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300 subsonic feed issues

Do not thinknits adjustable psa lower Anderson upper

You can look at the gas block and see if it’s adjustable or not. If it’s a factory-built Anderson upper, Anderson did make an adjustable gas block.

To measure the gas port, you’d have to remove the rail and move the gas block, and have pin gauges.
 
If it’s not locking back after you fire the last round, then the bolt is not cycling back far enough.

Almost impossible to get a .300 Blackout to cycle properly with both subs and supers, without changing SOMETHING. A 220grn subsonic round has a chamber pressure of around 25,000 psi, while a 110grn supersonic has a chamber pressure of a little over 50,000 psi. When you’re firing them in a direct gas impingement firearm, something has to change in order for it to function.

Are you using a fixed gas block, or an adjustable gas block? What is your barrel length? What is your gas port size? Pistol-length or carbine-length gas system?

Are you wanting to be able to fire subs AND supers, or do you intend on just running one of them going forward?

FWIW, working on folks’ .300Blk builds to get them to cycle properly is the current bane of my existence.
amen... have my little 300blk pdw assembled minus the barrel. I do not want an adjustable gb, and I am running a law folder so I think im just gonna hold out for a BRT optimum barrel with the larger gas port.

Tuning short .300's and Ar10's are a chore lol
 
riflespeed seems like the way, but I am so against adjustable gb's. I dont have alot of experience with them, but I know the smith recently installed a riflespeed for a customer and he seemed happy with it. Im just biased against them lol.
 
cmshoot cmshoot / David's Gun Room David's Gun Room - assuming money was no object and someone wanted to swap between sub and super ammo regularly - what would your recommendation be for an adjustable GB?

I dislike adjustable gas blocks immensely, but Riflespeed is my first recommendation, followed by Superlative Arms.
 
there are usually 4 versions of 300 blackout that you have to contend with.
1) supers
2) subs
3) supers with a can
4 subs with a can

trying to get them all to run without changing anything is maddening. I have a 300 that runs decent but I only shoot subs and 95% of the time with a can on it (that's what it was designed for, for the most part).

there are all sorts of options for tuning- adjustable gas blocks are the norm but you can run a BRT tube (if it's overgassed), heavier/lighter buffer, different buffer springs, adjustable bolt carrier or vented bolt carrier, and different barrels with different gas port sizes. that's what makes it difficult to troubleshoot. It all starts with ammo choices, then barrel selection (gas port size) and goes from there. Even the brand/type of suppressor can affect performance (flow through or traditional).

But yes the first step is to decide on ammo selection/load/configuration of the rifle/pistol (sub/supers, with or without a suppressor). Then shoot it and see what happens. If it's not loading the second round or resetting the trigger, load a single round in the mag and see if it locks back on the empty mag. That will give you some more data to figure out what is going wrong and where to look for answers.
 
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