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Discussion Starter #1
Members:

Anyone ever convert his or her HK93 (or other HK for that matter) to .300 whisper? Is it even possible?

Just curious.

--Erich
 

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Possible? Yes.

Practical? Not very...

Rebarreling to .300 Whisper would be pretty simple. A bit more difficult than replacing the 5.56mm barrel with a new 5.56mm barrel, since you'd have to find someone willing and able to make the barrel. Fluting the chamber would be the most difficult part: there are plenty of smiths who could make a barrel that would fit an HK91 trunion and front sight assembly, but not so many who can flute the chamber.

If you were going to suppress the rifle---and that's pretty much the only reason to build a .300 Whisper rifle---anyone who could make a .300 Whisper barrel for you could probably do the porting and/or threading for a suppressor. An integral suppressor would seem the best plan, since a muzzle-mounted unit would add a lot of bulk to the weapon in comparison, and you'd already be dealing with having a barrel custom-made.

I don't know if it would be necessary to modify/replace the locking piece. I suspect it might be, since H&K found it necessary to design a new locking piece for the suppressed versions of the MP5. You'd need to find someone familiar with the design who could fabricate a new locking piece, and this isn't likely to be cheap or simple to do.

But even after all of that trouble and expense, an HK93 wouldn't be a very practical vehicle for a .300 Whisper rifle. You would have to be willing to dedicate an HK93 to this use, rather than being able to simply switch upper receiver assemblies as is possible with the AR15 family. And the HK93 is pretty rough on cartridge cases. As .300 Whisper is an almost purely handloaded cartridge this would drive up cost and effort considerably.

An AR15-based .300 Whisper would be much simpler if you were looking for a semiautomatic rifle. For the quietest possible rifle there are small bolt actions that would make good vehicles.
 

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The conversion would be much "simpler" on a 91, as the bullet diameter woud not lead to a bbl change.

the ar platform is much more forgiving and we have a member of our range that regularly brings his 300 whisper. In full autp with the can it is a hoot.
 

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Using an HK91 for this would still require some major work.

It wouldn't really be a ".300 Whisper" unless you used one of the "G41" receivers and bolts Special Weapons has talked about fabricating (FMP HK91-clone receiver with the magazine well cut off and replaced with a new well to take M16 magazines, and a bolt with a 5.56mm/.223 Rem face that will fit a standard G3/HK91 bolt carrier). A round similar to the .300 Whisper could be loaded using heavy .308" bullets and reduced power loadings to produce a barely subsonic projectile, but the stock HK91/G3 barrel doesn't have a fast enough twist to stabilize these, so a custom-made barrel would still be necessary.
 

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Discussion Starter #5
AGC and Gato:

I thought it might actually be easier to use a 93. It's my understanding that the .300 Whisper will fit in any .223 magazine, so you would be able use standard 93 mags. I'm not sure about any other modifications besides the barrel, though.

As for ARs, I've seen a couple uppers chambered for it. It seems like a cool concept if I could buy a suppressor. It sparked my curiousity at any rate.

--Erich

P. S. Speaking of HK93s, I almost left the summit county gun show with a nice-looking $2000 HK93A2 (among other things). I was with a friend and he suggested I take a year off college to help pay for it and kind of brought me back to Earth.


[This message has been edited by SabiYume (edited 08-18-2001).]
 

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I might have to run that idea by a friend of mine. He has done a few of the 300/221 guns and they are a hoot to shoot. The 53 size barrel with a suppressor would probably be balanced quite nice as it is quite a light can. I currently have a Remington 700 in 300/211 and love it.

I might have to load up some of the mags to see if they will work with the rounds.

Chuck
 

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The idea of an HK53 or 33K size "300/221" sounds interesting.

If the rounds feed out of a stock HK .223 mag (or lightly modified one), one could get away with a custom barrel and possible locking piece.

Vector regrinds the locking pieces all the time, thus this should be with in reason. Besides can't see shooting many thousand of rounds a year due to the effort to make and find brass.

About the only down side I see is damaging brass that one has spent the winter making.
 

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A 300 whisper would work in the 93/53. Have your local smith make the correct exterior profile and chamber it. Send the barrel to Mike at Rim Country to add the chamber flutes. Chamber flutes may not be neccessary if your going to use subsonic ammo exclusively since the cases do not swell up very much.

If your going to use supersonic ammo, flutes will be necessary. I'd start off with the standard 55 grain locking piece for subsonic and the 62 grain locking piece on supersonic ammo. You will definitely need a 1:8 barrel for a 53 size gun. I'd suggest going with a 5/8X24 thred pattern.

I went to a firearms instructor school where a 300 whisper AR was being demo'd. The AR was 10 1/2" barrel with a very small suppressor (don't know what brand, but looked about 6"-7" long). The loudest sound I could hear was the bolt carrier slapping back and forth, a hissing sound from the gun, and the metal plates falling about 15 yards away. I was about five yards away from the shooter. Pretty slick set up.
 

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I think a .300 Whisper/ .300/221 would be more versitle in the HK SL8 or G36 platform because the barrel is removable but I never heard or seen a SL8/G36 .300 Whisper barrel. The overall length in the .223/5.56 vs. the .300 Whisper/.300/221 are the same. Will this work???

Swapping barrels for the inexpensive .223/5.56 ammo to the handloaded .300 Whisper would be an advantage in my wallet.

Is there any manufacturer that can make a HK SL8/G36 barrel in .300 Whisper?

For now swapping the AR15/M4 .300 Whisper uppers seems like the thing to do for semi or FA use.
 

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I think a .300 Whisper/ .300/221 would be more versitle in the HK SL8 or G36 platform because the barrel is removable but I never heard or seen a SL8/G36 .300 Whisper barrel. The overall length in the .223/5.56 vs. the .300 Whisper/.300/221 are the same. Will this work???

Swapping barrels for the inexpensive .223/5.56 ammo to the handloaded .300 Whisper would be an advantage in my wallet.

Is there any manufacturer that can make a HK SL8/G36 barrel in .300 Whisper?

For now swapping the AR15/M4 .300 Whisper uppers seems like the thing to do for semi or FA use.
The major down side to the HK SL8 or G36 is the HK9x auto sear / trigger pack does not work with these guns ;-(.

Agree the M4 upper is easier, however, not as interesting (besides nearly everyone setup for 300/221 already has an AR/M16 setup).
 

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The major down side to the HK SL8 or G36 is the HK9x auto sear / trigger pack does not work with these guns ;-(.

Agree the M4 upper is easier, however, not as interesting (besides nearly everyone setup for 300/221 already has an AR/M16 setup).
Good point! The SL8 or G36 would be strictly semi for civilians...???
 
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