Gas piston fit into new old stock gas cylinder ?

I have 2 new old stock gas cylinders one is a Mk II the other is a Mk III . Are they good to go or do they reaming , the Mk II has a raised lip or edge at the being of the bore that prevents the gas piston from entering . If you push in the gas piston from the muzzle end it will go all the way to the very end and stop at the last 1/64 '' . Do you have to chamfer the edge of the gas cylinder ? The Mk III the gas piston will go in from each end but can not go pass the vent holes , are there burs from the machining of the vent holes that need to be removed ? I hope this the right Bren Gun section to post in

They don'\t need reaming as such. I've never had to ream one but never say never!! As for the vent holes, maybe the gas cylinder just needs a good scrub

Peter the Mk II has a raised lip all the way around and will need to be removed ,it will be easy to do . I was just wondering if they all need some thing to make them work or were they drop in fit ? The Mk III has been cleaned and with strong lite appears to have a bur or 2 on the vent holes inside of the gas cylinder . I will see if I can get rid of them carefully using a closely fitting steel rod ,but not to score the bore . Thanks for your help.

Ah....., are you talking about the actual gas cylinder or the gas cylinder that forms part of the gun body? NOT the same thing. Photo please as I'm confused and there's not much about Brens that confuses me - except descriptions and civilianised names of parts!

Peter it is on the gun body at the end of the receiver . The barrel 's gas reg. slides into it at the front . the long gas piston that is attached to the bolt carrier will not fit into it, from the rear ,

Tr63, couple of comments. Your issue, is not strictly speaking, a semi auto problem. As parts kits, yoru guns are technically cut up machine guns. But as you move forward, there are particular issues with semi auto builds, so you are in the right place. 😆 and gas delivery is an important part of getting the semi autos to run.

Get a reference manual on Brens. As Peter comments, if we weren’t UK Amourers, then we tend to “ civilianize” the names of parts, and not very well. This leads to confusion and delay. Pictures are always helpful.

Case in point. There is NO Bolt Carrier in. Bren. It is the “ Piston Extension”, but in American shooters terminology, it gets called a bolt carrier. Easier for those trained in such things if we speak their languge. 😬

This is a question for a semi-auto build as the parts named are to used in 2 of my up coming builds . I do have the manuals you refer to and yes we here in the states may use the term bolt carrier in place of extension with the piston installed on it's forward end that goes in to the gas cylinder on the front end of the receiver . Maybe the semi-auto sub section is going to only cause confusion and may be better off not used

With all due respect, I disagree about not maintaining two sections. The Semi auto crowd is as large as the full auto crowd. This is a particularly American development. If we learn the items by their proper nomenclature, everyone will be on the same page. It is simply a lack of educating ourselves about proper Bren sections and individual parts that is causing the issue.

The answer, surely is staring us in the face, and cheap too........ Every Bren owner throw caution to the wind, sod the expense, splash out, contact Brian at BDL in SC and invest in the little Skennerton SAIS booklet. I know it's easy for me as I sort-of know the names and operation of the gun but I'll let you all into a little secret. I use that booklet too!

Thank you. I may have possessed that book in past years, and Lord knows where it is now, so I will order again. Good suggestion.