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NRA Action / 1911 barrels?


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Don't know if the KKM 6" in .355" is ready but my 5" shoots incredibly well. My 6" Schumann 40 barrels are great too. Have always like Kart, they definitely set the bar in 45 barrels IMO.

It is pretty tough to go wrong with a premium barrel, the fitting is far more important at this point.

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+ a bunch on the Kart. I have guns with both Kart and Barsto barrels and both are great. I have the Barsto's in both Glocks and Springfields and they are accurate. I use Kart barrels in my Bianchi guns as they work too well in both 9mm and 38 Super to try something else.

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I have not had a Kart barrel not shoot. The KKM 1 in 32 twist is a little picky with the load.

Listen to Jay. He knows as much about building AP guns here as anyone.

I will second that. Jay is currently rebuilding my SS Caspian into an action pistol. He fitted it with a KART. Here is a group he did with it @ 50. He must be doing something right.

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I have heard many times that Doug has a test fixture and would test several barrels until he found one that would shoot to his standard, that barrel would be installed in one of his guns. I have heard that the barrel had to go sub 1" at 50 yards for 10 shots.

I have not talked to Doug about this, but I have heard it long enough to believe it for the most part.

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  • 4 weeks later...
I have not had a Kart barrel not shoot. The KKM 1 in 32 twist is a little picky with the load.

Hi Jay,

I have just bought one of these barrels to try in my AP... it is in .38 Super. Any suggestions with loads ??

With my current Nowlin .38 Super I am using W231 and Sierra 115JHP's for match and W231 with 122 cast lead bullets.

Accuracy for both is less than half an X-ring at 50 yards ...

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I have not had a Kart barrel not shoot. The KKM 1 in 32 twist is a little picky with the load.

Hi Jay,

I have just bought one of these barrels to try in my AP... it is in .38 Super. Any suggestions with loads ??

With my current Nowlin .38 Super I am using W231 and Sierra 115JHP's for match and W231 with 122 cast lead bullets.

Accuracy for both is less than half an X-ring at 50 yards ...

for the Kart barrel that load will be fine with the bullet going 1100-1150 fps, for the KKM barrel you need to push the bullet around 1200 fps. The 122 grain bullets wont shoot out of the 1-32 twist, its meant for 115 grain bullets only. It will shoot ball ammo just as good as hollow points.

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I have not had a Kart barrel not shoot. The KKM 1 in 32 twist is a little picky with the load.

Hi Jay,

I have just bought one of these barrels to try in my AP... it is in .38 Super. Any suggestions with loads ??

With my current Nowlin .38 Super I am using W231 and Sierra 115JHP's for match and W231 with 122 cast lead bullets.

Accuracy for both is less than half an X-ring at 50 yards ...

for the Kart barrel that load will be fine with the bullet going 1100-1150 fps, for the KKM barrel you need to push the bullet around 1200 fps. The 122 grain bullets wont shoot out of the 1-32 twist, its meant for 115 grain bullets only. It will shoot ball ammo just as good as hollow points.

I will load some up for New Zealand...

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  • 2 weeks later...
Can anyone tell me what rate of twist is ideal for shooting 115 gr JHP at say 1150 FPS. Would 1-24 twist or 1-32 twist be better?

The Greenhill Formula may be useful. However, I believe the formula has been for successful in proving or disproving ideal twist rates for rifle bullets. Note sure why that matters, but perhaps it is due to the greater RPMs produced by most rifle loadings.

I would think based on what I have read or experienced that a 1:32 is not going to be ideal at your indicated velocity. Some have reported the need for 115's to go in excess of 1200 fps for best accuracy with a 1:32 twist rate.

Greenhill Formula

MJ

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The Greenhill formula needs the bullet length and diameter. Where the Greenhill formula seems to fall down is that it has no variable for velocity.

Some have modified the constant multiplier to allow for changes in velocity, but that has its own limitation. I developed a modifier based on the other modifiers found in the full Greenhill formula that seems to match real life fairly well. Thus, I need the bullet length, bullet diameter and velocity to give a twist prediction.

The normally used Greenhill formula also seems greatly off track for handgun bullets where the bullet length and diameter are much closer than for rifle bullets, for which the Greenhill was originally intended (an artillery).

As an example, using the standard Greenhill T = 150 d^2/L

so if d = .308 and L = 1.35, we get T = 10.5. Many .308 rifle barrels are rifles with a 1:10 twist, and it works. Match shooters have been using 1:12 twist barrels with some success. The feel is that over stabilizing the bullet will magnify any imbalance in the bullet.

Using my modifier for the above bullet, fired at 2800 fps yields a twist of 12.5 - that seems closer to the reality of teh match shooters using 1:12 twist barrels.

For handguns, let's look at a 45 bullet (0.451" diameter) with a length of 0.505". Greenhill says this should use a twist of 20". My modifier for a velocity of 850 fps changes that to 1:39". Since the 1:32" barrels seem to be working well, the normal 1:16" twist used on 45 barrels seems way too much over stabilization.

There are more modern ways, but they are more elaborate and harder to accomplish the necessary measurements.

If we take the 9mm bullet as having a length of 0.5", Greenhill says use a 1:37.8" (say 1:38") twist (or faster). Using the 1150 fps velocity, mine says use a 1:28.7" (say 1:29") (or faster) twist.

I've never had the chance to run meaningful tests, but from what I see in use, the velocity modifier seems in the ballpark.

Guy

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I was told by the current metallic sight champion that the 115gr XTP has a sweet spot of around 1150-1180fps. My current load in my 1/32 twist Schumann AET 6in bull barrel really likes 115jhps in that range....and I have the targets to prove it. ;)

That is what my research told me and why I bought the AET with the 1/32 twist, and am very happy.

Good luck,

DougC

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