![drozd blackbird stock drozd blackbird stock](https://cdn.replicaairguns.ca/images/products/large/DZDM00117_3_.jpg)
Almost anything could be made to work as a shim, e.g. Alternatively, you could add additional shims that sit in front of the barrel bushing (shown in above photo) or replace your existing shims with thicker ones. If your barrel breech is excessively long (OEM Barrels have been found to have inconsistent threaded breech lengths) causing greater than 1mm of seal protrusion and/or binding when inserting the mag, removal of material from the breech end of the barrel to reduce its length would be the best solution. Upon insertion of the mag, the seal will be compressed against the barrel breech by the gap amount, creating a tighter seal. NOTE: For best performance, the seal should protrude from the rear of the barrel bushing leaving an air gap of approximately 0.5 - 1mm, between the seal rim and the barrel bushing when the barrel is fully installed. See above image for results of a 1600 PSI test, performed by Mason Dawson, comparing the OEM Amber, OEM Black, Early Prototype, and Final Production Seal being offered now. Includes 2 seals that have been coated with silicone grease. The BB is maintained along the central axis of the bore by the extended length seal until entering the barrel. Offers greater barrel breech protection compared to OEM seal by eliminating the freebore distance, inside the barrel bushing, that the BB would normally travel before entering the barrel. Designed to withstand extreme pressures of 1600+ PSI and remain flexible at subzero temps encountered during sustained high rates of fire or when using CO2. Significantly reduces shot-to-shot muzzle velocity extreme spreads resulting in more consistent shot velocities and improved accuracy, compared to OEM seal.
![drozd blackbird stock drozd blackbird stock](https://images.airgundepot.com/ay/airgundepot/baikal-drozd-blackbird-bb-gun-mp-661k-177-caliber-400-round-hopper-8.gif)
![drozd blackbird stock drozd blackbird stock](https://i0.wp.com/drozdworld.com/wp-content/uploads/2019/01/product3-600x600-final250.jpg)
Creates a tighter seal between the barrel bushing and valve body, reducing air leakage and increasing muzzle velocity, compared to OEM seal. High performance breech seals (Qty 2) for Baikal MP-661K Drozd (Blackbird or Bumblebee). Item: 122873051729 High Performance Drozd Blackbird/Bumblebee Barrel Breech Seals (Quantity of 2).