300 RUM xcr

[Ironhead]

Here is a chart, The 150 does have a higher BC than a 175 it is also flatter and faster and it lacks energy at 500 yards by a couple hundred pounds which isn't much when your still packin 1500 lbs @ 500 yards. Also I have shot a few deer at close range and can't say I have ripped any in half with the bonded scirocco. The Idea behind a 7mm mag was to get a smaller bullet to fly faster. If you want to push a bigger bullet why wouldn't you step up to a 300?
http://www.remington.com/products/ammunition/ballistics/results/default.aspx?type=centerfire&cal=24

[bobcat]

It's too bad you can't get a 175 grain Scirocco in the 7 Ultra. You'd have a higher BC and less wind drift. In the 300 Ultra you can get a 150 or a 180 Scirocco. Take a look at this chart and notice how the 180 drops only 2 inches more at 500 yards than the 150 in either the 7mm or 300 Ultra.

http://www.remington.com/Products/Ammunition/Ballistics/comparative_ballistics_results.aspx?data=PR300UM5*PR300UM3

[BlackTail]

Ironhead, 

   Since you shoot the same gun I thought I would see if you have had similar results.  I went out to shoot some 150 sciroccos in my 7mm RUM for the first time.  First, I shot at 100 yrds and was shooting about a 1" 3 shot group, 3" high.  I then backed up to the 225 yrd range (that was the farthest you could shoot at this range) and took 3 more shots.  It was about an 1 1/2" group but it was 6" high    My buddy, who also shoots the 7 RUM happened to call right then and I was telling him about shooting at the 225 yrd range and was about to tell him where my gun was hitting and he finished my sentence..."it's hitting 6" high".  His gun apparrently did the same thing.  I've looked at a couple different ballistic charts and none of them have shown a 3" spike between 100 yrds and 225 yrds.  I know i could dial it down some but I will be hunting with 160 gr Partitions this year (I found 8 boxes of shells @ $30.00 a box and my gun loves them) so I don't want to be playing with my scope a week before the season.  Just wondered if you have seen anything similar to this?

[Intruder]

I'd recommend shooting the heavy bullet w/ the better BC too.  Take advantage of the 100 grns of powder capacity 

[bobcat]

Blacktail,  That sounds about right. With the high velocity, and being 3 inches high at 100 yards, the bullet will still be rising in relation to your line of sight, and 200 yards will be about the highest point in the trajectory. With that load you'd want to move it down a bit so it's only around 2 inches high at 100 yards.

Take a look at this ballistic calculator:

http://www.biggameinfo.com/index.aspx?page=/balcalc.ascx


 I just estimated the numbers, but it should be pretty close.

[Intruder]

Bobcat,
That's the same Bal Calc I use.  It's awesome!

[BlackTail]

Bobcat,  When I use that link you posted I'm not seeing numbers like you said.  When I plug in the 7mm sciroccos numbers and use a 325 yard zero, it says I would be 3.1" high at 100 yards, which is where I'm at.  However, it says at 225 yards it will be 3.9" high.  That's less than an inch of rise where I'm seeing a 3" jump.  The link you posted I have been on before as well as others.  Remington's website shows less than half an inch difference between 100 yards and 225 yards.  I've never used these calculators before, other than just comparing one caliber to another.  Have you had pretty good results matching up ballistic calculators to actual ballistics in the field?? 

[bobcat]

Yeah, sorry, I guess the link just takes you to the calculator with the default numbers plugged in. With the numbers I plugged in it comes out to be about 4.5 inches high at 225 yards, when sighted in 3 inches high at 100. So I don't know, that's still pretty close to your actual results. Maybe you're not exactly 3 inches high at 100 yards, or maybe what you think is 100 yards is only 90 yards. What would really tell you something is if you could shoot at 300 or 400 yards and then compare it to the calculator.

[Ironhead]

Blacktail, I haven't noticed a 3" jump  more like an 1", I am 3" high at a 100. Make sure your ranges are dead on or the ballistic charts will be different. 3" jump in 125 yards is pretty drastic.

[BlackTail]

Ironhead....Yeah I thought 3" in 125 yards was pretty drastic myself.

The ranges have all been verified.  I have both paced them off and checked them with a range finder.  My gun is shooting just under a 1" group at 100 yards so I'm pretty sure that I can say my gun is 3" high at 100 yards.  It's shooting and 1 1/2" group at 225 yards so I'm pretty sure I can say my gun is 6" high.  If I was spraying bullets all over the place I wouldn't even be asking.  The fact that my friends gun did the same thing, is just too weird.  I'm going to try and get out to the 400 yard range this weekend (if it's not a monsoon) and see where my gun is hitting out there.  At this point I don't know what to make of it??
Thanks for all the responses, though!

[littletoes]

Hmmmm.....maybe I'm not thinking this through corectly, but if the bullets are hitting higher...then doesnt' that mean that they are flying FLATTER?

Which would also indicate that they indeed have a higher BC? Perhaps all that is printed by bullet manufacutes isn't ture???

Doesn't it stand to reason, that if a bullet doesn't need as much "come-up" that that same bullet is flying flatter? Makes sense?

And for a previous answer, the 175 I was talking about was the Sierra Match King 7mm 175 grn.
http://sierrabullets.com/index.cfm?section=reloading&page=coefficients

[BlackTail]

littletoes,

That makes sense to me.  I was just asking if people had used those ballistic calculators and then went out and matched them up with in the field shooting.  I really didn't have time to shoot the sciroccos or the A-frames as much as I like before the season, so I'm sticking with the 160 gr partitions.  I've shot a bunch, they shoot great in my gun, and at this point of the year if I have time off, I'm in the woods and not at the range.  Playing with those new rounds will give something to do in the spring, though!

[littletoes]

Fully agree, too late for any load testing for this year, time to be hunting!

Hope you have some great luck, and me too.