I mean no offense in my response, but in my view I don't necessarily think you'll get better accuracy out of the polygon barrel and unless your going to shoot 1,000,000 rounds, I seriously doubt the longer life of the barrel will be an issue.
Both my P88 and P99's have regular ballard rifling and I know it would be almost impossible to find another production 9mm that is as accurate as the P88. (The SIG P210 is arguably the best and most accurate 9mm and it has ballard rifling also). Personally I think you'd be just wasting your money.
I agree with P88, you'd be wasting your money. There's no evidence to suggest that polygonal barrels are any more accurate than quality traditionally rifled bbls. The Walther barrels are among the most accurate.....and more than sufficiently durable.
I think the talk about gas sealing and higher velocity it hype too. If anything I think the P99 develops about as good velocity as one can obtain from a 4" bbl regardless of rifling type.
Last thing. Polygonal barrels are usually cheaper to manufacture. This is one feature not typically mentioned.
I am sorry if I gave the impression that I am going to throw away the original barrel. My interest is some what academic. I don't find any negative aspect to a lower manufecturing cost if it not ivolves lower performance. I do think that lowering the firing stress is important, especially with the polymer frames that tend to flex. What I really wonder why it is not possible to fire lead bullets with polygonal barrels.
BTW, if you are after bullet speed get the FN FiveseveN, as its muzzle velocity is 2133 fps.
The polygone barrel can not be used with lead because the lead will build up or stick to the rifling. Then as you keep on firing the pressures go up because its harder to push the bullet through the buildup, till eventually its more than the gun can handle and you get a kB! This has been a common occurance in Glocks. I don't know why the lead "sticks" to the polygone rifling and not the ballard type.
I have seen the FN Five-seveN for sale to civilians as well. I think a lot of distributors got stuck with them so they are quietly being sold to dealers who have a letter on record that they will only sell to law enforcement and not civilians. The letter of record is a wink and nod thing that allows FN and the distributor to deny they sold a pistol that shoots AP rounds to the masses. It's something imposed by FN to curtail their potential liability. It's fallout from the gun lawsuits. -Keep in mind, even if you're right, it is expensive to defend yourself in court. There is no Federal law preventing the average person from owning one.
As I understand it, they were supposed to be a compliment to the P90 submachine-gun. They shoot the same ammo as the P90. The P90 was originally geared for soldiers who were not infantry, such as tank and artillery crews. However, few countries have opted to purchase them for their militaries. I believe the list is short (Saudi Arabia, Peru, and Thailand). Personally, I think it would be a logistical nightmare to add another caliber that isn't general issue, but to each their own.
The problem in this country is that most agencies aren't buying the P90 to replace the MP5 or the M-4 (M-16 carbine variant), so there aren't that many people picking up the "matching" pistol in an uncommon caliber. -If memory serves, the ammo is also very pricey (something like fifty cents a round).
However, if you want a pistol that can punch through a standard kevlar vest at a 100 yards, knock yourself out... It'll be interesting to see if the gun can make better headway into the market after the ban sunsets. One can only imagine it could be a popular compliment to a civilian version of the P90 (assuming FN would make such a beastie).
I prefer the P99's original barrel. This is also one of the main reason I choose this great pistol over Glock , again just me.
As for comparison , I currently own a Jericho 941FS 9mm. (compact but full capacity version) that sports a polygonal barrel. For me , there's no discernible difference between the two in terms of accuracy.Both are combat accurate and very reliable.However , the options presented by the rifled barrel are far more practical in terms of bullet selection , economy , cleaning and maintennance.No kabooms to worry , except for highly over pressured ammos , ratings higher than +p+ ammos (owner induced or by accident). I would keep the orig. barrel even if there's a polygonal replacement.
Whether a barrel has traditional lands and grooves, or has a polygon (or polygon-like) twist, makes no difference to me. I don't shoot lead bullets through my semi-autos. Given a choice, though, I'd go with traditional lands and grooves, as it provides slightly more versatility. I am happy with my Glocks, HK P7s (not counting the P7M10 that has traditional lands and grooves), and HK USPs as-is.