Home Forums Hunting & Shooting Hunting Rifles Kimber Montana 7mm-08

Good info Doug, thanks for posting it!

I recall JB stating that RL15 seemed more temp stable than RL17, but I don't remember any details like what you provided.

We recently cold-tested a friend's 7RM load with 4831sc and it lost 60+ fps and POI was definitely high at 100y. My thought at the time was that the longer barrel time and increased muzzle projection were responsible for the higher POI. I was a little surprised with that much velocity loss since it's one of the "Extreme" powders but at 490 yards it seemed to match his regular drop data... at least close enough. If anything, POI was a touch high but I never went back to check drop values given the new inputs.

I think JB and others have stated that we shouldn't assume that any powder is temp stable without testing it, like you have. I believe the thought is that the powder behaves differently depending on the cartridge in question. And the load's barrel projection/deflection characteristics probably play a role, as always.

So far, RL15 has been good to me in the 223 and 7-08. I wouldn't mind trying H4350 but at 2.800" COAL for the Kimber, there isn't much room for that slow of a powder. In fact, the Lapua brass was cramped with the old Big Game load. RL15 is a touch faster and was just the ticket.

Jason

We're arguing about whether RL-15 is temp sensitive in the reloading section right now, and I am on the side saying that it is, and why I stopped using it.

Of course I am right because all powders are temp sensitive, it's just a matter of degree.

The military was happy with RL-15 until they started fighting in the desert heat and over wide temperature changes... that's when they found out it wasn't working very well, showing excessive chamber pressure and wide velocity swings, and they needed something a lot better. There's nothing like actual combat to show the limitations of equipment.

The military testing forced Alliant to try to improve the formula to meet the specifications. They couldn't do it and the military actually had to discontinue using RL-15 for fairly serious reasons in hot environs.

Bcause Alliant couldn't get RL-15 to meet the military requirements, they gave up and went with Fed GMM for only a few dollars more...maybe that was the strategy all along as everyone seems to be happy now.

The pressure on Alliant to retain the military contract may have had a hand in the development of the new Reloader series powders but as a result, current production RL-15 is less temp sensitive than it used to be. It used to be among the worst offenders, but now RL-15 is better than some double base powders, but not as good as others. It does have a good energy density so still has lots of fans.

RL-15 is reasonably predictable, so all the casual shooter really needs is a few more data points on the range card(s) to make it work over temperature variations. It's not a critical concern except at long range or when it's too hot outside.

If I had jugs of RL-15 sitting around I'd burn it, but I wouldn't buy any these days with so many more advanced powders available. I never had a problem making 4895 or Varget or H4350 work either.

This is old news for me, so currently I'm only interested in the new generation RL line-up.

I recently noticed an ad saying that RL-16 is out, but I haven't come across any for sale yet.

I know what I found... what I found was RL15 lost 100 fps from my summer bench time to winter weather. Varget lost approx 1/2 the velocity RL15 did.

Pat Sinclair (Scenarshooter) here on the forum makes his living shooting stuff here in MT. After I posted my findings on RL15 five or six years back he confirmed he'd found the same thing, and is why he runs Varget.

Since he's forgotten more about LR shooting than most think they know, I'll take Pat's word on the subject.

Ok, I surrender. (Grin). But, in MY temperature zone and with the accuracy I consistently get in my 7mm-08s along with good velocity, I will continue to use it as long as possible. As far as Varget is concerned, it is my powder of choice in my 308, but I don't get the accuracy in 7mm-08 that I do with RL 15. It won't hurt my feelers a bit if you guys save it for me.

Doug, like I said, for most of us I don't think it matters. But since I've found Varget equally (or more) accurate in my 308's, and it is more temp stable, why wouldn't I run it? And occasionally I do elk hunt below zero, and in areas where a long shot is possible.

As to the 7-08 MT, a nice round in a fine platform. Mine stubbornly refused to shoot 140's (have found that to be true with other 7-08's) but absolutely doted on 150 gr's and heavier. I settled on 46.5 gr's H4350 under a 150 NBT for 2,700 fps and took this decent 6pt. Bullet hit in ribs, traveled 32" of elk at an angle and was under the off-side scapula. One shot, one dead elk. Have never had one die quicker either.

That is a nice bull. Congrats!

Still in the infancy of load development, but 4451 and 4166 are kicking some Varget butt with 150's in the 7-08....and I'm a huge Varget fan. Speaking 7-08 only here.

I've done the cold weather stuff, but waiting on the dog days of summer to come to any conclusions. If things hold true, I'll post results this summer.

RL15 works great in our climate with 120's and 140's. The norm may be a 30 degree temp swing during hunting season anyway. I've yet to see a 95 degree day followed by a 15 degree while I'm chasing whitetails. Work up loads on like days and all is good...

Darik, I've used Varget, Hunter, H4350, RL17, 2000MR, etc., in the 7-08. It's a remarkably non-choosy round as far as powder goes.

However, I'll always take a 308. It's far less fussy accuracy-wise!

Well said...

Maybe coincidence because only a sample of 4-5, but I have found the 7-08 to be one of the most consistently accurate cartridge I have played with. But, I have mostly focused on 120s, either NBTs or TTSXs, which is enough with RL15 at 2900-3000 or unobtanium Big Game at .270 speed, and don't feel a need for much else in the cartridge.

Sold my last 3 lbs. of Big Game a couple weeks ago. It shot great in cool weather and hot, with no change in POI that I could detect.

First pic was HOT weather (95+ F) showing groups from 2 shooters. Second & third pics from a cool day (30-35 F).

This one in 7MM/08, will stay with me until I'm under the sod.(front)
I've had good luck with Varget and IMR 4350. Been useing Speer 145 hot-cors for whitetails. This one went thru a buck lengthwise.

Speer Hotcore is an underrated bullet.

Brad, couldn't agree more. That hit was on a buck coming at me, at a slight angle. Hit just to the side of the brisket. Found the bullet against the hide on the opposite hip. If I remember correctly 85% weight retention.Accuracy in the 7/08 is very good also.

My first deer was at 30 yds, 145 BTSP, do not believe it was a hotcore- hit the shoulder at hi-vel and completely disintegrated in the knuckle. My book load was supposed to have been at 280 speeds in my 7RM, but later was revised as the guys at Speer found out the loads were higher pressure in guns other than the 1st test gun.

That said, never had any issues w/7s from a 7/08 and shot many deer long ago using 130 Sierra SSP/139/140 Sierra BTSP and BT. Used 120s and 130 Speer in a 7BR rifle successfully, both Hornady SP and HP. The 7/08 like the mid-capacity 6.5s work well with many bullets.

I believe the 130 FB is a HC bullet, and underated/used in the 7/08 for deer sized game, the BTSP does well at 7/08 speeds and offers a nice BC.

Oddest thing I ever saw a bullet do was this exact combo back in the late 80's. My best friend shot a 4x4 whitetail at around 225 yards. He was using a 7-08 Model 7 KS with 130 Speer HC's. He shot the buck in the chest as it was facing him, and the bullet travelled the full length of the deer. In butchering the bullet was found in the rear leg hock! Weird.

Recovered bullet looked like a Speer ad...

I took this year's 7x7 bull with a 165 Speer HC from my 308. A nice, mature 7 year-ish old animal.

Personally, I'd never use Speer BT's, but the FB Hotcore's are the real deal. Biggest whitetail buck I ever took, right at 200 lbs dressed, was taken with a 308 Win and 150 HC. Bullet bunched both scapula's and exited.

I've always called them the Poor Man's Partition.

Bingo. I am not getting folks working up loads at 95 degrees when the hunting will be in the cold. Work up in the 50's or so and go kill stuff.

I don't think anyone stated that they were working up loads in 95 degree weather.

Good shooting 4th.

I've 'developed' loads in hot weather, keeping in mind that performance will be affected by weather. I confirm loads in cold weather prior to big game hunting.

I just work up a load whenever i can and shoot it all year.