Help me out with this ammo/accuracy issue.

[Desert Dan]

Ok guys so here's the deal. In spring I picked up a CA Ridgeline in 6.5 PRC. I got the barrel broken in according to the instructions from Christensen and started dialing it in. Being a 6.5 PRC the only factory ammo on the market so far is the Hornady 143 grain ELDX and 147 grain ELDM and since it's a hunting rifle I broke it in and zeroed with the ELDX. Initially as the rifle broke in I started getting groups at around .4 MOA at 100 yards. Then I moved out to 200 and it all changed. What I'm getting now barely qualifies as a group at all. It's like a shotgun spread. However the ELDM is around 3/4 MOA consistently (the holes in the pic below outside the orange were my fault). I started shooting three shot groups at the rate of around one shot every four to five minutes for 15 minutes, alternating between ELDX and ELDM for every three shot group so it doesn't seem to be an issue of the barrel heating up or any other different condition. Could my rifle - a sub-MOA gun - just not like the ELDX that much or is something else going on here? The pics below are from this morning at 200 yards. The first in two three shot groups from the ELDX and the second is the same from the ELDM. Any ideas? I'm bummed because I was counting on the ELDX for my go to hunting round until I start reloading. Thanks in advance!

 

[gbflyer]

Could be an atmospheric condition or your rest setup. Try shooting the groups closer together time - wise. A quality barrel and good stock job won’t move around too much with heat. I’ve never been successful with shoot/wait/shoot groups.

 

[30338]

What scope and rings?

 

[Desert Dan]

What scope and rings?

Swarovski Z5 3.5-18 with Talley medium rings.

 

[Gunnersdad49]

The ELDX is shooting .4” at 100 yards, and 4” at 200?

 

[Fatcamp]

Do you have success shooting MOA with other rifles?

 

[BIGEYES]

The time lapse between shots does not provide practical information on a hunting rifle. Fatcamp poses a good question. Your groups are affected by many factors ie., rifle rest, shooting technique, consistency of hold, range conditions ad infinitum. Using a lLight weight hunting rifle to shoot small groups is difficult, if all factors are not consistent shot to shot. A change in wind during a 15 min. shot string could provide targets such as yours. We call 'em weather reports.

 

[Shooter71]

I look at mechanical stuff and technique before ammo. If you were reloading you might be tempted to blame the load, when it’s actually the barrel hitting the stock or bad bedding. I only say that because I just bedded a Ridgeline..

Or parallax error.......

 

[Desert Dan]

The ELDX is shooting .4” 100 yards, and 4” at 200?

Here's a pic, four shot group. Haven't shot at 100 in awhile but yes.

Shooter and Big Eyes,
I guess I'll just keep shooting it and see what happens. Could be me. Maybe something like you mentioned. Just weird that the same pattern has played out the last three times I've shot withthe ELDM being right on and the ELDX scattered all over. Oh well hopefully it is just me and I can knock it off and that will fix it.

 

[Gunnersdad49]

The other thing to try is maybe lower the magnification on your scope. A lot of guys crank it all the way up, then try to “cheat” groups by aiming at the last hole.

 

[mt100gr.]

Here's a pic, four shot group. Haven't shot at 100 in awhile but yes.

Shooter and Big Eyes,
I guess I'll just keep shooting it and see what happens. Could be me. Maybe something like you mentioned. Just weird that the same pattern has played out the last three times I've shot withthe ELDM being right on and the ELDX scattered all over. Oh well hopefully it is just me and I can knock it off and that will fix it.

If that's the group I was seeing with the ELDM I'd zero it and call it macaroni. That match bullet kills well.

 

[xcrunner805]

You could try chronographing the factory ELDX. I read some reviews on other forums of people finding the factory eldx to have really inconsistent muzzle velocities.

 

[BRTreedogs]

I think your irritating yourself with the 2 different types ammo.
Re torque all action and scope screws.
Pick the better shooting ammo.
Check zero, shoot further and make sure the rifle holds it. After you verify it can me done try switching ammo again if your worried about bullet design.

 

[Desert Dan]

I think your irritating yourself with the 2 different types ammo.
Re torque all action and scope screws.
Pick the better shooting ammo.
Check zero, shoot further and make sure the rifle holds it. After you verify it can me done try switching ammo again if your worried about bullet design.

Probably what I'll do. ELDM is fine for a Coues deer or mule deer anyway. On the other hand ELDX is generally quality ammo so I feel like this is a puzzle that needs to get solved.

 

[Fatcamp]

Probably what I'll do. ELDM is fine for a Coues deer or mule deer anyway. On the other hand ELDX is generally quality ammo so I feel like this is a puzzle that needs to get solved.

Nope. Some ammo just doesn't perform out of some rifles. Move on.

Or start reloading and obsessing over 0.10. Either is a good path.

 

[Desert Dan]

Nope. Some ammo just doesn't perform out of some rifles. Move on.

Or start reloading and obsessing over 0.10. Either is a good path.

Haha yea I'm about to start doing that. My Amazon and Midway shopping carts are full of goodies at the moment. My wife is already rolling her eyes.

 

[BRTreedogs]

My rifle like 210s way better them 215s both quality bullets just how it goes some times.

 

[5 shot group]

If you're shooting factory stuff, just use what the gun likes the best.

If you're reloading...welcome to the rabbit hole

 

[Desert Dan]

Okay so update to wrap this thread up...
I went back to shoot some more today and I wanted to post an update not so much because I think anyone really cares how well (or crappy) some guy on the internet is shooting, but more because I figured maybe someone out there in the interwebs will benefit from it and I think I learned something today. Anyway...
I shot another few rounds with the ELDX today and something interesting happened. The first two three-shot groups were very acceptable, nearly as good as the ELDM has been firing. Then after I had the gun outside for about an hour in 100 degree temps the last two three-shot groups started opening up and drifting high just like they have been doing lately. ( the pic I posted yesterday had the shots scattered low which was the first time I've had that happen so I could very well be to blame.) I packed up and went home and started doing some research and found an interesting article. I'll post the link below in case anyone has an interest in reading some scientific studies on the effect of temperature and barrel fouling on POI it is a great read.
Thanks again to all the guys for helping me figure this out. I actually learned a lot.

StackPath

 

[Formidilosus]

Dan,

What’s in that article is not your issue.



This stuff is precisely why 3 shot groups tell you absolutely nothing, and will just as often give a false conclusion as a positive.


Take the rifle, degrease all screws, loctite and remount scope. Degrease action screws, loctite and remount stock. Ensure that the barrel is well free floated- a dollar bill is not enough. Bench it at 100 yards and fire a 10 round group with the ELD-M’s without letting the rifle cool. Let it cool, then fire a 10 round group with the ELD-X without letting it cool.


This will tell you multiple things-

1). If the ELD-M group is “good” (ie 1.5’ish inches), and the ELD-X isn’t- then you know the scope is working for now.

2). If the groups are not relatively round, but instead string- then the rifle needs to be fixed.

3). If neither ammo shoots decent (again around 1.5”) then the scope and the rifle itself are both suspect.


Shooting a couple of 3 shot groups is just guessing and will lead you to chase your tail. Shoot a couple of 10 round groups with only letting the rifle cool between diffesrwnt ammo. Then you’ll KNOW some things.