August 12th, 2017

Figure Out Exact Barrel Weight with PacNor Calculator

Online Pac-Nor Barrel Calculator

Can you guess what your next barrel will weigh? In many competition disciplines, “making weight” is a serious concern when putting together a new match rifle. A Light Varmint short-range Benchrest rifle cannot exceed 10.5 pounds including scope. An F-TR rifle is limited to 18 pounds, 2 oz. (8.25 kg) with bipod.

One of the heaviest items on most rifles is the barrel. If your barrel comes in much heavier than expected, it can boost the overall weight of the gun significantly. Then you may have to resort to cutting the barrel, or worse yet, re-barreling, to make weight for your class. In some cases, you can remove material from the stock to save weight, but if that’s not practical, the barrel will need to go on a diet. (As a last resort, you can try fitting a lighter scope.)

Is there a reliable way to predict, in advance, how much a finished barrel will weigh? The answer is “yes”. PAC-NOR Barreling of Brookings, Oregon has created a handy, web-based Barrel Weight Calculator. Just log on to Pac-Nor’s website and the calculator is free to use. Pac-Nor’s Barrel Weight Calculator is pretty sophisticated, with separate data fields for Shank Diameter, Barrel Length, Bore Diameter — even length and number of flutes. Punch in your numbers, and the Barrel Weight Calculator then automatically generates the weight for 16 different “standard” contours.

Calculator Handles Custom Contours
What about custom contours? Well the Pac-Nor Barrel Weight Calculator can handle those as well. The program allows input of eight different dimensional measurements taken along the barrel’s finished length, from breech to muzzle. You can use this “custom contour” feature when calculating the weight of another manufacturer’s barrel that doesn’t match any of Pac-Nor’s “standard” contours.

Caution: Same-Name Contours from Different Makers May Not be Exactly the Same
One final thing to remember when using the Barrel Weight Calculator is that not all “standard” contours are exactly the same, as produced by different barrel-makers. A Medium Palma contour from Pac-Nor may be slightly different dimensionally from a Krieger Medium Palma barrel. When using the Pac-Nor Barrel Weight Calculator to “spec out” the weight of a barrel from a different manufacturer, we recommend you get the exact dimensions from your barrel-maker. If these are different that Pac-Nor’s default dimensions, use the “custom contour” calculator fields to enter the true specs for your brand of barrel.

Smart Advice — Give Yourself Some Leeway
While Pac-Nor’s Barrel Weight Calculator is very precise (because barrel steel is quite uniform by volume), you will see some small variances in finished weight based on the final chambering process. The length of the threaded section (tenon) will vary from one action type to another. In addition, the size and shape of the chamber can make a difference in barrel weight, even with two barrels of the same nominal caliber. Even the type of crown can make a slight difference in overall weight. This means that the barrel your smith puts on your gun may end up slightly heavier or lighter than the Pac-Nor calculation. That’s not a fault of the program — it’s simply because the program isn’t set up to account for chamber volume or tenon length.

What does this mean? In practical terms — you should give yourself some “wiggle room” in your planned rifle build. Unless you’re able to shave weight from your stock, do NOT spec your gun at one or two ounces under max based on the Pac-Nor calculator output. That said, the Pac-Nor Barrel Weight Calculator is still a very helpful, important tool. When laying out the specs for a rifle in any weight-restricted class, you should always “run the numbers” through a weight calculator such as the one provided by Pac-Nor. This can avoid costly and frustrating problems down the road.

Credit Edlongrange for finding the Pac-Nor Calculator
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June 9th, 2012

6BR Shines at 500 Yards with PacNor Barrel

You don’t hear much about PacNor barrels in long-range competition, but FORUM member Wes J (aka P1ZombieKiller), proved that they can shoot “lights-out” in a rig assembled by a talented gunsmith. Wes tells us: “Since I restocked my 6BR more than a year ago, I have not had a chance to shoot it much since I have been playing the 100-200 game. Well, last week I decided to take it out and do some playing at 500 yards. I have to give some serious props to my buddy (and fellow FORUM member) ‘PREACHER’ who did the chambering and barrel work for me. He can certainly make a gun shoot good. The barrel is a PacNor 1:8″ twist. My load was 105gr Berger VLDs pushed by 29.6 grains of Varget.” The five-round, 500-yard group shot by Wes J with his 6BR, measured just 1.240″, as measured by OnTarget software. Now that’s one accurate rig!

6BR PacNor

6BR PacNor

This Editor knows something about the potential of a PacNor barrel. I have a 3-groove stainless PacNor SuperMatch on my trusty Savage-actioned 6BR. This barrel shoots quarter-MOA or better in calm conditions, and it cleans up super-easy. The interior finish is so good, I’ve never had to brush the bore or use abrasives, and after 750 rounds it shoots as well as ever. I attribute the easy cleaning to the fact the lands in a PacNor 3-groove are wide and flat, so they are gentle on bullet jackets. I think accuracy is helped by the fact that PacNors run on the tight side (0.236 land dimension) with a good amount of choke. That works well with the 105gr Lapua Scenars and 103gr Spencers I like to shoot. You can read more about my rifle, nick-named the “Poor Man’s Hammer”, in this Feature Article from our archives. In its last outing the Poor Mans’ Hammer put 3 shots in under 0.200″ (measured center to center) at TWO Hundred yards. If you get a good one, PacNor three-grooves can definitely shoot.

OnTarget SoftwareTarget Measurement with OnTarget Software
We used OnTarget software to measure the 5-shot group in the target above. This easy to use software is very repeatable, once you get a feel for plotting the shots. The basic version 1.10 of OnTarget is FREE, while there’s a modest $11.99 registration fee for version 2.10. In addition to group size (in inches), OnTarget plots distance to aiming point, and the software automatically calculates the group’s vertical height, horizontal dispersion, average to center (ATC), and group size in MOA.

You can run a measurement on a scanned target or a photo of a target. You’ll need some known reference to set the scale correctly. The target above had a one-inch grid so it was easy to set the scale. Once you’ve set the scale and selected bullet diameter and target distance, you simply position the small circles over each bullet hole and the OnTarget software calculates everything automatically, displaying the data in a data box superimposed over the target image. To learn more about OnTarget Software, read AccurateShooter.com’s OnTarget Product Review. This article covers all the basics as well as some advanced “power user” tips.

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