rinkrat311 wrote:
Thank you for the reply Hoot. I'll try to break it in more by shooting it, time and money for ammo being the obstacles there. I have a standard milspec buffer and spring in the rig now but I also have a T2 heavy buffer I can swap in if it would help. At this point I half to assume (Yea I know...) the gas tube to gas key interface is ok but I'll find out how to check that. The extension screw is vented and I checked it to allow air flow. I'll also check the BHO latch to see if it is within spec. I have a set of numbered drill bits on order, I will get and adjustable gas block in the mail soon I guess. It's curious that there is no standard gas port size for this cartridge like other more common AR cartridges...
I started this reply earlier today but got called away by better half and now I'm a couple of posts behind:There was a standard gas port spec when there was one make and model of barrel. Now there are more than can be accurately reported and with pistol, carbine, mid-length and rifle length systems, the number of port sizes has grown proportionally.
Keep in mind that the optimal port size usually gets bigger the longer the gas system because the available pressure to be sampled goes down the further down the barrel you take it from.
Here's a pressure visual:So, if you saw a report of the hole size someone used for a rifle length gas system, it would be necessary to have a larger sample hole than further back where a carbine length gas system would take it from. Ditto for the other length gas systems. Throw in dwell time which if you're unfamiliar with the term, refers how far from the muzzle the sample port is, which reflects how long you have before the bullet breaks the seal as it exits the muzzle (pressure now zero) for that sampled gas to work the action and you can see how this can spiral into a
table with one short leg affair. IE there's interactions beyond just pressure to contend with as far as how changing the hole size will impact cycling. The good news is the proper hole size is not a 1 or 0 dimension, otherwise everyone would be pulling their hair out if they loaded up a different weight bullet or a different powder charge weight. The window is wider than that. Properly chosen, the gas port hole size will accommodate a wide range (within reason) of loads in the 450b. That applies the most when the optimal length gas system is employed. If you wind up with a length that's either too short or too long for optimum, the window narrows. For your 16" system, the carbine is close enough to optimum to afford you a lot of forgiveness. For my 20" system, while a carbine will work, the sweeter spot moves toward a mid-length (IMHO) gas system.
Bottom line is what others have said. Changing the port size should be reserved until all else fails or you risk overshooting and having to install an adjustable block. There is beauty in simplicity. When you add another variable, the cause and effect monster raises his head a little higher, adding to the cost of more ammo to evaluate performance. Every adjustable gas block I own is because I went
a bridge too far with my port size or wanted to load some odd recipe outside the 9 dots and not beat up my brass. The latter being my 24" 6.5 Grendel.
Always starving for a little more power... Hoot