[Updated] Christensen MPR weird performance on Cheap & Expensive Rounds, and zeroing question

[PrismSync]

Hi Folks,
It's been a while since I lastly posted about my MPR, worrying that it might not be worth the price, etc. Thanks to everyone who offered advice there!

Now I finally get to shoot the rifle, so here are some updates. There is a somewhat bizarre pattern: cheap ammo "outperformed" expensive ones.

It performed fairly okay at around 0.8MOA with the cheap Sellier & Bellot FMJ rounds($1.2/rd) yet it really sucks at almost 2MOA when shooting the much more costly Hornady ELD Match 140gr($2.7/rd). Both are unmodified factory ammo as I wanted to find a benchmark before trying my reload (and ELDM factory ammo is terrifying me bc my bullets are going to be ELDM too)

Please see attached pictures for the groups, here below are the session info:

• Very slight wind, 62F weather (unlikely wind causing the issue, and it's not .22 after all)
• I did 3 groups of FMJ, and then 3 groups of Hornady ELD-Match. All at 50yds. No scope mounting adjustments, but I did turn the turrets for 20 clicks (1/4 moa per clk)
• All are 5rd groups, with short break in between as I load magazine (so unlikely overheating barrel)
• Was using a bipod and rear bag, so not as steady as bench rest, but wasn't unstable either

As you can see, the FMJs were giving 0.8moa groups, quite repeatable, and the ELDM just went everywhere. In two of the groups, there were even fliers that did not land on the 8'' target at all (I mean, it's 50 yds, not 500 yds, why....)

I did a little bit of research and it seems like a rifle might be picky about seating depths, but I didn't expect ELDM to be so bad. What else might be the possible reason for the ELDM's atrocious performance? Should I contact Christensen to examine the rifle?

As for the zeroing question, what I did was shoot a 5-shot group, and then turn the turret correspondingly. It in up/down it needed ~40 clicks with each click being 1/4 moa. (which is kinda okay, because the rail had 20MOA slant and I was shooting 50 yds close). but left/right also required a lot of clicks (~30) to zero, does that mean I might have mounted my scope too angled off to the side? How many MOAs for zeroing is considered an acceptable range?

Thanks for reading along. An irrelevant eye candy (if that counts) attached too : )

 

[Lost_Phil]

My buddy has several MPR's in 308 win, 300 win mag and 338 Lapua. All of them are grate shooters but he did find that they like heavier grain bullets. So, I would look for 144 Bergers, Hornady 147 ELDM's and higher to try out.

Now the one thing that does seem to stick out to me, it the amount of windage you had to dial in. I would recheck the scope to make it is not canted and is in fact level with the rifle. If it is level and the heavier rounds still have issues, I would send it back and have Christensen Arms go through it. They are very good with their customer support.

 

[Mjnelson]

Definitely hard to say with much certainty not knowing extensive details on your build, and the state of the parts (scope, rings, etc). Perhaps the scope was not at mechanical zero when you mounted it? Good rings properly torqued? Double check everything. Torque on the action screws. Make sure nothing is loose, scope rail, muzzle brake.
If everything is kosher and it won’t perform call Christensen and have them take a look at it. I’m sure they will take care of you.
Mike

 

[PrismSync]

My buddy has several MPR's in 308 win, 300 win mag and 338 Lapua. All of them are grate shooters but he did find that they like heavier grain bullets. So, I would look for 144 Bergers, Hornady 147 ELDM's and higher to try out.

Now the one thing that does seem to stick out to me, it the amount of windage you had to dial in. I would recheck the scope to make it is not canted and is in fact level with the rifle. If it is level and the heavier rounds still have issues, I would send it back and have Christensen Arms go through it. They are very good with their customer support.

Thank you Phil for the input! The windage does seem weird and I'll check the mounting again. So in a properly mounted situation, how many MOAs of windage to zero is considered "acceptable"? Like only a few clicks?

 

[PrismSync]

Definitely hard to say with much certainty not knowing extensive details on your build, and the state of the parts (scope, rings, etc). Perhaps the scope was not at mechanical zero when you mounted it? Good rings properly torqued? Double check everything. Torque on the action screws. Make sure nothing is loose, scope rail, muzzle brake.
If everything is kosher and it won’t perform call Christensen and have them take a look at it. I’m sure they will take care of you.
Mike

Thanks Mike. Pretty nothing was loose, but maybe I mounted the scope canted. It was a new scope so I assume the zero has not been adjusted, but I'll double-check everything. BTW, if the turret has its zero changed, how can I go back to the mechanical zero? Like going all the way to one end, and turning back while counting half the max adjustment range?

 

[Mjnelson]

Thanks Mike. Pretty nothing was loose, but maybe I mounted the scope canted. It was a new scope so I assume the zero has not been adjusted, but I'll double-check everything. BTW, if the turret has its zero changed, how can I go back to the mechanical zero? Like going all the way to one end, and turning back while counting half the max adjustment range?

Pretty much, go all the way one way, then count your minutes/Mils to the opposite way tell its stops, go back again half that.
As for it being canted, it would have to be so much it would be pretty obvious looking at the rifle.. even then it probably won’t interfere with your dope for a couple hundred yards… easy way to check is have it loose in the rings set at your desired eye relief and inset something flat and skinny, like a feeler gauge, and rotate it against your flat side of the erector housing and the flats of your scope rail. Tighten rings.
Mike

 

[PrismSync]

Pretty much, go all the way one way, then count your minutes/Mils to the opposite way tell its stops, go back again half that.
As for it being canted, it would have to be so much it would be pretty obvious looking at the rifle.. even then it probably won’t interfere with your dope for a couple hundred yards… easy way to check is have it loose in the rings set at your desired eye relief and inset something flat and skinny, like a feeler gauge, and rotate it against your flat side of the erector housing and the flats of your scope rail. Tighten rings.
Mike

That's pretty much what I did, used a bubble level, so I doubt if it's canted that much. So really don't know the reason. Do you believe "bullet goes to sleep" theory, i.e. only stabilizing until having flown several tens of yards?

 

[Lost_Phil]

That's pretty much what I did, used a bubble level, so I doubt if it's canted that much. So really don't know the reason. Do you believe "bullet goes to sleep" theory, i.e. only stabilizing until having flown several tens of yards?

No, I do not believe that, but you are in the beginning of its arc, which still not should be an issue with grouping. I would try the 144 or 147 grain bullets and see how it groups at 50 and 100 yards. If it still has flyers, I would contact Christensen Arms for an RMA and have them look at it.

Also, as far as windage settings when first setting up, the most I ever had to do was about 2.5 inches, so 7.5 inches seems a little excessive to me.