A Canberra gun maker is appealing what it calls an "unfair" decision by the ACT Firearms Registry, which prevented the business from designing the next generation of sniper rifles for Victoria Police.

Late last year Canberra-based GC Precision Developments was approached by Victoria Police to design high-powered rifles for use by special operations groups, and to present prototypes for evaluation.

However the ACT Deputy Firearms Registrar rejected the company's request to fit the rifles with suppressors and collapsing stocks, both of which were required by the brief.

Both modifications are illegal in the ACT, however GC Precision Developments applied for a permit to allow the manufacture of the items.

However according to company director Gareth Crook, the Deputy Registrar claimed it was impossible to approve the modifications under the Firearms Act, despite having issued identical permits to other gun dealers in the past.

"It was stated that he didn't have discretion under the firearms act to issue these permits," Mr Crook said.

"I was actually given a signed copy of a prohibited weapons articles permit for the manufacturing of self-made suppressors by another identically licensed firearms dealer.

"This permit was approved two months before my application was denied.

"We feel that we've been singled out as a company, and that there's a gross level of procedural unfairness displayed by the ACT Firearms Registry."

Mr Crook said the decision had hurt his company financially, and had the potential to erode the confidence of his clients.

He has been granted a review of the decision, and the matter will appear before the ACT Civil and Administrative Tribunal on Friday.

The ACT Deputy Firearms Registrar declined to comment.