Author Topic: CZ 550 UHR 300 Win Mag  (Read 5345 times)

8x68

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CZ 550 UHR 300 Win Mag
« on: July 05, 2014, 11:20:39 PM »
I have a CZ 550 UHR in 300 Win Mag. Anybody have any experience with this firearm, or info regarding reloads? CZ site suggests 165/168gr SST's, Interlock or 200gr DRT frangibles.  Just wondering if any of the match bullets from the major manufacturers would be any good? Thx

Offline ZG47

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Re: CZ 550 UHR 300 Win Mag
« Reply #1 on: August 12, 2014, 08:45:05 PM »
Given that they have apparently gotten good results with Hornady bullets, I suggest that you give Hornady a bell. The only thing to watch with the 165/168 bullets for .30 calibre rifles is that some were developed for use with 7.62x51 velocities and 1-10" twist velocities and some work better with 7.62x51 velocities and 1-12" velocities OR in other words, rotational velocities are more critical with some projectiles.
Don't worry about calculating revolutions per minute. That is idiot stuff for idiots! Most bullets hit either the target or the ground within a second of the trigger being pulled. In long-range shooting they usually hit within several seconds.Calculate everything per second, as in high school physics

Rotational velocity stays pretty much the same from when the bullet leaves the muzzle until the projectile goes through the transonic zone, according to my understanding.
Ratio for 1-12" twist is one to one. Ratio for 1-10" twist is 1.2 x muzzle velocity. ratio for 1-11" is 12/11 (1.09...).

Excessive rotation will increase friction from the air and reduce maximum range and will cause a hunting bullet to open more quickly than intended. This is why German 8mm magnum rifles have either a 1-300 (1-11.81") or 1-12" twist and do not have the same reputation for bullet blow up as U.S. 8mm magnums with 1-10" twist barrels. It is also why .30-06 target rifles were available from Winchester with optional 1-12" twist barrels and .300 H&H rifles sometimes have 1-14" twist barrels.

Coming back to the beginning, just tell the bullet company what you have and what you wish to do with it. They will give you good advice as to what will work best in your rifle for your stated purposes.
A good shot at close range beats a 'hit' at a longer range.

Able

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Re: CZ 550 UHR 300 Win Mag
« Reply #2 on: November 11, 2014, 02:44:53 PM »
I finally bought one of these a few weeks ago.  I was searching all over for info on the web without much success, so here are a few things I've discovered.

For ammo, I have shot the 165 gr GMX, 180 gr Hornady SP, 150 Barnes TTSX, PRVI 180 gr, and 200 gr DRT.  I bought a few other boxes but haven't shot yet.  I've only shot on a lead sled with a good wind, so not ideal conditions and I'm no benchrest shooter.  3 shot groups at 100 yards.

The GMX is the odd one out, it shoots all over the map, 3" or 4" groups.  The Hornady, PRVI, and DRT are all a hair over 1".  If 180 grains are bullseye at 100, the 165 are an inch or so higher, and the 200 gr are 2-3" lower.  The Barnes TTSX are the best shooters so far, just a bit over 1/2".  That works perfectly for me as the Barnes TSX is by far my favorite hunting bullet and the 150gr is very flat shooting.  So I plan to stick to that.

This is my 3rd CZ 550 and the trigger has a lot of creep.  I know how easy it is to adjust the trigger but you have to pull it out of the stock to do so and this UHR rifle has the cross bolts so I haven't done it yet, not sure what is involved without checking the manual.  But the set trigger is perfect so no rush to adjust the trigger yet.

The last nit is the scope mount.  It is very high.  I like the idea of the 1 piece base but wish it were lower.  I guess it is because the bolt throw is so high that the height is needed to clear the scope?  I'm using medium Warne QD with a 30mm Swarovski on my CZ 550 FS 6.5 and the bolt just barely clears the scope.

On this UHR I'm using a 30mm Leica 3.5-14 scope and the rings don't fit that well - I have the same issue someone commented on at the CZ-usa website - the supplied screws only get a minimal amount of thread into the base.  I solved that problem by ordering 18-40 screws from Brownells but it is stupid to have to do that.

Other than that it is as expected.  It is not light but not overly heavy.  The stock grip is much fatter than the CZ 500 FS but about the same as my regular 550 American.  I like the barrel contour - not a varmint but not too whippy that it heats up and sprays bullets like my old 7mm Sako this is replacing.  As long as the TTSX keep grouping well under 1" I will be very happy with this gun.


8x68

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Re: CZ 550 UHR 300 Win Mag
« Reply #3 on: December 18, 2014, 02:01:33 AM »
Hey guys

So far I have tried the Hornady 155 A-MAX (1:12" twist) in my UHR or HA Hunter as it's called in Canada.  The best group I got was a 3 shot .6" at 100yds (2 touching and 1 just to the left of 1st 2).  I was also using the Caldwell Lead Sled 'cause I ain't no "spring chicken" anymore. I shot approx 60 rounds testing different loads with the CZ. Temp was around 4C and the wind was about 20-35kmh blowing directly toward the bench. Not a bad session but I think I can do better.  I had noticed when I went to clean the rifle the trigger guard screws were not tight. Hopefully with tightening them the groups might me a bit better and more consistent. I am not using the 30mm scope mount (neat piece of work though) as I do not have a 30mm scope. I'm using a set of 1" Medium CZ rings with a Nikon Monarch III 4-16x42 SF BDC.  Ringmounts have been torqued using the Wheeler Fat Wrench so they are tight.  I plan to try Hornady 168gr SST and Hornady 180gr SST to see how they shoot. I wanted to try heavier A-MAX (1:12" twist) bullets but my local store was sold out. May get a box or two of Sierra BTHP MatchKing bullets and see how they perform. Haven't decided on what weight yet. Thinking 175gr to 200gr. I'm not sure if the 1:12" twist will stabilize anything above 200gr.
I'm sure I can do less than .5" groups just haven't found the right recipe yet....almost but not quite! I guess I'll just have to keep shooting!

I also just bought myself a CZ 550 FS in 9.3x62. What a pretty rifle. Shoots really well.  I was impressed!

Able

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Re: CZ 550 UHR 300 Win Mag
« Reply #4 on: February 10, 2015, 08:49:36 AM »
Quick update - I spent some time shooting over the holiday.  First I replaced the stock rings with medium Warne rings - much better for me and as low as I could go and still clear the bolt handle.

I shot an elk at 180 yards with the 155 gr TSX, complete pass through.

At 300 yards my best group was ~2.5" with the TSX bullets.

At 460 yards (farthest I could shoot), I was getting under 6" with the 155 gr TSX.  I tried a few different bullets, but the standout at that distance was the 178gr Hornady Amax - a 3" group at 460 yards but point of impact was something like 16" lower than the 155gr TSX at that distance!  The day after shooting that distance a coyote walked out in front of the target at 400 yards.  One shot from the TSX, my longest shot at an animal.

For now I'm set on the 155 gr TSX - flat shooting, plenty accurate, and I love that bullet for hunting.