Both Dyfed Powys and West Mercia are in the top 10 for most temporary licences granted – an indication they are struggling to cope with a backlog of permanent applications.
A licensing department failing to process a firearm certificate renewal in the allotted time results in the police having to issue a Section 7 Temporary Permit.
The Countryside Alliance said because of that, issuing a high number of temporary permits was a "clear symptom of an inefficient service".
Dyfed-Powys Police handed out 993 temporary licences in 2015, a Freedom of Information request submitted by the Alliance reveals.
That is the fifth highest of all police forces in England and Wales.
West Mercia Police is also in the top 10, with 508 dished out last year.
In total 3,273 temporary licences have been handed out by both forces since 2010.
The Alliance has now written to the chief constables and crime commissioners of the worst performing forces to ask what they plan to do about the problem.
Liam Stokes of the Countryside Alliance said: "Each of these Section 7 permits hides a plethora of further problems beyond simple licensing inefficiency.
"Temporary permits do not allow the possession of items such as expanding ammunition, on which many thousands of deer stalkers, stockmen and pest controllers depend, often for their livelihoods.
"When a renewal is finally granted the start date of the new certificate aligns with the end date of the expired certificate, not the expiration date of the Section 7 Temporary Permit, which with current inefficiencies can result in the loss of up to a year of a licence that still has to be paid for in full.
Neil Tipton, spokesman for West Mercia police commissioner Bill Longmore, said: "The commissioner has been mindful of issues over the length of time taken to process firearms licenses. He has discussed this with the Chief Constable, who is due to report back to the commissioner shortly on options to improve the situation."
No-one from Dyfed-Powys Police was available to comment.
The results showed regional disparities, with police force areas such as Cleveland and Derbyshire issuing no temporary permits at all in 2015 while Essex, the worst performer, issued 5,219.