M4 SBR inner barrel length
 

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.

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.

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. :)

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?

clicky linky^^


:D

Derp.

Thanks.

Doesn't stick out

Attachment 39919

Awesome, thanks coach.

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)

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.

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