BARRELS, FREEZERS, SCANNERS
By Geza Nagy

In the September 1994 issue of Precision Shooting, in my article "Testing A Kelbly-Built 6 PPC LV Rifle", I briefly mentioned that the first barrel that came with the new gun did not live up to my expectations. I just plain could not get that barrel to shoot well. I did not elect to name the barrel maker. It would have been unfair to a reputable shop who has turned out many fine barrels, a number of which shot like the proverbial house afire.

In several trips to the range, I must have shot at least 500 rounds through it. There were simply too many groups that measured between .350 and .500, even in good conditions. In shooting roughly a hundred groups, it only had two groups "in the ones". I called George Kelbly and ordered a second barrel chambered for the same gun. That one shot well, from the day it arrived.

George asked me to send the first barrel back to him. He was of a mind to have it deep-frozen, for purposes of stress relief. I had never heard of this, but obviously there was nothing to lose.

I sent the barrel back to George, as he had asked. However I asked that he also send the barrel to Photronics Engineering in California, because I wanted to see what a barrel scan on this confounded barrel was going to turn up (Photronic Systems Engineering Company, 6731 Via De La Reina, Bonsall, CA 92003, (619) 758-8000).

I phoned Steve Chernicki (at Photronic) and asked him to send the barrel and the scan back to me. The scan showed aslight variation of twist rate within the last inch, at the muzzle. Steve recommended that .8" be cut off and recrowned. First however I wanted to test the barrel "as is", to see if the deep freeze, stress relief had changed anything. Making two or three changes at one time does not allow one to pinpoint which of the changes was the one that improved things (or on occasion ... made them worse). So I ventured forth to my range with only one thing having been done to the barrel to this point... the deep freeze.

I arrived at the Central Jersey range early enough to have everything set up for our 7:00 AM starting time. It was a cool day and comfortable for shooting. The rising sun was not a factor at that time of morning. The first two groups were shot in a dead calm, with only light winds for the next four groups. The target face was perfectly clear throughout this entire session. One thing was clear from the start... there had been a tremendous increase in the accuracy of the barrel brought about by the deep freeze alone. A six group aggregate of .2245 is not shabby, even in the best of company. I had shot two of those six groups "in the ones" ... which is exactly the number of "ones" groups that I had fired in my precision 500 shots through this barrel. I bungled target #3, in chasing a shot that had gone to my left. That .315 group was the biggest of the six fired and entirely my fault.

Before each group I fired a fouler shot and a sighter shot, after cleaning the barrel. It was my practice to go back to the sighter target if my first shot on the record target looks out of "position". My cross hairs are placed at 6:00 o'clock on the ten-ring (mothball). I like to have my groups form just below that; target #6 herewith is a good example. I don't like to have my shots go into my point of aim; it is then difficult to get a precise point of aim.

I have now sent the barrel back to Kelbly Inc. with a request that they cut the final .8" off from the muzzle end of the barrel and re-crown it. This will leave the last 5" of the barrel with almost a perfect rate of twist for the bullet to go through, before exiting (see barrel scan). It certainly should help the bullet to become better stabilized.

Notice, if you will, that on the barrel scan, while the barrel designated twist rate was 1 in 14", the actual measured twist was 1 in 13.467". In a 6 PPC, I do not consider this a problem. I had two very good shooting barrels that had an average twist rate of approximately 1 in 13.750" in the last 14" of the barrel, by my crude measuring methods. I had a gain-twist barrel that was rated about 1 in 14.500" for the full length of the barrel and which measured about 1 in 15" closer to the muzzle. With this particular barrel 68 grain bullets would not stabilize in cold weather; they would partly keyhole and group around 8" at 100 yards... not exactly official screamer group caliber! It took temperatures above 75 degrees to stabilize the 68 grain bullets; it shot just fine in 90 degree weather. But 62 grain bullets would stabilize properly in cold weather with this barrel.

The barrel scan showed the groove diameter to be .2434, slightly oversize. This is no problem to me, as I shoot mostly .2435 diameter bullets, plus the pressure ring. This was measured one inch from the muzzle. These are some of the things that a barrel scan will tell you, that you can utilize to get the most out of your barrel.

The scan can tell you a lot about the barrel interior. It can show you where and how to cut the new barrel to get the most out of it. You do not want to have a bullet enter your barrel at a rough spot, or exit at one. A slight rough spot in the middle of the barrel may not be as critical as one at either end. Eliminate some of the variables.., presuming that they are ones that can be eliminated... and just possibly you may make an average barrel shoot better. Otherwise it is hit or miss when you start cutting off barrel length if you don't know these things.

Steve has new barrel scan equipment that has considerably reduced the cost of the scan operation. As I write this it costs only $82.00 for the initial scan, if the barrel is cleaned before sending it to him. There is an optional charge of $6.00 to measure the bore and groove diameter. UPS shipping and insurance is additional. Prior to the arrival of the new equipment it cost almost $150.00 to have a barrel scan made.

I must admit that I am not familiar with the cost of the deep freeze operation. George Kelbly had it done for me; I believe it was done in the Chicago area. The barrel is frozen in liquid nitrogen for an unspecified period of time. I know little about the process. But I do know this... it certainly improved the accuracy in this previously average barrel.

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