Cranfield Posted September 10, 2014 Report Share Posted September 10, 2014 Assuming all other factors are equal (sbs shotgun, cartridge size, weather, distance, etc), does the length of a shotgun's barrels affect the noise it makes ? As in , shorter barrels = more noise, longer barrels = less noise, or is barrel length irrelevant ? Quote Link to comment Share on other sites More sharing options...
bluesj Posted September 10, 2014 Report Share Posted September 10, 2014 (edited) I would say that longer barrels would be less noisey but only because the longer barrels will absorb more heat so take more energy from the hot gases, less heat = less energy = less noise. But don't think you would be able to messure the differance Edited September 10, 2014 by bluesj Quote Link to comment Share on other sites More sharing options...
Flynn Posted September 10, 2014 Report Share Posted September 10, 2014 A shorter barrel will often have a higher pressure of gasses when everything reaches the open air, as things are often still accelerating at that point. More pressure equates to more sound energy. In addition a longer barrel will absorb more of the energy from the expanding gasses and also bounce it around internally more, in addition to giving the gasses more time to slow down thus reducing the pressure waves coming out of the barrel and resulting in a "quieter" bang. It's all relative though - there's still a great deal of energy coming out of a longer barrel. With a typical faster burning powder, you'll be venting higher pressure gasses into the atmosphere and thus you'll get a more of a bang. Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted September 10, 2014 Report Share Posted September 10, 2014 In America where silencers are effectively banned they sell enormous barrel extensions which make the report much quieter Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted September 10, 2014 Report Share Posted September 10, 2014 http://www.guns.com/2012/11/10/the-metro-gun-subsonic-shotgun-barrel-system/ Quote Link to comment Share on other sites More sharing options...
JohnfromUK Posted September 10, 2014 Report Share Posted September 10, 2014 Yes, definitely. 25" barrels are a different noise (that seems louder). If you are watching/listening to a line of guns shooting, one of whom shoots 25" barrels, it is quite noticeable. From about 28" upwards I've not noticed much difference Quote Link to comment Share on other sites More sharing options...
Cranfield Posted September 10, 2014 Author Report Share Posted September 10, 2014 Thanks for the replies. I have recently acquired a 27" 12ga sbs to replace my old (condemned) 30" 12ga sbs and it seems much louder than my old gun, having quite a "crack".. A few friends have also commented that its loud. I was very surprised that it made quite so much difference Quote Link to comment Share on other sites More sharing options...
browning123 Posted September 10, 2014 Report Share Posted September 10, 2014 I once owned a AYA with 25" barrels, i had to sell it as it gave me a headache after shooting. Quote Link to comment Share on other sites More sharing options...
Cranfield Posted September 10, 2014 Author Report Share Posted September 10, 2014 I will give this a little longer as I have invested some money in it, but I will not have a gun that stays in the cabinet, so it may be moving on soon. Quote Link to comment Share on other sites More sharing options...
fortune Posted September 10, 2014 Report Share Posted September 10, 2014 I've got a couple of 25's, 26, 28s and various bore sizes and I cant say that i've noticed any difference in the report from any of them. Cartridges and burn speeds make a lot of difference though. The only time that I thought WOW was a Baikal Record out of one of the 25's. That was like an anti tank round. Quote Link to comment Share on other sites More sharing options...
clayman Posted September 10, 2014 Report Share Posted September 10, 2014 The amount of noise, ie the peak dB level, from any gun will depend on where you measure. Noise tests conducted by me for the CPSA at Reg Bates's ground in Notts measured a 10db difference between the side of the gun and the shooter's position - i.e. average 120dB at the muzzle, 110 at the shooters ear. We also found a small difference between the left and right ears, rather surprisingly with the left being higher than the right, for a right shouldered gun. Noise perception and actual noise are also different. The actual energy peak can be so quick and high that the human ear does not actually hear it. A typical shotgun discharge has a double peak, one of the powder burn, followed microseconds later by the shot load breaking the sound barrier and giving a sonic boom. The double peak is long enough for the ear to detect the average pressure the two make combined. Judging the "loudness" of any gun depends entirely on where the reading is taken, and the gun will have a sound "footprint" and its not linear around the gun. Any-one who has been near ported guns will tell you they sound louder than normal barrels, but that only because the footprint is different, the total noise energy is the same, just distributed into different areas, so if it sounds louder behind, its almost certainly less noisy out front, as the energy is the same, just the distribution footprint is different. We didn't test barrel lengths to see if there was any difference, but it would be an interesting project for BASC ballistics committee, or Dr Allsop at Shrivenham? Trawl the net and see if anyone actually has done a measured study - Peter Blakerly might have some info. As a guess, I'd suggest that noise differences are not the cartridge itself, but more likely the resonant attributes of any given gun. If you wack a tube it resonates ( tubular bells) - and as a hypothesis I'd suggest guns do the same and the extra noise is a longer resonance after discharge. Quote Link to comment Share on other sites More sharing options...
seeker Posted September 11, 2014 Report Share Posted September 11, 2014 (edited) There are several studies on the effects of barrel length in rifles and 1 quite readable one which measured pressure, velocity and noise differences with changes in length ... think 1 barrel, test gear and a hacksaw. It may be that the similar results would hold for a shotgun given that the sound is a function of muzzle pressure? "EFFECTS OF BARREL LENGTH ON BORE PRESSURE, PROJECTILE VELOCITY and SOUND MEASUREMENT. by Dater and Wong" ( dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf ) Some one asked why i prefer 32 to a 28... .. the bang is 4" further from my ear. Edited September 11, 2014 by seeker Quote Link to comment Share on other sites More sharing options...
kent Posted September 11, 2014 Report Share Posted September 11, 2014 You should be able to reduce the noise some by shell choice, I think it has much to do with the rate of powder burnt. I sometimes shoot a just legal s/s and can only say shell choice seems to matter. Of course we should all wear hearing protection I myself am starting to get certain ranges in my hearing lost by ignoring that factor a little too much in the past Quote Link to comment Share on other sites More sharing options...
dougall Posted September 11, 2014 Report Share Posted September 11, 2014 gosh never noticed...I guess the amateur scientist in mean thinks if the muzzles are nearer the report will be louder makes sense......from all other ballistic thoughts though can't believe it makes much difference....I do recall working at a clay shoot and an old Baikal,with short barrels was mentally loud compared to all others,several folk commented on it...we concluded at the time it was slightly off the face as traces of smoke 'appeared' after firing from the breech.......I guess it could have been barrel length... Quote Link to comment Share on other sites More sharing options...
TriBsa Posted September 11, 2014 Report Share Posted September 11, 2014 Generaly short exhaust pipes of the same diameter are louder than longer ones (straight through no silencers) and shotguns should be the same. A big factor for the shooter as Kent says is distance from muzzle to ear. The report from the 27" barrels is going to be about 10% closer. I'd guess gun weight would also be a factor in terms of resonance as Clayman says and also perception of noise as it is often difficult to diferentiate noise and recoil from the overall experience of it going bang. Quote Link to comment Share on other sites More sharing options...
clayman Posted September 11, 2014 Report Share Posted September 11, 2014 gosh never noticed...I guess the amateur scientist in mean thinks if the muzzles are nearer the report will be louder makes sense......from all other ballistic thoughts though can't believe it makes much difference....I do recall working at a clay shoot and an old Baikal,with short barrels was mentally loud compared to all others,several folk commented on it...we concluded at the time it was slightly off the face as traces of smoke 'appeared' after firing from the breech.......I guess it could have been barrel length... Very valid point. I'd go as far to suggest this could be the main difference between guns. The amount of leakage at the face will vary according to age, design, and gun quality. Every gun is going to have some degree of discharge at the action and it may well be this is the main difference between guns, rather than barrel length?? A tiny change, of say 1% to 2% pressure from the face would be a doubling of energy release right near the ear, and would certainly sound much louder. Quote Link to comment Share on other sites More sharing options...
arjimlad Posted September 11, 2014 Report Share Posted September 11, 2014 I recently acquired a 27" barrelled SBS and thought the same thing, Cranfield. Quote Link to comment Share on other sites More sharing options...
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