Thread: Keeping the 7mm ahead of the 30 cal?

Originally Posted by Greg Duley

Andrew, you cannot get 3471 fps with a 180gn Berger out of 30 inch barrels RUM without out blowing cases. Either your chronograph is inaccurate, or you're talking BS. The Nosler RUM brass you were using won't take anymore than 65,000 psi without popping primers. A 30" RUM at just under primer popping pressure will push a 180gn at 3400fps max. We built your rifle, and many like it, and have strain gauges on enough of them to know exactly what they will do. Do not try and reach Andrew's claimed velocity or you will end up with molten brass in your eye at the very least!
Also, the only 180gn Berger that will stand 3400fps with accuracy is the Hybrid. Don't waist your time with the VLD's.
As Kiwi Greg and Don say, it depends on what you're trying to achieve. If you want the absolute best long range performance in the wind, with minimal recoil, in the lightest possible walkabout hunting rifle, then this new bullet with a projected .400 plus G7 BC may well be superb in our biggest fast twist 7mm's. The barrel life will be reasonably short in the likes of our 7mmSF or Kirby's 7mm AM, but as a specialist long range lightweight hunting rifle, who cares! If you can handle more rifle weight and recoil, then the biggest 338's will beat it in barrel life and killing performance for sure, but it will need to be a big, long barreled 338 to beat it ballistically for drop and windage. At the very least a 338/416 imp like our 338 Thor, or a 338 Cheytac imp like our 338 Lunatic. An Edge, Lapua, or Lapua AI won't touch it. The 375 Cheytac imp, if the new bullets/twists all work out, certainly will beat it and the big 338's. But in a lightweight hunting rifle, I shot and killed a lot of deer with the 7mm 200gn Wildcat bullet (until Richard sold the business), and know exactly what a really big 7mm can do! Bring it on!

Greg

The trouble with any extreme over bore case like the very big 7mms when you talk about barrel life isn't just that its short its that they are sometimes very hard to keep tuned with the best BC bullet on offer for the entire short life of the barrel. Often you have to go to another lower BC bullet to keep it shooting after just half of the short barrel life, yes the barrel is still shooting but the best BC bullet can no longer be used so greatly changing the great ballistics it once had. Kerby had this happen to his 7mm Allen mag having to change from the 200gr wildcat to the 160gr AB, I am in no way saying that the Berger 195gr want be a great bullet but you may have trouble keeping it shooting in the big 7mms, now the target guys who don't need to push it hard to get expansion at long range will be very interested in this bullet in a medium case as a great windy day bullet.

Don,
That may have been the case with the thin jacketed VLD's in some barrels, but it depends more on how hard pressure and velocity wise you are driving them. I have had the old thin moly coated 180 VLD's shoot in a Kreiger barrel for well over 1000 rounds before it started to destroy them. This was at 64,000 psi and 3200 fps. Kirby ran a lot of rounds through that barrel doing testing for his customers, at some pretty serious pressures and velocities. You can get away with this due to the high quality brass they're based on. Someone else on this forum has a habit of doing the same thing occasionally, eh Kiwi Greg?

I have run many more rounds through one of our 7mm SF's than Kirby has through his own personal 7mmAM you're talking about, without any deterioration in accuracy, but we run the Lapua brass at 65,000psi, not the 70,000 plus some others run.
Anyway, this certainly isn't the case with the Hybrids and other similar ogive and jacket thickness bullets. That's the advantage of them, they are very throat tolerant. If used as a lightweight hunting rifle/load combination, the barrel life even with the biggest 7mm's or any other overbore cartridge will last for years. If you want to bust lots of rounds at gongs etc, then don't pick a big 7mm or any other largest case in any calibre, whether it be 22 cal on up. Build a 338 Edge and bang away to your hearts content, but do realise there are other cartridges that are better in the wind if a high round count is not important to you.
Horses for courses!
Greg

The 195gr will be a hunting bullet so should have a hunting jacket? not like the 180gr target hybrid with a thick jacket that even you admit will only expand up to a modest distance.

Don,
The 180gn 7mm and 300gn 338 Hybrid's I have lots of experience with expand just fine out to 1000 yards no problem. Not sure what you mean by modest distances? They are no different to SMK's, in fact expand better in my opinion. We have no issues with them terminally at all, and their superior ballistics makes them go to's for us. Sure, 180gn and 300gn A-Max's would be even better, but that's not likely any time soon by the sound of it. In the small and medium 7mm's out to 800 yards the 162gn A-Max is superb, but it ain't as good in the wind as the Hybrid, and that's a fact. I'll take hitting them in the right place first over a small terminal advantage any time! Do you think the CE's you've got for your 375 build are going to expand any better? Not in my experience they won't. I can show your footage of a Bull tahr hit smack in the middle of the shoulder with the 252gn CE doing 3550fps at 600 yards that takes off like he wasn't even hit. But we found him 100 yards away dead, hit exactly right in a very strong wind. There's no such thing as the perfect bullet yet, but they're working on it. When Smitty from CE puts his new alloy tips into his long range bullets, then we'll be almost there I reckon!
Anyway, the Red stag Willie shot at 720 yards on Monday night while we were in a "big country" headwater with a 180gn Hybrid out of the 7mm Fatmax just rolled over dead. Point of the shoulder, DOA!!
Greg