Reader Forum

Group Gauge There it is again, one of those "Why didn’t I think of that?" articles. Paul Mazan’s "Making A Group Gauge" in the April 2017 issue has given me another interesting shop project. I have always carried a small pocket-sized steel tape measure to measure the target group size along with the distance to move the group center on the target to where I want it to be by adjusting the sights. Now I’ll use this. This brings up an age-old question of how group size is supposed to be measured.

I have been shooting rifles for a little over 77 years now but never shot in competition except for my military training during the early 1950s. The target pullers marked the targets and I don’t remember exactly how they measured the groups. I have mostly thought the groups were measured as the distance between the center of the farthest two holes, which can leave plenty of estimating an exact location if it’s a very tight "one hole" group.

Not so long ago I read that an alternative is measuring the span of the outside distance of those two holes and subtracting bullet’s diameter to arrive at a more exact center-to-center distance. Another "why didn’t I think of that" piece of information. According to your directions in the article, you are measuring group size as the distance between the inside edges of the bullet holes. I think maybe you’re using the old target rule of "if it touches the line, it’s in" here.

Perhaps that means my fabulous 300 clean wasn’t all that good after all? Author Paul Mazan responds. I would love to take full credit for the Group Gauge idea but Brownells sold them years ago. If memory serves the idea came from Reid Coffield who was also working there at the time and shot High Power with me. Years later, I lost mine and went to buy another but couldn’t find them listed so decided to make one for myself.

I found it so handy I then made a couple more for friends and thought others might like to have a quick project to make a handy tool. Regarding group measurement, you are correct. I was a High Power shooter for many years and shots were scored based on the inside edge of the bullet hole in the target. In fact, when the AR-15 became the preferred Service Rifle the rule was changed to score .22caliber holes as .30 caliber because the AR shooters felt they were at a disadvantage using the smaller bullet.

I felt they already had the advantage of lower recoil and faster shot recovery in rapid fire and always joke that I stopped shooting High Power when it became "centerfire Smallbore." Not knowing how others measure groups, I went with the only rule I’m familiar with and measure to the inside edge of the holes farthest apart. Anyone that disagrees is certainly free to use any method they please for their own records. The real key to measuring accuracy with a particular bullet/ powder combination is consistency.

I use the same method all the time and that allows me to get accurate feedback on whether anew load is performing better or worse than what I was using. It doesn’t matter if I’m shooting .17 caliber or my .577 Snider, I always use the inside edge of the two holes farthest apart in a five-shot group just so I’m comparing apples to apples. Colt 1917 I have a Colt 1917 with a cylinder that wouldn’t completely turn to lockup from a cocked hammer and would only finish rotation when the trigger was pulled.

I installed anew pawl and the revolver was perfect on four cylinders, however, there remains a bit of resistance at the end of a double action trigger pull on the other two. Fletcher M. Pool Ordway, CO I believe the corresponding notches on the cylinder need to be dressed but I’m hesitant to do it myself as I haven’t worked on 1917s before. How would you go about fixing this? John Tate RK Campbell responds. Two thoughts without close examination.

The hand may have peened with use and could be shortened or polished a very small amount to fix this. The other possibility, the cylinder is wobbling on its axis. I am certain ejector rod shims for the Smith & Wesson will work the same for this gun. Brownells stocks shims from Power Custom. It sounds like that finishing rotation isn’t being powered by the trigger being pulled, but rather somehow pressure is being released and then the cylinder turns. I would look to the hand and then check cylinder wobble.

Remington 513T Trigger I have a Remington Model 513T .22 rifle that I’ve sent to two gunsmiths to adjust the trigger as the pull was inconsistent, varying from 2-3.5 pounds when measured. Is it possible to get a diagram of the trigger system and any information on this kind of problem related to the Model 513T? I am concerned about any alterations to

the trigger system and parts. Also, is there any replacement triggers or parts for this rifle that will provide a good target trigger? We think you should call Brownells and order in a copy of their venerable book, Encyclopedia of Modern Firearms-Hardcover Edition. It’s a massive collection of technical detail on outof-production firearms and includes a section on the Remington 513/513T taken straight out of a factory-issued field service manual.

Disassembly/reassembly is thoroughly covered as is the correct way to increase or decrease trigger pull. As for an aftermarket trigger, ask to speak with one of their in-house technicians when you have Brownells on the phone about the Encyclopedia. He’ll know right off whether they have one in stock or which aftermarket trigger maker could sell you one. Browning BAR Problem I have a Browning Bar II Safari that a customer brought in with a complaint was that it was damaging the brass cases upon ejection.

He showed me several that were dented right where the taper meets the main body of the case. He also said it wouldn’t fire reloads that he had. I inspected the rifle and, like most, found that it was dirty and fouled. I lightly cleaned and lubed the action, firing three factory rounds and three of customer’s handloads. The rifle worked, placing a small, double set of scratches on one factory case and a small dent in the taper of another.

With the handloads, the rifle put two slightly larger dents in the tapers of the cases. R. Rothnie Some research online revealed this problem is reported quite often. Some recommend backing down the gas pressure but I’m not leaning in that direction because the heavy carbon fouling found would indicate that the gas push may be not up to snuff now. I have since thoroughly cleaned and fully disassembled the rifle, looking for wear or rough spots. It is chambered in 7mm Remington Magnum and has a muzzle brake.

I have redone several Remington semiautomatics but this is the first BAR I’ve been into. My generation was the M14, M16, and M60. If a quicky clean up job got off six mixed rounds with no problems, a thorough cleaning might prevent them showing up again. Include everything in that thorough cleaning, including the muzzle brake. Gas ports are not to be excluded either but do not enlarge port diameters in the process The suggestion given you on "backing down" gas pressure would likely lead to operating malfunctions.

Namely, short cycling of the action, less than ideal levels of extraction, failures to feed, and misfires. Change Shot Impact How do you change the pattern placement with a shotgun since you don’t use the sights? Rob Starczy Do you mean change the point of impact or the density of the shot pattern? We only ask due to a longstanding belief that the pursuit of arising pheasant or swiftly passing mallard indicates a shotgun is not aimed, rather, it is merely pointed.

Whether or not the pointing is successful depends entirely on how much the moving bird, be it feathered or of clay, is led. Sometimes, the chance of success is enhanced by allowing wider dispersion of a shot charge with a lesser restrictive choke. Conversely, when the bird being sought is wild turkey, a more restrictive choke is favored. A shotgun being used in pursuit of deer leans more to being aimed. This is primarily ammunition related.

Slugs have been gaining in popularity among whitetail seekers who have no qualms regarding scopes, rifled shotgun barrels with or without integrated cantilever mounts, or other aids to enhance point of aim. Joseph English Citadel Arms Finally, crafters of custom-made stocks take upward of twenty measurements of a client. When combined, these ensure the resulting stock will be properly shouldered regardless of being pointed or aimed. AG