54R Bren Issues

[Joe H]

Djandj,

Here is a simple way to check headspace on a Bren. The rim thickness on the 7.62 is .063" so you can use the same headspace dimensions as the .303. The Bren was never designed for the 7.62x54r so I'd keep the headspace as low as possible.

Strip the frame, carrier and bolt. Remove the firing pin and extractor from the bolt. Take a properly resized MT case or unfired 7.62x54r case with the powder and bullet removed. The 7.62 x 54r is within .001" of the .303 british rim so you can check using the .303 headspace dimensions. Check the rim thickness. It should be about .063". It is a little difficult to check since the head is not flat. Glue on a .003- .004" piece of shim stock on the head of the case. Slide the case in the barrel. Now only install the bolt without extractor, no carrier spings etc, only the Bolt. Push it into the locked position. Push the bolt forward with your finger. The case should be snug under the bolt. If it isn't check Item 3 above. With your finger still pushing on the bolt and using a feeler gage you should have between .002" and .005" between the bolt and locking shoulder. If its .010" or better you may have problems. If its .015" plus IMO you definitely will have a problem. You probably will have to replace the locking shoulder with a longer one.

Every time the bolt closes the relationship of the carrier and bolt should be as in the attached pic. The carrier should have to travel 3/8" to 1/2" before the bolt unlocks. If you don't you may have problem 2 above.

The second pic shows the gap between the bolt and locking shoulder on a Bren that was having the same problems as you.

Joe

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