M4 SBR inner barrel length

[Zack The Ripper]

Quick and short: I'm going to be doing a change on my M4 and make it into an SBR. I'm tossing a 7" barrel/RIS onto it with a FirePig/SoundHog.

The only inner barrels I really see at that length are the 147mm Angy Gun TBBs and the 230mm ones as well, I think the 230mm would be too long though according to my calculations (7" = 177.8mm).

I may be answering my own question, but is the 147mm TBB my only option aside from getting a longer one and cutting it?

Edit: forgot to mention, its an AEG.

[coach]

you want shorter?

I used this one on mine and already thought 153mm was pretty short and it's a 4" OB. BTW, with a 7" barrel/RIS you could probably go with a longer IB.

Your best bet is to take your front end in and check the IB length against what you are building. I was trying to calculate lengths of a new outer barrel with a suppressor with a 590mm inner. Could have gone with either the 7" or 10.3" outer but wanted to have a part of the suppressor hidden inside the 12" JP rifles front end.

[Zack The Ripper]

Well I just want to have an inner barrel that doesn't poke out the muzzle, but I also want to utilize as much barrel length as possible.

So you are saying you use a 153mm IB in a 4" OB and still have room to spare?

[coach]

Originally Posted by Zack The Ripper

Well I just want to have an inner barrel that doesn't poke out the muzzle, but I also want to utilize as much barrel length as possible.

So you are saying you use a 153mm IB in a 4" OB and still have room to spare?

will dig it out tonight and check for you but I recall it coming near to the end but didn't stick out of the muzzle. but I think it was partially in the muzzle.(not visible)

the 590mm comes to about 1.5mm from the end of the 335mm suppressor.

[Zack The Ripper]

I have a friend that has an SBR and he just told me I need a 175mm IB. Any idea where you got you 153mm IB?

[coach]

Originally Posted by coach

I used this one on mine

clicky linky^^

[Zack The Ripper]

Derp.

Thanks.

[coach]

Doesn't stick out

ImageUploadedByTapatalk1380710565.001364.jpg

[Zack The Ripper]

Awesome, thanks coach.

[Stealth]

Prometheus makes a 185mm barrel which would be perfect in this case.

Do not cut an inner barrel unless you have a good way to restore the factory crown.
Also, do not cut any coated barrel of any kind (Madbull comes to mind)

[Zack The Ripper]

Thanks Stealth.

I actually bought a 6.02 bore 230mm long TBB (seems to be a quality brass) and it only sticks about half way into my mini-soundhog so no need for cutting it. Should work out just fine. Excited to get it rear wired and test it out.

[Krawch]

Measure from the beginning of the feeding tube in your magwell 7" outer barrel + about 3" past your delta ring where the outer barrel connects to your receiver