Tight Bore Inner Barrel Length

[Old School Punk]

Hi Guys; Sorry if this has been discussed endlessly already, I did a few searches and couldn't really find the answers that I am looking for, so here goes.

I am curious about this Tight Bore Barrel upgrade that lots of guys do on their airsoft guns. In particular I am trying to get my head around how you determine the length of inner barrel that you need to order.

ie; Say I have an MP5 AEG and it shoots hard, but it isn't particularly accurate. Say I want to increase the accuracy of it, so I buy a silencer for it and mount it on the gun.

Then do I just order a 2 foot long chunk of inner barrel and cut it to length when I get it installed in the gun? Or do you have to take some measurements of the existing inner barrel and add on the length of the silencer, and then order an inner barrel exactly to length?

Also in general what do you guys think of this upgrade? Is it worth the money and hassle? What are the upsides, and what are the down sides?

Thanks for any knowledge that you gents can pass on to a lowely noob like me.

Gordo

[The Saint]

Assuming proper manufacturing and installation, switching to a tightbore will improve grouping without also having to switch to a tightbore that's longer than your stock inner barrel.

Generally, people don't cut down inner barrels. They find and settle for the length nearest to their needs. Inner barrels are manufactured at lengths equal to stock inner barrels for different guns. If you need an inner barrel that's longer than any for MP5s, you can use lengths meant for M16 or AK or whatever.

If you feel the need to get a longer inner barrel, basically any length will do provided you keep under ~650mm (to avoid needing a boreup kit) and have a matched cylinder to provide sufficient air volume.

[ILLusion]

Just find out the length of your silencer and add that length on top of the length of an MP5 inner barrel (229mm).

Next, find an index of all inner barrel lengths, and get the model that's one level SHORTER than what you calculated, just to save you from having to cut the barrel and crown it. Many high quality inner barrels are coated or plated in some way and do not react well to cutting as they can not be re-finished.

Also, if you are upgrading to a significantly longer barrel, you will also need to check some index's to see what cylinder type matches the new barrel you're going with, and also to see what cylinder currently exists in your gun to see if you will need to upgrade your cylinder as well to match the air volume required.

[CDN_Stalker]

You won't find a big increase in accuracy or consistancy win an MP5 with a tightbore, I didn't in either of mine (a TM SD and an A5). Even with stock barrels of stock length they'd shoot an easy 2" hole at point of aim at 30ft indoors. When I added a tightbore to each (a custom cut 300mm 6.03mm to my SD) I still get the same accuracy and consistancy as with the stock barrels (Note: Both my guns are TM and come stock with a 6.08mm inner barrel, I have no idea how good or lame the clone inner barrels are).

And with the A5 type front end, you'll need tools to cut away and grind out the inner flange inside the rear of the outer barrel, or else nothing longer than a 229mm inner barrel will fit. Not a problem with the SD though.

Oh, and range? In 2006 in front of a few people I was shooting 0.28g BBs across a large pond, I judged the distance to the rock I was aiming over at an easy 200ft, and my BBs were sailing over top of it and was getting easy mansized groups with each burst. My A5 had the stock 229mm inner barrel, a spring and bearing spring guide that gave me 360fps (w/0.20g) consistantly, and I had a Guarder clear hop up rubber in it as well.

[zone 69]

http://arniesairsoft.co.uk/?filnavn=...andbarrels.htm

[Old School Punk]

Hey thanks for the responses guys. I don't know if I am SmARtT enough to figure this all out, but hey it sounds interesting.

Honestly I am not really planning on upgrading the bore on my MP5, I understand that that gun is more suitable for close quarter combat, and thats fine with me.

The point I was trying to get at was really about the cutting of a barrel to suit your situation. Based on what a couple of you have said, it is a lot better to get a barrel that closely matches your length needs, (that didn't come out right ), versus getting one that is way too long, and then cutting it down to size.

This whole thing started because I am looking at the Jing Gong - Dragunov SVD (Ya I know it really a bastardized AK47 Hybrid thingy ) but it is somewhat affordable, and somewhat accessible.

Anyway I read on a couple sites that this gun has an inner barrel that only runs half the length of the outer barrel? Huh? How the fuck does that work? It just stops a foot from the end of the gun, and then the BB is left to rattle it's way out from there? Sounds kind of chincy to me.

So I was thinking that if I got this gun, in might be a suitable candidate to try to upgrade the inner barrel on.

I see now though that you can't just stick 3 feet of inner barrel onto a stock gun and expect it to shoot great, am I right? This may actually involve upgrading a whole wack of parts in this puppy if I want to do it right.

I think that I will just go slow on this project, and try to learn as much as I can about gun upgrading from guys who appear to know what they are doing.

Thanks again for reading and responding, I do appreciate it.

Gordo

[CDN_Stalker]

Now the REAL question is............. where are you looking to buy this gun from? Any in Canada that you are going to buy?

[Old School Punk]

Well of course it's in Canada, and of course it's been here since 1987!

Gordo (born at night, but not last night) LOL

[m102404]

You're getting it just fine.

Many AEGs have inner barrels that do not run all the way to the tip of the outer barrel. Yes, the bb exits the inner barrel and flies down the remaining outer barrel. But if it "rattles it's way out of there"...it wouldn't really work in the first place would it? But some AEGs are poorly setup and the bbs do clip the remaining barrel or silencer. It's immediately apparant because your rifle is shooting all over the place.

The longer the barrel the more air you need to push down it to get the bb out the inner barrel before the piston stroke ends. How fast is largely dependant on spring stiffness. How much is largely dependant on cylinder porting.

Look at the inner barrels listed on Airsoftparts.ca. Jugglez is nice enough to list off what barrel fits what model (note...some are a bit longer than others for the same model...that's a manufacturer thing). Don't sweat 5mm here or there...

Airsoft AEGs are pretty innaccurate anyways...in that at best you'll get small groups of shots instead of large "shotgun" patterns. A solid combination of good heavier BBs, a consistant airseal/compression and a good barrel (doesn't necessarily have to be a tightbore...but they tend to be better made than stock barrels) will result in the optimum accuracy for a given setup. Just slipping in a longer/tighter barrel may not be the best thing to do.

Get the rifle that you want...try it out and use it as is first. Then you'll really be able to zone in on what you want/need to do to it...if anything at all.

[Old School Punk]

Holy Snot, thank you for the detailed response!
That was very nice of you M102404!

I think that I will take you r advice and proceed slowly.

Again, much appreciated.

Gordo