HK53 build, gas tube length

1278 Views 9 Replies 5 Participants Last post by Discogodfather, Mar 8, 2017

MaxKrax

Discussion Starter · Mar 1, 2017 (Edited)

I got a vector receiver and an imported 8.3" HK53 barrel from gatewood supply for my HK53 build. I bought a cocking tube labeled as an HK53 tube from HKParts.net. when I piece the parts together it is obvious that the gas tube is too long by somewhere around 1"-1.5". What gives?

I do have a friend who also has an HK53 already built and he has a US made 10" barrel on it, it appears the gas tube is a good fit for his. Am I missing something here? I was under the impression a correct HK53 barrel is 8.3"

Don't get me wrong, it appears HKparts.net is willing to work with me but they also insist they sent the correct gas tube for a 53. Can someone shed some light on why the gas tube is longer? Did I get the wrong barrel? It does have HK markings on it

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Guido02

· #2 · Mar 1, 2017

Without pictures and measurements of everything it's hard to determine what your issue is. But the cocking tube for a 53 should be just under 8 inches and the barrel is 8.3.

Pending you have the correct cocking tube, If I had to guess based solely on the your statement that the cocking tube is an inch to long....

Your reciever is a 93 receiver and hasn't been cut back for a 53 cocking tube yet.

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MaxKrax

Discussion Starter · #3 · Mar 1, 2017

Ok, that does make sense, my receiver is a Vector Arms V93 receiver. I didn't know it was different from a 53 receiver. Do you know of a good source of information regarding what I need to do to cut it down?

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MaxKrax

Discussion Starter · #4 · Mar 1, 2017

I'm guessing I just need to cut a slot in the receiver a slip the cocking tube onto it but is there a source for all the measurements for the cut? Any help would be appreciated

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gopherboy128

· #5 · Mar 1, 2017

http://www.tscmachine.com/images/HK53/HK-53large6.jpg

Look at where the cocking tube lines up with the front of the reciever, that will give you a rough estimate.

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Guido02

· #6 · Mar 1, 2017

Are you dead set on doing it yourself? If not I'd send it to One of the supporting vendors.

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MaxKrax

Discussion Starter · #7 · Mar 5, 2017

Yes I'm doing it myself. I think I found someone that is going to trade me my 93 receiver for his 53 receiver. Hopefully that will fix my issue

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11C ABN

· #8 · Mar 5, 2017

your aware that you can cut the top section of the receiver, to facilitate this build.

Go look at reverse stretch MP5 it's the same concept

Do it yourself is not an issue. Insure that you can weld? Tig is the best method' others have used a Mig welder just a lot of clean up and be aware that heat is an issue. Holecreeks tutorial on weaponsguild and youtube is very informative. JFK's tutorial on PSG1 build is another great tutorial.

Use the search mode for build info. Good luck. stay safe

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MaxKrax

Discussion Starter · #9 · Mar 6, 2017

I can weld, but tig is a no go for me. I might explore having someone cut and weld it for me but I'm still working on this trade deal to trade it for a hk53 receiver that is ready to go, that will be my first choice.

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Discogodfather

· #10 · Mar 8, 2017

It's just a cocking tube, no gas involved. Basically, an arbitrary spec measurement will probably not help you much. This is where custom fitting and experience come in. The top of the receiver needs to be cut back enough to allow the cocking piece to have a .015"-.030" gap when the charging handle is fully folded down and resting against the cocking tube. Too much gap and it will not fully unlock the locking piece on the bolt carrier and makes charging a real pain, too little and you risk not fully locking the rollers.

The HK33/53, like the HK91 series, uses a leverage trick to allow the bolt carrier locking piece to be unlocked before the charging stroke occurs. As the lever is folded out, it nudges the bolt carrier open.

I would take my time and cut too little rather than too much. If you get it into the ballpark, you can then address the issue by modifying the cocking piece. Let's say you get it too tight, you can sand or turn off a couple of thousandths off the cocking piece end to compensate.

The reality is this is a very critical thing to a successful build, and I would mock it up many times before I committed. I have done several reverse stretch builds on MP5ks and 53's, and it just take patience. If you can take pics and post them during your process we can all help.

The problem with someone giving you a length is that following that length might not be right, and result in some pretty bad gaps or no gaps at all. Also, adding material to the cocking piece is a huge pain, and requires TIG and re-hardening since it is a heat treated part. So erring on the side of a little too tight is better to shoot for.

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