doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com How to change Point of Impact ??

Patterning a handfull of SXS's for the upcoming turkey season, I ran into a dilemma with my LC Ideal 12ga. It was one of five guns put to the patterning board in the last couple days. All but the LC Ideal placed even patterns both above and below the point of aim. The two pics below show a 20yd and 40yd pattern. These are the 7th and 8th shot showing the same low pattern. Examination shows a high percent of pellets below the POA. IF there is one thing I don't need in my shot delivery is low pellets. I've changed the pitch to 2 1/2". Is this a barrel physics problem? DAH issue? OR What? to move that pattern up? Any suggestions? In answer to Jims comments. For the pattern work, all shots were sighted down the rib to keep consistent shot to shot. Did not use the quick mount and shoot technique. All the guns I keep have been fitted and dimensions are close to identical. For the last 8 years, all the clay games[skeet,trap,5stand,SC] I shoot are from a low mount position to imprint consistency in every gun mount. All the clay games are just practice for upland and waterfowl. This mounting position is always constant to have the right eye aligning as an extension of the rib line. Regarding this LC, it is a good fit, but haven't been happy with the results on game or clays. I've used Orlen and Skeets for barrel work, but never asked for this type of choke fix you suggested. Randy
20yds, 1 oz, #8's


40yds, 1 oz, #8's

You left out some important details about how you shot these patterns. Namely, did you carefully aim down the rib? This is how you determine if the barrels shoot straight. Or did you mount the gun quickly, as you would in the field, and shoot as soon as the comb touched your face? This is how you determine how the gun fits you. If the barrels shoot low, with careful aiming, you move the POI by removing metal from the choke area, on the side you want to shift the patten toward. If you mounted and shot quickly, you want to move your eye in the direction you want the pattern to go. This is done by raising or lowering the comb, like the rear sight on a rifle or pistol. Changing the pitch will have little or no effect on this. It's not a DAH(drop at heel) problem. The drop at the comb, or at the face(where your face sits against the stock) is what you need to be concerned with.

Bend the barrels. All this stock modification is not getting to the root of the problem. Put the barrels in a bending jig and bend them. It shouldn't take much and it will be invisible to future owners. End of story.

Your testing may be incomplete, she just might not like the shells she is being feed. Use differant shells and then keep pattern testing before changing anything.

You have a lot of work to do and you're burning daylight.

The easiest way is to adjust the comb height - use moleskin, tape, cardboard, whatever you like. The formula is 1/16" of comb adjustment equals POI movement of 1" at 16 yards, 2" at 32 yards, etc. You can take more draconian and permanent actions to alter the gun once you have taken these temporary steps and try it out.

First, please answer the questions I asked.

Jim, I did, As soon as you first posted I put answer to your questions in my original post.

I've bent barrels. Pretty simple, but probably not for the faint of heart. Any hydraulic arbor press makes a fine barrel bender. A pile of soft 2x4's and 4x4's and some 1/4" rubber sheet for the thin barrels, will keep you from putting a flat in your barrels. Randy's problem could be fixed in a few minutes this way. ...or countless hrs of messing with the stock.

Bending the stock up would raise it as well. It probably would take an 1/8th inch to make a noticeable change in POI.

What are the drops at heel and comb nose? Are you seeing much rib, or does the bead seem to rest right on the receiver with no rib visible?

I missed seeing the answer, sorry. It says the problem is in the gun. As both barrels are shooting low, bending the barrels up would be the easiest remedy. Removing metal from inside the muzzles will move the patterns in that direction BUT will make the patterns a bit larger. If you're happy with the chokes as they are, bending the barrels seems the way to go. Old man Purbaugh is said to have used a drawer in his shop, to bend barrels. He would put the barrel(s) in the drawer and lean on it until it bent. I like the idea of a press, better. Best wishes with it.

It is still not clear that this pattern occurs for both barrels. Did you pattern both? It would seem that before anything else is done, you need to establish that both barrels are printing off in the same direction as that is a major factor in what path to take for a remedy. It also appears to me that your pattern is as much off to the right as it is low.

Chuck,Jim. I'll have to give serious thought on the bend. That resolve really works with my head. I get bothered with a ding in the barrel let alone knowing I bent the barrels. Brother bends stocks all the time and will probably mess with that first. Joe, DAH 2 5/8", DAC 1 1/2", bead rides above the breech slot, no rib shows. Mike, Shot both barrels. Also shots made off hand so slight lateral movement is most likely operator error. Also, the LC is lightweight gun at 6 1/2# and I wouldn't mind the chokes being opened, its now M/F. Randy

Just shoot OVER'em, Randy! How hard could it be?...Geo

Personally, I would lean towards the stock bending first. On my SxS guns, with the bead sitting on the breech with no rib showing I would shoot low. Every one of them. I like them set up so I would really have to mash my cheek down to get that sort of alignment. Maybe this is to compensate for barrel flip. On my O/U guns the pattern prints more in line with the rib line.

+ 1 what Mike said. With that amount of drop and rib picture, all of my guns would shoot low. Bending barrels makes me real nervous.
Joe

Mike, I think the stock bend is my next step, thanks.......

George, Good line. I never thought of shoot"n over em. I can't believe it took this long for someone to come up with that idea. That's the easiest fix of them all. I'm going to give that idea some thought, not much thought, but some just the same. My wife said to sell it, that would take care of the problem too. George, hope all is well. Randy

OR - you could just read the gunfitting articles at shotgunreport.com so you know how much to bend the stock. Bruce Buck is a shooter and coach of mucho experience and he certainly tells the straight truth.
Read it and be happy

WtS

Where does it hit if you mount and shoot fast? 1-1/2" DAC ought to have your eye high enough. Is it only low when you aim deliberately down the rib?

By pattering I don't see big problem here and considerable POI shift. Moreover you are going for turkey with this gun? Aim at turkey head and everything will be just fine

Wait a minute, you said this was not off the bench, but hand held. Before you start bending anything, go back and try this off the bench so you are not as likely to induce the flinch factor or some other variable. Then working off the bench, add moleskin to raise the comb, be careful about making the stock wider as you add height as that can change point of impact side to side. From the photos, it is hard to know just how far off in inches the pattern is, but 1/16" change at the face moves the pattern approx 1" at 16 yds. Once the bench point of impact is where you want it at 16 yds, (I like about 60% of my pattern above the point of aim so I can hold low and see the whole bird in flight) get off the bench and mount and shoot to find out if the dynamic shots are significantly different from the static bench shots. Adjust as necessary. One other point, you said all your guns are setup the same, but seldom are all guns matched with stock thickness at the comb/cheek contact point. It may be your problem is resolvable in a slight change in cast. So just be aware of that while making adjustments.

George, have you and Geno been exchanging notes? Seems like Geno has the same solution that you guys use in the South. I'll bet he lives in southern Russia. Geno, no offense, just a little Yankee/Rebel humor. Obviously, very little humor.

Jim, Next test period, I'll shoot instinctively and see what that shows.

This pattern testing was a loosely structured event. 8 shots taken, hand held, same ammo, two distances. All shots clearly showed a tendency to pattern low. There was a lateral movement of the pattern from shot to shot. Primarily to the right. Flinch?? I close my eyes before I pull the trigger.

Because I didn't have a pattern plate till recently, the guns I have and shoot the best are set up to align my eye down the rib with just the bead sitting on top the rib line. The four guns I tested with this LC are set up this way and patterned evenly around the POA. Are all the guns set up identically, not exactly. They all have in common when the gun is mounted, my right eye aligns with the bead sitting on the rib. I know this is a crude experiment and my methods similar to those used in the South, but my inquiry was to seek options that others have found to resolve the issue of low impact. Other than bend the barrel, I'll shoot off a rest, use the increase of comb with patches and stock bending both to height and cast. Thanks for all your help. I'll report the results once I get my taxes done. Randy

Randy,

Of all the advice you've received thus far, I like your wife's best. Seriously.
Perhaps you should invite her to join the board.

Barrel flip on a flat shooting gun isn't something I had considered before. Starting with an artificial comb raiser makes total sense to me. Good luck Randy, and let us know the results.