7mm shootout

[Gabriel]

Hi,
I'm planning on buying a rifle chambered to one of the 7mm mag. cartidges. Currently I've narrowed it down to the STW, Ultra Mag. or Lazzeroni. Do any of you have any experience with these guns. I can't find a good model in 7 STW but might get a custom gun. Can someone tell me what the practical, in the field differences are between these cartidges when using a 140 grain bullet.

 

[Mysticplayer]

The big difference between the cases you mentioned will be recoil, muzzle blast, and throat erosion. The vel. difference would be 100fps or so. In fact, depending on barrel, each case could overlap the other for vel. vs accuracy. Bullet construction may also be an issue.

These cases are overbore so gains are small for massive increases in powder.

For hunting mid size game under 700yds with 140gr bullets, my choice would be the good old 7 Rem mag. This will be within 200fps of the others and field performance is negligible.

If you plan on using heavier bullets, then the story changes. These big case magnums start to make sense when 160 and heavier VLD bullets are in mind. Of course, longer heavier barrels will also be needed to make them really work. This is the stuff for 1000yd type pokes.

If you want a good walk around hunting rifle, even the 280 AI or 7X57AI are excellent choices. I like to keep impact vel. under 2800fps because of meat damage and bullets blowing up (not a fan of expensive premium bullets). Get an idea of the ranges you want to hunt, size of game, type of shots you will take and go from there.

As long as you can get a (conventional)bullet into the boiler room at 1500fps or faster, you are going to need a knife.

Good luck...

Jerry

 

[Guest]

[ 07-11-2003: Message edited by: S1 ]

 

[Mike Liane]

To member 963: I'm impressed with your success with the 7mmUM and the 162 A-max. I'm in the process of trying to do the same thing with the same rifle and bullet. Can you share the powder and charge that you used? You don't happen to know the overall length of the loaded round? Mine seems to have a long throat and if I seat just off the lands I can barely get a round down in the magazine. Any info. would be much appreciated. I hope I can accomplish as much as you guys did. Thanks, Mike.

 

[Guest]

[ 07-11-2003: Message edited by: S1 ]

 

[speedbump]

Gabriel,

I had a 7mmRUM built this spring, primarily for 1K matches & the occasional coyote. I've posted on it here before, but here's a synopsis:

I tried 8 different powders & 3 different VLD bullets (used some Sierra 130MKs for a warm-up too at 3,671fps).

The bullets it liked best were Cauterucio (GTB) 176gr VLDs seated .005 into the lands. Also tried were Caut. 156s & JLK 180s. The 156s shot very well, the 180 JLKs not as well.

Powders tried were: IMR7828, RE19 & 22, MRP-2, H1000, WC860, H50BMG, &5010 pulldown. Luckily, the 5010 pulldown (milsurp) produced the best loads by far, & at $4.00 per pound was affordable to shoot.

The combination resulted in a .740BC bullet traveling @ 3,360fps. It consistently shoots sub-1/2MOA @ 300 yards & @ 3.25" 5-shot groups at 500. Wind is not much of a factor at 500.

It takes roughly 17-18MOA from a 100 yard zero to 1,000. Flat, flatter, flattest (maybe?). The computer shows it running @ 2,200-2,300fps at 1,000 but I have yet to confirm that. One of the other members here, 'Fatboy', has seen its trajectory personally through his spotting scope to 1,000 & can attest to its arc. It uses roughly 1/5 the windage of a .308 at 1K.

Throat erosion is measurable, but NOT extreme so far. Recoil is moderate, it has NO muzzle brake, & I shoot it from a sling in conventional 1K LR matches, what it was designed for. I squeaked into the top 20 in the Wimbledon Cup with it this year at Camp Perry.

I have alot of tweaking to do with the load, it's still below its potential IMHO. I have some Retumbo on back-order, it's hard to get some powders down here in 'Mayberry'.

I was going to try the LRBT 162s as mentioned in another post, but with the performance I'm getting for the $$$ with Cauterucio's, I think I'll pass for .048BC - for now.

The 7mmMag is proven, the 7mmSTW is far more efficient in terms of powder burn vs. velocity, & the one conversation I had with Lazzeroni convinced me to never call back.

Hope this helps you. Good luck & good shooting!