Cooper .300 Win Mag not grouping

[dkhunt14]

Brass is HSM and neck sized and trimmed to length. I am not using a bushing die, just a standard RCBS neck die.


Thanks for any help
David

I would try new brass, ( I like Norma) then I would full length size. I am not fond of neck sizing for accuracy. I believe full length sizing with .002 bump is the better way to go. Matt

 

[davecb]

Thanks everyone. This gives me a few things to look for. I'll post back when I get the chance to try out a few things.

Dave

 

[davecb]

I just ordered 50 pieces of Norma brass to try. I am also going to try another brand of factory ammo. I am also going to check the lugs for proper contact as mentioned earlier.

Thanks again
Dave

 

[Dusty Stevens]

I cant believe they only shoot 47yds and actually give you the target. Its very misleading

 

[davecb]

Ok, here are the pics of the three bolt lugs after marking them with a sharpie. Definitely more contact on one lug than the other two. Does look like the other two are making a small amount of contact but not nearly as well as the one. I used a fired case and pressed the primer out about 1/32" just to give the bolt some resistance when closed.
I did not get a chance to load any more ammo for it this weekend but my buddy did buy a box of Fiocchi ammunition with the 185 Hornady SST. It shot better than the HSM factory loads and at least as well as any handloads so far. Still not great but a fuzz under 2" at 200 and right at 1" at 100(three shot groups). Seems like it always put's two shots really close and one out.
My buddy is going to call Cooper and see what they say. Doesn't look right to me.

Thanks again.
Dave

 

[onelastshot]

I own a Cooper 22-250AI and had some problems regarding the scope rings when I first received the rifle. The impression I got from Cooper was to let them set the procedures. Simply put call them and follow their instructions. The rifle is too much of an investment to take any chances in voiding the warranty.

Make a log of who you've spoken to and exactly what their advise is.

 

[Dusty Stevens]

Only one lug making contact is a function problem its not whats making those groups huge. They are good about replacing barrels when you find a bad one- they want you to be happy

 

[drover]

Just to correct some misinformation that is being posted in regards to the test target and groups.

If the rifle is newer than 2012 than it is shot at a measured 50 yds in the test tunnel at their new facility. If the rifle was built prior to 2012 at the old facility then it was shot in a test tunnel which was a bit short of 50 yds. The rifles are shot off sandbags by a person, not clamped in a vise as been mentioned here. Their shooter uses a Leupold 36X scope and of course their are no wind conditions to contend with. (p.s. test tunnel is not in a basement, their is not a basement in the old or new facility).

The accuracy guarantee for centerfires is 1/2" at 100 yds, not 1" at 100 yds. The accuracy guarantee is clearly stated in the paperwork and on their website.


As far as the problem with the rifle - Unless I missed it I do not see that you have tried a different scope. IMO this should be the absolute first thing to do, if the problem persists after replacing the scope with a known good scope then I would send it back to Cooper and let them make it right. If the owner purchased the rifle new call Cooper, explain the problem and ask for a call slip to ship it back on their dime. They will stand behind their product and make it right, even in the best of companys sometimes an item that is not up to par gets out the door.

drover

 

[davecb]

You are correct drover, I have not tried a different scope yet. I do have two other Nightforce scopes that I can put on and try(8-32 NXS and a 12-42 BR) to help eliminate a scope issue. The scope on it now is a Nightforce 5.5x22 NXS and even though the gun doesn't group, it does still seem to track correctly at different distances. I guess it still could be a possibility. Next chance I get, I'll switch scopes and see if that helps.
I have no doubt that if there is a gun issue, Cooper will make it right. I've heard nothing but good things about their firearms and warranty. I am just trying to eliminate any other possible contributing issues before having to send it back.

Thanks
Dave

 

[drover]

Here is a link to a test firing of a Cooper rifle - you can clearly be see the set-up and that they are not fired from a mechanical rest or vise. This is a demo upload but all of the rifles are test-fired from this same set-up.

drover

 

[LHSmith]

First, I admit I was wrong on the accuracy guarantee. I think Coopers are a great gun...just that I would prefer a true custom for that money. Watched the linked video and I must comment: 1/ They use a Caldwell BR rest ($159) to test? Sure would NOT be my choice to test rifles costing upwards of $2K 2/ The shooter doing the testing has the rear bag backwards and the pistol grip of the stock nestled in the bag ears....... a beginners mistake in setting up a rifle in bags 3/ I don't know why the tester felt the need to prove he could get a scope mounted and sighted in under 2 minutes.....that's just silly. It did shoot a nice group though.........but so do most of the guns that guys bring to hunting camp when they only check them at 50 yards......even in the wide-open outdoors.

 

[dkhunt14]

I'd send it back, a Remington pump will shoot that good. Matt

 

[drover]

First, I admit I was wrong on the accuracy guarantee. I think Coopers are a great gun...just that I would prefer a true custom for that money. Watched the linked video and I must comment: 1/ They use a Caldwell BR rest ($159) to test? Sure would NOT be my choice to test rifles costing upwards of $2K 2/ The shooter doing the testing has the rear bag backwards and the pistol grip of the stock nestled in the bag ears....... a beginners mistake in setting up a rifle in bags 3/ I don't know why the tester felt the need to prove he could get a scope mounted and sighted in under 2 minutes.....that's just silly. It did shoot a nice group though.........but so do most of the guns that guys bring to hunting camp when they only check them at 50 yards......even in the wide-open outdoors.

As I said it was a demo video to show how little work it takes to get the rifles to shoot a test group, it was obviously shot that fast for that purpose. As far as the shooter being a beginner he is far from that, he is an ex-marine sniper and he has won some 1000 yd competitions. The equipment he is using is probably representative of what most non-competitive shooters use so using it to test the rifle is not inappropriate and it certainly works for them. Depending on the shooter some may use sandbags front and rear rather than an adjustable rest.

I often hear stories of hunting rifles that shoot small groups but it seems as though when I am around they just aren't shooting all that well that day. But in reality in there are a lot more rifles capable of shooting 1/2" groups than there are shooters capable of it. However the point of my posting the link was to show that the rifles are not shot from a machine rest or vise.

drover

 

[davecb]

The test group sent with the rifle said it was shot with a 36x Leupold off of sand bags using 168SMK's and IMR4350.

dave

 

[RockyMtnMan]

Definitely try a different scope before you waste anymore time. Just because it is a NightForce doesn't mean it can't be at fault. Simple swap and shoot one group with an identical load that was shot previously and compare the groups. Not saying that the scope is the culprit for sure, but that's definitely something that needs to be ruled out. Best of luck to you.

 

[tsquared38016]

When I first started shooting my 300 win mag last year I tried some Hornady Custom Lite recoil loads. They shot less than 100 moa at 100 yards and helped me train up to the recoil. I now shoot Norma brass with Hogden H4831 and 210 VLD Bergers.

 

[FURMAN]

I have a couple things to say. First to the Cooper naysayers I would suggest you stay out of this thread. They guarantee .5 moa for around 2k. Most "customs" do not have this kind of guarantee. They also are not doing load development for 2k they are simply doing a qc check at 50 yds to ensure they are to their standards. It is still up to the owner to find the best load. To the OP I did not see in this thread how you have gone about your load development. I would suggest starting with a Berger VLD at the lands and doing a ladder or OCW. If you have already done that please report back. I also agree with changing the scope, if nothing else it will give you the confidence that the scope is not the issue. How are you cleaning? Are you sticking with one powder at a time? I have had rifles that hate being cleaned and hate changing powders. I couple of my rifles will not shoot tiny groups until after around 10 rounds. If this were my rifle and you have not already done it I would replace the scope and do a ladder at the greatest distance you can. I prefer no less than 600yds but that is not always practical or possible.

 

[fourpower]

Hello all, I've checked the forum out for a while now but just joined recently. I've been trying to work up some hand loads for a buddy's Cooper and I'm having issues. The gun is new and the test target that was sent was fired using IMR 4350 and 168 SMK's. I've tried dupicating the load and have not been able to get anything to group better than around 1.25"@ 100yds or 2"@ 200. I've tried different seating depths from .010 jammed all the way to .100 jumped.
I've even used the Berger 168 VLD's, 210 VLD's and a few of the Hornady 208 AMAX's. None have grouped better than the SMK's.

My buddy purchased several boxes of HSM ammo loaded with the Berger 168's and 210's. The 168's would not group better than 4" @ 100 and the 210's were way too hot(flattened primers and black smoke ring around a couple). If memory serves me right(at work right now) the HSM's were loaded with a .234" jump though. They were seated so deep that part of the ogive started in the case neck.

I know without a doubt I'm not flinching or having issues shooting the gun. It has a brake on it and is a pleasure to shoot. I'm certainly no benchrest shooter but have successfully worked loads up for other firearms that recoil MUCH more than this gun. I've been using a heavy front tripod rest and rear bags and have also tried a Bulls Bag with heavy sand.

The gun has a Ken Farrell one piece base and Ken Farrell rings holding a Nightforce 5.5x22 NXS scope. Base has been bedded and torqued as well as the rings.

Brass is HSM and neck sized and trimmed to length. I am not using a bushing die, just a standard RCBS neck die.

I'm getting to the point of contacting Cooper to see what they have to say. I know they shoot their test groups at close range but I'm wondering how many groups they had to shoot to get the one tight test group(pretty much one hole). Just thought I would probe the minds of some on here first.

Thanks for any help
David

I had same problem with different gun and it drove me crazy! finally checked barrel with bore scope and it looked good. then took off brake and looked at the inside with bore scope and you could see that the bullets were just hitting the brake a little! had to redo and bore brake out a little but the problem was solved. I have 3 coopers and had one with bolt problem and called them and they got it fixed right up great people to work with.

 

[Milo 2.0]

I cant believe they only shoot 47yds and actually give you the target. Its very misleading

It's 42 yards, and the charges used may not make it to 500, lol

 

[MrMajestic]

Excuse me if I missed it however I don't believe anyone mentioned your hold. I have found that sporter weights can be very finicky when it comes to the hold off a bench. Some actually require a death grip! A zero cost and effort try? JMHO