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Discussion Starter #1
Would taking aabout 1/3 of the weight from a .308 1919 barrel allow for a faster firing cycle, and therefore give me a faster rate of fire with a crankfire unit?

I had considered turning down a bbl on my lathe. I would leave the rear end that slides on the bearing surface and the front end towards the booster at the original diameter, but taper it down in the middle gradually at each end. I also thought about cutting cooling "fins" into this same non-critical middle area of the barrel to reduce weight.

Would this harm the weapon in any way?

Just thinking out loud here!


Balming
 
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I would say your rate of fire with a crank is limited to the timing on the crank and the fact the gun needs to be completely locked up before it will fire. Making the barrel lighter will increase bolt speed but it may also increase wear or cause a beating to the sideplates in the area where the back plate slides it. I think for what you will gain in bolt speed you probably won't see much of an improvement in cycle rate.

I have a full auto 1919 and in 7.62 it screams already compaired to 30-06 or 8mm so I'd say the barrel and bolt are moving about as fast as you want them to.

My opinion.
 
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there was a post recently about shortening the barrel to 16" to speed rate.
 

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Discussion Starter #5
twistedpuppy said:
there was a post recently about shortening the barrel to 16" to speed rate.

Hmmmmmm........

I have a gun coming from John McGuire at the end of this month in .308 and 8mm. I think I'll leave that gun alone and keep it as he built it, and build up one myself as a shorty.

I can do the lathe work to the barrel in my shop, but how is the shroud shortened correctly? Take the material from the middle and re-weld it together in a jig, or take it from the rear and rethread it ?


Balming
 

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Turning the bbl down in O.D. will ALSO increase the heat build-up in your weapon, resulting in more bbl wear. The shorty set-up is a good way to lighten the bbl AND shroud. It'll get the desired results you are looking for, as well as add to the "Cool" and "Wow" factor at the range, as well as provide light to read by! (The muzzle flash will increase more as the bbl shortens!)
 

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If he wants to keep the length would a A6 barrel do the same thing instead of lathing a A4 barrel?
 

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The A6 had a lighter barrel and was able to handle measurably less sustained fire than the A4. Also, it had a different booster and I do not know if the diameter was different as I have never measured it. It is possible that the booster dia was set differently for the lighter barrel.

In the end, however, I think you are on the right track with building a shorty. I love mine!
 

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Turn fins on it if you so desire. It increases the overall surface area and improves heat exchange. I have a .308 I turned fins on but they are not deep fins. If you go too deep your barrel will still overheat too quickly.

The stock thickness is about what it ought to be for a 1919. Can't comment on ROF though:(
 

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Discussion Starter #10
Well, I think I just made a deal for a 1919 kit in .308 and a sideplate, so we will see what transpires.

I do like the idea of turning some shallow cooling fins into the center of the barrel.

I may turn them about 1/4 inch wide and the same deep, spaced about 1/4" apart.

If nothing else it will look cool!:rolleyes:


Balming
 

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balming said:
Well, I think I just made a deal for a 1919 kit in .308 and a sideplate, so we will see what transpires.

I do like the idea of turning some shallow cooling fins into the center of the barrel.

I may turn them about 1/4 inch wide and the same deep, spaced about 1/4" apart.

If nothing else it will look cool!:rolleyes:


Balming
You'd do better with 1/8". Such thick fins are better cut with a V shape to them so the heat concentrates itself toward the tip of the smallest area which would be the tip (^) of the fin . If I can get home anytime soon I'll snap some pics and email them to you. Mine are 1/8"

Take a look at the contour of an original USGI A-6 barrel. You can safely machine your fins to a tapering depth similar to the 1919 A-6 contour while leaving the fins and external dimensions to the original A-4 O.D.

Don't try to unify it and carry the outside dimensions to match the tapering depths of the cooling fins. I say this because you want the maximum heat exchange up towards the muzzle area where it thins anyway. Leaving the original O.D. intact and just cutting deeper as you go forwards gives the maximum amount of surface area and greatest dissipation.

In the 1919 with it's reciprocating barrel the air is constantly being exchanged through the fins and you'll notice it throws heat allot better. You can still burn the barrel up in this configuration however so give some cooling time. Cooling fins don't neccesarily work on all MG's as efficieintly as you may think. In aircraft installations fins are great but they are less effective on the ground usually, this especially goes for weapons with fixed stationary barrels. In this case it is a good means of lightening up the weapon and it does seem to throw heat off quickly but I don't really have anything to test it against.

I have one barrel I did like this and it seems to work pretty well. Anyone can tell you I am a nut for weapons with cooling fins anyhow:D

I'm still looking for a DS-39 kit!!!!:)
http://home.claranet.de/abpw/16-mgs/images/DS-39_by_Frodo.jpg
 

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An A6 barrel will slide right in place of an A4 barrel, but are they in 308 or '06? Lightening the barrel will increase rof, but also pounds the backplate and buffer disks more and the barrel doesn't cool as well and you end up cooking off rounds...especially with a crankfire. The shorty kits seem to be the way to go.
 
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