Thread: SMLE 303

One thing to remember with the 303, the bolt locks with lugs at the rear. If you take a video of the bolt as it fires you will see it bends quite appreciably under the pressure load of firing a round. All quite normal..however, the design relies on the brass cartridge, at the moment of firing, expanding to meet and grip the chamber walls. If you have oil or grease in the chamber prior to firing, there is no grip between the chamber wall and the brass. So the bolt takes all the pressure load. Which eventually, as robust as they are, leads to wear and tear and headspace issues. Easy to solve at the range, use a swab with isopropyl alcohol or better, brake cleaner, to wipe the chamber out. For a day hunt do before leaving home and re-oil on returning and cleaning the rifle.

Originally Posted by Jhon

One thing to remember with the 303, the bolt locks with lugs at the rear. If you take a video of the bolt as it fires you will see it bends quite appreciably under the pressure load of firing a round. All quite normal..however, the design relies on the brass cartridge, at the moment of firing, expanding to meet and grip the chamber walls. If you have oil or grease in the chamber prior to firing, there is no grip between the chamber wall and the brass. So the bolt takes all the pressure load. Which eventually, as robust as they are, leads to wear and tear and headspace issues. Easy to solve at the range, use a swab with isopropyl alcohol or better, brake cleaner, to wipe the chamber out. For a day hunt do before leaving home and re-oil on returning and cleaning the rifle.

I always wipe the chamber and barrel out for all my centrefires with meths to remove the oil before firing. Wasn't for that reason though.