BRP Reciever

[MDMike]

Question. I have one of the complete BRP recievers purchaced in a Weaponeer group buy a while back. Has anyone built on one of these. If so, I would really like to hear from you. Thanks, Mike

[Bil]

Mike-I have one of their rear halves-would you mind posting a pic of yours,I am interested in how much more complete the entire receiver is.I have fit some parts to my half,the fit is very good.Thanks. ---bil

[MDMike]

Bil,
Thank you for your reply. This 80% reciever has a block installed so that no parts can be installed until the semi modifications are performed. The ejection port has not been cut and the rails cannot be installed until the block has been removed. It is a full length reciever, from one end to the other. From where the butt stock locks on to where the booster screws in. I have had it for a while and have not done anything with it as I have not have had time. I believe that some members of the board have had some experence in building on these recievers and was wondering about the strength of the receivers. My other choice is to have my three cut reciever welded back together. I have had the mods done to my bolt and my "grip stick". I was supplied with a "bolt block" and a buffer spring by BRP but as I have said I have done nothing with the project yet. The reciever looks well made with the exception of the rivets that are used in the barrel door. I attempted to install the buffer but could not get it to turn enough to lock. That is where I stoped and put everything back in the respective boxes and put it all away. I guess I need some guidence in getting the thing together. Another item I need help with is the assembly of my 1919A4 kit. I have a parts kit and an SA right hand side plate as well as all the rivets. The semi modifications have been done to the internals but I lack time to put this kit together as well. Thank you, Mike....

[ruqikr454]

MDMIKE I also have one of the receivers from the same group buy and did not assemble it yet. I will try to answer your question regaurding the buffer not twisting onto the BRP receiver as best I can. First off make sure the buffer fits on your 3-cut and it will only twist on in 1 direction. If I recall some guys were using dycome (spelling?), you can also use paint or magic marker on the inside of the receiver where the buffer goes and try to install the buffer, where the dycome or marker rubs off needs to be filed or ground down, go slow and keep checking and also re-doing the marking compound.
Also if you look in the stickies there is a tutorial on the rear of the BRP receivers, some were known to be thin and would crack. The stickie covers how and where to put the weld.
viewtopic.php?f=9&t=2181
Some time hopefull in the near future I will have the time to assmble my BRP and reweld my 3-cut!
good luck! ruqikr454

[Bil]

You can use the 3 cut to see how the buffer fits,I had to open up the slot a little on mine.I tried it with both yugo and German,one fit better,I can't remember which. ---bil

[Abominog]

Mike,

The one thing you will need is TIME. Time to read how things work, time to figure them out during your enlightened moments, time to put the thing aside when you're frustrated before you mess it up, time to work on it.

You already know some of the mods you'll have to make to the receiver. You've also identified the SEMI mods to the gripstick and bolt, which you can send out to have done (highly recommended). Still, you'll need to know how this all works and fits together.

I'd recommend J. Baum's MG42 book(s), for which there's a sticky somewhere (I think it's a sticky, if not search on my username and you'll find it).

I'd also suggest that you go through the BIY and STICKIES section and print out every diagram, most photos, and discussions about building parts (such as the recuperator). Put them in a 3-ring binder for reference.

Building one of these isn't like slapping together an FAL. It is truly a learning experience, and takes...time.

[bolex]

Well said. I did the 3 ring binder and purchased the gripstick and bolt mods. Location of the cam is the most critical part and after that I would say the rails. Because you have the whole receiver you have eliminated the major issues of getting the receiver parts in line with each other. Please post photo of your receiver so that can see what it looks like.

[xanadu_trader]

Built mine up on a BRP 80%. Removing the blocking plate is easy – I sawcut the plate down the center and rocked the two pieces up/down till they popped out. You then need to clean out the remaining weld from the inside of the receiver before setting the rails. One of the problems I encountered was that the rivet holes for the rails were welded shut, so spotting the exact location was difficult. I clamped my receiver in a Bridgeport to get the alignment as straight as possible before drilling.

You should also check the trunnion (if it was installed by BRP) to make sure it’s usable. Some earlier dummy guns had worn out ones.

[ruqikr454]

You should also check the trunnion (if it was installed by BRP) to make sure it’s usable. Some earlier dummy guns had worn out ones.

If I remember correctly BRP used trunnions with one of the inside rails milled off so it could only be used as a dummy receiver until the trunnion was replaced.

[Bil]

I am surprised at the restraint that JBaum has shown,with the 'trunnion' word being thrown around here.It is a camming piece,not to be confused with the camming section. ---bil

[xanadu_trader]

Oops - my bad. One more thing, use caution in clamping the receiver when drilling/milling. It's a stamped receiver and can bend real easy if you apply too much force (found this out the hard way...)

[MDMike]

OK, thanks all. Yep the camming piece is de milled (ground on one side) to be unusable. I had read on here that the recievers were prone to cracking in the back by the charging handle. That advice on fitting the buffer was much appriciated. Looks like this is going to be a nice "long winter's night" (several of them) project but I believe it will be worth while. I believe the ejection port also needs to be milled out. Like one board member said, work on it and when you get fusterated, walk away. Thanks again all, Mike

[Bil]

Mike-if you need some rail rivets,send me a PM with your address,I will send you some free ones when I get home,about 2 weeks. ---bil

[propos]

Good grief, bil. How many rivets did you get. You building a full size replica of the Titanic?
ruqikr-454. It's dykem. Which reminds me I've got to get some. I'm working on my semi Suomi and it works better than magic marker.

[ruqikr454]

It's dykem. Which reminds me I've got to get some. I'm working on my semi Suomi and it works better than magic marker.[/quote]
Thanks, I was close!
Not to steal the thread but, How's the Suomi comming?

[propos]

well, like I said. I'm working on the receiver. I have the slot cut for the trigger housing and I have the front filler 95% fitted. The barrel and shroud have been fitted to the receiver. Oh, BTW, the barrel has an extension welded onto it. I was going to start on the ejection port tonight but I'm tired(working 10hr. days) and decided to only prep the area prior to removing everything that doesn't look like an ejection port. I'm leaving the magwell alone for awhile. It's going to be a real bear to hog out. The ejector is located in that area and if you drill in too far, well, oops there goes the ejector. There is 3/8" of metal thickness in that area and since I don't have a mill, it's drill press, dremel, and files.
I just sent in my money for a group buy on a modified bolt. Once I have that in hand, I can continue with the magwell and finishing the slot for the rear sight. A slot in the top of the bolt rides in a lug on the bottom of the rear sight. Plus a groove in the bolt has to slide over the ejector so I'm waiting until I have the bolt to use as a gauge for those items.
When all of that is done then the welder gets fired up. There are side plates that hold the FCG that have to be welded to the bottom of the receiver. I'm investigating using a US carbine FCG in the Suomi.
This has got to be one of the more challenging builds. It looks simple but without a mill it is very labor intensive. But well worth it in the end.
If you're curious, skip on over to weaponeer and check out the Suomi thread. I think it is up to 214 pages at the present time.
So, there you have it. My Suomi build so far. I'm tired.

[PKw VI Tiger1]

FYI when I built mine using the 80% reciever from the same group buy the camming piece that came with it was ground but the area where the rollers ride was fine so I used it and haven't had any problems. I cut the ejection port with a dremel tool using the dust cover as a guide if that helps any.

[ruqikr454]

Propos,
I am also building 2 suomi's and sent Tommerr 2 bolts to convert, I am going to start in on my receivers shortly! (hopefully the help of a friends mill)!