Inner Barrel

[homeflake210]

I have a CA M15A4 and I am converting it into a SPR with This (its a GB-Tech SPR MK12 Mod 0 Conversion Kit) and i want to put a PSG-1 inner barrel into it. Will that barrel fit (with the silencer on) and is there any other barrel that would be more suitable?

 

 

 

Any help is appreciated.

[muiman62]

I have a CA M15A4 and I am converting it into a SPR with This (its a GB-Tech SPR MK12 Mod 0 Conversion Kit) and i want to put a PSG-1 inner barrel into it. Will that barrel fit (with the silencer on) and is there any other barrel that would be more suitable?

Any help is appreciated.

<{POST_SNAPBACK}>

 

barrel as in inner barrel? it will fit if you put a silencer over it, but you will have suckback.

[visionviper]

You could get a 550mm inner barrel, as opposed to a 509mm barrel, and I don't see there being any problems with suckback.

[muiman62]

509mm is m16 and AUG. psg1 is 590 mm and 650mm

[bernie3674]

it will suckback, buy a new cylinder

[muiman62]

bernie- would a bore up kit work do you think?

[Hissing_Sid]

Why bother with a longer barrel?

It won't make the gun more accurate.

 

Buy a standard length Prometheus 6.03 barrel and fit that.

 

All this stuff about fitting longer barrels and hiding them by silencers is utter nonsense.

[Sale]

Word. Check what length is recommended with that SPR kit and use that kind of an inner barrel with the best quality.

 

-Sale

[Mikkel]

barrel as in inner barrel? it will fit if you put a silencer over it, but you will have suckback.

<{POST_SNAPBACK}>

 

 

Suckback is an urban legend.

If your BB travels about 330fps (Uk limits right?), and your inner barrel is 550mm, then your bb can travel a distance that equates 181 inner barrels, each second!

So unless your ROF is going above 181, then you don't need to worry

[TriChrome]

Why bother with a longer barrel?

It won't make the gun more accurate.

<{POST_SNAPBACK}>

 

I'm sorry, but that's incorrect. A longer barrel will make the gun more accurate. On your theory a stock TM MP5K with a 110mm inner barrel will shoot just as accurately as a stock TM S-System M4 with a 363mm inner barrel. I own both, and I assure you there is a large difference in accuracy.

 

Even my TM G36C with a 247mm inner barrel shoots poorer than my M4A1 and that's a much smaller difference in barrel length.

 

The longer the barrel the more time the BB has to stabalize it's flight path.

 

 

On the cylinder/suck-back issue, I would install a M16 length type-0 cylinder and it should be fine. It's a $15 part, so why not? I don't believe the suck-back is as big an issue as some people make it (basically saying I believe there's more flexibility), but you're moving up over 200mm in length, so I'd get a new cylinder.

[Tommygunn]

TriChrome,

Why is my CQBR with a 285mm TN barrel just as accurate, if not more so, and able to achieve the same range as everyone else's guns? I put it down to a tightbore and to some extent a decent hop rubber.

 

As far as all this suck back business is concered just make sure the volume of the cylinder on firing(not total volume as some of it is taken up by the piston/cylinder head) is greater than the barrel volume.

[TriChrome]

I can't answer your question since I don't know what the other peoples guns have in them. Accuracy is just as dependent on the internals of the guns (and the right combination of internal parts), if it has a tightbore barrel or not, which brand of tightbore, the FPS, what brand of hop-up, the shape of the hop-up, how the shooter shoots, than the length of the barrel.

 

But I will guarantee if you have the same gun, and use 2 different length barrels in them (with the correct cylinder for each if there's that much difference in length) and put it in a gun clamp, and test fire it inside, the gun with the longer barrel will have better groupings.

 

I've actually done something similar to this (although not as scientific) when I had my cousin's AK-BS upgraded last week. He left the stock 229mm barrel in it, then we stuck in a M4 length barrel in the same gun. The M4 length barrel had better grouping at 50 yards, so we left it in and he ordered a silencer to cover the extra length.

 

As far as range and accuracy; they're two different things. Range is dependent on FPS (and the hop-up system). And to mention it, a longer barrel gives you a slight boost in FPS, which would also prove that at the same range, a longer barrel gun will be more accurate just due to that fact (why do you think the FPS listed for a MP5K is 250-260 stock, whereas a M4 is around 280 FPS and they have the same exact spring in them?).

[homeflake210]

What exactly is suckback?

[Tommygunn]

It is where there is not enough air volume in the cylinder to push the bb out of the barrel. If it runs out of air before the bb has left then the bb will slow and in it's wake create a vacuum. You will get a loss in velocity.

[Sale]

But I will guarantee if you have the same gun, and use 2 different length barrels in them (with the correct cylinder for each if there's that much difference in length) and put it in a gun clamp, and test fire it inside, the gun with the longer barrel will have better groupings.

Comparing an MP5K with 110mm barrel to an M4 with 363mm barrel is a pretty extreme comparison. The beef here was a 590mm barrel against a 509mm barrel, as it seems. An M4 barrel is over trice the length of an MP5K barrel (which is basically the shortest you can get), while there's less than 20% difference between a PSG-1 barrel and SPR barrel. You're talking about over 300% increase against 20% increase. Catch my drift?

 

In real rifles the "inherent accuracy" of a barrel can be seen at 25-30cm. Beyond that it's all about getting higher muzzle velocity without dangerous pressure levels, and extending the sight radius if you have iron sights. Pretty much the same goes for airsofts. An MP5K is not going to be as accurate as an M4 (with equal quality parts), but a full length M16 variant won't give that much of an advantage over an M4. Actually none at all.

 

About suckback: It's not about the piston starting to go backwards before the BB has left the barrel. It's about cylinder volume compared to barrel length (volume). Put an MP5K cylinder in an M16 and you'll see a clear drop in muzzle velocity. It's less noticeable if you don't go into such extreme examples, but the cylinders are matched to barrel lengths for a reason.

 

-Sale

[8 Ball]

I'm not even gonna start on the length of the barrel. I'm already having fun on another thread. But I would suggest going with G&P SPR/R, not the GB-Tech.

http://www.wgcshop.com/pcart/shopper.php?i...it%20for%20AEGs

G&P has never failed me, and it's about $300 cheaper.

[Hissing_Sid]

Suckback is an urban legend.

If your BB travels about 330fps (Uk limits right?), and your inner barrel is 550mm, then your bb can travel a distance that equates 181 inner barrels, each second!

So unless your ROF is going above 181, then you don't need to worry

<{POST_SNAPBACK}>

This is nonsense.

 

What has "a distance that equates 181 inner barrels, each second!" got to do with anything?

 

Suckback happens when the piston reaches the end of it's stroke while the BB is still in the barrel.

 

Do the sums.

Work out the volume of the cylinder and then work out the volume of the barrel.

You will find that the volume of an unvented cylinder equates to a barrel roughly 70cm long (IIRC).

However.

That doesn't account for air bypass.

A BB is usually about 5.91-5.95mm diameter. A normal barrel is 6.08mm diameter.

That means there's a 0.05mm air gap all the way around the BB which means air can escape past it as it travels.

 

On top of that there's the potential for some air to escape back past the piston, some to escape out of the cylinder head, some to escape between the cylinder-head nozzle and the feed nozzle and some to escape between the feed nozzle and the hop-up.

 

Basically, it's up to you what "safety margin" you go for but, personally, I wouldn't bother with any barrel longer than the longest barrel Marui fit just in case it ends up causing me more trouble than it's worse.

 

There's a big potential for disaster and no potential at all for improvement due to the longer barrel.

 

Speaking as somebody who's fitted a whole range of barrels to the same gun, I am confident that there's no quantifiable benefit to fitting stupidly long barrels.

 

Except for making you feel better if you've got a tiny penis.

[bernie3674]

hissing is right, and a bore up will help, as long as it's for PSG-1