Had my 458 winmag converted to a Lott and upon test firing found that the impact point is now 30" lower and 10" left of where it was originally hitting. What's up with that. I've had the front site lowered and the adjustment on the back site is in the lowest setting, so I think I can get it printing close to center but was wondering what happened? Any ideas?

The barrel harmonics have changed and the bedding was disturbed (unless you had it rebedded after rechambering).

George

The front lug was squared and the barreled action was rebedded. The trigger was worked over and the safety also worked over. I just can't figure it out. The barrel was checked where the lug is welded to the barrel and found to be OK and the barrel was checked for straightness. I have no clue.

Improper installation of barrel to action (may be crooked), bedding perhaps but thats almost too much for a bedding problem, sight installation wrong or off center, crown has a burr, are a couple of things that come to mind.
That is a lot of error and it would concern me for sure..I would start with having a competent gunsmith check it out..

What make of barrel? Does it group at 100 yards?, does the barrel look to be straight in the action, does it fit pretty good in the original stock? You need to investigate this and see exactly why it is that far off...It may be fine but I would be very suspecious.

Lowering both sights won't get you anywhere as it will probably reamain the same except shoot lower...

With Iron Sights:

1, To elevate impact, elevate rear sight or lower front sight.

2. To lower bullet impact, lower rear sight or elevate front sight.

3. To move bullet impact to the left, move rear sight to the left or front sight to the right.

first thing I would do is mount a scope and bore sight it, then sight it in on the range and see what happens...If the bore sight and the group you fire are pretty close you probably don't have a problem..

Ray- When I mentioned that my sites were lowered, I meant the front sight. The rear site is in the lowest position, thus allowing me to bring the impact up but what I'm wondering is why such an impact change. I've got targets to prove that the gun was hitting dead on at 50 yards and really close at 100.

Peg Leg ,,, ;
You need to raise the rear sight to raise the poi.. Have you tried turning up the 200 yard leaf on your express sight ...With it printing to one side I would suspect the sunlight as much as anything ..Does the fore sight have a hood, if you have a full overcast sky try shooting it ...
Yesterday I was shooting one of my rifles was printing about 6 " right I made a quicky front sight hood from duct tape and the group centered right back up ...

gumboot- I know what to do with the sights as I've been shooting high power for about 20 years but I have never experienced anything like this before. It's like I have never shot this gun. Dennis Olson was the smith so you can take his work to the bank. He and I are both drawing a blank. He has worked the gun over a couple of times trying to figure this out. Hoping that some of the more experienced hunters and shooters here have any ideas.

What load is it hitting low with ?? Or put another way , Have you tried a different load in it ..?????

I think the bore is shot out. It does not take much to shoot out the bore on a big bore IMHO.

Was it a re barrel, or a re chamber?

The gun wears it's factory barrel and is in good shape according to Dennis. It was rechambered to the Lott. Man, can't wait to start load development with a Lott again. Here come the recoil headaches.

have you invested (with todays prices a box of Lott is an investment, not a purchase) in a box of factory 458 Lott?

Rich
DRSS
Knowledge not shared is knowledge lost...

Pegleg,I hope you have fun with the Lott.What bullets do you plan to shoot? I ordered TAC Ramshot powder the other day and plan on continuing my load testing and practice once I get the Lott rebarreled.

Sharpshooter- No I haven't tried a box of factory ammo. Good idea. Maybe I'll sell the wifes car and buy a box.
Shootaway-I will be shooting Northfork 450 gr. softnose and cup-point solids. I've been using imr4320 and it has worked good in the past. I've also tried 4198 but got pressure before I got the velocity. I've got some Thunderbird 8208 I might try and it has a burn rate close to the old "T" powder. Might be too fast. We'll see. I am also going to take Jeff's advise and try H335.

I,m trying AAC 2230 in my Lott ... I had such good results with it inmy Win mags I figured it is worth a try ..

Pegleg, that is serious poi differences. I don't care what powder you use that alone would not present this kind of a problem. Ray's comments above are worthy of checking out.
On the powder issue, when I did a 458 wm to 458 lott conversion none of the powders I used in the 458wm worked well, I went with a faster powder in the 458 lott and got much better accuracy. In both lott's that I own R-15 works the best.

Yep, I'm betting the rebedding &/or bbl lug or reinstallation is the problem. I had a M70 rechambered to 458lott & it still shot POA. There is no excuse for a 30" diff. in POI/POA.

IMO,there are two factors.One is barrel wear(drop) and the other is bedding(shooting to the left or right).

Well the rifle is on it's way back to me and I will find out myself what the hell is going on. I have complete faith in Mr. Olson and his work and will try H-335 and also give RL-15 a try. I like RL-15 in my 375. Maybe it will like my Lott.

quote:

Originally posted by shootaway:
IMO,there are two factors.One is barrel wear(drop) and the other is bedding(shooting to the left or right).

When I recently had a rifle reglass bedded, the POI had moved about a foot verticaly. Let us know what happens, but I doubt any powder change is going to make up more than 2"-3".

quote:

Originally posted by fredj338:

quote:

Originally posted by shootaway:
IMO,there are two factors.One is barrel wear(drop) and the other is bedding(shooting to the left or right).

When I recently had a rifle reglass bedded, the POI had moved about a foot verticaly. Let us know what happens, but I doubt any powder change is going to make up more than 2"-3".

Are you sure it was from the bedding? What makes you think so?

Got my rifle back and will shoot it tonight. Hope to have good news. It feeds slicker than snot with the Northfork cup-point solids. Couldn't be happier!

When working up your loads, don't forget
IMR-4320. It works very well in the Lott.

Bull1

Pegleg,
IMR-4320 is the ONLY powder for the Lott and you can get an easy 2300 FPS with it and at decent pressures..

I am sure that Dennis can fix it..He can just about fix anything..

A must read for Lott shooters is Rifle magazine, no. 135, May-June 1991......

Took the Lott to the range to see how things were going to go. Got it printing to center of target and all is looking well. I loaded up 6 cartridges to test and will fire these 6 pieces of brass until they are wore out.
I think I have found the problem with the rifle in that the crown is really sluffed off on the bottom of the barrel. I will have that repaired and try again. This could be an easy fix.