I'm wondering if some of the problems SYR and BSM have been...

I'm wondering if some of the problems SYR and BSM have been having are due to inadequate drill-spacing. Spacing for SYR is at-best 60m x 120m and for BSM 50m.

BAT's grade-control drilling has been to a much tighter 50m x 12.5m spacing.  Notwithstanding any unforeseen issues in the design of BAT's plant, BAT should be able to achieve much more consistent ore consistency from mining ( that is ore is mined that is a better match to expectations of ore grade ).

It's also worth noting that BSM refurbished a second-hand mine. How much of the original plant equipment remains and are some of their problems due to the mix of new and second-hand equipment. It also looks like they never published a scoping, let-alone their own independent feasibility study for the mine (so it is difficult to establish what planning actually went into what they have constructed). No wonder they had problems. Grades of the BSM resource are also relatively low, so this may be contributing to some of their problems  achieving intended flake distribution.

Looking more into the background of the SYR and BSM reserves:

• SYR - Syrah issued a reserve update 15 November 2016. This used drill hole spacing of 60m to 120m in the plane of mineralisation.
• BSM - The asset was acquired following the announcement 2 September 2015. The focus in the report is the Loharano deposit. Essential this is based on 100m-spaced pitting and trenching. I can't see that the recommended 50m drilling was ever done on this deposit. They have since done 50m-spaced drilling at a separate Mahefedok Deposit. It's not clear from quarterlies where the material currently being sold is being mined from. They are scant on detail.

BAT announced a group resources update 18 October 2018. Drilling is on a grid down to a 50m by 12.5m spacing, which has the purpose for carefully identifying grades  for mine planning. It is described in the announcement as follows:

The Measured Mineral Resource was defined in areas of close spaced RC and DD drilling of 50m by 12.5m and confined to material above the top of fresh rock. The Indicated Mineral Resource was defined within areas of close spaced diamond drilling of less than 200m by 50m, and where the continuity and predictability of the lode positions was good. The Inferred Mineral Resource was assigned to areas where drill hole spacing was greater than 200m by 50m, where small isolated pods of mineralisation occur outside the main mineralised zones, and to geologically complex zones.​

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You can see the tight drill-spacing in this chart from the 18 October announcement. I'm thinking that BAT's initial mining will come from the Buffalo deposit which has had the grade-control drilling completed.