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Endcap features

Posted: Mon Mar 23, 2015 9:20 am
by Griz
What effects would be expected from a long extenson of the endcap bore back into the last chamber?

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Re: Endcap features

Posted: Mon Mar 23, 2015 12:16 pm
by Bendersquint
You would catch more gas/heat/sound than if it wasn't there.

Re: Endcap features

Posted: Mon Mar 23, 2015 12:20 pm
by a_canadian
As was recently reported in these forums the total length of metal bore ought to be kept to a minimum in any suppressor to a) maximize effiency of suppression and b) minimize interference with POI as compared to no suppressor on the same weapon. Besides which the tube mouth itself lacks features which might serve to re-direct flow effectively. I'd suggest shortening it by half and clipping the edge asymmetrically.

Re: Endcap features

Posted: Mon Mar 23, 2015 12:23 pm
by Bendersquint
a_canadian wrote: I'd suggest shortening it by half and clipping the edge asymmetrically.
I wouldn't but thats just me.

Re: Endcap features

Posted: Mon Mar 23, 2015 1:13 pm
by T-Rex
Bendersquint wrote:
a_canadian wrote: I'd suggest shortening it by half and clipping the edge asymmetrically.
I wouldn't but thats just me.
I agree, from other data posted here
Most recommendations exclude clipping the last baffle, at least with 60* cones. I don't see the exit cap being different.

Also, didn't gunny post something, not too long ago, regarding exit passage data.
He had a design which gave the end cap venting ports to allow the gases to exit w/ much less pressure and further reduced the noise signature.

Re: Endcap features

Posted: Mon Mar 23, 2015 1:20 pm
by Griz
My application is a dedicated 300 BLK silencer that will be pinned and welded, so I don't care about POI shift.

I didn't find much when I searched, but I don't know what to call this feature. I'll search out that thread that discusses total length of metal bore.

I have not seen many pics that show an extended endcap bore. Many seem to have a small lip but nothing like my example above. I wonder if that's because of POI shift concerns in commercial cans and Form 1 builds just don't do it because commercial cans don't do it.

Re: Endcap features

Posted: Mon Mar 23, 2015 4:38 pm
by twodollarbill
(picture)... is how I have made all my endcaps.
I have been more than pleased with the results.

Re: Endcap features

Posted: Mon Mar 23, 2015 6:27 pm
by whiterussian1974
Gunny50 has done some excellent work on end port diffusion. I would view his research as definitive as it incorporates several different aspects into a single design.
You can PM him to contribute to this thread. Or just search.
(It incorporates a series of radial relief ports to pull the exit gas outward from the boreline.)
viewtopic.php?f=10&t=123579&p=909419&hi ... al#p909419

Re: Endcap features

Posted: Tue Mar 24, 2015 1:08 pm
by gunny50
Bendersquint wrote:
a_canadian wrote: I'd suggest shortening it by half and clipping the edge asymmetrically.
I wouldn't but thats just me.

I would also leave it as is, Trapping gas longer will please you, not many cans are made this way as it takes longer to machine and that way will cost more.
A radius at the bottom might work the gas harder as it will flow back towards the cones in front and collide there.
Make the start of this Tube / inner cone with a sharp edge, splitting gas better as well.



Gunny

Re: Endcap features

Posted: Tue Mar 24, 2015 1:11 pm
by a_canadian
Well I'll consider myself well schooled on this point guys, thanks.

Re: Endcap features

Posted: Tue Mar 24, 2015 3:27 pm
by Griz
Thanks for the input, I really appreciate it.

It is indeed a pain to do because a tool small enough to get deep in there is not very rigid.

Re: Endcap features

Posted: Tue Mar 24, 2015 3:41 pm
by Bendersquint
Griz wrote:Thanks for the input, I really appreciate it.

It is indeed a pain to do because a tool small enough to get deep in there is not very rigid.
Why not use a face grooving tool?

Re: Endcap features

Posted: Tue Mar 24, 2015 3:44 pm
by T-Rex
Griz wrote:Thanks for the input, I really appreciate it.

It is indeed a pain to do because a tool small enough to get deep in there is not very rigid.
That's why you cheat and, either, put it in the rotary table on a mill or put a bit in the 4th axis on the lathe. :D

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Re: Endcap features

Posted: Tue Mar 24, 2015 5:14 pm
by Griz
Bendersquint wrote:
Griz wrote:Thanks for the input, I really appreciate it.

It is indeed a pain to do because a tool small enough to get deep in there is not very rigid.
Why not use a face grooving tool?
Because I'm a novice and don't have one :) Everything I had on hand was too big once I got about halfway in. I had to grind a tool for it and had a hard time getting the geometry right and once I had clearances ground so nothing rubbed it was pretty springy.
That's why you cheat and, either, put it in the rotary table on a mill or put a bit in the 4th axis on the lathe.
I'm thinking of doing just that for my baffles. I have a X2 mini-mill that I converted to CNC. I'm thinking of turning the OD and the bore on the lathe so that I know everything is concentric, then moving to the mill to finish it.

I was planning on a smooth cone, but if I'm doing it on the CNC mill there are all kinds of crazy fluting or steps I could do. Thinking spiral steps maybe. It's my first silencer though so I should probably keep it simple. I'm already straying a little from the herd with my endcap :)

Re: Endcap features

Posted: Tue Mar 24, 2015 10:51 pm
by yondering
T-Rex wrote:
Griz wrote:Thanks for the input, I really appreciate it.

It is indeed a pain to do because a tool small enough to get deep in there is not very rigid.
That's why you cheat and, either, put it in the rotary table on a mill or put a bit in the 4th axis on the lathe. :D

Image
More details, please? Got any video of that thing in action? I've thought of putting together something similar, but a bit different, on one of my lathes.