I have a Rem. 700 with a custom bbl that I cannot boresight. If I adjust my scope so that the reticle intersects the target that is centered in the bore, the bullet will strike approx. 18" low and 8" left at 100yds. I had a hell of a time getting it on paper. Once I got it dialed in, I could no longer view the target stand in the bore. This bbl groups "ok" at 100 yds., but the discrepency between where the scope and the bore point worries me. Has anyone seen this type of situation? I have some theories about what's going on, but would like to hear from more experienced and knowledgeable folks. If the bbl is bent, how will this affect my point of aim/impact at longer ranges. I am pretty confident in the bedding job and the bbl is floated. The bbl is 26" long and a #4 contour .25-06. I've got some other issues to overcome with this bbl, but I've never seen this before. Thanks for any insights.

I would look to improperly aligned rings/bases before I started worrying about a bent barrel.

I respect Rick's opinions on optics, but I think he's off-base this time. The alignment of the rings and bases should have nothing to do with where the bullet strikes relative to where the barrel is pointing.

When a bullet strikes substantially out of alignment with the bore, it is typically because the bore is bent. This is not actually a problem, unless the bending is related to metal stress, in which case the bend may change as the barrel heats up. Unless you see your point of impact changing after several shots, then there's not much to worry about here.

Another possibility is that the crown of the muzzle is "dinged", causing the bullet to fly slightly out of alignment with the bore. What matters is whether the gun shoots consistently and shoots where your scope is pointing.

Hummm bent barrel lopsided crown. Lots of things can cause that. But, after the bullet leaves the barrel it travels perfectly strait, well outside of falling. The line of site through the scope is strait as well. In short if it groups ok and you can site it in forget about it. Ive seen lots of guns with bent barrels that shoot wonderfully. I you have it straightend you will only add stress to the barrel and then you really will have a problem. lots of time the barrel isent realy bent. The drill just decided to take a walk when the barrel was made. So it only looks like it has been bent, in reality it was just made that way and thats just fine as long like i said you can site it in and get good groups out of it. Rod Henrickson

quote:

Originally posted by Stonecreek:
I respect Rick's opinions on optics, but I think he's off-base this time. The alignment of the rings and bases should have nothing to do with where the bullet strikes relative to where the barrel is pointing.

When a bullet strikes substantially out of alignment with the bore, it is typically because the bore is bent. This is not actually a problem, unless the bending is related to metal stress, in which case the bend may change as the barrel heats up. Unless you see your point of impact changing after several shots, then there's not much to worry about here.

Another possibility is that the crown of the muzzle is "dinged", causing the bullet to fly slightly out of alignment with the bore. What matters is whether the gun shoots consistently and shoots where your scope is pointing.

Stonecreek,

You may well be right brother, because I ain’t firing on all 8 cylinders today.

The bore might not be bored straight & there fore it has a bend in it. Unfortunitly this is not uncommon in factory barrels

Thanks for the responses. I am confident in the integrity of the crown and the scope/rings/bases question has already been explored and dealt with. I also believe that the bore is warped. I guess it's hard for me to grasp the idea that the bullet can consistently hit a point so far from where the bore appears to be aiming. Does the bbl flex that much as the bullet slides down the tube? If not, wouldn't the line of flight be at an angle to the boreline? And if the line of flight is at an angle to the line of sight, it seems that the bullseye hit at 100 yds is just where the line of flight intersects the line of sight and that as range is increased, the flightline would angle away from the sightline. Hope I'm not just rambling.

Assuming that your rings/bases are concentric to the center of the receiver you can check to see if, and how much, your barrel may be “bent†by using a long 1 inch or 30mm round bar (depending on your ring size.)

The bar must be long enough to reach from the rings to the muzzle, and it helps if you place a perfectly centered mark on the end to use as a reference. You can also hand a plumb line from the end of the bar.

Remove your scope and place the round bar in the rings with one end extending out the the end of the barrel. You should be able to immediately see if the bore and the end of the round bar are in vertical alignment.

Another way to check for bends, etc, is to place a laser cartridge in the chamber. If the bore is not straight with the chamber you will not get a clean, round dot projecting out of the barrel. You will get either no dot at all, or you will get a partial dot with halos of red light around it signifying that the laser beam is bouncing off the barrel wall somewhere down the bore where it deviates from straight.

Although it is too difficult to explain, it is quite easy to look down a rifle barrel and tell if it is bent.
The trick is to ignore the rifling and look down the "flat" of the bore.
An experienced gunsmith should be able to do this.
SDH

quote:

Originally posted by Rick 0311:

Stonecreek,

You may well be right brother, because I ain’t firing on all 8 cylinders today.

You're still better off than I am -- I think I flat lost a few cylinders a while back, so I just putter along as best I can.

quote:

Originally posted by Stonecreek:

quote:

Originally posted by Rick 0311:

Stonecreek,

You may well be right brother, because I ain’t firing on all 8 cylinders today.

You're still better off than I am -- I think I flat lost a few cylinders a while back, so I just putter along as best I can.

PM sent to explain.

Homesick, if I am boresighting at the range, I do it at around 30 to 35 yards and not at 100. The bullet will cross the line of sight of the scope in two places one at 35 and one at 100 if you are sighting in at 100. I usually just bore sight at a rock or bright object and dial in the scope to the same image. It is just to get you on paper at 100. Error visually can be great trying to bore sight at 100, but 18" seems extreme.

Can it be cocked receiver ring threading? I'm trying to lay that out in my head but its late, and I can't get there from here.

There is an easy way to sight in ANY gun in less than 5 shots at 100 yards. First make sure your scope adjustments are centered. Set up a target at 25 yards and fire one shot at the bottom edge of the bullseye. Find your hole in the paper and then point your gun at the same spot on the bull and make the gun immovable such as in a cradle or wedgend on some sandbags. While looking through the scope move the adjustments so that your scope is aligned about a half inch above the hole in the target. The next shot will be at 100 yards and should be on the paper. Move your scope the same way as at 25 and then shoot for group. I do this about 75 times a year so either had to get good at it or spend a lot of my and other peoples money wasting ammo sighting in rifles. I sell guns and scopes so I have to do this a lot. I have boresighted many rifles also and it just doesn't work as good as the process I just described. I have tried sighting down the barrel on bolt guns at our 400 yard bunker and all that will do is get you on the paper at 25 yards. Your original question was if you should be able to see the same spot through your barrel as your scope? It all depends on the load you are using and the bullet as to where it will impact the target. I have seen different brands of bullets impact a foot or more apart at 100 yards even with the same weight.

quote:

I have a Rem. 700 with a custom bbl that I cannot boresight. If I adjust my scope so that the reticle intersects the target that is centered in the bore,

After you have it zeroed, what does it look like if you install an optical collimator-type boresighting device in the bore? Do the collimator grid and the scope reticle coincide?

An interesting thread but...

HOLD ON! WAIT A MINUTE!

This is a new member - how much experience/how good is he at VISUAL boresighting?

Has he repeated the process on a subsequent day with the same results?

What are the "other issues" with the barrel? Whose barrel is it? Who did the gunsmithing? Who mounted the scope? Are the rings aligned?

IMO these questions have to be answered before anyone can offer intelligent answers to the problem.

quote:

Originally posted by sonofagun:
An interesting thread but...

HOLD ON! WAIT A MINUTE!

This is a new member - how much experience/how good is he at VISUAL boresighting?

Has he repeated the process on a subsequent day with the same results?

What are the "other issues" with the barrel? Whose barrel is it? Who did the gunsmithing? Who mounted the scope? Are the rings aligned?

IMO these questions have to be answered before anyone can offer intelligent answers to the problem.

Exactly the purpose of my question about a collimator.......

I know. Just thought I'd try to cover ALL the bases here.

S'funny how somebody posts a question like:

"My XYZ gun groups poorly. Why come?"

and everybody jumps in with answers. Whoa! A little more info is needed...

sonofagun and El Deguello- I'll try to clarify. The collimator indicated that the scope was aligned with the bore. It showed that I should hit about 5" high and that was right where my first group, this past weekend, was. I will not give the name of the barrelmaker/gunsmith as I do not think he is my problem and I will not cast doubt on his fine reputation. He has been very generous with his time and knowledge and patient with me. He made sure that the rings and base were properly aligned and checked his work with a collimator. He also made sure the action was bedded properly. As for repeating the process on subsequent days, yesyesyesyesyes and yes. I have doublechecked myself so many times that I can close my eyes and visualize exactly the views thru the scope and the bore. I have boresighted many rifles over the years and I understand that it is merely a device for getting on paper quickly. Up until now, though, my bores and scopes have pointed at roughly the same zip code. Please understand that I'm not asking how to fix it. The last 5 shot group I shot on Saturday, after making small windage and elevation adjustments, measured .84" and the last shot nearly doubled the size of the group. Three shots went into one slightly enlarged hole. I just want to understand how accuracy and consistency can be attained when the groups are nowhere near where the bore appears to point. As for other "issues", my main issue is copper fouling. When I last had this rifle in to the smith, I complained of copper fouling. He proceeded to inspect and clean the bore. He said there was 70 to 80 rounds worth of copper fouling. Now I only have about 200 rounds thru this tube and I have never shot more than 25 rounds between aggressive cleanings. I went thru an exhaustive breakin period and have dozens more hours cleaning than shooting. After shooting less than 20 rounds on Sat., I went home and spent the next 6 hrs. cleaning. There is 2 problems with this routine. Without borescoping, I don't know if I got all the copper out. And although I'm fairly anal about cleaning, I don't like it very much. I'm starting to think that I should try Blackstar and moly. Thanks for taking time to think about this.

Excus me, Homesick, but would there happen to be a bulge in the barrel about 1 inch back of crown? I just happened to have a rifle in with just this problem today. The barrel pointed straight, but bullets hit about a foot right at 50 meters.

I say if it shoots that well, don't get an ulcer over it, be happy. As far as cleaning, get some Wipeout, fill the bore with foam, leave it over night with the muzzle slightly low. Push a patch ot three thru tomorrow and put it away clean.
Lyle