50 BMG form 1 finally arrived. Tested, works well.

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

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50 BMG form 1 finally arrived. Tested, works well.

Post by ranb » Fri Mar 28, 2014 10:17 pm

For over two years I was trying to design a 50 BMG silencer I could make on my lathe. Mailed it in on June 10, 2013 check cashed a month later, approved on March 23.

My largest project to date is a reflex design for a 338 ultra mag bolt gun but there is a big difference between suppressing 93 grains of powder and 235 grains. This one will be 2 x16 inches 316 SS or 4130 all 60 degree cones and spacers 100 % welded together. The tube will be .065" and just slide over the core with the ends welded. I think the blast baffle will be .010" and the others a bit thinner.

Simple and rugged, I hope. Barring any problems I'll have it finished in time for the 4th Annual KRRC Silencer Shoot in July. It should be the baddest suppressed rifle on the line. :)

Image

Chances are it will look different than this by the time it comes the lathe.

Ranb
Last edited by ranb on Sun May 31, 2015 2:14 pm, edited 4 times in total.
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Re: 50 BMG form 1 finally arrived.

Post by Wicked » Sat Mar 29, 2014 12:15 am

Glad to see you still going at it. This will be fun to watch.

How many builds does this make for you?

If there is a "Lifetime Form1 Suppressor Achievement Award' I will submit and second your nomination.
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Re: 50 BMG form 1 finally arrived.

Post by ranb » Sat Mar 29, 2014 8:40 am

This is stamp #17 or so. Not all of my cans have been that successful. My 458 socom and AK cans were too short. A few of my aluminum cans gunked themselves together so I can no longer take them apart for cleaning. I'm using all steel from now on so I can chemically clean.

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Re: 50 BMG form 1 finally arrived.

Post by doubloon » Sat Mar 29, 2014 9:56 am

At the very least they were a learning success.
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Re: 50 BMG form 1 finally arrived.

Post by JohnnyO » Sat Mar 29, 2014 10:57 am

50 bmg definitely steps it up a notch, good luck with yours.

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Re: 50 BMG form 1 finally arrived.

Post by redtazdog » Sat Mar 29, 2014 1:49 pm

I hope the OD of your barrel behind the threads is concentric to the bore since you don't have a shoulder behind the threads
for the can to rest.
Keep in mind that if the threads are concentric to the bore but the barrel behind is off concentric .001 just one inch behind the threads it will be near the same at one inch after and way off at the end of 16" as it adds up every inch.
I have been cutting and threading barrels for over 20 years and have a problem with trusting
the OD and threads on factory barrels on most guns to be concentric.
I know you would need a much bigger lathe to get that barrel set up on to re profile the muzzle end
with a shoulder and new threads or at least check it to be concentric, but I think it would be well worth it to find someone with
one to use for a couple hours.

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Re: 50 BMG form 1 finally arrived.

Post by gunny50 » Sun Mar 30, 2014 8:18 am

ranb wrote:For over two years I was trying to design a 50 BMG silencer I could make on my lathe.
This one will be 2 x16 inches 316 SS or 4130 all 60 degree cones and spacers 100 % welded together.
The tube will be .065" and just slide over the core with the ends welded.
I think the blast baffle will be .010" and the others a bit thinner.
Simple and rugged, I hope.
Ranb

Ranb,
For what gun is it?
You are going to take that brake of when shooting it with the can, why not integrate a brake in your design?
I would gage the barrel and threads to be safe, or take a larger hole if needed.
Better safe than sorry.
All depends on what options you have on machines.

Gunny

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Re: 50 BMG form 1 finally arrived.

Post by JohnnyO » Sun Mar 30, 2014 10:29 am

Use the end of the muzzle as you shoulder

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Re: 50 BMG form 1 finally arrived.

Post by ranb » Tue Apr 01, 2014 4:39 pm

LAR Grizzly Big Bore; the brake is coming off and will never go back on. :) I am looking at using the muzzle as the shoulder. I will make a generous bore for the baffles. Suppression is thrid on the list of priorites after safety and accuracy.

Ranb
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by ranb » Sat Aug 02, 2014 11:49 am

I finally got around to starting the project after I got a 1-1/2 14 tap to chase the threads I cut. The largest threads I've cut so far in steel have been 15/16-32. I cut 1-3/4" threads for my 510 whisper can but they were aluminum and a piece of cake.


Image
I started out with using a piece of scrap aluminum tube to make a thread protector. I cut the threads for 85% thread engagement, chased it with the tap and now I have a snug fitting thread protector.

Image
Then I tried my luck on a piece of 304 stock for a steel thread protector. It was very slow going, taking off just .002" at a time after the first few passes. I only had a few passes left when I heard a snap; the tool bit broke. The threads looked decent so I decided to chase them with the taper tap.

Image
I got about half way through the piece when the tap got stuck while backing out to clean the chips and re-lube. I had to cut the end of the piece off then cut it in half to remove the tap. A third of the way down on the left side you can see that the threads are galled. They did not look like this until after I removed the tap.

I think I might have bitten off more than I can chew on this project. The threading tool has been in use for years and I periodically sharpened it on my grinder, I think I screwed it up the last time it was sharpened. Time to get new inserts.

Any advice is welcome. Thanks.


Randy
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by 300sniper » Sat Aug 02, 2014 4:26 pm

ranb wrote: Then I tried my luck on a piece of 304 stock for a steel thread protector. It was very slow going, taking off just .002" at a time after the first few passes. I only had a few passes left when I heard a snap; the tool bit broke.



Randy
A .002" doc is not getting you below the work hardening from the previous pass. I think you need to be a little more aggressive with your doc in 304.
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by ranb » Sat Aug 02, 2014 7:46 pm

Much more and the lathe is not able to turn the barstock. Maybe I need a better lathe? Just using a half horsepower motor right now.

Randy
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by CMV » Sat Aug 02, 2014 10:49 pm

What part are you making out of the 304? That stuff is crappy to work with. One i'm working on now is 4130 chrome moly for the tube & 416 SS for everything else. The 4130 is a nicer material to work with to me & is stronger than 304 so maybe that's an option for you. Stock Car Steel is a good place for 4130 DOM tube in many sizes. Just have to do more maintenance since it's not stainless. I bought a bunch of 416 stainless in different sizes & that's what I use for anything now since it's so much nicer to work with. Haven't come across 416 tube though - that would be nice.

I use this for threading. The inserts last a long time, just flip the tool around for internal/external threads, & the price is nice. http://www.mesatool.com/products/threading-tools/ 2nd one down on the left side. This is how it does on GR5 Ti

Image
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by ranb » Sat Aug 02, 2014 11:15 pm

It will all be 304 stainless, maybe. I used 4130 for a few other silencers in the past (my 223 and 338 ultra mag cans) when I couldn't get good stainless tube. The 50 bmg can will have all the parts including baffles and spacers welded together, so I need to keep them all the same material.

Ranb
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by Bendersquint » Sat Aug 02, 2014 11:54 pm

ranb wrote:It will all be 304 stainless, maybe. I used 4130 for a few other silencers in the past (my 223 and 338 ultra mag cans) when I couldn't get good stainless tube. The 50 bmg can will have all the parts including baffles and spacers welded together, so I need to keep them all the same material.

Ranb
If you are welding it why are you worrying about threading it?

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Re: 50 BMG form 1 finally arrived, problems building it.

Post by ranb » Sun Aug 03, 2014 6:48 am

The silencer is welded together. It screws onto the muzzle. The threads I'm trying to make are for a rear end cap.

Ranb
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by CMV » Sun Aug 03, 2014 1:08 pm

What are you using for cutting fluid? If you haven't, try Tap Magic (or whatever you use) with some anti-seize mixed in. I keep a small jar with that mix & an acid brush. Works MUCH better than Tap Magic alone. I do about 20% permatex anti-seize & the rest cutting oil. Messy, but effective.

Also, why the 85% thread engagement? You might have better luck (esp w/ the tap) @ 65% & those are still strong threads.
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Re: 50 BMG form 1 finally arrived, problems building it.

Post by Bendersquint » Sun Aug 03, 2014 1:46 pm

CMV wrote:What are you using for cutting fluid? If you haven't, try Tap Magic (or whatever you use) with some anti-seize mixed in. I keep a small jar with that mix & an acid brush. Works MUCH better than Tap Magic alone. I do about 20% permatex anti-seize & the rest cutting oil. Messy, but effective.

Also, why the 85% thread engagement? You might have better luck (esp w/ the tap) @ 65% & those are still strong threads.
I would want more than 65% for a 50BMG, but thats me.

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Re: 50 BMG form 1 finally arrived, problems building it.

Post by CMV » Sun Aug 03, 2014 4:13 pm

This is why I suggested less than 85%:

Image

From Machinery's 26 in the part about tapping.

Anyway, make the hole a little larger, add some anti-seize to the cutting fluid, & see if the tap doesn't work better for you.
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Re: 50 BMG form 1 finally arrived. Making progress.

Post by ranb » Tue Aug 12, 2014 7:01 pm

I bought new inserts for the threading tool. I turned the inside for 75% engagement and made the first pass taking off .010" at 125 rpm (slowest speed on lathe). On the second pass the insert chipped. I replaced the insert and took of .005" and it chipped again. With the third insert I hand turned the chuck at about 30 rpm taking off .010'". By the time I down to the final pass the third insert chipped. I was able to finish the threads with the tap and they turned out fine. The end cap threads on with very little play. the rest of the silencer will be the same old stuff just bigger.

Image

The top space is where a bushing will go to mate against the barrel in front of the threads on the muzzle.

Randy
Last edited by ranb on Thu Aug 14, 2014 6:12 pm, edited 1 time in total.
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Re: 50 BMG form 1 finally arrived. Making progress.

Post by ranb » Thu Aug 14, 2014 6:11 pm

I finished making the front bushing for the rear end cap. It will be welded in place then turned down. When done the end cap will mate against the barrel in back of the threads, in front of the threads and on the muzzle face.

Image

Image

The front bushing is welded to the end cap. I used as little heat as possible to reduce warping. but my freehand welding still leaves something to be desired. I cut a small .050" shoulder to mate with the first spacer. With the rear end cap finished, the rest will be routine baffle and spacers.

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Re: 50 BMG form 1 finally arrived. Making progress.

Post by ranb » Fri Aug 15, 2014 11:34 pm

I've been waffling more than Kerry the last few days trying to decide on a baffle configuration prior to cutting any more parts. More 60 degree cones means more weight so I though I might increase the length of the blast chamber and make some of the baffles 90 degrees.

Image

Will the bottom design suppress significantly less than the top design? Thanks.

Randy
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Re: 50 BMG form 1 finally arrived. Making progress.

Post by Scared_of_zombies » Sat Aug 16, 2014 12:54 pm

ranb wrote:I've been waffling more than Kerry the last few days trying to decide on a baffle configuration prior to cutting any more parts. More 60 degree cones means more weight so I though I might increase the length of the blast chamber and make some of the baffles 90 degrees.

Image

Will the bottom design suppress significantly less than the top design? Thanks.

Randy
90's don't work nearly as well as 60's.

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Re: 50 BMG form 1 finally arrived. Making progress.

Post by wp6529 » Sat Aug 16, 2014 10:55 pm

There seems to be a lack of fusion in the welding. I'd setup so you have something to rest your hand comfortably on and go at it again, also with more filler. Build it up a bit and then turn it down in the lathe to give a nice clean radius. You can weld in short sections opposite each other and let it cool before the next pass to help limit distortion.

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Re: 50 BMG form 1 finally arrived. Making progress.

Post by ranb » Mon Aug 18, 2014 7:43 pm

Image

The tube and ends caps are finished. I added some fill wire to the last weld on the rear end cap. So far everything appears to line up well. The flash really brings out the ugliness of the insta-rust finish LAR puts on their 50 cals. :)

Ranb
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