Best way to change barrel length on HK94 to MP5 conversion?

[Saber Cat]

When converting a HK94 into a MP5 are you better off cutting the HK94 barrel down and adding a flash suppressor or replacing the barrel with a 3 lug threaded barrel and selling off the HK94 barrel?
Let me know your thoughts.

[K1196A]

I recently had the same decision to make, and after discussion with Mike at TSC, I opted to have my 94 barrel cut. His basic thought on it was that the 94 barrel is likely to have a lot less rounds on it compared to a SMG barrel from a demilled kit, which is what I had. Now, that said, if I had a brand new MP5/MP5-N barrel I might have gone the other way and had the new barrel installed. I think the biggest factor to consider is barrel condition - a good HK smith can make the barrels cosmetically indistinguishable.

[SLUHstud]

I would try to find the nicest MP5 barrel i could find and replace it.

Pat

[Las_Vegas_HK]

Depending on your modivation, cost versus authanticity, the cut down HK94 barrel with added three lug piece is alot less cost and in the end you will have a hard time telling any difference.

Like the other poster said, if it was a threaded Navy barrel, that would be a different story.

[AviatorDave]

Depending on your modivation, cost versus authanticity, the cut down HK94 barrel with added three lug piece is alot less cost and in the end you will have a hard time telling any difference.

Like the other poster said, if it was a threaded Navy barrel, that would be a different story.

I agree. But I still went with a used navy barrel just for the authenticity aspect. It worked out fine, it shoots just as well as the 94 barrel did. Next time I'll just get a standard 3 lug barrel and add the navy threads myself though, the navy barrel was quite a premium over the non-threaded barrel.

[Shattered Mind]

When converting a HK94 into a MP5 are you better off cutting the HK94 barrel down and adding a flash suppressor or replacing the barrel with a 3 lug threaded barrel and selling off the HK94 barrel?
Let me know your thoughts,
John

My thoughts are no 94 has seen the amount of ammo an MP5 has. And even IF it has, it was one or two at a time... not mag dumps. The 94 barrel is much more likely to be in better shape, unless you accidently find a NEW MP5 barrel somewhere for BIG bucks.

And my apologies to the in country barrel makers, but I feel there is no way they can make a barrel as good as a hammer forged barrel from the Fatherland.

[CZ-75]

I have had 2 conversions done where I insisted to have a NIW German 3-lug SMG barrel installed.

In Hind-sight, I would have opted for adding a 3-lug adapter, similar to the way Mike at TSC Machines does his.

I had a conversion done by a reputable smith, who pushed out the HK94 barrel, and pushed in a NIW MP5 barrel. The end result was not good.

When a new barrel is put in, the smith doesn't even try to allign the barrel pin channel with the holes in the trunion. rather, they rotate the barrel 33.33%, then ream a new barrel pin channel. This gets the 3-lugs alligned properly without the need to be pinpoint precise in how the stock barrel pin channel lines up.

In an HK94, the original barrel was pressed in and pinned at the factory. Why add an element of uncertainty just to shorten the barrel?

Maike at TSC MAchines (and Curtis Higgins and a few others) can cut down the existing barrel without needing to remove the barrel from the host weapon. Then, they turn it down, thread it, and attach a 3-lug tip.

[AviatorDave]

Threading the outside of the barrel is numbskull simple on a lathe. You just locate the barrel using the chamber centerline on the headstock end, and a live center on the muzzle end and have at it.

It's like lathe turning 101.

But CZ-75, just curious - why was your end result not so good? What happened?

[CZ-75]

When the barrel-pin channel was reamed, the result was holes in the trunion that were "ever so slightly" more than the intended diameter.

Eventually, the barrel pin sheared, and allowed the barrel to walk forward a small distance... enough to allow the bolt carrier to start smacking into the trunion, rather than the rollers engaging the way they should.

The result was a bolt gap that read "in spec" until you put rearward pressure on the bolt (no one ever does that).

I went through 2 bolt carriers. each one cracked where the forward section of the tube that catches the recoil rod.

It took more than one trip back to the smith to get it right. Even he didn't realize what had happened, and said the bolt gap was OK.

Funny thing is... I ended up calling around to other smiths to describe the problem. Curtis Higgins figured it out in less than 5 minutes over the phone based on the symptoms I described. But it took the original Smith 2 attempts to figure it out... even after I told him what Curtis said.

So... the lesson is... don't just check your gap. Be SURE your bolt head is LOCKED when you check the gap. Mine was able to move back and forth a mm or so but I never realized it until it was too late.

[AviatorDave]

How did he fix it? Press the barrel out and start over?