300 RUM xcr

[BlackTail]

Well I'm back.  I got you pm jackelope (thank you).  I'll try and get those pictures up this evening. 

[bcrawford]

OK think we all like the gun, who likes the new X mark pro trigger they have on them now? I am not impressed It has been out and adjusted still way to heavy. I don't like a light trigger but but I still cant get used to it. I have a new trigger on the way should be here in a few days. I hope I just got a bum setup out of the box any one else have any problems?

[jackelope]

here's a pic of blacktail's cannon...

[GoldTip]

Actually the BC for a 150gr .284 cal Scirocco is higher at 0.533 than the BC for a 175gr A-frame .284 cal at 0.493.  The A-frame sighted in 2.4" high at 100 yards will be 32.2" low at 500 yards where a 1.8" high sight in at 100 yards for the 150gr scirocco will leave you only 25.3" low at 500 yards.  And this is all with factory loads from Remington.   When loaded with a 175gr bullet for the 7mm Ultra, you would be better off with a standard 300 win with 180gr bullets.

Either bullet will more than do the job for virtually any hooved animal in the US, but if you really want to take advantage of the 7mm Ultra, the 150gr Scirocco is where it's at.

[BlackTail]

I still haven't had a chance to shoot either the scirocco or the A-Frame.  Went to go shooting tonight but didn't get out til late and my buddy had to put a new scope on his 300 wby (dropped gun, broken scope ).  He's leaving for Canada on Sunday to go moose hunting so getting his gun sighted back in was top priority.  I'm going to try and shoot tomorrow.

Goldtip,  looks like you got your ballistics off the remington site.  While it's pretty easy to assume that the 150 sciroccos will shoot flatter than the 175 A-Frame, it also says that the 150 has more energy.  Even out to 500 yards.  Does that sound weird to anyone???  I would have thought the 175's would pack more punch 

[GoldTip]

The 150gr scorocco has more energy because the equation for energy uses Mass x velocity with the velocity squared, so any high velocity round will have a very high energy as well even out to 500 yards.  It works out so well for the 150gr scirocco because of its' very high ballistic coefficient and therefore maintains it's velocity even out to long range.

[bobcat]

Energy figures are just a number, and don't mean much. The heavier bullet WILL "pack more punch," regardless of what the energy figures show. The heavier bullets also have a higher ballistic coefficient, and therefore retain their velocity better than the lighter bullets, and for that reason they are also less affected by the wind. If you like the Scirocco that is fine, but if it's available in a 160 or 175 grain version, you will find that it will perform better than the 150 grain, especially on larger animals like elk. The 150 grain is what you would want to shoot out of a 7mm/08 or a 280 Rem. The only reason to use a bullet that light out of your magnum is if you can't handle the recoil you will get from the heavier bullets.

[GoldTip]

Bobcat, the LONGER bullet for diameter will have a higher ballistic coefficient, not necesarilly the heavier bullet.  Yes, a 160gr scirocco for the .284 caliber would be almost both ballistic and energy pure magic, but they don't make them, but I wish they would.

[bobcat]

I realize that...I'm talking about a heavier bullet in the same style bullet, having the higher BC.

How about a 160 Nosler Accubond? I bet it's got a higher BC than the 150 Scirocco.

[GoldTip]

Ya know I haven't paid much attention to the accubond to be honest.  Is it a boat tail bullet?  I have read a few good things about it.  Ya know anyone who has used them?

[bobcat]

Yes, it is a boattail, and the 160 in 7mm has a BC of .523. Check it out:

http://www.nosler.com/index.php?p=11&b=5&s=3

[Ironhead]

Just found this thread, and I have to disagree with bobcat about the only reason to shoot a magnum is to lob a heavier bullet. I shoot the 7 RUM and shoot a 150  swift scirocco that will flat nock the shiat out of any thing in front of it.
 It is one of the best big canyon rifles I have ever owned. If I wanted to shoot a heavier bullet I would shoot my 300 RUM. The 7mm's are meant for a lighter faster bullet. The recoil is no problem, I just want a flat shootin deer machine and this is definately what the doctor ordered. Only bad thing I can say about this gun are ammo prices, factory loads are around 60.00 a box hand loads are a must in my opinion.

[ICEMAN]

I hear ya' on the brutal cost for the Ultra mag stuff. I have about 140empties, might start reloading this spring...

[littletoes]

GoldTip-Contrary to popular belief, WEIGHT does indeed contribute to Ballistic Coeficient, otherwise our bullets would be aluminum!

Ironhead-but once you try the heavies (like the 175 grn 7mm!) at longer ranges, and you see your impact, you won't go back to the light stuff for longer ranges. Plus your come-ups are less, and boy do they cut the wind.

[bobcat]

The 7mm's are meant for a lighter faster bullet. The recoil is no problem

Who told you that?    And for some, recoil is a problem. But yeah, I'm sure with the 150 grain bullet recoil isn't bad, that's why I said that would be one good reason to use the lighter bullet. But if it were me, and I was going to use a lightweight bullet, I'd go with the Barnes TSX. At least with that bullet if you were to shoot a deer at relatively close range, say within 200 yards, it probably wouldn't rip the deer completely in half, like I'm sure the Scirocco might have a tendency to do. Truth is any reasonable weight bullet will work, in the 7mm I'd say anything from 140 to 175. I just prefer heavier bullets, like in my 270 I like 150's whereas a lot of guys love the 130's. And in a 30-06 I prefer 180's. There is very little difference in drop at long range between the lighter bullets and the heavier bullets, contrary to popular belief.