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Compensator Machining Methods

kgregg

Aluminum
Joined
Jul 29, 2004
Location
Indianapolis, IN
I'm considering trying my hand at making my own rifle compensator. I am planning on making them out of 4140 but I have a few questions on the methods I was planning on using.

I have a South Bend Heavy 10 lathe and an import mini mill. My plan was to:

* center drill/tap the inside
* put the stock between centers and turn down the outside to X diameter
* Do any kind of aethetics (grooves, etc)
* Place the compensator in a horizontal rotary table on the mill
* Cut the ports (either along the axis or perpendicular to the axis) at 45 degrees either side of top center (placement is up for debate at the moment)

In playing around with this idea, I chucked up a piece of 1" aluminum in the rotary table and attempted to use a ball end mill to cut some grooves along the axis of the rod. I got quite a bit of chatter and the cut was not clean at all. I was taking very light cuts.

I thought maybe I needed to buy/make some kind of tailstock for the rotary table but now I'm wondering if I am going about this all the wrong way.

This is similar to what I was thinking:

http://www.bushmaster.com/shopping/brakes/yhm-28-5c1.asp

It is a flash suppressor and not a compensator - but same idea.

Has anyone here made a compensator? If so, what was your method - or if you haven't made one, how would you go about it?


thanks,
Kevin
 
I see nothing wrong with your way of doing this. Cratter is caused by something being loose/weak, a talestock should help as would some suport under the part, a V block shimed to hight. you mite try a starter hole for the mill bit and/or a 4 flute bit instead of a 2.
 
Thanks, I hadn't thought about resting a V-Block under it. I'll give that a shot. I was using a 1/4" 4 flute end mill - maybe I'll get a new one and see if that helps as well.

thanks,
Kevin
 
chatter is usally an indication of one of two things.
1. too fast a speed.
2. too slow a feed.
now this isnt to say that a nonrigid setup wont cause chatter but if your setup is rigid check the other two options.

if you are picking up chatter due to a thin section get some surgical tubing and either wrap on the outside if possible or cram in the inside.
you will sacrifice some of the tubing but it will deaden the harmonics in a small cross section...jim
 
The example that you show will not accomplish a thing in terms of recoil compensation. The bore for the bullet has to be pretty tight, no more than a few thou oversize, maybe .010, and that might be loose. Some others here can give you more information on the actual numbers.
 
I couldn't find a good example of a compensator, but yeah - I see what you were saying. My plan was to make one with a small bore and slots at the top and either 45 degrees or 90 degrees to either side.
 
I am thinking of building the same thing. What about doing all of the milling first on square stock, and then turning it? Wouldn't the slots and holes come out much cleaner that way? I am a novice machinist, so this is just a question more than anything.
 
That doesnt seem like a bad idea at all to me. The only down side for me is that it wouldn't fit in my collets when I moved it to the lathe. I suppose if you first drilled and tapped it, you could then move it to the mill, then back to the lathe mounted on centers.

Other than wasting a little extra material, this sounds like a good idea.

On another note, what material are compensators made out out? I see ads for some made out of 4140 but is that really necessary?
 
Narrow slots are going to be a pain through thick walled material. The more conventional holes would be much easier. Just a thought.
 
Kevin...I've been a firearms manufacture for many years ..
First off.. I need to know ....
What weapon is this to being mounted on ?
What caliber are you working with?
Are you going full auto?
Are you trying to reduce the felt recoil or counter act it ?
Are you trying to minimize the flash?
If you can provide me with this info. ..I'll help you on workable design...
It a shame that you'll do all that work and come away with some thing that you'll not be satisfied with..
Regards,
Robbie
 
Robbie-

Thanks for the offer. The first gun I would like to try it on is an AR-15 varminter in .223. No full auto. It's a pretty big, heavy barrel. I'm not concerned with the flash. What is the difference between reducing the felt recoil and counter acting it? I guess I just want to minimize the recoil & flip to keep on target better.

thanks again,
Kevin
 
I'll provide you with the style like the AR18.. It will work perfectly ..I'll dig up the drawing for you ...Give me a couple of days ...
Regards,
Robbie
 
Well......I guess more of a sniper type of rifle. Most likely will use it in some long range competitions, but definately won't be a full blown bench rest gun.

We are still in the design stages for the action, and waiting to get it EDM'd, so I thought I would start working on the comp.

Do you know if there is actually some sort of science/math to it, or is it just trial and error to see what works best?
 
CyberK... A little bit of both..I moved here 5 Yrs. ago the gun "STUFF" is still packed up.. Have to dig the drawings out..
Regards,
Robbie
 








 
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