Final Semi Bolt Design??

[HerrMueller]

Ok..I've been reading my belt-fed heart out for a few weeks.And I don't believe I've found a finalized Semi Auto bolt design/Blue print release anywhere on this awesome web site.I'm almost done making J.B's Semi Mod parts He has so gratiously shared with all of us and my question is..What are the latest and the correct mods I'm supposed to make to my bolt?? I've read alot of stuff but its old and seems to change daily.Has anyone completed a bolt design that works 100% ??..What is the final Semi Bolt supposed to look like?..Could there be a Semi-Bolt Build put on the site like what Pirate did with the receiver.?? He covered the Grip stick and bolt too but it sounds like alot has changed since he started.(Your build is awesome Pirate..Great Job!!)I'm still confused as to what i'm supposed to end up with.I'm going to use the FAL fcg and J/B's internal bolt config. A good Set of photos and some detailed explainations of all the steps would be great. I would help anyway I can.How about some input?? Thanks goes out to all the guys who put their heart into this site and its content.

[gunslingerdoc]

Patience my son - Im planning on trying to take some pics of bolt mods and others that are required. Once I get a chance to measure things I plan to beam them to 7.62X51 and ask him to cad us up a set of drawings.

Hopefully this weekend

[HerrMueller]

Thanks G. S ..I talked to Pirate and Salt6 for a bit last nite on live chat..he also said he will be posting some updates ect. Looking forward to the info..

[Abwehr]

Since I bought my SA MG42 from BRP, (by the way, I have the highest admiration to you guys that are building your own), I have not had to worry about bolt modification/s. But i do have a question; have any of you tried to duplicate the BRP Bolt and Firing Pin design? From the excellent photos I have seen of your work, they appear similar, but a little differnt to the BRP. The Bolt and Firing Pin has worked great in mine, and I was just wondering why you didn't just copy it.

[Pirate]

Using the original firing pin with a striker has several advantages. I used a 3/16" rod for
the striker that is more ridgid than the smaller dia. brp. the original fp has the proper
dimentions and protrusion and is properly hardended. the striker can be made with
hand tools and is a lot simpler to make than a one piece pin. it also seems less prone
to binding and sticking that can cause slam fires. my gun works with all types of ammo
and I have eliminated the blown primer problems that occurred with the ar fcg single
piece fp assy.
I have put a lot of time and money into this build and the end result is a gun that is safe
and reliable. I haven't cut any corners or been satisfied with mods that aren't 100%
I want this build to look and function like it came form a professional builder, and not
a kitchen table bubba.

[Abwehr]

Pirate,

Thanks for the info. I understand what you are talking about with the BRP Firing Pin. This is probably the one area that is weak with the Firing Pin being loooong and skinny. This does tent to make the break easier. After I recevied my gun from BRP, I felt several spare Firing Pins were necessary and I ordered seval from Brian. So far, I have not had any trouble with the Bolt or pierced primers, and have not broken a Firing Pin, YET, LOL.

It sure is refreshing to read what you stated about putting the time and effort in making a professional build!! I agree that quality does count, even if you are building it yourself. I have built a number of AKs and several SA Stens and I try my best to build it to shoot and look like a professional did the work. Another part is the possiblity of harming myself if the build was "bubbaed", and it did blow. Since I am an engineer, I do look at my builds from the aspect of funtionability and safety. I don't want 50K psi gas, brass or steel blowing my face or hands off!

I hope that everyone will follow your lead!

[HerrMueller]

Abwehr ...Are there plans available to build a legal semi auto sten?? I would like to do a Mark 5..Thanks HerrMueller

[Abwehr]

As far as I know, there are no plans. There is the Semi Sten kit for the MkIII gun. Here is the website: http://www.semiautosten.com/

The problem is the springs, they want to bind up and collapse, becoming useless after 100-200 rds. I think they can be changed out with standard springs, but it will take some time to find the right combination. As to the MkV, there is a guy on the Yahoo Sten Forum that built one from the MkIII SA parts. BUT, he did major modifications to the bolt and springs to get his working correctly. IF you were to built a SA MkV, you can use the kit, but some diminsions would have to be checked and a maybe some minor modifications that would not be difficult. If you want a project that will take some time to complete, the SA Sten is the one to go with, just expect a lot of FTF. This is just a fun piece to play with for now.

There is supposed to be a very nice SA conversion coming some time in the future, but I don't know when. From what I have seen, it is very nice and will actually work! Currently, it is at ATF for final evaluation. I hope it comes out soon as I would like to have one that works at least 50% of the time.

[HerrMueller]

I knew from the start..and looking at full auto ones at machinegun shoots, that it would be difficult to do.I like a challenge..i will keep you up to date on my findings .

[j. bergmann]

here are the two designs i have come up with . the top is the final design that has prevented the last three round burst that i was getting with the bottom design. the bottom design would slam fire the last three rounds in a belt , im assuming due to less fristion/weight of a full belt. the top design has eliminated this problem. im going to video the gun agian this week , and if salt would be so gratious to post it for me you will see it in action. john

[j. bergmann]

heres is another picture

[j. bergmann]

the new design worked great with the ww2 spoon type ejector bar. i didnt have to modify it at all.. what i did do solve the burst problem was move all the internal parts forward so the would be less chance of inertia helping the firing pin move. ive got 6 complete bolt kits made if someone is interested of the top design.

[HerrMueller]

Hi John..I just got all the internals done from the prints that you posted..Now it looks like you changed the set up??? LOL !! Just my luck..I have not tried the bolt in my gun yet because its still in 4 pcs (the receiver) So I guess i'll be getting back to you some time later to let you know how I made out.I did make the parts a little tighter to the I.D of my bolt.I also honed the inside of the bolt to true it up..it was scary inside.Did you try a heavier firing pin spring??If your getting slam fires it could be too light...Just a thought.. Thanks for all the help. HerrMueller

[j. bergmann]

ya , i tried several different firing pin springs but they got to tight and would not work. the problem was the inertia of the bolt striking the barrel was causing the bolt parts in mass to fly forward on the anti bounce spring which would allow the firing pin to strike the primer. by reversing the mass of parts, this eliminated the problem. i do have some updated drawing that are not on the sticky posts , they are in a previous post about parts for sale. john

[j. bergmann]

here they are

[HerrMueller]

Hi John..thanks for the updated print..it looks like you used alot of the same parts?? just reversed them?? Cool deal..I'll work on it.. HerrMueller

[HerrMueller]

Hi Again.I found the prints but the fireing pin is the old design...Could you post the new firing pin print with
the firing spring stop on the front of the pin ?? I just need the DIM. off the front to put the spring stop on..Thanks..sorry to be a pain..H. M