nikon prostaff scopes

[jd3020]

hey guys I have a nikon prostaff 3-9x40 bdc mounted on my ruger m77 markII 243 rifle. I have used this thing for probably 2 to 3 years now and i have never had a bit of trouble on it. Recently i went to the range with it to make sure it was on for my girlfriend to shoot. everything looked good it needed a little adjustment but not a big deal. After getting it home and thinking it would be fine for her to shoot just for a couple of days i deceided to take her to the range and let her shoot it and put it on paper for her. after she shot 6 times or so i noticed she was left about 3 inches and high about 2. Now we are using a caldwell leadsled with a bag of shot for weight. after a few more shots she was still to the left and high so i adjusted for it. then she went right 2 inches and down 2 inches. Has any one else had this issue with a prostaff or is it just her. I watched her shoot and she isnt doing anything different. she does the same thing every time. She had a set that was right in the bulls eye and then the next three with no adjustment were 2 inches low but dead center. I have it close enought for now for deer season being a week away but i was just wondering if there was a problem with this scope or if it was just her.

[Palmetto-Pride]

Two things could be happening first when you sighted it in last was the barrel temp pretty hot when you made your last adjustment? I know with most rifles a hot and cold barrel will have slighty different points of impact also She may look thru the scope a little different than you. Different people using the same scope will see the crosshairs a little different. Did you try shooting it before you made any adjustments to see if it was on for you?

[Skadoosh]

What scope rings are you using?

[Marquezj16]

Different people using the same scope will see the crosshairs a little different.

^^^^^^^^^
This is probably the reason.

[jd3020]

When i sight in i normally load three in the clip and shoot my three then make adjustments, so yes i would say the barrel was heated up at MY last shot. When she started shooting she would shoot one and then put another in so it didnt heat up like it did on me. How ever after her first six shots I shot three and it was right on before any adjustments were made. After probably 15 shots or so i let it cool down and moved on to my 270 and then brought it back out when i got done with it. That is when it was shooting 2 inches low at 100 yards and i thought it would be fine so i left it. The scope rings i am using are the ruger rings that came with it and i believe they are a high ring.

[Skadoosh]

Was the scope properly installed so that there is no scope creep? Rings lapped or anti-slippage rosin used during scope installation?

[jd3020]

i installed the scope so i cant say any of that is true. the rings can only go on one way because they have that special lip on them. I have never had any problem with this gun. last winter i dropped a coyote at 250 yards with no problem. i just dont understand why when i go to sight it in for a new person to shoot it now wants to be all scattered and i cant get it back to zero

[Skadoosh]

Re-install the scope but this time put witness makes to see if there is any slippage.

[jd3020]

and also on the note of adjustments when the first six were 2 inches high and 2 inches left 8 clicks each way should of put the cross hairs at dead center correct. being one click is 1/4 inch at 100yards is what it says on the scope

what may i ask is whitness makes?

[black mamba]

Witness marks are marks on the scope tube immediately before and after the scope rings, so you can "witness" whether or not the scope moves in the rings from recoil. If it does move, one witness mark will be covered up, and there will be a gap between the other mark and the scope ring.

[warbirdlover]

Sounds like loose scope rings.

[tahunua001]

I bought a prostaff 3-9x40 when I was 16 for my fisrt deer hunt. 6 years later it is still zeroed. I bought a 3-9x40 BDC for my AR15 2 years ago...it is still shooting MOA groups at 200 yards.

if I didn't know better I would say she's flinching

[jd3020]

I thought the same thing with her flinching but like i said it was pretty much perfect conditions and the gun was on the lead sled with weight on it. we tried it with a hand on the forarm and off the forarm and pretty much same results. I watched her from behind and never saw her pull or anything. After season i will remove the scope and re check and put some witness marks on it to see.

[tahunua001]

did you try different ammo? I know when I first started I didn't know much about ammo or guns in general so I would always get the cheapest ammo that walmart had(80 gr remington corelocks). I had a horrible time trying to zero it between me making one adjustment, my older brother making another and my best friend making another. eventually I went to get more ammo and walmart had a special on 100gr federal powershoks so I picked up a couple boxes. it took 5 rounds to zero and the rest of a box to make sure my older brother and my hunting buddies could all hit the same thing...all of us were hitting reasonably close to the same spot with all of our groups being within 1-2 MOA. ever since then that's the only bullet i get for it... you might have issues with bullet weight to barrel twist ratio or just poor ammo. you may also have a fouled barrel if you shoot a lot of soft lead but I rarely see soft lead 243 ammo so doubtful that is the case.

[TX Hunter]

I think your scope is not holding its setting.

[jd3020]

I normally run remington 100grain core lockt. being its a nikon scope i have the "nikon spot on" app on my computer and iphone and i found that winchester and remington made the same ammo. so the last box i bought was winchester 100 grain power point. same 2960 fps and bc is 0.356 same ammo just different maker as far as i can see. i have always shot remington 100gr psp core lockt. never anything else.

[HKGuns]

As the others have said that sounds like a classic case of your mount not being secure. That would be the first thing I checked at least.

[jd3020]

i have wiggled and pulled and checked all the screws and bolts and i cant find any thing lose but as for now i am going to leave it being low as to where i know where its at. im in an 4 inch circle at 100 yards so she will kill what ever is there providing she is aiming in the right spot. but as soon as deer season is over i will check it all over. as goes for missrouri weather its calling for rain the next 2 days so there will be no time to go sight in if i try and fix it now.

[Cowboy_mo]

You said you have always use Reminton ammo but now were using Winchester. Now, while they both show the same muzzle velocity, bullet weight, and ballistic coefficient, they don't use the same bullet.

It could definitely be the difference.

[jd3020]

yes i have always used remingtons and when we were at the range over the weekend i was still using remingtons i picked up the box of winchesters because when i looked at my spot on it showed the same information even through the bdc yardage and the same information even on the ballistics table. same point of impact etc so i dont see where there would be much difference. but as far as the scope goes it has always been with remingtons.

[bman940]

JD, The guys have given some excellent rason's for the issues you are having.
Soemtimes if the scope is canted a tad that will affect shot group. If the rings are not tightened the same on both sides that can also cause a slight force pull to the over tightened side. I think you are wise to consider remounting the scope after the season. Maybe some friction tape or lapping will help. It has been my experience that the problems are usually in the mounting but sometimes there can be a scope issue as well.

[jd3020]

I agree with what they have said on the scope moving. Last night while cleaning my 270 i pulled the 243 back out of the safe and took a good look at the scope. i grabbed ahold of it and tried to move it and at one point i thought it may have just a little bit. when i set the scope on the rings im 95% sure that i put the front ring all the way as far forward as it would go and after looking at it last night it looks as tho it may have slid forward about a 1/4 of an inch. This may be my problem. If this is the problem and all my bolts are tight what can i do to keep it from moving?

[bman940]

Friction tape or lapping would be my suggestion. Quality rings are definitely worth the money as well. Just be careful when tightening the rings if you use a friction tape.

[jd3020]

i understand the quality rings. the bad part about the ruger is that weaver stlyle rings will not work on it becuase of the way the top of the barrell is made. So there for you have to buy the rings from ruger or someone that sells the ruger rings, which is what i did and they were 30 bucks a piece. Friction tape and laping compound is that something i need to get from a gun shop or can i get it else where?

[jd3020]

ruger high.jpg here is a picture of the ring that i use. this is a generic picture off of the web but as you can see the round notches at the bottom of the ring and that has to sit inside the top of the barrell