Disadvantage of adjustable gas block?

[jrcii]

All,

I'm gathering parts for a 300 Blk SBR that will be fire subs and supers both suppressed and unsupressed. I was under the impression that when switching ammo and/or adding/removing the can, you probably will need to adjust the gas block.

But, recently people have told me otherwise.

To cover all the possibilities, I'm still leaning toward an adjustable block, but I'm curious what you all think are the downsides (besides increased cost) of adjustable blocks. It would seem to me that they can only help, and, if you don't use it, it will still perform like a standard one.

Thanks,

JRC

[RGoose]

Downside would be adding an additional mechanical complexity where none existed before. This can possibly increase the likelihood of a failure however minute. From my admittedly little experience with 300 BLK an adjustable gas block may not be necessary. My buddies shoots very reliably with or without a suppressor either sub, or super sonic ammunition with just a standard gas block. My experience with his rifle has led me to start piecing together my own 300 Blk sbr. The adjustable gas block may operate a little at a more "optimized" level by controlling excess gas (i.e. getting gassed in the face when running a suppressor) but I don't think it's necessary to have a reliably function weapon.

[tom12.7]

Another downside could to be to use a more complicated solution than a simple buffer swap could be for tuning. I tend to prefer dedicated porting for most. One of the great things about 300 Blackout is that a properly set gas port offers a wider range in operation than it's 5.56 counterpart in SBR and can combinations. A proper 300 Blackout port can have a wider operation overlap. That overlap may be finer tuned with masses in a simpler manner with mass than a more complicated gas block.

[kirkland]

Just one more thing that you have to muck around with that is really probably unnecessary for operation. I was under the impression that the 300 blk was designed to run suppressed and unsuppressed with both subsonic and supersonic ammunition without messing around with the gas port or buffer.

[lysander]

Expense?

[mtdawg169]

IMHO, adding an adjustable gas block to 300blk is just asking for problems. Proper porting should allow super/sub/suppressed/unsuppressed function, without the use of an AGB.

[Defaultmp3]

MicroMOA has reason to be biased, as they make adjustable gas blocks, but here is the information they found in relation to .300 BLK gassing: http://micromoa.com/300-blk-port-size-testing/

[tom12.7]

I could be biased for specific porting for certain uses over all 4 functions. One of the great things about this cartridge is the reduced span that envelopes all 4 modes compared to a 5.56 counterpart. That does not mean that specific porting for any of the four may not work better with a dedicated port.
I shoot a lot of 300 Blackout, I may prefer to use a dedicated 9-9.5" using supers with more of a moderator than a traditional silencer with a reduced gas port H2 or A5H2 traditional Colt spring in range. That porting may not function without the supers and/or a can, it is intended for a more specific use.
A user has the ability to tune a 300 BLK gun much more than using the H2 buffer carbine action for all four modes.
Even with that, the range in porting for subs w/o a can is far less than 5.56 in SBR applications for most. A simple buffer swap as an option can have a larger degree of improved use for 300 BLK than 5.56, just adding more mass with the higher gas drive options does work very well.