Home Forums Reloading Big Game Rifles Whats causing this?

A year or two ago, Mule Deer wrote an article about different things that can affect grouping.

IIRC, one of those things that cause one shot out of the group, as shown here, was the magazine touching the bottom of the action. I think he eliminated the problem by shimming the action so that it did not touch the magazine. Or by shimming the magazine to get it away from the action bottom.

Maybe he will see this and comment. The entire article was very interesting. It was about little things that have a big affect on accuracy, things that you normally would not think about.

I remember that article as well.

I'm right handed and when my flier is aways right, it's me, the trigger and "pull". For me dry firing during my grouping attempts help me be more consistent.

I've learned there is no silver bullet to fixing every problem, but rather a bunch of small changes get me where I want to be. I like round robin groups: 3 bullseyes on one target 9 shots = three shot groups every 4th shot. Just a different lens to see the group through. Of course, barrel, trigger, breathing, timing between shots, fatigue and 100s of other factors are all important, but finding the combo for you, the rifle and the shot is the fun parts.

Mule Deer has forgotten more about shooting than I may ever know, but damn it is fun to-learn! !

THE VAGARIES OF RIFLE TROUBLESHOOTING

One early October day Eileen and I went to the Virgil Binkley Shooting Complex, the official range of the Broadwater Rod & Gun Club, to try some new handloads, shoot some new-to-us rifles, and sight in other rifles for Montana�s big game season. It was a perfect day for shooting, cool enough so that barrels didn�t get hot quickly, and almost completely calm.
One result was that Eileen became certain the used Remington Model 7 in .260 she�d bought a few months ago was erratically placing some shots to the left of the main group. Her first suspicion was a defective scope�as it should be, since while writing an optics column for the now-defunct NRA women�s column for a couple of years, she�d had six scopes go bonkers on her rifles. Then she remembered that the 3.5-10x scope she�d put on the .260 had been rebuilt a few years ago by Leupold, and had been proven reliable on several rifles since.
We also knew it wasn�t a problem in scope mounting. Eileen has known how to mount a scope correctly, without over-tightening the ring screws, for several years�ever since a new, custom .308 she�d ordered acted really screwy. The big problem, it turned out, was that the head of production at the custom company had tightened the rings screws on the 2.5-8x scope she�d sent along like the lug-nuts on a 3/4 �ton pickup.
The problem was diagnosed pretty quickly, because the guy was there when Eileen decided to switch scopes. After she got another, proven scope mounted, the guy said, �Now really tighten down those ring screws.� (When she refused he tried to take the screwdriver away from her, and she thought about stabbing him with it.) The rifle started shooting better immediately, and when she sent the �defective� scope to Leupold they couldn�t find anything wrong with it. It has worked perfectly ever since.
I was involved in my own shooting, including fire-forming 50 new Norma cases in my 6mm PPC benchrest rifle, so only made some short comments when she asked questions between shots, such as, �Well, sometimes skinny barrels do that.� But when we both had shot all we needed to, she showed me the target: In each 3-shot group her little rifle would put a couple of shots into less than an inch, but the third shot would jump 2-3 inches to the left, randomly. Allowing the thin barrel to cool completely between shots didn�t help; even with a cold barrel some shots would jump left.
I asked to take a look at the rifle, so Eileen cleared the chamber and handed it over. These days the injection-molded stocks Remington uses are pretty stiff, so tend to work pretty well, but some of the older injection-molded stocks were rather floppy, and not just on Remington rifles. I grabbed the barrel just in front of the forend, then tried to pull the forend tip away from the barrel, and found this stock one of the stiff ones. Next I tried to move the forend tip back and forth on the barrel, and could feel a little play and hear a dull click as the tip wiggled back and forth. �That�s probably the problem, right there,� I said, handing the rifle back. �Grab the barrel like I did, then push the forend tip back and forth.�
She did, and her eyes immediately widened. �Oh, yeah! So what do we do now?�
�Well, we could free-float the barrel, but a lot of the time skinny barrels don�t shoot all that well floated. Instead we�ll try epoxy-bedding the forend tip.�
�I want you to show me how.�
�Sure.� Eileen has a taken a much greater interest in how her hunting firearms work in the past few years, ever since the Great Scope Mounting Incident. She used to let me load her ammo and mount her scopes, but last year she set up her own handloading bench, and has mounted scopes in several kinds of rings.
We packed up our rifles and ammo and pointed the pickup toward town, planning to check our box at the post office to see how many millions of dollars had shown up, then go home and have lunch. (Checking the mail is a 6-times-a-week lottery for freelance writers. Some weeks the bills outnumber the dollars, but over a year the checks usually come out ahead.)
We parked in front of the post office just as our friend Bev came out the front door. Her husband Jay was sitting in their pickup, finishing up a cell-phone call, with their two wire-haired pointing Griffons in the pickup bed. So we went over to say hi and pet the dogs, who wagged their short tails eagerly. Bev and Eileen started talking about dogs, and Jay and I started talking about hunting. (What else?)
I�d spent most of September in Tanzania, while Jay had been bowhunting elk. He hadn�t gotten one yet (in about one in three years he arrows a bull, and in the other 2/3 he �gets his elk� during rifle season), but reported that blue and ruffed grouse numbers were far above average in the local mountains. Bev overheard us and said that Jay didn�t really have to arrow any more grouse, since there were already had more in the freezer than they could eat. Jay said he really liked grouse and guaranteed they didn�t have too many.
Then he said, �Hey, can I ask you a rifle question?�
�Everybody else does. Why should you be different�
He laughed, then said, �You know that Super Grade Model 70 my dad sent me last year?� I nodded. It�s a pre-�64 .270 made in 1949. Jay and his dad are pre-�64 loonies, especially liking .270�s. �Well, I�ve shot it a bunch now, and it always starts making one group, then makes another group to the left. What�s the problem?�
Now both Eileen and I laughed. Jay looked puzzled until we explained about just coming from the range, then I asked. �How about the scope?�
�I bought a brand-new Leupold, so that can�t be it.�
I laughed again. �Why not?�
�Well, it�s brand-new!�
�So what? Brand-new scopes can be defective, even Leupolds. One thing I learned a long time ago is to never put an unproven scope on an unproven rifle. If there�s a problem, often you can�t tell whether it�s the scope or the rifle. You have any proven scopes lying around?�
Jay frowned a little. �Yeah, but maybe it�s something else. What do you think about loosening up the forend screw a little?�
I shrugged. �That might work, but I always tend to suspect a new scope.�
�I�ve got that six-power you sold me a few years ago. I sold that rifle and kept the scope. I could try that.�
�Why don�t you, and if that doesn�t work try fiddling with the forend screw. And if that doesn�t work, I�ll come with something else.�
�Okay!�
It turned out we did have a check in the mail, for $24 from somebody wanting my new hunting book. Since there weren�t any bills we were ahead for the day, so headed to the �big city� of Helena for lunch and some errands (including a shell-holder for a new-to-me rifle and three soft rifle cases, on sale at Capital Sports & Western Wear, which ate up most of the $24 check). Eileen and I talked about rifle troubleshooting for some of the half-hour drive, and I mentioned that people often post on the Campfire when they have an accuracy problem with one of their rifles. A bunch of people post suggestions, and few suggestions match.
�A lot of the time,� I said, �both the scope and rifle are new, so it�s almost impossible to tell what might be happening. Sometimes the symptoms are pretty clear, though. A few months ago a guy posted that his rifle was shooting erratically, but only sometimes. It would shoot a decent group, but then the next group would have a bad flier, in any direction. Sound familiar?�
Eileen grinned. �Sounds like over-tightened scope rings to me.�
I nodded. �That�s what I suggested, but the other suggestions included everything from having a gunsmith re-bed the stock to �properly breaking in the barrel.��
�Did he ever find out what the problem was?�
I nodded again. �Yeah, a few days later he e-mailed, saying he�d loosened the screws on the scope, then tightened �em again the way I suggested, and the rifle started shooting good groups.�
�You must be some kind of genius.�
�Yeah, right.... Most of the time there�s no way on earth to tell what�s wrong. And you know too well there can be more than one problem.� She sighed, remembering. The same custom rifle had shot consistently after the scope-ring problem was diagnosed, but 1-1/2� groups aren�t what a 21st century shooter expects from a .308 Winchester with a medium-weight Lilja barrel. I tried a bunch of different loads, but none did any better than the first, 150-grain Ballistic Tips with 47 grains of Varget. If a .308 won�t shoot with that load, then there�s something wrong with the rifle.
I was finally accepting that fact, but darned if I could figure it out, so finally called Charlie Sisk, the well-known Texas gunsmith. I could almost hear Charlie thinking on the phone before he said: �Well, it kinda sounds to me like the magazine could be binding.�
My eyes widened. �Thanks, Charlie. I do believe that might be it. I haven�t run into that for a long time, so didn�t think about it. And I don�t expect to see it in a custom rifle.�
�Let me know how everything turns out.�
�You bet.�
I put the rifle in one of my workshop vises and used a safety pin to probe the top of the magazine box. Sure enough, there wasn�t any gap between the magazine and the stock. I took the rifle apart (for maybe the 19th time) and filed the bottom of the box until the tip of the safety pin could be inserted between the top of the magazine and the stock, then went to the range with some 150-grain Ballistic Tips and 47 grains of Varget. The first group was under ��, and the second was smaller. Mystery solved�after over a year of dinking around with scopes and loads.
I called Charlie that evening and told him what I�d found, and the results. �I owe you a Margarita or two the next time we get together.�
�Hell, John, you don�t owe me anything. I was thinking one end of the box was binding against the stock!�
So you never know. Sometimes we�re right and sometimes we�re wrong, but the world is still always full of very firm opinions from people who�ve never seen the troubled rifle in question. Once in while, like a broken watch that�s correct twice a day, long-distance opinions are even right. Excuse me while I go show Eileen how to epoxy-bed a forend tip. I sure hope it works!

If the scope ring screws aren't over torqued try seating the bullets deeper 1/4 turn of the seating stem at a time. If the one bullet starts moving into the group continue until the bullet is in the group. AussieGunwriter posted this tip a few years ago and my son tried it and it worked for him.

I guess that I guessed wrong, because I thought the rifle in the article was on a Mauser action.

My 72 year old memory is not like it used to be.

I had a rifle that would do that, 2 shots overlapping and 1 shot about a foot off. This was the second center fire rifle I had ever owned. It was a sporterized 03 Springfield. The problem was not the scope, because the sighting equipment was a Lyman 48 rear sight and the military front.

At the time I didn't reload and I had a job sacking groceries for .40 cents an hour. On those wages, paying for enough .30-06 cartridges to do a bunch of testing was out of the question. About 3 shots a week was all I could afford. Since ammo was scarce, well ammo was not scarce, but money was, so I had to learn how to shoot pretty good. I did shim the forearm, as was the first thing the gun writers of the day suggested. No difference. I also cut and re crowned the barrel, but that did not help either.

I was looking through a catalog and saw where I could buy an 03 barrel for $4.95. I knew someone who had a reamer and a lathe, so I bought a barrel. The barrel was for an 03A3, and my rifle was an 03 Mark 1, made about 1917. I used in anyway.

That fixed it. I could keep 5 shots in about 1 1/2 inch with the Lyman 48, and after I had sacked a lot of groceries, I was able to get a scope. For a long time I carried a group in my bill fold that measured 5/8 inches for 5 shots, using Military Match ammunition.

The only reason I am writing this is because I know there is at least one more thing to take into consideration when you have a rifle that causes 1 shot to go way out of the group--a bad barrel.

I don't know which shot it was that went out, because, as I said, I was using an aperture rear sight and I did not want to walk 100 yards and back after each shot.

I believe this is due to the barrel heating and pushing against the speed bump.

Try shooting one shot every fifteen minutes.

JB,

Thanks for your contribution. Makes me think we should generate a sticky with a list of typical problems that could cause inaccuracy in bolt rifles.

Regarding scope ring issues. Never considered too tight would affect groups.

I had an older Leupold with windage adjustment issues. Turned out the rings were too tight. A Leupold tech suggested I remove the scope and place the objective against a mirror and turn the windage adjuster while viewing the double picture of the crosshairs to see if there was movement. Never thought of checking function with a mirror. Removed from the rings it functioned fine. (In addition to that you can used this method to center the windage and elevation.) The Leupold tech said to tighten the scope cap screws to 22 in/lb and the problem would be solved. I reinstalled the scope and proved the problem was solved with the mirror. 22 in/lb is about what two fingers and the thumb can generate with a typical screwdriver.

Lose the pressure point, and make sure the barrel isn't touching the barrel channel. And as mentioned, check to see if the mag box isn't crammed against the bottom of the stock/floorplate.

Bedding will probably help.

I shoot a LOT of M700's, and love taking factory M700's, tune them, develop a load, and make 'em into a shooter.

You don't mention which shot the flier is. If it's the third shot, odds are the barrel is heating up and moving around on the pressure point.

Casey

Had the same problem you're having with a new Rem 700 CDL 257 Roberts bought in 2009. I noticed when cleaning that the bore had a tight spot in the middle of the barrel. Gunsmith confirmed tight constriction about two inches long halfway up the bore and told me to send it back to Remington to get rebarreld. Got it back from Remington three weeks later after they fire lapped the tight spot out along with most of the lands. It still shot terrible and velocity was extremely slow. Traded it in on a Kimber and never looked back.

Hey, that's what some guys do here....

How about a 1 shot group! Can't get any tighter groups!!

Then you can brag about the 1-hole groups.