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Runnout on an Bird cage flash hider

lowCountryCamo

Stainless
Joined
Jan 1, 2012
Location
Savannah, Georgia, USA
I'm getting ready to thread a barrel .5-28 so I did a practice run. My threads are a tight fit on an a2 bird cage I had laying around. I ran the mock up in the lathe with the FH threaded on and noticed a pronounced wobble at the end .015". The mock up is still in chucked so it's running true. Anyone ever had this experience? I think it was from DPMS but whether they made it... ?
 
I'm getting ready to thread a barrel .5-28 so I did a practice run. My threads are a tight fit on an a2 bird cage I had laying around. I ran the mock up in the lathe with the FH threaded on and noticed a pronounced wobble at the end .015". The mock up is still in chucked so it's running true. Anyone ever had this experience? I think it was from DPMS but whether they made it... ?

It simply means that the threads in the flash hider are not concentric to the OD of the flash hider and possibly the ID as well. It can also be that the shoulder on the flash hider is off. The OD is not a major concern as long as the ID runs true. If the ID does not run true you can try truing up the shoulder. Failing that you can re-cut the ID with a small boring bar or deep reach end mill. The best way to do this is to make a 1/2 X 28 stub and not remove it from the machine. Then screw the flash hider on and make the cuts. If the hole in the flash hider is large enough to let the bullet pass safely then I wouldn't worry about it.

Muzzle devices should be ridged tapped or the threads cut with boring bars. Using tapping heads, cutting and tapping in different setups or going from the lathe to mill for interpolation are seldom reliable ways of threading. I know, I have been down this road before.
 
I see a good number of flash hiders, brakes, etc from different companies that seem to suffer from quality control lately. I check and double check to make sure no bullet strike will occur. Some are so bad I take it back off and return them. The pissing match starts so I quit using their parts.
 
I see a good number of flash hiders, brakes, etc from different companies that seem to suffer from quality control lately. I check and double check to make sure no bullet strike will occur. Some are so bad I take it back off and return them. The pissing match starts so I quit using their parts.

You should just buy a small mill/drill and a cheep 6 inch dividing head and center and make your own. Making brakes is about $100 an hour so it does not take long to pay for it.
 
Speerchucker, out of curiosity is there any simple design you would recommend for newbie making brakes?

It is something I have been thinking forr a while now but never attempted because lack of knowledge in the matter.

Cheers
GST
 
Speerchucker, out of curiosity is there any simple design you would recommend for newbie making brakes?

It is something I have been thinking forr a while now but never attempted because lack of knowledge in the matter.

Cheers
GST

The old KDF or Weatherby brake is the one most people make. There is a photo of the setup with a completed hotdog and a cookie finished except for the threading. Just disengage the dividing head and quick index off the face plate as you are working in divisions of six. Find exact center with an edge finder, drill a hole completely through, advance the dividing head 4 holes in the face plate and drill through, advance four holes and through again and one ring of holes is complete. Then advance the table .300 and advance the head 2 holes and drill to get the next set of holes in between the first set, then 4 holes and drill, 4 holes and drill. Then advance the table again and repeat until you have the number of rings of holes you want. It takes about 1/2 hour to drill each hotdog. Then cut them in the band saw, face, crown, ridged tap and zip polish on a mandrel with the belt sander. About 3/4 of an hour to knock out a finished brake. Use the best machine drills you can find (I use Norsman) (not jobber length) and toss them in the scrap after about 16 to 20 feet. You cant use enough water when drilling, I surround the whole rig with splash guards when in use.




Gunsmith Rod Henrickson Brakes.jpg
 
So you just run your thread minor dia most of the way through the brake, with an exit hole say .03" over bullet dia ?? I need to make a brake for a .416 rifle in the works...should fire a 300+ grain bullet over 3000 fps so it will want/need a brake.

Sort of thought about using one of these...would have to open up exit hole but they tell how to do that.........rifle is a muzzle loader which will fire pre engraved bare bullets (no sabot) so being able to see into there might be nice, you just make a powder funnel that fits through the brake.

M11 Muzzle Brake - Precision Armament




Bill
 
Thanks speerchucker,

I am no expoert on Brakes, never had one, explains lot of shoulder bruises....:rolleyes5:

I've seen a lot of them with holes at an angle toward the rear to direct the gases back. Does this make a difference in felt recoil or regular angle holes are as effective?

GST
 
Thanks speerchucker,

I am no expoert on Brakes, never had one, explains lot of shoulder bruises....:rolleyes5:

I've seen a lot of them with holes at an angle toward the rear to direct the gases back. Does this make a difference in felt recoil or regular angle holes are as effective?

GST

Yeah it makes a BIG DIFFERENCE ! One of my buddies used to own a Karate studio and he had one of those load-cell type punching mats to measure punch's in PSI. We took it and his laptop to the range one day and put the mat up against a wooden box filled with 200 pounds of sand. We tested about 20 different brakes that day. Most all of the brakes gave the same reduction, or very close. The ones I make with the big holes were a touch better but not enough to get all worked up about. Same with the howitzer brakes, as I call them, with the big slots in the sides. I had some shorty brakes I had made that had 4 rows of holes. The recoil was almost 1/3rd higher than the ones with 5 rows of holes. The same brake with 6 rows of holes made very little if any difference. There is a sweet spot where you need a certain amount of gas vented off. Going beyond that sweet spot makes little if any difference. As soon as we angled the holes forward recoil shot up by 1/3rd again. The difference in noise between angled forward and angled back was only 1Db. But it was one of those $300.00 workers compensation units that we borrowed from a friend. By no means exact equipment. I did test some brakes with the holes angled back but the blast coming back was disconcerting and unburned powder tends to come back at very high speed so I abandoned that project. I never measured them on the punching bag but they definitely worked VERY WELL! Much better than the howitzer brakes even. In controlled situations on the bench with proper eye and hearing protection I could see using brakes with the holes angled back. But for normal shooting or if people were on the bench next to me I would be to scared to use them. Its just to damned dangerous for this little black duck.

ADD NOTE: One odd thing we did note when we were measuring the Dbs was that while the noise was all at about the same level, the brakes with the big holes were decidedly more painful to shoot. They seem to make a sharper and harder crack. I found them to be louder sounding even with hearing protection. More of a crack like a whip with a big rush of gas. The brakes with small holes gave a more muffled whump. Still very unpleasant without muffs but decidedly more bearable.

Another thing I have always noted is that down range noise of guns with brakes is 50% to 75% less than without a brake. The RCMP actually took a hard look at them as they do act as a downrange suppressor but vetoed the idea of lumping them in with suppressors. Probably because by the time it dawned on them to test them, there were already several million of them in service in Canada and the gun makers were offering them as standard equipment.
 
I made those original KDF blanks for Mr. Klienguenther at KDF. Mr. K would demo the effeciveness of the brakes by screwing one on to a 300 Winchester magnum and fired it with the but stock on his forehead! Perhaps this contributed to his later Alzheimers.
The muzzle brake contributes to a great deal of muzzle blast, if the ones with the angled holes holes make the felt recoil any less, they will greatly increase the noise the operator has to endure.
In those early days, they were pushing a knurled thread protctor with the muzzle break. At the range when practicing you could fire many rounds without the brusing and wear hearing protectors. When hunting you really do not feel the recoil and the knurled ring protected the threads. I am not sure what the weight change did to the point of aim.
 
I made those original KDF blanks for Mr. Klienguenther at KDF. Mr. K would demo the effeciveness of the brakes by screwing one on to a 300 Winchester magnum and fired it with the but stock on his forehead! Perhaps this contributed to his later Alzheimers.
The muzzle brake contributes to a great deal of muzzle blast, if the ones with the angled holes holes make the felt recoil any less, they will greatly increase the noise the operator has to endure.
In those early days, they were pushing a knurled thread protctor with the muzzle break. At the range when practicing you could fire many rounds without the brusing and wear hearing protectors. When hunting you really do not feel the recoil and the knurled ring protected the threads. I am not sure what the weight change did to the point of aim.

Odd you bring that up Fred. Some times a rifle will shoot to the exact same point of impact with the brake on or off. With other guns there can be a foot difference. There seems to be no rhyme or reason to it either. I have seen Remington mountain rifles that shoot exactly the same on or off and others that are right off the paper. Same goes with heavy barrels. I have even tried making brakes with no holes but of the same length and weight as the brake. They will still not take the same point of impact in some guns. Its an enigma to me.
 
As soon as we angled the holes forward recoil shot up by 1/3rd again. The difference in noise between angled forward and angled back was only 1Db. But it was one of those $300.00 workers compensation units that we borrowed from a friend. By no means exact equipment. I did test some brakes with the holes angled back but the blast coming back was disconcerting and unburned powder tends to come back at very high speed so I abandoned that project. I never measured them on the punching bag but they definitely worked VERY WELL! Much better than the howitzer brakes even. In controlled situations on the bench with proper eye and hearing protection I could see using brakes with the holes angled back. But for normal shooting or if people were on the bench next to me I would be to scared to use them. Its just to damned dangerous for this little black duck.


I made one with the holes angled back 10 degrees for a 6-284.....ONCE I laid down next to a RR track and shot it at a woodchuck, took the brake off after that......HUH ?? WHAT ?? WOW that was loud :-).
 
Does this look within reason for a .416 Speerchucker ?? Minor dia is .578 for a 5/8-24 thread.

Yq8DwZD.jpg
 
Does this look within reason for a .416 Speerchucker ?? Minor dia is .578 for a 5/8-24 thread.

Yq8DwZD.jpg

You don't want to run the minor diameter through the entire brake ending with what amounts with a single baffle to redirect gas at your freebore diameter. Rather the thread diameter should only be as long as necessary to butt against your shoulder (like the length speer suggests) with the remainder of the brake being freebore diameter so that each cut or hole you make is it's own baffle.

Like this:

1.jpg
 
I have only put on maybe one brake for a customer, and it was made like I drew it up. It was a fairly cheap one from Brownells, I do not recall the brand.

Thanks for the info guys :-).
 
Looking at the M16 A2 FH drawing is looks like the runout for the end of the flash hider could be a maximum of about .006"
 








 
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