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Posted: 2/6/2016 1:13:11 PM EDT
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Hey guys. I'm building a .45 acp sbr. It's going to be total anarchy. I can't wait. Anyway, I had a question that I haven't been able to get a definitive answer on. SO here goes.
What is the maximum length for a handguard relative to barrel length that will allow for a suppressor/muzzle device to be flush? I've busted out the 'ol ruler and it seems to me that the handguard needs to have an exact top length that is .75" shorter than the barrel. That should allow for a muzzle device or direct thread suppressor to be pretty much snug, right? My confusion is coming from browsing for handguards on SLR rifelworks' page. They have a bunch of very specific length handguards but they say that their 4.25" is perfect for 5.5" barrels and that seems just a little short to me. Link to SLR Anyway, if anyone can help me clear this up I'd really appreciate it. At least tell me i'm not crazy. Thanks |
| For the outward appearance that it sounds like you are going after, allow me to add to your problems and point you to also look at the ID (Inside Diameter) and OD (Outside Diameter) of the handguards. It sounds like you want the device to sit flush against the handguard and sort of look like a continuation of it? Most handguards are going to be larger diameter than your can or brake, actually allowing that muzzle device to sink down inside of the rail if necessary. |
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The general consensus is a barrel 1" longer than the handguards, but that will leave approximately .5" of barrel exposed between the end of the handguard and the shoulder of where the muzzle threads start.
I built a 300 sbr and wanted a minimal amount of barrel showing, so I opted for a true 8" barrel and used the MI G3 M-Lok rail which measures an actual 7.25". This left me ~.25" between the handguard the muzzle device. Hope that helps |
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Hence why I went the route that I did.
Aside from getting a longer barrel that I could then have cut down and threaded to stop exactly at the end of the handguard I chose to use..... This combo got me the smallest, acceptable amount of gap with the handgaurds and barrel length I wanted., without some custom work. |
| That does help, but i'm under the impression the the measured length of a barrel starts a little further back in the receiver than the length of the handguard. For example, a 10.3' barrel is physically 10.8" long but the chamber isn't counted in the barrel length. Does that make sense? So for example my mk18 upper has a 10.3" barrel and a 9.5" handguard with just a teeny little gap between the suppressor and the handguard. .05" to be exact. Does that measurement hold true for all barrels? I understand that barrel lenght is measured from the front of the bolt face, so would it be the same for a .45 or 9mm? |
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Handguard lengths are not specified in a standardized way so the only way to know for sure is to test fit the parts.
Handguards are generally made to lengths determined by various gas system configurations until you get to handguards that are longer than those that cover a rifle length gas block. Your idea seems to have some technical flaws, but if that is what you want you can always either cut a tube style handguard to a particular length or have a barrel made to your specs. |
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