Firearm accessory mounting system

1. An adaptor system for mounting an accessory to a firearm, the adaptor system comprising:

a barrel insert that includes a plurality of lugs with slots interposed between the lugs, the barrel insert being within the interior and at the outer end of a barrel of a firearm;

an adaptor base with lugs that are sized to be inserted through the slots in the barrel insert and wherein the adaptor base is rotatable within the insert so that the lugs of the adapter base align with the lugs of the barrel insert; and

a biasing member that biases the adaptor base outward against the insert so as to increase the frictional engagement between the adaptor base and the insert; and

wherein the adaptor base includes a mounting component that is adapted to receive an accessory;

wherein the biasing member comprises an annular spring; and

wherein the adaptor base includes a shaft and a flange and the spring is positioned about the shaft and wherein the lugs of the adapter base are also positioned about the shaft inward of the annular spring.

2. The adaptor system of claim 1 , wherein the adaptor base includes an opening that is aligned with an opening of the barrel and the adaptor base has an inner threaded surface that comprises the mounting component.

3. The adaptor system of claim 2 , wherein the adaptor base includes two rows of lugs extending about an outer annular surface of the adaptor base shaft and wherein the two rows are offset longitudinally from each other.

4. The adaptor system of claim 2 , wherein the adaptor base is sized to receive a compensator, a silencer or a flash suppressor for a firearm.

5. The adaptor system of claim 4 , wherein an indexing component aligns the accessory with the barrel into a desired orientation.

6. An adaptor system for mounting an accessory to a firearm, the adaptor system comprising:

a firearm barrel comprising a bore and a muzzle end, the bore comprising a first diameter sized for a projectile to be fired therethrough, the muzzle end comprising an opening through which the projectile may be ejected,

wherein an interior of the muzzle end comprises:

a first plurality of lugs extending radially inwardly adjacent the opening;

a plurality of slots interposed between the first plurality of lugs; and

an annular groove positioned behind the first plurality of lugs;

an adaptor comprising a longitudinally extending shaft and a second plurality of lugs, the second plurality of lugs extending radially outwardly from the shaft and sized to be inserted longitudinally through the plurality of slots of the firearm barrel,

wherein the shaft of the adapter is rotatable within the interior of the muzzle end of the firearm barrel such that at least a portion of the second plurality of lugs can be positioned within the annular groove, with a forward portion of the second plurality of lugs being in contact with a rearward portion of the first plurality of lugs;

a biasing member positioned to bias the adapter in a longitudinal direction away from the bore of the firearm barrel, such that the forward portion of the second plurality of lugs will remain in contact with the rearward portion of the first plurality of lugs,

a locking jam configured to maintain the adapter in a rotational orientation with respect to the barrel, the locking jam comprising:

at least one internal flute shaped to engage a protrusion that protrudes radially from the shaft of the adapter; and

at least one longitudinally protruding member shaped to engage a longitudinally recessed portion of the muzzle end of the firearm barrel;

wherein the biasing member comprises an annular spring; and

wherein the adaptor base includes a shaft and a flange and the spring is positioned about the shaft and wherein the lugs of the adapter base are also positioned about the shaft inward of the annular spring.

7. The adapter system of claim 6 , wherein the biasing member comprises an annular spring.

8. The adapter system of claim 6 , wherein the adapter further comprises a mounting component configured to receive an accessory.

9. The adapter system of claim 8 , wherein the mounting component comprises a thread configured to receive a threaded portion of the accessory.

10. The adapter system of claim 6 , wherein the adapter further comprises an accessory comprising at least one of the following: a compensator, a silencer, or a flash suppressor.

11. The adapter system of claim 6 , wherein the firearm barrel further comprises a chamber end positioned at an opposite end from the muzzle end, the chamber end comprising a cavity sized for positioning therein of a projectile cartridge.

12. The adapter system of claim 6 , wherein an innermost surface of the first plurality of lugs defines a second diameter that is larger than the first diameter of the bore of the firearm barrel.