Question about barrel length and bullet velocity. Please help!


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Shawn Michael
December 31, 2006, 01:21 AM
I understand that having a longer barrel allows more of the powder to burn and accelerate the bullet, to a point. So the barrel is an acceleration chamber.

I am thinking of purchasing a SW .500 mag and have been grappling with barrel length. After handling the guns, the 7.5 seemed the most well balanced and least cumbersome in my hand. But am I losing power?

The guy at the gun store says no. "the barrel is long enough to stabilize the bullet and these flat bullets roll when they exceed the speed of sound so this is fine." and he said (paraphrase) "So basically you have a slow heavy bullet that will attain its max speed, and a pointed or rifle type bullet, like a .460 will really hurt with a few inches off the barrel but not a 440 grain .500" Is he correct? Thanks for help!

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JohnKSa
December 31, 2006, 01:34 AM
The guy's full of it, the bullets won't roll if they go supersonic.But am I losing power?I gotta ask--compared to WHAT?

Will another inch give you some more velocity? Yup, probably you'll probably keep gaining some velocity out past a foot of barrel length. However, big bore cartridges tend to get less out of more barrel than the smaller calibers. The expanding gas has a lot more bore volume to fill and that means it has a harder time keeping significant pressure on the base of the bullet.

But if there's something you want to do with a handgun that CAN be done with a handgun, I feel pretty safe in assuring you that the power that you're going to have at your disposal with a 7.5" barrel 500 Mag will be sufficient.

Shawn Michael
December 31, 2006, 01:53 AM
That makes sense, appreciate the answer.

My brother in law suggested the .500 because he loads them light (like the
.500 special) but if necessary can got way up.

I am going for my first handgun hunt (boar, I will have sasauge for a year)

I am trying handgun because the experience I had with rifle from LONG range 7mm mag/scope was not really what I hoped for.

I do think there is some concern about getting a good shot placement with a handgun and I know some think it is unethical to the quarry to have less percise shot placement.

Thanks for clearing up the misinformation.

shooting on a shoestring
December 31, 2006, 02:24 AM
SM, Yep JohnK is right, the salesman is full of it. To the point, revolvers develop most of their velocity in the first couple of inches of bullet travel. Snubbies (2 inch barrels) will have about 80% of the velocity of 6 inch guns. There is approximately a 35 to 50 fps increase for each additional inch of barrel length. You will get the largest increase going from a 2 to 3 inch barrel, less increase between 3 to 4 inches, and not much at all from 7 to 8 inches. So from a velocity standpoint, anything around 4 to 6 inches of barrel will get you all the practical velocity you can expect out of a load.

Longer barrels do have a longer sight radius, but in the real world 6 inches is plenty, your trigger pull will have more to do with making or missing the shot than how much sighting error you have.

Big bores are fun! But be sure to shoot it alot using your hunting load so you can see just how short your range is. Try hitting a 3x5 file card at various ranges out to 50 yds or so. Thats about how much control you need in your shot placement. At whatever distance you can nail a 3x5 card standing at the firing line, you can take a shot at live game. Your ability to hit game will be less than your target ability due to the adrenalin rush.

.500 S&W is expensive to shoot, even reloaded. I personally use .45 Colt in a 7.5" Blackhawk. I can put 300 gr bullets between 1250 to 1300 fps. That is terribly powerful, and all I can shoot well. But to each his own.

ArchAngelCD
December 31, 2006, 02:39 AM
If the only reason you are buying the 500 is the fact you can load them light then you might want to reconsider and look at the 460 again. Of course you can fire the S&W .460 Magnum from your 460 but you can also fire the .454 Casull and the .45 Long Colt too. I really like the S&W 460V but there is nothing wrong with the 500 either. I just wanted to mention the versatility of the 460 since you mentioned the light loads for the 500.

This Model 460XVR comes in a 7.5" barrel and comes with a lot of goodies too. (like a Lothar-Walther Custom German Rifle Barrel and 360 Recoil Compensator) http://whttp://www.smith-wesson.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&catalogId=11101&langId=-1&productId=39901&tabselected=over&isFirearm=Y&parent_category_rn=15707

Of course so does the 7.5" 500 Hunter but for some reason I really like the 460. Maybe it's because I don't reload and the availability of the 3 different rounds for the 460 is a selling point for me, especially the cheaper .45 Colt. http://www.smith-wesson.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=11101&storeId=10001&productId=24951&langId=-1&parent_category_rn=15707&isFirearm=Y

Shawn Michael
December 31, 2006, 04:13 AM
My brother in law has all the reloading stuff (which I have always been a little intimidated by) and second, I just think .50 is cool...it is as much a toy as anything practical, but I rarely buy anything fun so I figured I would go for it. I ordered the black/silver .500 linked in the post above. When I saw it, it just looked and felt perfect to me.

I really want to learn to reload as well, living in Calif who knows what will happen.

After a lot of misinformation, I enjoy the knowledgable posts.

I have previously owned a single shot pistol called a "competitor" which was in .308 with a 16 inch barrel so I know a little about the subject but this really helps.

Thanks

Magnumite
December 31, 2006, 04:24 AM
In that pressure range, you are looking at about 35 to 50 fps/inch velocity loss for each inch of barrel length. I would say possibly more. A 7.5" barrel is pretty efficient and the greater portability will allow you enjoy the gun more.

Even at 7.5", its a biggin'!

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