Scope question

[Remington742]

Okay so I am shooting a 870 with a cantilever type scope mount with a Nikon prostaff slug hunter bdc scope on it. I have shot several brands of slugs through it and the slugs that group the best are shooting low at 25 yards and high at 50 does anyone know why this would happen. If it helps I did buy it and haven't sighted in at a specific range but am pretty sure it was zeroed at 100 yards. I just don't understand why it is low at 25 and high at 50. Thank you in advance.

 

[Hardwoodmaterials]

Your scope sets above your barrel so you will shoot low until your line of sight and bullet cross paths.

 

[fairchaser]

Your scope sets above your barrel so you will shoot low until your line of sight and bullet cross paths.

A pictures worth a thousand words.

 

[Remington742]

The light field at 50 yards didn't even touch the target it was a foot low and 6 inches right

 

[JimFromTN]

This may seem like a stupid question but are you holding it right. You don't hold a shotgun the same as you do a rifle. You actually have to grasp it firmly by the fore-end and pull down to keep the muzzle from rising while the slug is still in the barrel. I would have expected the 2.5 inch lightfield hybrids to be the best shooters.

Something else you may consider is to buy an aftermarket sear spring. They are about $5 and take 15 minutes to install. You can reduce the trigger pull from 7 to 8 lbs to 4 to 4.5 lbs.

 

[Remington742]

Yes I held down on the fore end shooting from a bench rest. The two that were a foot low with the light field were 1 inch apart.

 

[DaveB]

From ever thread i have read slug guns are very particular about what they will shoot with any degree of accuracy. Matter of fact, you will see some folks expounding on a particular sabot, like a Jones Purple or a Smith's red coupled with a Hornady XXX and 2 or 3 Pyrodex pellets.

Is your 870 barrel rifled?

 

[Remington742]

Yeah it's a rifled barrel

 

[Aquaholic]

Paying attention also to this

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[JimFromTN]

The vertical stringing on some of them would indicate an improper hold or a barrel heating up. The lightfields are a slower heavier load so they would hit low in comparison to a higher velocity, lighter slug. Make sure the barrel nut is finger tight. You don't need to use a wrench or anything. Make sure you rings are tight. The recoil from a shotgun can shake screws loose. Don't use a lead sled. It could break your scope.

If you want to shoot some cheaper stuff, try these. They aren't sabots but they are accurate. You can probably find them cheaper somewhere else. I was hitting clay pigeons at 100 yds with these out of my 870 with a hastings rifled barrel bracing against a post, no bench or rest.
https://www.midwayusa.com/product/18361 ... ifled-slug

 

[DaveB]

Your 870 is a very popular choice among slug gunners so there should be a ton of info you can get hold of. I'll check another site I hang out at and see if anyone there has any hands on experience.

I do not know slug gun ballistics. Here is a sample:

REMINGTON ACCU-TIP SLUG
Gauge 12
Length 2 3/4 inches
Slug Weight 385 grains
Velocity 1,850 fps (muzzle); 1,611 fps (50 yards); 1,401 (100 yards)
Energy 2,925 ft-lbs (muzzle); 2,218 ft-lbs (50 yards); 1,677 ft-lbs (100 yards)
Trajectory +2.7 inches (50 yards); +3.6 inches (100 yards); 0.0 inch (150 yards)

Gauge 12
Length 3 inches
Slug Weight 385 grains
Velocity 1,900 fps (muzzle); 1,656 fps (50 yards); 1,439 (100 yards)
Energy 3,086 ft-lbs (muzzle); 2,344 ft-lbs (50 yards); 1,771 ft-lbs (100 yards)
Trajectory +2.5 inches (50 yards); +3.4 inches (100 yards); 0.0 inch (150 yards)

 

[Remington742]

On the Remington Accu tip the farthest up is the first shot at 50 yards the second one down is the second but aimed a little lower at the base of the red dot rather than the center.

 

[Jcalder]

I'm not a shotgunner but I would be looking for what groups first. Once you find what your gun likes you can try the various yardages to figure out your dope.

And to add to an earlier comment. Just because one is lighter than the last it does not mean it will shoot higher. Same a heavier load may not shoot lower at that distance. Barrel harmonics plays a part in that


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[Remington742]

Just checked the scope it's good and tight. The Remington Accu tips seem to group good. Thanks for everyone who answered. It makes more sense now.

 

[bartd]

Perplexing to say the least. Sometimes guy's use a rest that is on the barrel and that causes a change when not rested in forend. It sounds like you have worked from the mount up and everything is tight. I have the same scope on a T/C slug gun and it definitely shoot's Winchester sabot's better then any other brand so that might be it. I ran these chart's for you to see if perhaps the data can help in any way?

 

[Remington742]

That helps alot thank you. I couldn't get to that point for some reason on Nikon's site. Thank you again.

 

[Remington742]

Thank you to everyone who gave advice. The two grouped together we're the before I moved it up 6 clicks to get it a little high at 50. The single was the last shot. I need to move it a little right but up and down seems good. Thank you again