Improving the 308 Win performance

[nralifer]

I ran 2000MR, kissing cousin to the LVR. By that I mean, the powder charge @nralifer is using on the 150BD2 is almost the same as my 2000MR charge I use to launch 168 Hybrids on SRP Remington UBR brass. 2800 is what I get from my double lugged long range purposed built M1a. The bearing surface of the 168 Hybrid is closer to that of the 150-155 class bullets than they are to traditional 168s. Can't run the SMKs the same way.

What speed and with what charge of the 2000MR can you get the 168 Hybrid in a bolt gun? Would be interesting to know.

 

[nralifer]

I tried to put @nralifer on the spot to provide more details about his products, which he did.

Remember, bullet length is very important. In the case of tipped bullet you have to subtract from the bullet OAL the length of the tip. In the case of an aluminum tip you should subtract half the length of the tip since aluminum is denser than plastic. The JBM stability calculator allows you to do this.

 

[bamban]

What speed and with what charge of the 2000MR can you get the 168 Hybrid in a bolt gun? Would be interesting to know.

I don't have any 308 bolt gun with enough twist to run a meaningful comparison. Have a few gassers in 308s including a couple of NM heavy contour barreled Garands.

In my double lugged purposed built long range M1a, using fireformed SRP Remington UBR, CCI41, 168 Hybrids at 2.93, load is right at 50 grains of 2000MR. Prone matches are single loaf only, not restricted to mag length.

I am running them at 2900 in the 28 inch 30-30 bolt action prone gun.

There is another 308 prone gun I have not shot, but we optimized the barrel twist for the 150 FB. Intended match, 300 yard prone. Can't remember whether the twist is 14 or 13 Krieger at 28 inches.

 

[nralifer]

The 308 case is capable of good performance depending on how you care to apply, and configure it.. AR 18" barrel 200 gr SMK 2673 fps...or 225 gr ELDM at 2477 fps .. mag feed slows it down 208 gr 2500 fps, 168 Berger 2800 fps. 2825 with 150 gr gold dot... I don't usually shoot light 150 gr bullets in 308, for lack of BC. ..All in 18" AR... I have a modified AR to feed 2.940" to 2.960" cartridges depending on the modified mag brand, to go with the modified reciever.
Bump it up to a long action bolt gun, long barrel, bi metal hybrid cases for magnum like velocities 200 gr SMK are now 2952 fps, and 225 ELD-M 2719 fps, its what's possible from a 308 case. Even have some 250 Atips to try,... as I was already running 2620 fps for the 230 Atips in Lapua brass cases. The hybrid cases allows for more velocity, some of these loads are over 3700 ft/ lbs of muzzle energy out of the 308 case I have experimented extensively with the 308 case. And the Bimetal cases have given my 6.5 Creedmoor a new lease on life, as I was done with that caliber, as it couldn't keep up with my 308 heavy bullets...now its got a new lease on life, and settled on a performance load for the hybrid cases running 153 Arips at 2956 fps, 150 SMK 2980 fps, and 147 at 2979 fps average velocity and grouping...big improvement over factory 2700 fps area, loads. It takes alot of time, expense, and effort to experiment with components, altering firearms, testing available powders, and a machine shop to do the alterations, action, barrels, chambering, throating.
It's easier for the average guy to just by a magnum in that caliber...but I already have the 300 RUM and it's heavily altered too, so it can feed 4.00" cartridges...so it's high velocity with 250 Atips.
Right now I'm working on a high velocity load for a 358 Win in a 16" AR ! A "bunny load" as a friend described so he's gonna see my version of a bunny load. Question...Is it possible to reach 4000 fps with a 358 Winchester in a 16" AR? For 30 yard jackrabbit, type accuracy, with expendable LC brass.

The 150gr 308BD2 has the same G7 BC as the Berger 168 Hybrid and it can be pushed faster and penetrate better. No need for bimetal cases. I use 2950 fps from a 20" barrel but the fact is that it is possible to get 3025-3050 from the same barrel. I know that 2950 is safe in ambient temps in the 90s. I'm not that fixated on speed. The are very deep penetrators in game and as a result are excellent to use in quartering shots. With that bullet, I have seen 32" penetration in bear which died immediately.

 

[3chester]

I don't have any 308 bolt gun with enough twist to run a meaningful comparison. Have a few gassers in 308s including a couple of NM heavy contour barreled Garands.

In my double lugged purposed built long range M1a, using fireformed SRP Remington UBR, CCI41, 168 Hybrids at 2.93, load is right at 50 grains of 2000MR

This is not about the 308 Win but, on those M1A's do you send in the trigger group, to have them reworked for bit lighter pull, less creep, etc or just use them stock?

 

[bamban]

This is not about the 308 Win but, on those M1A's do you send in the trigger group, to have them reworked for bit lighter pull, less creep, etc or just use them stock?

No, I do the trigger work myself. I tested the prototype on the faster locktime adjustable trigger for a friend before he introduced them. All NRA/CMP legal mod, since all internal.

ShootingSight

shootingsight.com

 

[nralifer]

What is "better"?
Flatter trajectory? Use a lighter bullet
More energy? Use a heavier bullet
More speed? Use a longer barrel or some of the newer powders.
More energy at subsonic speeds? Use the heaviest bullet your twist will allow.
You can try a bullet with less engraving pressure/shorter bearing length to increase your speeds too--certain monos and cup/core bullets would fall under this area

But every cartridge has its limitations


Ive gotten a178 ahh up to 2950fps from a 21" 30-06.
I havent had time yet to fool with that bullet in the 308, but I will try it at some point.

Just remember that you'll need enough energy for the animal you're hunting AND you'll need enough speed for reliable expansion for the bullet your using.

Excuse my ignorance but what is a 178 ahh?

 

[BEEMAN]

Excuse my ignorance but what is a 178 ahh?

My guess is absolute hammer hunter.

 

[nralifer]

My guess is absolute hammer hunter.

If that's the case the BD2 wins hands down. Because of the BC difference the BD2 will have close to twice the bullet energy at 600 yds snd the gap widens further after that. We have already shown the 175 gr BD2 from the 308Win using SRP brass, LVR powder and a 26" barrel at 2900 fps. To be fair he has not responded to my query though. What you say makes sense.

 

[nralifer]

I don't have any 308 bolt gun with enough twist to run a meaningful comparison. Have a few gassers in 308s including a couple of NM heavy contour barreled Garands.

In my double lugged purposed built long range M1a, using fireformed SRP Remington UBR, CCI41, 168 Hybrids at 2.93, load is right at 50 grains of 2000MR. Prone matches are single loaf only, not restricted to mag length.

I am running them at 2900 in the 28 inch 30-30 bolt action prone gun.

There is another 308 prone gun I have not shot, but we optimized the barrel twist for the 150 FB. Intended match, 300 yard prone. Can't remember whether the twist is 14 or 13 Krieger at 28 inches.

I wish I could give you some meaningful data for the M1A, but mine doesn't shoot very well and I don't think that we can take advantage of the somewhat higher pressures that bolt guns can take. We are working on a 135 gr BD2 which is about 0.090" shorter than the 150 gr BD2 and whose BC is quite good, exceeding that of most, if not all, 150 gr lead core bullets. Still working on low velocity loads to test the minimum impact speed at which it opens up in gel. So far the G7BC = 0.218, so it shows some real potential in the M1A and AR10 platforms since it can be loaded to an OAL=2.89" or less, and it's lighter weight should allow for pretty good MVs. Here is a photo of the bullet

 

[bamban]

I wish I could give you some meaningful data for the M1A, but mine doesn't shoot very well and I don't think that we can take advantage of the somewhat higher pressures that bolt guns can take. We are working on a 135 gr BD2 which is about 0.090" shorter than the 150 gr BD2 and whose BC is quite good, exceeding that of most, if not all, 150 gr lead core bullets. Still working on low velocity loads to test the minimum impact speed at which it opens up in gel. So far the G7BC = 0.218, so it shows some real potential in the M1A and AR10 platforms since it can be loaded to an OAL=2.89" or less, and it's lighter weight should allow for pretty good MVs. Here is a photo of the bullet

The 135 looks good. Mag length ammo for my purpose is not a critical requirement. I only shoot from magasine length if I have to. Boat tail junction above shoulder is where I start. I've hunted single loading.

I still say the 175BD2 is the best compromise. My McCoy 308 Garand 11.25 Obermeyer is set up to run heavy loads, I will order some 175BD2 to run in it. This rear lugged Garand is also purpose built to run heavies at higher pressure. It loves the Juggernauts, but at 2650 I did not see any big advantage at 1K over the 168 Hybrids running at 2800.

If the rifle ran well with Juggernauts, it should digest the 175BD2s with no issues. It will be fun to see how well I can group with these, now that I can see the front sight again. Thanks to the toric lenses from cataract surgeries.

 

[nralifer]

The 135 looks good. Mag length ammo for my purpose is not a critical requirement. I only shoot from magasine length if I have to. Boat tail junction above shoulder is where I start. I've hunted single loading.

I still say the 175BD2 is the best compromise. My McCoy 308 Garand 11.25 Obermeyer is set up to run heavy loads, I will order some 175BD2 to run in it. This rear lugged Garand is also purpose built to run heavies at higher pressure. It loves the Juggernauts, but at 2650 I did not see any big advantage at 1K over the 168 Hybrids running at 2800.

If the rifle ran well with Juggernauts, it should digest the 175BD2s with no issues. It will be fun to see how well I can group with these, now that I can see the front sight again. Thanks to the toric lenses from cataract surgeries.

I appreciate your enthusiasm for the 175, but the fly in the ointment is that the 175 needs a 1:10 twist. Actually the 150 BD2 has the same BC as the 168 Hybrid, but is stabilized by a 1:11 twist. It being 18 gr lighter than the 168 but with the same G7 BC, you should see a higher MV.

 

[bamban]

I appreciate your enthusiasm for the 175, but the fly in the ointment is that the 175 needs a 1:10 twist. Actually the 150 BD2 has the same BC as the 168 Hybrid, but is stabilized by a 1:11 twist. It being 18 gr lighter than the 168 but with the same G7 BC, you should see a higher MV.

Thank you.

Will switch plan and order the 150BD2s.

Order placed.

 

[bamban]

150BD2 came in today.