Barrel Length

[jb3k9]

I'm shopping for my first hand gun. I think I want a 40 cal, but can't decide on barrel length; 4" or 4.25". Does anyone have preference and why?

[JLA]

Quarter inch aint gonna make that big a difference in accuracy or terminal balistics.. Get the 4 inch and have a more concealable weapon.

[woolleyworm]

What is your intended purpose for the gun? That's the biggest deciding factor. If you want a range gun, then go longer. If you're looking for a CCW, the go as short as you're proficient with.
'
By all means, if this is your first handgun purchase, try/rent/borrow as many as you can and get a feel for them. If you have a local range, go hang out there for awhile and make some friends.

Welcome to the forum also; where you from?


Semper Fi,

Woolley

[Old Guy]

1/4 of an inch won't make that much difference. I have a 4" XD that shoots quite well for a defensive pistol.

[NGIB]

Make sure to rent one before buying one. I have no idea why so many folks start with a .40, maybe the gun stores push them. Nothing really wrong with the caliber but it is very snappy to shoot and costs more than 9mm does. Shooting a handgun well requires a LOT of practice and ammo cost is a huge factor...

[mesinge2]

I always try to recommend a 22 for someone just starting to learn. But if your looking for a self-defense weapon then IMO it is best to start with either a K frame 38 SPL or a 9mm Service-size pistol depending if you want a revolver or a pistol.

Be sure to find a range that has a few guns to rent and try as many as you can. Only you can decide which is right for you.

[group17]

I would also suggest a 9mm for your first pistol.
Get use to it then move up to 40 cal which is snappier.
As I got better with shooting I moved down to shorter barreled pistols.

[JLA]

I started out on a 9 mil BHP copy. Got proficient with it then jumped right to a 1911 .45ACP. There are WORLDS of difference between them and the .40 falls right between the 2.

If you like modern 'plaztiks' then I would recommend you look at some glocks and XDMs in 9mm and .40 S&W. If you are a die hard 'steelhead' as I am, look at some 1911s, BHPs and copies thereof, even the CZ75 & 85 and the Beretta M9 (92). I particularly like the CZ 75 9mm, its quite comfortable and very accurate.

[RunningOnMT]

Welcome to TFF jb3k9.

One thing to consider; the rifling in a barrel imparts a spin to the bullet giving it more stability and accuracy. The bullet doesn't actually spin at the same rate as the rifling, rather it skids across the rifling which only gives it a relatively slight rotational nudge. Naturally the longer the barrel the more time the rifling has to impart the optimum spin, TO A POINT. But that optimum length not being practical for handguns we settle for less than optimum.

The .40 S&W being a little higher velocity than some other handgun loads, it has occured to me that it's not as accurate as say a .45 acp out of the same length barrel. I owned an XD40 with a 4" barrel and I personally found it's accuracy did not meet my expectations. I traded it in on a 1911 and my marksmanship increased substantially. I have never looked back. I have acquired several handguns since, all in .45 cal except for my GP100 .357 mag w/6" barrel.

Of course my experience may not be yours or someone elses. I think though it would be worthwhile to go to a range and rent a few pistols to not only compare the various models out there, but also the calibers.

[JLA]

Originally Posted by RunningOnMT

Welcome to TFF jb3k9.

One thing to consider; the rifling in a barrel imparts a spin to the bullet giving it more stability and accuracy. The bullet doesn't actually spin at the same rate as the rifling, rather it skids across the rifling which only gives it a relatively slight rotational nudge. Naturally the longer the barrel the more time the rifling has to impart the optimum spin, TO A POINT. But that optimum length not being practical for handguns we settle for less than optimum.

The .40 S&W being a little higher velocity than some other handgun loads, it has occured to me that it's not as accurate as say a .45 acp out of the same length barrel. I owned an XD40 with a 4" barrel and I personally found it's accuracy did not meet my expectations. I traded it in on a 1911 and my marksmanship increased substantially. I have never looked back. I have acquired several handguns since, all in .45 cal except for my GP100 .357 mag w/6" barrel.

Of course my experience may not be yours or someone elses. I think though it would be worthwhile to go to a range and rent a few pistols to not only compare the various models out there, but also the calibers.

I must disagree ROMT. I have tested expansion and penetration with nearly every hangun cartridge ever and none of them exhibit signs of skidding when I inspect the fired bullets. Jackets are cut clean and crisp by the rifling indicating the Bullet spun the exact pitch of the rifling thru the length of the bore. Lead also engraves cleanly and spins smoothly.

I have seen examples of bullets skid and they exhibit smeared jacket or lead down the bearing surface of the bullet. Furthermore a skidding bullet will not hit a consistent point of aim as the twist obtained is insufficient to stabilize the round and the distortion of the jacket causes turbulence in flight.

Excessive velocity and undersized projectiles are just about the only things that will cause a bullet to skid in a rifled barrel.

[RunningOnMT]

Originally Posted by JLA

I must disagree ROMT. I have tested expansion and penetration with nearly every hangun cartridge ever and none of them exhibit signs of skidding when I inspect the fired bullets. Jackets are cut clean and crisp by the rifling indicating the Bullet spun the exact pitch of the rifling thru the length of the bore. Lead also engraves cleanly and spins smoothly.

I have seen examples of bullets skid and they exhibit smeared jacket or lead down the bearing surface of the bullet. Furthermore a skidding bullet will not hit a consistent point of aim as the twist obtained is insufficient to stabilize the round and the distortion of the jacket causes turbulence in flight.

Excessive velocity and undersized projectiles are just about the only things that will cause a bullet to skid in a rifled barrel.

Well you obviously have more experience than I in this matter so I'll have to stand corrected. However, the fact that there is the presence of clear rifling marks on the bullet wouldn't necessarily indicate that the bullet followed the exact rifling in the barrel and not skidded.

Under such circumstances metal will move. There is tremendous forward momentum in the bullet as it travels through the barrel and bullet materials be they lead or copper jacketed are softer than the barrel material. The initial impression in the bullet could essentially be recut or moved over while the old impression was ironed out by continous skidding. Also it would make sense that as it exits the muzzle the bullet will have the impression of the final twist.

It would be interesting to precisely measure the twist rate of rifling on the bullet and compare it to the rifling in a given firearm in several different barrel lengths.

Another point is that if there was no skid then the passage of the bullet through any length of barrel would impart the desired spin on the bullet. Once the spiral motion is begun it will continue at the same rate, IF THERE WAS NO SKID.

While there are a number of reasons manufacturers select certain barrel lengths such as developing velocity by gas expansion the minimizing of shooter error in acquiring a sight picture along a longer axis, etc., it would at least seem to me that another reason is to allow enough time for friction of the rifling to impart the required spin.

Finally your last statement that "Excessive velocity and undersized projectiles are just about the only things that will cause a bullet to skid in a rifled barrel" hints at the point I was originally trying to make. It is my belief that all but the lowest velocity .40 cal ammunition will not be imparted with the desired spin rate in such a short barrel due to skidding.

As I said I realize that you have more experience on the subject and I could very likely be full of puckey, but occasionly I'll choose to not let the facts get in the way of a spirited debate. Besides presenting my misconceptions and faulty logic to a more knowledgable person is how I learn best (the socratic method).

Oh, just thought of one more point, "when a barrel is worn, what wears?" The tops of the lands, right? How could this be if the bullet always rode in the grooves?

[woolleyworm]

Originally Posted by RunningOnMT

Oh, just thought of one more point, "when a barrel is worn, what wears?" The tops of the lands, right? How could this be if the bullet always rode in the grooves?

Often what wears a barrel out isn't the rifiling, but throat erosion in the chamber ( leade area ). The bullet will make contact with both surfaces inside the barrel, but it's said to "ride in the grooves". It technically rides on both if the bullet/barrel combination is correct.

[JLA]

Originally Posted by RunningOnMT

Well you obviously have more experience than I in this matter so I'll have to stand corrected. However, the fact that there is the presence of clear rifling marks on the bullet wouldn't necessarily indicate that the bullet followed the exact rifling in the barrel and not skidded.

Under such circumstances metal will move. There is tremendous forward momentum in the bullet as it travels through the barrel and bullet materials be they lead or copper jacketed are softer than the barrel material. The initial impression in the bullet could essentially be recut or moved over while the old impression was ironed out by continous skidding. Also it would make sense that as it exits the muzzle the bullet will have the impression of the final twist.

Not exactly, If the projectile were being 'ironed' out by the rifling the final diameter of the bullet would be the diameter accross the lands. Take american made .30 caliber rifles for exaple. they all spec .300 across the lands and .308 across the grooves. Fired projectiles leaving these barrels measure .308 accross the bearing surface as they originally did in their unfired state and .300 accross the engraving from the rifling. Now just for giggles we will consider a foriegn .30 cal, say the .303 british, which employs a nominal groove diameter of .313 and a bore diameter of .303.. Make sense??

It would be interesting to precisely measure the twist rate of rifling on the bullet and compare it to the rifling in a given firearm in several different barrel lengths.

Actually this is quite possible, and quite simple. Plug the bore of your pistol and melt some cerrosafe into the bore to take a cast of the bore and its rifling. Then when its set up tap it out and compare fired projectiles to the rifling impression on the cerrosafe cast. The pitch and size of the rifling grooves will match quite nicely..

Another point is that if there was no skid then the passage of the bullet through any length of barrel would impart the desired spin on the bullet. Once the spiral motion is begun it will continue at the same rate, IF THERE WAS NO SKID.

You are partially correct here. It doesnt matter if the barrel length is 2 inches or 2 feet, the bullet WILL get the spin. Where you're wrong is, bullet spin is a measure of inches per revolution, wich in turn is directly affected by muzzle velocity, which is affected by barrel length, meaning the faster a bullet goes the faster it spins, and the slower it goes the slower it spins. For example, if a bullet is going 2500 fps from a 1:10 twist barrel it is spinning at a rate of 180,000 RPMs. The same bullet traveling 3500 fps from the same 10 twist is going 252,000 RPMs. MV x (12/twist rate in inches) x 60 = Bullet RPM, or simple equation after order of operations have been applied..MV X 720/Twist Rate = RPM..

While there are a number of reasons manufacturers select certain barrel lengths such as developing velocity by gas expansion the minimizing of shooter error in acquiring a sight picture along a longer axis, etc., it would at least seem to me that another reason is to allow enough time for friction of the rifling to impart the required spin.

Again, here you are partially correct. Manufacterers select barrel twist rates based on ballistic performance of the cartridge they are chambered for. Its why you dont see too many production run magnum class ceterfires with less than 24 inch barrels, and by the same token, you dont see too many production run .223 rifles with more than 22 inch barrels. Barrel length affects velocity, and thus spin, but only in this relation.

Finally your last statement that "Excessive velocity and undersized projectiles are just about the only things that will cause a bullet to skid in a rifled barrel" hints at the point I was originally trying to make. It is my belief that all but the lowest velocity .40 cal ammunition will not be imparted with the desired spin rate in such a short barrel due to skidding.

If you use a bullet that is sized to the extreme dimension within the bore of the firearm, for example, .40 cal handgun uses a .401 diameter projectile, then the bullet will obturate under pressure, the rifling will engrave the bullet and it WILL NOT skid down the bore. Excessive velocity is restricted to the use of cast lead projectiles as they are far softer than jacketed bullets and if the velocity limitations are pushed, it will cause the bullet to skid and foul the bore heavily with lead. Undersized bullets will skid in a barrel no matter their composition. if they arent big enough to grip the rifling the cant spin.. period..

As I said I realize that you have more experience on the subject and I could very likely be full of puckey, but occasionly I'll choose to not let the facts get in the way of a spirited debate. Besides presenting my misconceptions and faulty logic to a more knowledgable person is how I learn best (the socratic method).

I agree. Plus I enjoy sharing my wealth of knowledge..

Oh, just thought of one more point, "when a barrel is worn, what wears?" The tops of the lands, right? How could this be if the bullet always rode in the grooves?

Actually when a barrel wears, it wears everywhere a bullet touches it. Lands, grooves, chamber throat, muzzle etc.. The reason rifling lands wear harder are because they are the part of the bore that dig into the bullet and cause the most amount of heat and friction. But here we are talking over thousands of rounds before you even notice a difference in appearance. accuracy on target will diminish long before you notice the rifling is visibly worn..

Whew... My brain hurts..

I just want to elaborate a little more on the barrel twist.. the info above is accurate and correct, and if you think about it With a given rifling twist rate, the quicker the bullet passes through the rifling, the faster it will be spinning when it leaves the muzzle. To a certain extent, then, if you speed up the bullet, you can use a slower twist rate, and still end up with enough RPM to stabilize the bullet. But you have to know how to calculate RPM so you can maintain a sufficient amount.

Examples...

It is generally believed that, for match bullets, best accuracy is achieved at the minimal spin rates that will fully stabilize the particular bullet at the distances where the bullet must perform. That’s why short-range 6PPC benchrest shooters use relatively slow twist rates, such as 1:14″, to stabilize their short, flatbase bullets. They could use “fast” twist rates such as 1:8″, but this delivers more bullet RPM than necessary. Match results have demonstrated conclusively that the slower twist rates produce better accuracy with these bullets.

Generally speaking, among bullets of the same caliber, longer bullets need more RPM to stabilize than do shorter bullets–often a lot more RPM.

I hope this helps you to understand what happens when the pin hits the primer..

[RunningOnMT]

Thanks much for this info. I feel as if I'd been driving a car for 50 years believing they ran on pixie dust.

However, I followed you down to: Actually when a barrel wears, it wears everywhere a bullet touches it. Lands, grooves, chamber throat, muzzle etc.. The reason rifling lands wear harder are because they are the part of the bore that dig into the bullet and cause the most amount of heat and friction. But here we are talking over thousands of rounds before you even notice a difference in appearance. accuracy on target will diminish long before you notice the rifling is visibly worn..

According to what you're telling me though is the bullet rides in the grooves not on top of the lands. If so I would think the corners of the lands might wear so that slowly the lands became narrower. While I'm sure they do to some extent, what I have seen are lands that look about the normal width but with the tops worn down. How would this be if the bullet were passing through the barrel riding in the grooves and not skidding across the lands?

[JLA]

Originally Posted by RunningOnMT

Thanks much for this info. I feel as if I'd been driving a car for 50 years believing they ran on pixie dust.

However, I followed you down to: Actually when a barrel wears, it wears everywhere a bullet touches it. Lands, grooves, chamber throat, muzzle etc.. The reason rifling lands wear harder are because they are the part of the bore that dig into the bullet and cause the most amount of heat and friction. But here we are talking over thousands of rounds before you even notice a difference in appearance. accuracy on target will diminish long before you notice the rifling is visibly worn..

According to what you're telling me though is the bullet rides in the grooves not on top of the lands. If so I would think the corners of the lands might wear so that slowly the lands became narrower. While I'm sure they do to some extent, what I have seen are lands that look about the normal width but with the tops worn down. How would this be if the bullet were passing through the barrel riding in the grooves and not skidding across the lands?

Again, because this is where the projectile generates the most heat and friction. And heat and friction are the 2 most profound causes of wear.

Its not all too different than a bushing on a mandrel that supports a load. The mandrel contactes the entire bushing but it will wear fastest in the places the load bears the hardest, which are known a stress points in the machine world and are usually given double lube detail by maintenance minded operators..

Think of the rifling lands within a barrel as stress points. they are smaller than the projectile so they engrave into the projectile causing it to rotate. This hard contact causes alot of heat and friction to mount and over time will wear the tops of the lands down. The reason the grooves dont wear as fast is because they arent undersized to the bullet like the lands are. they simply provide support and keep the bullet straight and expanding gasses behind the bullet. When you shoot jacketed you use a projectile that is the same as the groove diameter of your weapon, cast lead gets sized .001-.002 over groove size for better gas seal since its a much softer metal..

Now youre thinkin, "well couldnt we lubricate bullets and stop barrel wear?" and the answer is yes. Bullet mfgrs have been using moly for decades for this purpose, and when properly applied and used exclusively in a bore will cut wear to nearly nothing. Same goes for cast lead. Folks have been using animal based fats to 'grease' their slugs for a couple centuries now. and it works as well today as it did during the civil war.

In fact bore lubrication is a conductive to good accuracy as it is to preventing barrel wear. the less heat and friction within the bore, the less the bullet will distort during its trek down the bore and the more true it will fly...

[Mosin_Nagant_Fan]

Personally, I couldn't hit the broad side of a barn at 20 paces with anything less then 4" (Maybe 3.75", but that's logistics). I have a 2" S&W .38spl revolver and can't keep it from flicking off target, but with my ~4" XD 9MM, I have almost no problems with, at least, hitting my target.