Shares in machine gun maker Manroy plummeted on Monday after the company said it had failed to confirm an eight million pound contract.
The delay in securing the deal will mean its 2012 figures would take a hit, the firm said.
At the time of its annual results in February the group said several large orders had been delayed and were expected to be received during the second half of this financial year.
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One of those, a $10.4m order from the US Department of Defense was announced last week.
But today the company said a substantial order for heavy machine guns from an existing customer, a large part of which was forecasted to be fulfilled during the current financial year, had not yet been confirmed.
"The board believes it will receive confirmation of this key HMG export order, which is expected to generate approximately £8m in revenue, within this financial year," Manroy said in a statement.
"The delay in timing of awarding the contract...means it is now unlikely that deliveries and, therefore, sales from this export order will be realised in the current financial year ending 30 September 2012."
The firm said that revenue for the year ending 30 September 2012 was now expected to be in the region of £7.5m against market forecasts of £11.3m.
However, it stressed that, as a result of this delay, revenues for the 12 months ending 30 September 2013 are expected to reflect the full benefit of the contract fulfilment in that year.
Manroy's shares fell 10% in early trading on Monday following the announcement.
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