Hmm that might be a smidge small. I think recommended gas port size for 18” rifle gas is 0.0995 but some others may chime in.
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The published specs from SOLGW are a good guide and I give them kudos for having the nuts to do so. Still, keep in mind that they drill their holes with a certain philosophy in mind with certain ammunition. The philosophy, as near as I can tell, is to have a combat reliable weapon with true milspec ammo.
What this means is that their stuff will run full power ammo with either an A5H2 buffer and rifle spring or an H2 or H3 buffer with a springco blue or red spring. I find this to be a bit of overkill.
Still, my point is that a .093 port on an 18" barrel with rifle gas should be fine. Just don't go too heavy on the spring ir buffer. If it is short stroking, it's something else.
Was the 18" running fine at some point and then started having trouble or has it always had this problem? If the former, check the gas key and rings. If the latter, you have a gas leak or stoppage some place other than in the BCG.