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What would yu do here? Question for those with hands on experience...

Posted: Wed Jul 19, 2017 1:39 pm
by Grey_Wolf
Good afternoon guys...

I've never had a question before, but I do now... and so I'm hoping that someone with experience & hands on, who's done this before can answer it for me.

I bought a kit, my 1st DIY, from SDTac almost two & a half years ago, but never started on plans for it until a few months ago due to medical/finance issues. It's a 7.6" Carbon Steel tube, stainless steel spacer tube, thread protector, end cap & centering tool. And I bought the same freeze plugs from NAPA that SDT sold. I'm shooting 5.56mm (.223) & the can will be going on a 10.5" barrel.

I've got understanding of the blast chamber & baffles down, but I've not been able to find a direct answer to the question rattling around in my head; as to whether or not the 'end cap' hole should be at the same size as the baffle holes, or can they be different? It's kind of assumed that they would be the same size, within most of the posts I've read here and videos I've watched over the years. I've never found an exact answer though... and I don't want to assume. Back in 2015 before & after buying the kit, I watched ALL of SD's vids, many others, and have done a lot of reading... Per one of SD's older vids, it says to go 1/4" on the baffles for .223/5.56 with no direct mention of the end cap; that I remember... And as yu all know, those vids are pretty much all gone now... Then most recently, I came across a great chart posted here by someone of vast knowledge, that has all of the baffle tolerances for every caliber (Thank yu!) and he wrote 9/32 for .223/5.56 ... which makes sense to me on the baffles, allowing extra tolerances, 'to include aiding of gas pressure dispersion' along with the other important baffle issues. I'm no expert here though, and now that Form 1 is in works ... 9/32 is where I plan to drill my baffles. But the end cap that I got from SD, I planned to keep at 1/4" because that size is at SD's suggested sizing in the original vid that I mentioned and it always said, go with a 1/4" drill bit for .223/5.56 - Would it be wrong to think this is because the end cap isn't performing as a baffle?

Anyway, now that those vids are gone, I was hoping I could get another opinion/answer on my question, from those who've done this before... Should the end cap be 9/32 just as the baffles would be, or is it okay to keep with 1/4" on the end cap?

Thank you guys for your time, really... It is appreciated
~Grey Wolf

Re: What would yu do here? Question for those with hands on experience...

Posted: Wed Jul 19, 2017 2:13 pm
by propeine
Grey_Wolf wrote:Good afternoon guys...

Snip
Thank you guys for your time, really... It is appreciated
~Grey Wolf
You would want to get larger as the bore got further from the muzzle due to machining inaccuracies, not smaller. One company and some guys here even taper their bores with the smallest being the blast baffle and the largest being the end cap. 0.25 is pretty damn tight 7" from the muzzle IMO.

Re: What would yu do here? Question for those with hands on experience...

Posted: Wed Jul 19, 2017 3:00 pm
by crazyelece
.25 -.223 = .027

.027 / 2 = .0135

that means with perfect tolerances the bullet will have .0135 inches between it and the endcap

For reference a typical human hair or a sheet of paper is .004 thick

I usually go around .06 over bore diameter

.223 + .06 = .283

9 / 32 = .28125

Re: What would yu do here? Question for those with hands on experience...

Posted: Thu Jul 20, 2017 7:34 am
by Sergeant
.25 -.223 = .027

.027 / 2 = .0135

that means with perfect tolerances the bullet will have .0135 inches between it and the endcap

For reference a typical human hair or a sheet of paper is .004 thick

I usually go around .06 over bore diameter

.223 + .06 = .283

9 / 32 = .28125
I have done this with great results. Lately I have been "over-boring" the first 3 baffles (starting with the blast baffle ). Not sure it's any quieter, but it has a more mellow tone. Certainly not any louder. More work on that though before i am sold on it.
That being said, I would follow Crazyelese's very sound advice.

Re: What would yu do here? Question for those with hands on experience...

Posted: Thu Jul 20, 2017 12:01 pm
by T-Rex
I concur.
.265" (17/64) is my "go-to" size for anything .22cal related.
As stated, it comes down to tolerances and being able to hold them, once several inches from muzzle.
Grey_Wolf wrote:Would it be wrong to think this is because the end cap isn't performing as a baffle?
Why do you think this?
The end cap is a baffle. It's restricting flow and preventing a sudden release of gas, is it not?

Re: What would yu do here? Question for those with hands on experience...

Posted: Thu Jul 27, 2017 7:32 pm
by sub-sonic
for what its worth my freeze plug silencer is 11 inches long with 11 baffles and is .265 all the way. 9 years and way over 10 thousand rounds of SS109/M855 and its still .265

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