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Barrel length . . . it has to matter!


c10250

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Help me out here.

 

People say that barrel length does not have any effect on your pattern. In other words, a 26” barrel will pattern the same as a 28” barrel (with the same choke). How can this be? Heck, when you dial in say, a skeet choke, all you’re doing is opening up your barrel earlier.

So how can a choke open up your pattern, and cutting two inches off your barrel have no effect?

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Guest cleefurd

Both arguments have validity,

 

You almost answered your own question... almost.

When you open up your skeet choke, you are still only changing what happens in the vicinity of the choke. Barrel length affects velocity, but the compressed load does not care how far it has travelled before reaching the choke tube/mechanism. Think of it like a water hose; I can take a sprayer and attach it to a 100' hose, dial in the "shower" setting, take that sprayer and put it on a 10' hose, and get the same pattern when I let the water out. The pattern is affected by the orifice (choke), not the ambient arrangement of pellets over 14" or 30".

 

One thing about your statement can play a factor, if the difference in barrel length has ENOUGH of an impact on velocity w/ your particular load, you may notice a patterning difference on the ALL chokes due to aerodynamics of rotating bodies in a gaseous environment. If I pitch a curveball with a rotation of the wrist, it won't manage to curve until delivered with sufficient velocity to compress air on its high pressure side, thus transitioning towards the low pressure void opposite the direction of the spin, but before that force can become apparent, it must overcome it's own straight-line momentum. At slower velocities that will occur sooner, and in particular the pellets around the perimitter of the load will wander more readily, being out of the "draft", and having some rotation imparted to them by the friction of the choke they were in contact with. This would play out in a significant (measurable) sense more readily in a barrel/charge combination that was short/weak enough to manifest this phenomenon. THAT is why very long barrels using hi-velocity magnum loads DO reach out farther. They take each variable to an extreme, and elevate the straight line momentum variable to a high enough factor, as to effect denser patterns at longer ranges.

 

It's NOT the choke or the barrel length, it's the attained straight line momentum derived from velocity alone, irrespective of barrel length. It just so happens that barrel lengths help facilitate that velocity through the limitations of propellants (gunpowder) and excessive pressure limits that would be required to attain these peformance levels in short barrels.

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Guest cleefurd

In a nutshell;

 

The velocity curve has flattened considerably at 26", the increase is typically negligible across an additional 2" (for the 28" alternative you mentioned). If however you are using hi-velocity magnums, the difference in velocity would be more meaningful since the propellants burn rate (slower, higher surface area propellants that burn at accelerated rates the longer they are engulfed, which is good for LONG barrels, and keeps pressures safer) would keep pushing hard out to the end of longer barrels. So then MAYBE, you'd see a pattern difference between a 26" and 28" barrel, however slight.

Edited by cleefurd
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I recently read an article in a gun magazine that stated that the "modern" propellants (I assume the last few years) used in shotshells reach their maximun velocity in the first 20"-22" inside the barrel. Because of this the SBE 2 that I bought last week I got with the 24" barrel. I like a shorter barrel for turkey hunting and hope the article was correct.

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Guest cleefurd

That's a great multi-purpose length, points quick, and has enough tube to glean most of the "goose getter" shell's powder too. I had a BPS Upland Special for years that had a 22" barrel, and it did about 80% of my fowling. I liked one short barrel, and one looong one for birds wearing oxygen masks with 3" and above magnum loads.

Edited by cleefurd
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Guest cleefurd
With lead shot the barrel length does make a difference.

With steel shot makes very little difference if any.

 

Have to agree. Straight line momentum of lead is greater than that of steel, the latter being sufficiently lighter, slowing down more quickly which then patterns based on more convergent velocity spreads closer to the muzzle than does lead. Lead's velocity convergence to TVEL (terminal velocity) occurs much further down range due to higher specific gravity. Barrel length is still secondary by its role towards attained velocity and resultant straight line momentum. In fact length alone has no direct physical effect on the patterning, only a contribution to straight line momentum. Velocity retention due to mass properties (loosely analagous to B.C.), and the differing barrel lengths abilities to deliver those culpable velocities are disparate functions. This is Aberdeen Proving Ground's assessment of exterior balistics from "anti-frangible projectiles"... i.e. lead shot. I promise I had no means of "figurin" that out on my own, but it does make sense. Barrel length does not provide the disparity, the velocity at which barrel length can play a supportive role is only an associative function. So yes longer barrels contribute to the velocity factor, but for the sake of argument, a 10" barrel would give the same results if propellant and metalurgy limitations were moot, and the instant acceleration of the shot did not distort it to a point where patterning factors were further complicated. Dad worked at White Sands Missile Range for 32 years, so while I'm no rocket scientist, I was taught where to research for trivial explanations.:D

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This all goes back to the Blackpowder Days. Back in the Blackpowder Days, which lasted through WWI for shotshells, you needed a long barrel >30" to develop full velocity because of the propellent. Also, with a longer barrel you could make a longer taper on the choke, which prevents scrubbing of the lead shot (the lead shot get deformed and cuases flyers in the pattern). Additionally, a longer choke and forcing cone prevent "set-back". this is when the shot hits a constriction and the back of the shot column rams into the front of the shot column and once again you get deformed shot. This is why your typical .410 has pattern issues from the get go.

Fast forward to today and you still have people that believe that you have to have a long barrel for a shotgun to have "knock down power" and be effective. After all this is what Old Grandad said, right. Well, not anymore. From a velocity standpoint: this is outdated. There ARE ,however, reasons that you might want to have a longer barrel though, velocity not being one of them. Number one, would be for longer shots it helps to have a longer barrel because even though your not sighting down the barrel and you have both eyes open and are focusing on the target, your subconscious brain is aware of the blurred barrel and helps you to hit and track moving targets at longer ranges. It also does one more very important thing- it keeps you from stopping your swing and shooting behind the bird.

So, no you don't need more than about 14" of barrel to reach max velocity with modern shotshells. it does help your lead shot patterns to have longer forcing cones and longer chokes though, although this doesn't matter at all with steel shot or tungsten because the shot is so hard it can't deform from barrel, forcing cone, or choke scrubbing, nor is "set back" an issue.

Lastly, an auto or pump, especially a 3.5" gun like a SBE with its super long receiver doesn't need as long a barrel as a O/U which has a short receiver. Take a 24" SBE and put it beside a 28" O/U and see just how long that SBE is in OAL. It is longer because of the receiver. A 28" barrel Auto, or pump is a long gun, especially if it's a 3.5" receiver magnum.

That being said, a lot of shooting is psychological and if you believe something works for you, it probably does. The old placebo effect.

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ive tryed this. using an 870 w/24", and another 870 w/30" barrel. shot 5 times at 5 pieces of white poster board with each gun using the same screw in full choke, at a range of 30 yds. and the proof was in pudding .

 

a 30" inch barrel with the exact same choke, had a very noticeably tighter pattern. but most people will believe what ever thier told vs trying it for them selves.

 

i posted a link in the waterfouling forum some months ago. these guys are shooting birds at an airport at distances of 65-75 yds with shotguns with 40" barrels, using heavy field loads.argue with them that a short barrel will do that.

 

i prefer a 26-28" myself.

Edited by splashtx556ftw
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Guest cleefurd
and a water hose is hardly a valid comparison, unless you fillit with lit gasoline.:rolleyes:

 

 

And lit gasoline has ??? to do with the association between barrel length and patterning?

 

Point was, neither water nor shot care how far they have journied, their pattern is derived from velocity and pressure at which they arrive upon their respective orifice or choke.

 

It was an analogy, effort to illustrate, visualize, convey.

 

Lit gasoline... used to flame, confuse, obfuscate.

 

You so mean.:o

Edited by cleefurd
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I recently read an article in a gun magazine that stated that the "modern" propellants (I assume the last few years) used in shotshells reach their maximun velocity in the first 20"-22" inside the barrel. Because of this the SBE 2 that I bought last week I got with the 24" barrel. I like a shorter barrel for turkey hunting and hope the article was correct.

 

Modern handgun/shotgun propellants burn within 13-15 inchs. Rifle propellants, about 28 - 30 inchs. Still like you thought, a 24'' barrel is a great barrel length.

 

Plus Tucker brought up in a different thread that pumps and autos have a longer sight plane than O/U's and S/Ss due to the longer receiver. So a 24'' auto has a 28-30 inch sight plane as to a 28'' O/U has a 28'' sight plane.

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ive tryed this. using an 870 w/24", and another 870 w/30" barrel. shot 5 times at 5 pieces of white poster board with each gun using the same screw in full choke, at a range of 30 yds. and the proof was in pudding .

 

a 30" inch barrel with the exact same choke, had a very noticeably tighter pattern. but most people will believe what ever thier told vs trying it for them selves.

 

i posted a link in the waterfouling forum some months ago. these guys are shooting birds at an airport at distances of 65-75 yds with shotguns with 40" barrels, using heavy field loads.argue with them that a short barrel will do that.

 

i prefer a 26-28" myself.

well your intitle to believe what you hear. ill believe what ive seen and done to check it out for myself.

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Guest cleefurd

I rest my case, the longer barrel developed more straight line momentum, the barrel length did not change the pattern, the resultant velocity did. A short barrel COULD do that if it were capable of handling a propellant with sufficiently fast burn rate to MATCH the velocity attained in a 40" barrel, with its efficient utilization of larger slow burning powder charges that gradually reach much higher velocities than can be attained in the abbreviated barrel. By the time one concocted a powder charge that could make a short barrel replicate the fastest velocities attained by a 40" barreled safe load, the shorter barrel or action in all likelihood would sustain excessive pressure related damage, potentially catastrophic. Seen the aftermath of those who tried.... covered that in posts 2 and 3...... but I bet for that ONE shot, that short little barrel patterned like the long daddy 40" inchers do, then croaked.

Edited by cleefurd
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this weekend im going to use a 2 3/4"magnum in the short barrel and a skeet load in the long barrel. and if i can get the pic to post you will see that the longer barrel patterns better even against the hotter load of the short barrel.

 

gun manufacturers will tell you it makes no difference.why? i do not know. granted, it was not like the 24" made a 60" pattern, and the 30 " made a 12" pattern. but it did make about a 7-8" tighter pattern, which makes for a lot dencer pattern.there are goobs of proffesional skee ,trap shooters that will tell you length does make difference.

 

and about your idea above, the answer is NO. you will end up with the gun in your face.this is why there are longer barrels, so you dont have to risk your eye site to greater ranges.we have shot them through chronagraphs to check the velocities of the to and there was only 18fps faster out of the 30". not enough to mention.

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Guest cleefurd

GP loads will of course show little difference, you still got it right, and the chrono idea will help too, gun manufacturers do this all day long, then its plums2plums2plums, not skeet/long,hot/short take picture photo plum orange banana logic. Why don't you trust them?? They have data, and decades of results based validation, they would LOVE to agree with you carte-blanche trust me, they could sell way more barrels that way, if they could get everyone to believe that every patterning niche were contingent upon barrel length. Why would they tell you barrel length DOES NOT change patterns, velocity and chokes do, if it weren't true??? They sell longer barrels primarily to safely take advantage of loads that DO reach higher velocities well beyond the GP load that peters out after the 1st 16"-24" of barrel. They KNOW that tests which seem to disprove their logic are flawed as soon as someone starts mixing and matching barrels and cartridge selection until some anomoly arises. That's easy to do actually. Way too many variables now; buffers, wads, different barrel steel, etc. Use the same barrel stock similar shot origin, identical choke configuration and metallurgy, triple checked chrono data, machine rest for "exit moment" elimination, and the load that DOES get going a whole lot faster WILL group tighter down range, back it off until the round delivers similar velocity with ALL variables held constant such as wad selection, peak chamber pressures, from both barrels long and short and you will note essentially identical patterns.

 

Or on second thought, perhaps they are just failing to discard years of experience, in favor of hear-say, urban legend, and what Wal-Mart ammo does in a yard long O/U barrel vs K-Mart ammo out of a semi-auto entry gun.

Edited by cleefurd
spell check
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Guest cleefurd

BTW splashtx556ftw,

 

You asked, and I produced documented data from my old scrapbooks gleaned from Aberdeen testing of anti-frangible projectiles (i.e. shot) Unless I'm reading you wrong, from beginning to end you refuse to believe what the experts, manufacturers and historical data conclude, in favor of your own best attempts at controlled testing... which I admire.

 

I have told people for years for example that wind acting on a bullet at the firing line has a greater effect on it than wind near the target 1000 yds away. Most will argue that the slowed bullet gets pushed further down yonder, since it has more time to drift. I beat them every time, simply because they are right AND wrong. While the bullet is shoved more per foot travelled the more it slows down, it CHANGED directions at the muzzle, when the wind pushed it NOT just to the left or right, but off course for the next 999 yds. I HAD to believe an expert to benefit from that, and the last time I shot a National Championship I cleaned the 1000 yd line for the Wimbleton Cup, and got in a shoot-off ... which I lost, guess I missed something after all. But I try to learn, and I try to share. Hope you know that I am trying to help.

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Guest cleefurd

 

Cool stuff! So that long barrel makes it quiet, and the "Dead-Ringer" wad stopping choke tightens patterns according to them. They don't seem to make any mention of how those extended barrels affect groups, unless I missed it.

 

Still cool ... 74 decibels is extremely quiet.

 

(Just re-read the article. Seems they DO reference improved grouping at 40 yds. I missed that the first time I viewed it. Interesting. Apparently they're onto something, outside the norm component and results wise. Pretty sure Aberdeen never tested THOSE barrels on SG ammo. Hmmm...)

Edited by cleefurd
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ok...........if it makes no diff at all, tell me why, why are out there with a gun that looks like its got a 4ft piece of pipe on it????? why not a 20 or 22 inch barrel?? i ll be the first to admit, maybe under laboratory conditions. it makes no diff at all. but in my back yard,it does make a difference. after all, i dont hunt in thier lab. i have tryed this over and over with so many guns i cant even remember them all. and ive yet to see a short barrel deliver as "tight" a pattern as a long one.and until some one comes to my house with a gun and proves different, im gona stick to my belief.;)

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ok...........if it makes no diff at all, tell me why, why are they out there with a gun that looks like its got a 4ft piece of pipe on it????? why not a 20 or 22 inch barrel?? i ll be the first to admit, maybe under laboratory conditions. it makes no diff at all. but in my back yard,it does make a difference. after all, i dont hunt in thier lab. i have tryed this over and over with so many guns i cant even remember them all. and ive yet to see a short barrel deliver as "tight" a pattern as a long one.and until some one comes to my house with a gun and proves different, im gona stick to my belief.;)

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Guest cleefurd

From what I read on the link you provided, that extension benefits only the mental welfare of the surrounding cattle, and to reduce noise levels to a hush around suburban airports using them for pest control etc.... same link you sent me, that made no mention of patterns in regards to the long tubes.

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