How fast can cast boolits be shot in a 7mm-08

[kiwi]

Hi, I have just bought a Sako 75 Hunter in 7mm-08 I have the RCBS 145 Silhouette mould casts at 161 grains with my mix only fired 30 rounds so far very impressed
with the results loaded 15 16 17 grains of 2400 15 was the best 5 shots at 100 metres 1.3" edge to edge no chrono results dropped 3.5" from 50 metre zero probably
good enough to hunt with,
I like to know how fast I can push this boolit and expect the accuracy to be with in 1.5 MOA, and what powders to use, I am new to 7mm's this is my first. Robert

[Fireball57]

Welcome, Kiwi ! My RCBS Silhouette 145 hard-cast fired in a heavy 25mph wind in a McMillian custom target rifle will group five shot groups, all touching with 25.0 grains of 748 with a Rem 9 1/2 primer. 2.815"OVL Cheers!

[303Guy]

Hello kiwi, welcome aboard. :drinks:


What is the twist rate of that Sako? I've played around with heavy boolits in a 303 Brit using AR2208 and I estimated the velocity to be around 1800~1900 fps. We've got a full range of suitable powders to choose from and finding the optimum powder for maximum velocity shouldn't be too difficult. You might look at W748 which can be loaded quite low, even low enough to leave unburned kernels in the bore. My thinking is for a low peak pressure and a slow pressure rise with long pressure duration, the idea being to avoid rifling skid and also boolit deformation on launch into the bore.

[303Guy]

A welcome to you too, Fireball57. :drinks:

[fast ronnie]

Welcome fireball57 and KIWI!!!!!!!!!!!![smilie=2:

[kiwi]

Hello kiwi, welcome aboard. :drinks:


What is the twist rate of that Sako? I've played around with heavy boolits in a 303 Brit using AR2208 and I estimated the velocity to be around 1800~1900 fps. We've got a full range of suitable powders to choose from and finding the optimum powder for maximum velocity shouldn't be too difficult. You might look at W748 which can be loaded quite low, even low enough to leave unburned kernels in the bore. My thinking is for a low peak pressure and a slow pressure rise with long pressure duration, the idea being to avoid rifling skid and also boolit deformation on launch into the bore.
Thanks 303, The Sako has a 9.5" twist I have plenty of AR 2208 but no W748 and have a 3 pounds of 2400 also got given 3 500 grams of Nobels No 3 rifle that is great in the .222
similar to 4198 in burn rate will try in the 7-08 on a big learning curve here, mostly been shooting cast in 308, always wanted a 7x57 but the Sako came long first. Robert.

[gloob]

From my Lyman 7mm cartridge reloading guide, the fastest load they list for cast 7mm-08, out of a 1:9.5 twist 24" barrel:

#287641, 160 gr #2 alloy
34.0 grains of 2015 powder
2322 fps

Max load of SR4759 is 26.0 grains at 2154 fps. Unique, 15.5 grains at 1769 fps. 2400 is going to be somewhere near halfway between, I would imagine.

If you get your alloy right, it would seem like you have a bit more room to work up, but listen to your gun and brass and your targets.

They don't list accuracy, but other notable powders for velocity are:
IMR-4895, H335, W748, and 3031 all nipping on the heels of 2015. Mid to high 2200s.


all touching with 25.0 grains of 748 with a Rem 9 1/2 primer. 2.815"OVL Cheers!
If they're all touching, that's great. It's interesting that my guide doesn't list 748 for the 145 gr cast. But for the 160 gr cast bullet, it lists a start of 34.5 gr and max of 39.0 grains of 748, topping out at 2299 fps.

FWIW, I have so far kept my own 7mm-08 loads well below all of the start loads in this guide, myself. One of my most common loads is 24 grains H335 under a 130 grain cast, which is pretty similar to Fireball's load. I haven't been too concerned with long range ballistics and the associated recoil. I am more inclined to use jacketed bullets for that. But for the OP, it looks like there's some room to grow.


similar to 4198 in burn rate
For the 160gr cast, it lists IMR 4198 max load of 29.5 gr, 2181 fps, 36,100 CUP.

Most of the loads max out in the 3x,xxx CUP range, with only the Unique, SR-4759, and 2015 loads breaking 40,000. And none of these loads show as compressed. So I suppose the max load is where the bullets start flying off the paper.

[kiwi]

Welcome, Kiwi ! My RCBS Silhouette 145 hard-cast fired in a heavy 25mph wind in a McMillian custom target rifle will group five shot groups, all touching with 25.0 grains of 748 with a Rem 9 1/2 primer. 2.815"OVL Cheers!
Thanks Fireball57, Your rifle has a longer throat than mine I loaded mine at 2.775" and they were jammed in the rifling need to back off some

[MT Chambers]

They can be shot just as fast as you can work the bolt.

[kiwi]

On a Sako 75 that can be pretty fast

[oldblinddog]

Isn't AR2208 Varget? I'm shooting a 185 gr in .308 W over 25 gr of Varget as a starting load. I think it would work for your 7-08 with that boolit. I had that combination years ago and it shot very well, but that was before Varget came along. Seems like I was loading IMR 4198.

Use a magnum primer with that Varget load.

[kiwi]

Yes Varget is AR2208 I have quite a lot of it, it's the best powder in my 6mmBR and for J-words in the .308, have it on the short list for the 7mm-08 along with H4895 and Nobels No 3 rifle which similar to 4198, bought a 100 Norma cases and have a pile of .243's to neck up going to be busy in the next few weeks, we are heading into winter down-under that will limit the days at the range.

[oldblinddog]

The 7-08 is a great cartridge (any 7mm really). Try that load and let us know.

[MBTcustom]

Better hang back to about 1800fps if you want repeatable accuracy. Use a short bullet that has a good shape (shy away from bore riders) and use powders on the slow side. Cast your bullets out of Lyman #2 or equivalent.
Work your way up till accuracy goes south, take a step back, check for accuracy at distance (200 and 300 yards) then proceed carefully and repeat. With a 9.5 twist rate, it's going to be real hard to get above 2000fps and still have repeatable accuracy at distance (remember that 1" at 100 yards does not always mean 2" at 200 yards etc etc.)

[gloob]

a pile of .243's to neck up going to be busy in the next few weeks, we are heading into winter down-under that will limit the days at the range.
If you have a way to turn necks, I would try to hang onto that pile of .243. 308 cases are cheaper, and a good deal on a .243 is just around the next corner. If you're just swimming in .243 cases, I would think you could trade for 308 cases in your favor.

Converted .308 cases come out about 10-15 mils too short, though, if that's gonna bother you.

[kiwi]

Goodsteel,
Thanks that's the best answer so far my plan is to get a load that shoots well at 200 metres the local rifle silhouette club .22 RF is setting up a 200 metre CF range and I want to shoot it with cast boolits 1800fps is plenty fast enough.
gloob
I have 2 6mmBR's and a 6mm Rem and I don't really like .243's no chance of buy one unless it's for the action, and I have 5 .308's so necking down 308 cases is not on, all cases are hard to come by down here along with all other reloading components, at least I have all the boolits I can cast at a good price, Robert.

[TXGunNut]

Wow, two new posters on one thread! Welcome to both of you.

[MBTcustom]

Goodsteel,
Thanks that's the best answer so far my plan is to get a load that shoots well at 200 metres the local rifle silhouette club .22 RF is setting up a 200 metre CF range and I want to shoot it with cast boolits 1800fps is plenty fast enough.
gloob
I have 2 6mmBR's and a 6mm Rem and I don't really like .243's no chance of buy one unless it's for the action, and I have 5 .308's so necking down 308 cases is not on, all cases are hard to come by down here along with all other reloading components, at least I have all the boolits I can cast at a good price, Robert.

Believe me, I wish you were closer. I'd trade a bushel basket full of goodies for a chance to enjoy a trip to your country for a week. (sigh)

[runfiverun]

the rcbs boolit has it's drawbacks but accuracy is not one of them.
I'd try about 25 grs of your varget to start and see where it takes you.
I was using 24 grs of 4895 in the wifes 7x57 for man,,, forever it seemed like.
I worked the trigger over and made 50 pieces of brass that 100% fit that rifle]
she got so she hated that rifle 'it was soooo boring to shoot'. [her words]

she made the local paper twice shooting that rifle during the deer hunt, once for shooting through two bucks with one shot [I wasn't there I was at work at the time, she was with some friends] and once for the biggest buck of the year.

then she traded it off for a savage 30-06. [I wanted to cry]

[kiwi]

Goodsteel,
You need more than a week, Though we are not a big country there is a lot to see I've been here 68 years and not see all of it, Robert.

[UBER7MM]

Better hang back to about 1800fps if you want repeatable accuracy. Use a short bullet that has a good shape (shy away from bore riders) and use powders on the slow side. Cast your bullets out of Lyman #2 or equivalent.
Work your way up till accuracy goes south, take a step back, check for accuracy at distance (200 and 300 yards) then proceed carefully and repeat. With a 9.5 twist rate, it's going to be real hard to get above 2000fps and still have repeatable accuracy at distance (remember that 1" at 100 yards does not always mean 2" at 200 yards etc etc.)

Goodsteel has good advise.

For your 160 grain boolit in an 1:9.5" twist barrel in 7mm'08, try starting at 23.4 grains of AR2206H (4895) or like powder and work up .3 grain increments, shooting 3 shot groups. I suggest a new target for each powder grain increase. Then graph them all on one sheet of graph paper for analysis. Depending on your barrel length you probably find the smallest group in the 24 grain range. (This powder range also works for the 7x57).

You might also look into fillers such as Dacron polyester (pillow stuffing) for non-case full loads.

I hope this helps,

[kiwi]

the rcbs boolit has it's drawbacks but accuracy is not one of them.
I'd try about 25 grs of your varget to start and see where it takes you.
I was using 24 grs of 4895 in the wifes 7x57 for man,,, forever it seemed like.
I worked the trigger over and made 50 pieces of brass that 100% fit that rifle]
she got so she hated that rifle 'it was soooo boring to shoot'. [her words]

she made the local paper twice shooting that rifle during the deer hunt, once for shooting through two bucks with one shot [I wasn't there I was at work at the time, she was with some friends] and once for the biggest buck of the year.

then she traded it off for a savage 30-06. [I wanted to cry]
I would like a 7x57, when I bought the Sako there was a Ruger No1 International in 7x57 for $50 more it was a hard choice but the Sako won out it's more practical for what I am doing right now,
I was at the range earlier today sighting the Sako in put a Leupold 12x on it, was sorting out the seating depth for the RCBS 145 Sil loading 15 grains of 2400 5 shot groups were 1.6" - 1.7" at 100 metres not a bad start need to fine tune the depth a little more I think, will try Varget and H4895 next, I am using necked up Winchester .243 cases first don't want to wreck any new Norma cases will use them when I have some good loads sorted out, My round count is only 55 so it is coming together quicker than I thought it would I'll get the chronograph out next week if the weather plays ball, Robert.