Dennis & Brian\'s Build

I started to build the RGG gun last week with my friend Brian. He is a semi-retired machinist so I am really in an apprenticeship program. I am a self-taught home shopper so I am learning a lot about how to do things the right way. I thought it may help others if I post some of the things I pick up during the build. I built the D&E with another home shopper friend up to doing the firing pins. Given all of the problems with the design and all of the polished brass I decide to leave it as a model and build the RGG as a shooter. We are making it of steel. The bolt carrier, barrel plates and ejectors are made from 1144 stress proof.

First, cleanliness and deburring are mandatory. Second, building a good fixture saves a lot of time and makes for accurate parts. We decided to do a one piece bolt carrier so the first thing Brian did was make a fixture out of MIC 6 aluminum tooling plate to hold the bolt carrier and front and rear barrel plates. The fixture, shown below, only had the center hole for the hex sleeve and the .187 hole for the pin when we started making parts. The little plug setting in the lower right front replaces the hex sleeve for the front plate. Brian also circle ground an end mill for cutting the flat bottom holes. It is shown in the second picture and was used instead of a reamer for final size and to get the flat bottom. We need to turn the front of the bolt carrier, cut the flats and the groove to finish it. Oh, did I mention cleanliness and deburring are mandatory?

We did the ejectors individually instead of in a strip and slitting them. This was actually easier than I anticipated. Just time consuming. Of course, DRO’s were a major advantage doing them and especially the bolt circle function with all of the center drilling, drilling and reaming of the bolt carrier and barrel plate parts as well as on the ejectors
More later.

Welcome and Good Luck to you on your build.

Later 42rocker

Congratulations on your start, Dennis & Brian
It looks like you guys make a good team

Jerry/Cutter

[Dave]

Welcome to the forum! Got your post fixed up. Nice work!

So many different ways to do this project.  Good luck on your build.  Keep the pictures a rolling.
Looks great.

Don

Dave Thanks for fixing my post and for the great forum.

Yesterday we finished the bolt carriers. We had to put it back in the lathe and turn the front diameter and the groove. The thing I learned here is how to verify a piece is running true. The chuck in the pic is a three jaw adjust true. I don’t have one for my lathe so I use a standard four jaw chuck and place the indicator on top and center the piece and I am done. Brian showed me that even though you indicate the part on top it can be cocked in the jaws and still not be running true. In the second pic the indicator showed the part was cocked in the chuck and running out .003. So, you need to check both ways or indicate close to the jaws and again out on the end.

We then bolted the bolt carrier to our fixture and set it up on the Tomach mill, yea sweet, to mill the flats. There were three holes all together on both bolt carriers that the bolts would not go into after milling. So we had to put them back in a vise and mill an additional .003 off the flats on those three holes. No pic of that. Guess I was too concerned with the problem to take pictures. Then glass beaded it to debur and fitted all the bolts. The bolts are from Jerry/Cutter and were PERFECT! Thanks Jerry.

We decided not to use the tube on the main shaft but turn down a .500 piece and mill the hex. When we tried this we realized we would need a follow rest for the main shaft and the barrels. Most of the stuff Brian does is larger industrial stuff so he never had a need for a follow rest on his lathe. He designed and made a follow rest shown in the pic. He had some carbide pin gages which he used for the tips.

Again, I am just a home shopper who has the opportunity to work with someone with a lot of experience and I am just trying to pass on the little things I am learning. This is of course not the only way or even the right way but it is what we are doing. It also helps to have a will tooled machine shop.

More to come.

[Dave]

Very nice. Its nice to see how other people skin a cat....

I like the follow rest idea. Please keep up with the pic share.

Later 42rocker

Very nice work.  Brian really knows his trade. Looking forward to seeing more progress from you two.

Welcome.

We made a little more progress. The follow rest works so we did the center shaft from .500 round stock. Turned and threaded both ends and turned the center where the hex goes. We then chucked it up in a 5C indexer mounted on the mill. Instead of using a tail stock to support the outboard end we used the mill vise to shorten the amount of shaft floating in air. We could then indicate the shaft, tweak it up or down as needed, tighten the vise and mill.

We milled the ejector slots for the front barrel plate on the Tormach. That went very well.

Next we wanted to mill the ejector slots on the bolts. We decided to do those on the Tormach so we came up with the setup shown to hold the bolts. The block in front of the rear jaw was milled and ground flat and a groove cut in for the bolt. The parallel on the right was milled square for alignment. Most parallels are not square on the ends. It was also not hard so it was easy to mill. We will try cutting the groove with this setup tomorrow.

Very nice work you guys!
With a great presentation

We weren’t able to work on the gun much this week. We did get the extractor slot and pocket cut on the bolts and milled flats on the bolt plug so we could tighten them with a wrench. Holding the bolt in the vise worked fine for milling the slot and pocket. We need to drill the pivot holes and the extractor spring hole and the bolts will be finished so we can start turning down barrels.

It all works until it doesn’t  :?:

Everything was going great until we decided it was time to see how all the parts fit together and worked. That created a great deal of confusion and aggravation. We spent the day making test bolts and a 4 inch test barrel to study loading and extraction. After much testing and correspondence with Jerry, aka Cutter, we came up with want we think will be a workable configuration and procedure for finishing the bolts and extractors. We decided to drill the pivot hole in the bolt and extractor separately. In order to get the bolt and extractor to load and extract without binding we did the following:

Drilled the bolt pivot hole .080 as shown on the drawings but drilled the extractor pivot hole .069 off the top of the extractor. This lifts the extractor flats .011 up off of the flats on the bolt.

Milled an additional .005 off of the rear flat on the bolt.

Cut a .026 x .250 radius on the extractor tip.

We experimented with Bic lighter springs and felt they were to strong so we ordered springs from Lee Spring.

We did get a day’s work in yesterday and got all of the above done on the bolts and extractors. We milled a pair of aluminum soft jaws from MonsterJaws to hold the extractor for both drilling and milling as shown in the pictures. We milled the same jaws to hole the bolt for drilling. Using soft jaws like this was a new experience for me but it really is a great way to accurately hold small parts. Brian picked up the DOM tubing and started to make the barrels. We ordered the barrel liners from Brownells and some snap caps for testing as we were not thrilled with using live rounds testing the bolts and extractors. As the saying goes, a picture is worth a thousand words so enough from me, here as some pictures.

A few more pictures

And a few more

If your drilling out that tubing 5/16 the barrel liners may not fit. The barrel liners I got came in around .316 -.317 diamter even though they say 5/16. I drilled the tubes out with a 8 mm drill. Then it only took a couple minutes with some emory on the barrel liners to get a nice slip fit.

My liners came in heavy on the OD, too.  I put them in the lathe and ran a file on them until they slid in.  Great pictures.

Don

 Thanks for the heads up on the liners being oversized. As long as the liners are big I guess we can make them smaller. Glad you didn\'t tell me they came in undersize as we already bored the tube. We should have waited until we received them but assumed the spec\'s on Brownells site were correct. The liners just shipped today so we won\'t know for sure until Monday or Tuesday.

Any suggestions on what to use other than brass for the housing. Also, any mandatory mods in order to get this gg to shoot reliably. I have looked at so many things on this site I am not sure what is actually necessary and what are just personal improvements.

Looks good!!  You\'re off and running!

I couldn’t work on Thursday so Brian set up his CNC lathe to turn down and thread the barrel blanks and ream the inside diameter. This was before Bzrkr give me the heads up on the liners being oversized. Our liners should arrive tomorrow so I will mic them and see if we have additional work to do.