is listed in my profile if you wish to attack me personally. I can't guarantee I'll read anything you send me, but at least it will keep it off LRH.

If you want to do both, than we may have just flushed another troll from our midst.


People, beware the bait.

 

[lerch]

Hey Bart B

Remember when you debated me about fluted verses non fluted barrels. Remeber how you said removing any material from a bull barrel reduces its regidity??? You said "The thicker a barrel is for a given caliber and length the less it will bend." that is a quote from your post

Looks to me like maybe ya need to decide which side of the fence you are on

steve

 

[Bart B]

Lerch, yes, I remember about the fluting stuff. This issue is not about whether or not a skinny/whippy/light barrel is more rigid/stiff than a fat/heavy one. I already know that thicker ones for a given length are stiffer.

Give me a barrel's dimensions as well as whether it's 416 stainless or chome moly steel and I'll calculate what it's resonant (or fundamental) vibrating frequency is with one end held still and the other end free to vibrate; most are around 40 to 60 cycles per second (the answers may surprise folks). A mechanical engineer working with vibration problems for civil engineers' construction issues gave me the computer software (which I'll share with anyone who wants it). Here's an example:

Here's three 416 stainless steel barrels, .308-in. groove diameter, 30 inches long, screwed 1 inch into a receiver...
1.1-in. dia. for 2 in. from receiver, .7-in. muzzle diameter, 4.85 lb. mass, resonant frequency = 48.95 Hz
1.2-in. dia. for 2 in. from receiver, .8-in. muzzle diameter, 6.09 lb. mass, resonant frequency = 51.37 Hz
1.3-in. dia. for 2 in. from receiver, .9-in. muzzle diameter, 7.45 lb. mass, resonant frequency = 54.03 Hz
The thicker and stiffer they get the higher their resonant vibration frequency is.

This issue is about which barrel (stiff or whippy) is or can be most accurate. All I've stated is that there is no difference accuracy wise; both can shoot equally as good. But so many folks haven't quite understood that. Go back and read what I've said and you might understand what I'm talking about. I don't know how I can make it any simpler.

 

[Centre Punch]

GG,
I think you will find that it is the short stiff barrel that oscillates with a higher frequency, but you are correct in saying that the thin barrel oscillates with greater magnitude.

Ian.

 

[goodgrouper]

Yes, that is what I meant. A shorter barrel will have a higher frequency. /ubbthreads/images/graemlins/wink.gif

 

[lerch]

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???

Not to mention that all of the benchrest shooters and extreme range enthusiasts shoot barrels that look like sewer pipes!!

IF consistancy is our goal as long range enthusiasts and we strive to eliminate as many variables as possible it only makes sense to me that a solid, stiff barrel would eliminate many problems

just seems to make sense to me

steve

 

[bailey1474]

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.

 

[uncleB]

BartB,
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. 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).
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. 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 (dont want to mis quote you)than a remington. and how do you do your static and dynamic measureing on your computer game.
Dude it is time to do the right thing once in your life,just admit that you are a total fraud and lets move on before Len hits the NUKE button.
UB

 

[Ballistic64]

[ QUOTE ]
Centre Punch, increasing sight radius between front sight (or fore sight) and rear sight (or back sight) doesn't help aiming. The shooter sees the same angular error between line of sight and line to target for a given angular displacement regardless of the distance between the two sights. Increasing sight radius reduces the amount of impact change per click on the back sight and makes it easier to see for eyes that have degraded somewhat; that's all.

OK, now that I've said that, dozens, hundreds or thousands of folks will say I'm wrong. But if each one of these naysayers looks into an aperture rear sight through twelve front aperture sights all aligned in a straight line and 3 inches apart (the furthest one being 36 inches in front of the rear sight; typical of Palma rifles), they will notice that for a given amount of misalignment with the downrange target, each one of those twelve front sights have the same angular error relative to the target's bullseye and they'll all stay aligned with each other.

[/ QUOTE ]

This is not necessarily true.While the front sights do have the same angular error,the front sight is a further distance from the rear aperture than the one closest to it and is more accurately brought into the center of the aperture.This is nothing new,it is the same reason silouette pistol shooters prefer longer barrels and has nothing to do with aging eyes.A very short sight radius (front sight to rear sight) is much easier for aging eyes to bring into alignment with a given target but is hardly as accurate.

 

[ds]

I am not sure how clear cut this is, firstly I use a fairly heavy profile barrel like 32mm dia, no taper for 28" and have found load development to be very easy - may be due to less magnitude of vibration. Now having said that in .22 BR they use long skinny barrels with tuners ( a lot has been written and proved by Calfee on that) but in .22 the ammunition is all factory fodder so you have to tune the barrel to the ammo. With centre fire you can tune the ammo to the barrel by altering COL length - change bullet seating, change the harmonics. I think some centre fire BR rules have changed to allow tuners, I guess it will take a few years to see if they become popular or not if so barrel profiles are likely to become longer and thinner.

In Rifle Shooter D.Tubb said he thought fat and heavy barrels were more accurate but has since changed his mind - the T2K profile being optimal.

Has anyone given any thought to what is meant by accuracy and duration of it, in other words if you want one 5 shot group a thin barrel may well be able to do that but a 20 shot group a heavy barrel is likely to change less - more steel to absorb more heat, less in bore dimension changes plus another advantage more resistant to torque.

Just some thoughts and no flame to anyone.

David.