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Recommendation Needed for Ideal 5.45x39mm Barrel Length. . .


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QUESTION (for you 5.45x39mm aficionados):

If you could have any barrel length on your AK 5.45x39mm rifle, what length do you believe would serve the 5.45x39 best with accuracy?

 

The reason why I'm inquiring is because the possibility has presented itself where I could have a Saiga IZ-240 Rifle conversion made with an RPK-74 barrel. The OEM length of the RPK-74 barrel is approx. 23 inches.

 

Providing the gunsmith is able to make this work. . . what length should I request to have this barrel cut down to? I have been unsuccessful with locating anything on the internet which reflects optimal barrel length to ballistics regarding the 5.45x39mm cartridge.

 

I'm leaning toward a 20" barrel, but if I gain absolutely nothing in accuracy with a 20" versus an 18" or 16" barrel via bullet velocity, etc., it would be kinda fucktarded of me to go with the 20" barrel simply to wield around the additional weight. Perhaps the 5.45x39mm cartridge was developed around the premise of a 16" barreled battle rifle? Ummm. . . but if that was the case, it seems kinda silly for Russia to have come out with the RPK-74 (which has a 23" barrel), no?

 

My IZ-240 Rifle will strictly be used at the rifle range, not for hunting or other endeavors.

 

 

All insights and suggestions will be hugely appreciated. Thank you in advance!

 

~Gary

Edited by Gary
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im gunna say 16", as that was the size of the first production run of these rifles and still standard. the krinks are made to fill a niche for those requiring the same weapon in a more compact pakage. and youll get optimum velocity from the 16" over the smaller models. the 20" inch prolly wont make much more difference. maybe a tad more accurate, and better for sustained fire, but id stick with the standard if it were me.

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Well, I guess I was able to largely answer my own question.

 

According to Wikipedia, the muzzle velocity of the AK-74 and the RPK-74 follows:

 

AK-74 (16.3" barrel length): 900 m/s (2,953 ft/s)

RPK-74 (23.2" barrel length): 960 m/s (3,149.6 ft/s)

 

Granted, specifically with the RPK-74 data, the 5.45x39mm bullet type is not specified, not that I could locate (i.e., 5N7, 7N6, 7N10, 7N22), yet providing the derived data is essentially uniform regarding the type ammunition, it is logical that with a 20" barrel I would be able to obtain slightly higher bullet velocity with my shots, regardless of ammo type.

Edited by Gary
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yes. thats really all you gain in the 20" over the 16. as far as accuracy, that depends on the shooter and the ammo used. i dont think the 20" would offer a significant advantage over the 16 in that department. maybe a heavier barrel with better harmonics may play a role in it, but its not a large bullet to begin with so i dont see it being a huge factor. the 16" barrel is damn near pushing the max capabilities with the cartridge to begin with. but all in all, id just stick with the 16" barrel and be done with it. and id leave the barrel on that comes from the factory if it were me. no real gain worthy of barrel replacement that would make me want that. but if you want the cool factor to it, then fuck it, go for it. big_smile.gif in the end its just what you want.

if it were me, id save that money and put it towards an rpk 74 and get the whole package, and have both.

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. . . maybe a heavier barrel with better harmonics may play a role in it, but its not a large bullet to begin with so i dont see it being a huge factor. . . all in all, id just stick with the 16" barrel and be done with it. and I'd leave the barrel on that comes from the factory if it were me. . .

I pretty much totally agree with you.

 

The problem facing me though is: I can't use the OEM barrel that came with my IZ-240 rifle because the gunsmith (who shall remain nameless for the purposes of this thread) friggen cut my barrel down to approx. 13 7/8" when he wasn't suppose to cut it at all (reportedly, my barrel got mixed in with a group of barrels he had in his shop that were earmarked for cutting).

 

So now a replacment barrel needs to be secured, and a Bulgarian RPK-74 barrel seems to currently be the only thing available for procurement. With that being the situation, I figured why not go for a slightly longer than standard 16" barrel for my rifle, since the rifle will only be used shooting paper targets out at my local rifle range?

Edited by Gary
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well since thats the case, then id replace it. hell, since its gotta be done, try out the longer barrel and see what it does. it cant do any worse than the factory one. is it a new barrel also? it may look pretty damn cool with a long barrel minus the rpk furniture. im curious to see how it will shoot. and who knows, it may do better than we think being a smaller caliber with a heavier barrel. itll just be a food game trying to see what she likes best. keep us posted on your finished product and give us a range report.

 

i personally cant speak of the accuracy difference in the two barrels, as i only have a 16, and most of my buddies have the same. i dont know anyone who has a rpk or barrel for this caliber. should be interesting.

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well since that's the case, then I'd replace it. Hell, since its gotta be done, try out the longer barrel and see what it does. It can't do any worse than the factory one. Is it a new barrel also? it may look pretty damn cool with a long barrel minus the rpk furniture. I'm curious to see how it will shoot and who knows, it may do better than we think. Being a smaller caliber with a heavier barrel. It will just be a food game trying to see what she likes best. Keep us posted on your finished product and give us a range report.

 

i personally cant speak of the accuracy difference in the two barrels, as i only have a 16, and most of my buddies have the same. I don't know anyone who has a rpk or barrel for this caliber. Should be interesting.

 

Yes, I'm relatively sure that it's a new barrel (sure as heck should be, for how much it costs). I'm obviously curious like you as to how well it might shoot with an additional 4" and possibly slightly thicker barrel.

 

Right now though this is all speculation. The gunsmith has only informed me that he believes it would work. . . . but naturally he won't know squat until he gets the barrel and determines whether it's a decent fit (i.e., whether he can make it work).

Edited by Gary
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sickness -- I appreciate your recommendation, but. . . "ain't happening." In my opinion, anything beyond 20" for the length of the barrel would not be to my satisfaction or preference. No, none of what I've conveyed within this thread would I be getting for free. Quite the contrary. wink.png

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sickness -- I appreciate your recommendation, but. . . "ain't happening." In my opinion, anything beyond 20" for the length of the barrel would not be to my satisfaction or preference. No, none of what I've conveyed within this thread would I be getting for free. Quite the contrary. wink.png

 

Uhh.. so wait. The smith chopped your barrel up - his mistake - and he is charging you for the new barrel to make it right?

 

How the hell does that work? I'd report his ass to the Better Business Bureau, and take out a nice fat ad in the local paper describing the fiasco. Maybe toss some fliers around town. Don't let this guy take your for a ride, man.

 

If you're set on keeping this gun though.. I guess 20" would be alright; but I'd probably do like toshbar said and just get a long brake installed to make it compliant. Not what you were looking for; but it is the cheapest way out. By the time you pay for the parts and this guy's labor, your probably going to be a long ways towards a new Saiga. Just sayin'.

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Get your old barrel back in there and have him permanently put a long brake on it. A tantal brake would be le schweet on a 13".

 

Put the krink gas block on too.

That is precisely the "fix" which the gunsmith wanted to pursue; weld a long muzzle brake to the barrel. But I told him "hell no!" Cutting the barrel was his fuck-up and I'd be damned if I was going to accept something, a modification to my rifle's conversion order, which was not to my satisfaction.

 

A 13+ inch barrel provides less bullet velocity than the standard 16 inch barrel, period. I'd experience diminishing rifle performance at my rifle range with a shorter barrel, period.

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id stick with your original plan. again like you stated, its speculation. we wont know until you get it to the range. do you plan on running any optics on it?

 

and i would hate to have a brake welded on. after one shooting session mine gets filled with shit and nasty as fuck. i like being able to clean it. but thats me.

 

has this smith offered you any form of compensation for his fail? i would hope that he will offer you something for his fuck-up. if not then that sucks. but you gotta do what you gotta do. how far out til you get this project shootable?

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id stick with your original plan. again like you stated, its speculation. we wont know until you get it to the range. do you plan on running any optics on it?

 

and i would hate to have a brake welded on. after one shooting session mine gets filled with shit and nasty as fuck. i like being able to clean it. but thats me.

 

has this smith offered you any form of compensation for his fail? i would hope that he will offer you something for his fuck-up. if not then that sucks. but you gotta do what you gotta do. How far out til you get this project shootable?

Dude, this IZ-240 Rifle conversion project has been ongoing for well over two friggen years.

 

I readily admit that such comes off sounding entirely insane. . . . yet all will be explained once (or if) I ever receive my rifle back from the gunsmith. But to answer your question directly regarding a projected arrival date for my rifle, the gunsmith informed Jane (a.k.a., AdminGirl) of the forums here, that I would have my rifle conversion by SHOT SHOW, which is January 16th, 2012. With this new wrinkle of trying to find a replacement barrel, that projected date is likely shot to shit.

 

The compensation part of the rifle build's equation has yet to be determined. At this point I simply want my friggen rifle completed and shipped to me (but hell, I felt that way two years ago).

Edited by Gary
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Well, this is all moot now.

 

Upon contacting K-VAR to purchase the RPK-74 barrel, I learned that the gas port in the new Bulgarian barrel is not the correct distance; the barrel will not work for our (the gunsmith's and my) purposes.

 

The only 5.45x39mm chambered barrel K-VAR had in stock that met my requirements was their AK-105BL item:

(5.45X39) 16" Hammer forged chrome lined barrel assembly. Includes full length barrel (22mm dia.), rear sight block assembly w/ rear sight leaf, lower handguard retainer assembly, front sight/gas block assy w 24mm threads. thread protecting barrel nut. So that's what I ordered and it's to be shipped this Monday to the gunsmith. The item was obtained at dealer cost.

 

The rep from K-VAR stated he had no idea when they would receive new 5.45x39mm barrels in stock. . . could be months.

 

~Gary

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Where are you going with this build? What's it for? The paper doesn't matter how fast the bullet is going, and higher velocity doesn't mean higher accuracy as many people incorrectly presume.

 

that is true, but bear in mind that higher velocity generaly equals flatter trajectory, in turn bringing better accuracy. the simple fact that its 5.45 will bring better shooting results in the accuracy department vs. the 7.62 variant.

 

well gary, glad you got your barrel. hope all works out well for ya. keep us posted on the results.

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