Heaviest 30 cal. round (High BC) for the 308 Winchester in a Semi-Auto??

[OneCleanShot]

Gentlemen:

I am interested in shooting an accurate 308 semi auto rifle out to 1000 yards for local tactical matches and some fun with friends. The rifle has a 26" Stainless bull-barrel, air gauged, and cryo-treated. Twist is 1:10. I have only shot factory loads so far to just short of 600 yds with Federal's Sierra Match 175gr (.243 G7 BC) being the heaviest so far. After reading Brian Litz's books and scanning the G7 BC's it looks like Hornady has a 208gr AMAX with a .324 G7 (.633 G1 BC) and Berger has some very good 185 and 190 gr low drag/ high BC projectiles. Is it possible to load these for the given rifle with enough powder at the correct cartridge length for around 2500-2600 fps at safe pressures? Or, are these typically for something like the 300WM to push out there? I am starting to pick up some loading equipment and will soon start down that rabbit hole.

As always, thank you for reading and for your time and experience.

 

[BryanLitz]

"Magazine length" will constrain the weight/length of the bullet you can use practically.

The .308 Win is highly versatile, and if you can throat out a chamber and single load rounds, you can shoot the longest/heaviest (230/240 grain) bullets well. But these will be seated way WAY beyond magazine length.

So backing up and considering what you can do within magazine length without the bullet nose going below the case neck, or the back of the bullet taking up all your powder capacity, you're practically limited to ~185-190 grains.

My advice is the Berger 185 LRBT (Juggernaut) bullet. Good combination of BC, mag length compatible, and jump tolerant.

If you're willing to single feed rounds, you can step up to 200-230 grain Hybrids but they won't be mag friendly rounds.

Take care,
-Bryan

 

[Rob01]

Yeah I wouldn't go over 190s. The 208s are an excellent bullet in the 300WM and even in a bolt .308 they work for people but in a semi auto I wouldn't use them.

Look at the Hornady 178 BTHP. Has a .530 BC and you can get decent velocity out of them.

 

[ORD]

+1 on all of the above.

With mag-length constraints, I generally stick with the ~175gr class bullets for .308 semis which work VERY well out to 1,000 (and further if you REALLY need it), but Bryan, as usual, is right on with the 185gr Juggernaut bullet recommendation. I haven't worked up any loads yet, but I've got a box sitting on the bench waiting for a rainy day to load 'em up and test 'em out. I have high hopes for them...depending of course on how my t&e with them goes, but I'm sure I won't be disappointed as Berger has yet to let me down.

 

[CK_32]

I am starting to pick up some loading equipment and will soon start down that rabbit hole.

As always, thank you for reading and for your time and experience.

This right here scares me and throws a red flag. Before you start pushing the limits of pressure and going wild reloading. Learn and start reloading first. Your trying to run for the Nobel Prize with out even taking a science class yet.. This will not end well. Start with normal proven bullets and loads and get your basics. THEN start experimenting. And I suggest you really understand what your messing with. Agin the fact that your already looking to push the limits before you've even started is not a good attitude to start reloading with.


I wish you the best of luck. Please be careful. Do not rush reloading. I grantee you'll screw up enough just doing the basics, we all have.

 

[OneCleanShot]

This right here scares me and throws a red flag. Before you start pushing the limits of pressure and going wild reloading. Learn and start reloading first. Your trying to run for the Nobel Prize with out even taking a science class yet.. This will not end well. Start with normal proven bullets and loads and get your basics. THEN start experimenting. And I suggest you really understand what your messing with. Agin the fact that your already looking to push the limits before you've even started is not a good attitude to start reloading with.


I wish you the best of luck. Please be careful. Do not rush reloading. I grantee you'll screw up enough just doing the basics, we all have.

I am certain that you misunderstood me.

I just wanted to know what was possible. I did not say i was jumping right into anything. I did not want to buy 500 200 gr bullets to find out that it was not the way to go for my rifle. I know the 150 gr bullets work for the 308 win but I also know there are better ones out there for my application and was seeking the knowledge before jumping as evidenced by my post asking for advice. As I will be feeding from the magazine, I suspected that the cartridge length would be magazine limited which would probably limit my bullet length as the heavier VLD projectiles tend to be long. I was just trying to find out if anyone had gone there before.

Additionally, I have taken plenty of science classes and am quite comfortable with the science and technology of LR shooting and reloading but do not have the experience of some of the others here. Learning before leaping was indeed the purpose of my orginal post.

 

[OneCleanShot]

+1 on all of the above.

With mag-length constraints, I generally stick with the ~175gr class bullets for .308 semis which work VERY well out to 1,000 (and further if you REALLY need it), but Bryan, as usual, is right on with the 185gr Juggernaut bullet recommendation. I haven't worked up any loads yet, but I've got a box sitting on the bench waiting for a rainy day to load 'em up and test 'em out. I have high hopes for them...depending of course on how my t&e with them goes, but I'm sure I won't be disappointed as Berger has yet to let me down.

Thank you for your post. I have not tried the 175 Sierra Match factory ammo to 1000 yds yet. I will this summer but hope to be reloading and have some of my own to try. 185 gr juggernaut is in the book. If you think of it, get back to me with your experiment.

 

[OneCleanShot]

Yeah I wouldn't go over 190s. The 208s are an excellent bullet in the 300WM and even in a bolt .308 they work for people but in a semi auto I wouldn't use them.

Look at the Hornady 178 BTHP. Has a .530 BC and you can get decent velocity out of them.

Thank you for your post. Is the 178 gr boat tail hollow point a factory round from Hornady?

 

[ORD]

Thank you for your post. Is the 178 gr boat tail hollow point a factory round from Hornady?

Hornady makes the 178gr BTHP available in their "Match" lineup. Here is one example, but make SURE you do NOT mistakenly purchase the "Superformance" ammo which is NOT a good idea for most semi-auto platforms: Hornady Match Ammo 308 Winchester 178 Grain Boat Tail Hollow Point Box

 

[OneCleanShot]

"Magazine length" will constrain the weight/length of the bullet you can use practically.

The .308 Win is highly versatile, and if you can throat out a chamber and single load rounds, you can shoot the longest/heaviest (230/240 grain) bullets well. But these will be seated way WAY beyond magazine length.

So backing up and considering what you can do within magazine length without the bullet nose going below the case neck, or the back of the bullet taking up all your powder capacity, you're practically limited to ~185-190 grains.

My advice is the Berger 185 LRBT (Juggernaut) bullet. Good combination of BC, mag length compatible, and jump tolerant.

If you're willing to single feed rounds, you can step up to 200-230 grain Hybrids but they won't be mag friendly rounds.

Take care,
-Bryan

Thanks for the post Brian. I suspected feeding from the magazine was going to limit my length/ weight combination and was trying to find out if anyone had gone down this path before. Sounds like 185-190 grains is going to be it for me then. I will try the Berger 185 LRBT first up then.

I also have notes from your book indicating the Berger 185 Hybrid and 190 VLD have higher G7 BC's. They also are longer. I may experiment with these as well unless you can think of a reason why i should not use them for my application. Again, its long range targets and tactical matches so terminal ballistics are not currently important to me.

I have read both of the books. Well done. They have helped me separate the wheat from the chaff in numerous discussions as well as make decisions on some pieces of equipment. I am rereading the large book currently.

PS: GO STATE! ha ha ( Class of '83)

 

[rchman]

What about the 155gr scenars?

 

[CK_32]

I am certain that you misunderstood me.

I just wanted to know what was possible. I did not say i was jumping right into anything. I did not want to buy 500 200 gr bullets to find out that it was not the way to go for my rifle. I know the 150 gr bullets work for the 308 win but I also know there are better ones out there for my application and was seeking the knowledge before jumping as evidenced by my post asking for advice. As I will be feeding from the magazine, I suspected that the cartridge length would be magazine limited which would probably limit my bullet length as the heavier VLD projectiles tend to be long. I was just trying to find out if anyone had gone there before.

Additionally, I have taken plenty of science classes and am quite comfortable with the science and technology of LR shooting and reloading but do not have the experience of some of the others here. Learning before leaping was indeed the purpose of my orginal post.

Yea you'll have to excuse me it's just VERY common for guys to come into reloading and say "I have all my stuff what's your guys' 308 loads?!" To cut time and run our tested and worked load so they don't have to with no logic in the dangers or care about it or real understanding what they are potentially doing. I'm sure many reloaders can attest to witnessing at least a few threads as I just described.. But that said I'm glad you have a head on your and to actually offer some help I wouldn't go above 178 or 185's just for the fact that I've run 175s and they do a dam fine of a job in both my 1:12 and 1:10 rifles.


Also there is a reason they are so popular, that said heavier bullets usually buck wind better but they often usually drop faster as we'll. So to every bullet there is and like wih everything will be both pros and cons. You'll find heavier isn't always the best. Try the common proven 155, 168 and 175's to get a good base of proven great projectiles which should give you a good base to test and see your self later what the heavier bullets can do and if they suit you better than the lighter bullets and again give you something to compare them to already using and seeing what the lighter bullets can do.


So heaviest I'd say 185's from a 1:10, reccomended 155,168 or 175's.

 

[OneCleanShot]

What about the 155gr scenars?

The Lapua 155 gr Scenar has a G7 BC of .236 (G1 BC =.462) which is very good for a 155gr projectile but does not match some of the 155gr offerings from Berger and gets whooped by the 168gr-190 Berger bullets and the 185 gr Scenars and other "heavy" 308's. The G7 BC's here are up to .291 (G1 = .570).

For my application, which is long range (for the 308win) targets up to 1000 yds, heavy and high BC bullets is what I am looking for. I am trying to figure out just how heavy/high BC I can go given the constraint of feeding a semi-auto from a magazine.

 

[ORD]

I am trying to figure out just how heavy/high BC I can go given the constraint of feeding a semi-auto from a magazine.

Just keep in mind when researching/doing your due diligence on various bullets that the MAX COAL for your average .308 gasser due to mag constraints is somewhere around 2.82" (generally, 2.80" to 2.82" depending on which mags you are running as some have a little more wiggle room than others).

 

[GhostFace]

Thank you for your post. Is the 178 gr boat tail hollow point a factory round from Hornady?

Yes, you want the #8105, it's standard pressure and not the Superformance line that caused some semi autos problems. It has the 178 BTHP (.530 BC) and it is damn fine ammo. I believe they may be resuming manufacture of this again as the bullet was on the temp suspended list but those are now in production again.

 

[OneCleanShot]

Just keep in mind when researching/doing your due diligence on various bullets that the MAX COAL for your average .308 gasser due to mag constraints is somewhere around 2.82" (generally, 2.80" to 2.82" depending on which mags you are running as some have a little more wiggle room than others).

Ok. thanks again. I think I have that one in the book as well. They are polymer FAL mags. What rifle are you building the 185 gr Bergers for?

 

[FCS]

OCS,

What is the OAL to touch lands with 175 SMK? 185 Juggernaut? Max OAL the mag will allow you to run?

Adjustable gas block?
Way to heavy up buffer?
Heavier buffer spring available?

I'd suggest you look at chamber and magazine before attempting to pick bullet.

Gas guns are not bolt guns; port pressure, port location, dwell time, gas volume cycling action, etc. are all variables that you don't have to deal with in a bolt rifle but can/will cause you issues in a gas gun.

 

[TwentyFiveTwenty]

Just keep in mind when researching/doing your due diligence on various bullets that the MAX COAL for your average .308 gasser due to mag constraints is somewhere around 2.82" (generally, 2.80" to 2.82" depending on which mags you are running as some have a little more wiggle room than others).

The alpha mags are AI compatible and can take max COALs of up to 2.920 in the 308 model. This doesn't help for most (any?) gas guns.

 

[johngfoster]

OCS,

What is the OAL to touch lands with 175 SMK? 185 Juggernaut? Max OAL the mag will allow you to run?

Adjustable gas block?
Way to heavy up buffer?
Heavier buffer spring available?

I'd suggest you look at chamber and magazine before attempting to pick bullet.

Gas guns are not bolt guns; port pressure, port location, dwell time, gas volume cycling action, etc. are all variables that you don't have to deal with in a bolt rifle but can/will cause you issues in a gas gun.

FCS beat me to it. Reloading for gas guns (read "semi-auto"--even piston guns are "gas guns") is not like reloading for bolt guns. The points he lists above are very real considerations that must be factored in. The gas system, whether direct impingement or piston, will be affected by the weight of the bullet, the powder you choose, and the amount of powder you use. Take for instance the M1 Garand: Chambered in 30-06, a gas piston design semi-auto. You can't just shoot any bullet out of it. If you shot the heavier 180gr + bullets you stand to break your rifle by bending the op-rod. It is not just the weight of the bullet, but the burn rate of the power needed to propel the heavier bullet at useable speeds. You need to use slower burn rate powders in order to do this, but this creates a larger pressure spike, which drives the piston harder, which will bend the op-rod. Then there is the issue of recoil. Not just a matter of if you can handle the pain from the "thump" on your shoulder, but how it will affect the rifle during the firing cycle. Heavier bullets produce heavier recoil, and this makes keeping the rifle on target while the bullet is traveling down the barrel harder. It makes shooting technique/follow-through more critical. What good is it if you can lob heavy bullets 1000yd, if you can't do it accurately?

Shooting heavier bullets in a semi-auto can be done, but you need to know what you are doing, and what the limits of your equipment are, and you need to have your shooting technique down pat. Learn to walk before you run. Get the basics of reloading down with established loads in the 168-175gr range first, then venture CAREFULLY out into the world of the heavies. Just my advice.

 

[ORD]

Ok. thanks again. I think I have that one in the book as well. They are polymer FAL mags. What rifle are you building the 185 gr Bergers for?

I'll test it out in several different rifles, but primarily for a custom Armalite-pattern 22", 1:10 twist Rock that I built myself and a POF P-308. These are already proven performers with a wide range of bullets from 155gr to 178gr. I'm more or less trying the Juggernauts for $#!T$ and giggles at this point because I can.

As for the "polymer FAL mags"...I'm assuming you mean for a RRA LAR-8. If so, then you might not have as much room to work with as other mags as all of the ones I have seen were prettymuch limited to 2.805". You'll have to measure yours and see what you come up with as there may be some slight differences.

 

[OneCleanShot]

OCS,

What is the OAL to touch lands with 175 SMK? 185 Juggernaut? Max OAL the mag will allow you to run?

Adjustable gas block?
Way to heavy up buffer?
Heavier buffer spring available?

I'd suggest you look at chamber and magazine before attempting to pick bullet.

Gas guns are not bolt guns; port pressure, port location, dwell time, gas volume cycling action, etc. are all variables that you don't have to deal with in a bolt rifle but can/will cause you issues in a gas gun.

Thanks for your post. The rifle is a direct impingement RRA LAR8. I do understand the issues you have mentioned but do not ( like many ) have the equipment to measure any of the above pressures/ dwell times on my rifle. I have used many types of factory ammo from 150gr to 175 gr thus far successfully. It is not a finicky weapon in that regard to date. Before moving on to reloading heavier, I will do all the research i can. This post is my first step in that direction. I will not be leaping into anything.

Because I will now be using the rifle to 1000' yards, I am beginning to eliminate as many variables as is possible. Factory ammo has been very good thus far to 600 yds but the jump to 1000 yds is, by all accounts, more than "just another 400 yds". Reloading is a must, I believe, to minimize mean velocity spread. Heavy, high BC bullets help the 308 out to the edge of its performance. I am planning on finding a load with a heavy, high BC projectile that is SAFE and DEPENDABLE in my rifle and that can be fed from the stock magazine. I was just trying to find out who, if anyone, has gone down this path before me and gain from their experience. This is an interesting, enthusiast hobby for me.....I will not be pushing any safety limits.....just giving it the best effort to consistently hit what i am aiming at through some long distances by using the best technology out there.

Rock River has been good about answering questions as I have gone along. JP Enterprises is also not far from my Minnesota house and will fit a custom gas block if i need them too. They are enthusiasts as well as builders and reload extensively for their range guns so I plan on using them for that too. I will see what I can do with the stock gas system first. I have not thought about a heavier buffer spring....so thanks for that.

Thank you again

 

[OneCleanShot]

FCS beat me to it. Reloading for gas guns (read "semi-auto"--even piston guns are "gas guns") is not like reloading for bolt guns. The points he lists above are very real considerations that must be factored in. The gas system, whether direct impingement or piston, will be affected by the weight of the bullet, the powder you choose, and the amount of powder you use. Take for instance the M1 Garand: Chambered in 30-06, a gas piston design semi-auto. You can't just shoot any bullet out of it. If you shot the heavier 180gr + bullets you stand to break your rifle by bending the op-rod. It is not just the weight of the bullet, but the burn rate of the power needed to propel the heavier bullet at useable speeds. You need to use slower burn rate powders in order to do this, but this creates a larger pressure spike, which drives the piston harder, which will bend the op-rod. Then there is the issue of recoil. Not just a matter of if you can handle the pain from the "thump" on your shoulder, but how it will affect the rifle during the firing cycle. Heavier bullets produce heavier recoil, and this makes keeping the rifle on target while the bullet is traveling down the barrel harder. It makes shooting technique/follow-through more critical. What good is it if you can lob heavy bullets 1000yd, if you can't do it accurately?

Shooting heavier bullets in a semi-auto can be done, but you need to know what you are doing, and what the limits of your equipment are, and you need to have your shooting technique down pat. Learn to walk before you run. Get the basics of reloading down with established loads in the 168-175gr range first, then venture CAREFULLY out into the world of the heavies. Just my advice.

Thanks for the Post JohnG.

All good advice. I plan on using it all.

My primary goal is obviously to hit what I am aiming at consistently at ranges to 1000 yds. I am not discounting at all the multitude of other things that go into long range shooting such as the rifle, the optics, atmospheric data, ballistic software, shooting technique, reading the wind etc etc. My post is only dealing with the external ballistics of flinging the 308 win to 1000 yds. Heavy/ high BC rounds provide an advantage here as does reloading to minimize mean velocity spread and other variables and so I was attempting so discover from others how heavy/ long they have gone on a semi auto 308 gasser fed through the magazine.

Safety AND 100% reliability are not negotiable of course.

 

[FCS]

Thanks for your post. The rifle is a direct impingement RRA LAR8. I do understand the issues you have mentioned but do not ( like many ) have the equipment to measure any of the above pressures/ dwell times on my rifle. I have used many types of factory ammo from 150gr to 175 gr thus far successfully. It is not a finicky weapon in that regard to date. Before moving on to reloading heavier, I will do all the research i can. This post is my first step in that direction. I will not be leaping into anything.

Because I will now be using the rifle to 1000' yards, I am beginning to eliminate as many variables as is possible. Factory ammo has been very good thus far to 600 yds but the jump to 1000 yds is, by all accounts, more than "just another 400 yds". Reloading is a must, I believe, to minimize mean velocity spread. Heavy, high BC bullets help the 308 out to the edge of its performance. I am planning on finding a load with a heavy, high BC projectile that is SAFE and DEPENDABLE in my rifle and that can be fed from the stock magazine. I was just trying to find out who, if anyone, has gone down this path before me and gain from their experience. This is an interesting, enthusiast hobby for me.....I will not be pushing any safety limits.....just giving it the best effort to consistently hit what i am aiming at through some long distances by using the best technology out there.

Rock River has been good about answering questions as I have gone along. JP Enterprises is also not far from my Minnesota house and will fit a custom gas block if i need them too. They are enthusiasts as well as builders and reload extensively for their range guns so I plan on using them for that too. I will see what I can do with the stock gas system first. I have not thought about a heavier buffer spring....so thanks for that.

Thank you again

190 SMK, while not super high in BC or latest n greatest bullet has worked very well for me from the magazine in a custom AR. RRA is going to have a fairly long freebore chamber. 190 Nosler CC is another option.

You'll want to restrict the gas (adj gas block), probably heavy up buffer weight and buffer spring if you are going to run the heavies.
I've taken the 190s out to 800 (far as I can go at "home" range) with very positive results.

Best wishes on your endeavor.

 

[OneCleanShot]

190 SMK, while not super high in BC or latest n greatest bullet has worked very well for me from the magazine in a custom AR. RRA is going to have a fairly long freebore chamber. 190 Nosler CC is another option.

You'll want to restrict the gas (adj gas block), probably heavy up buffer weight and buffer spring if you are going to run the heavies.
I've taken the 190s out to 800 (far as I can go at "home" range) with very positive results.

Best wishes on your endeavor.

Thank you. I put your notes in my book.

 

[Graham]

BC will only get you so far without velocity.

My .308 match load is 45 Varget in Lapua brass with a JLK 180 VLD LBT. That's 2740fps with a (verified, not advertised) .580BC bullet.

It runs 2.925 OAL, so you need to take the spacers out of your AICS mags, but they fit just fine in AW mags.

 

[OneCleanShot]

BC will only get you so far without velocity.

My .308 match load is 45 Varget in Lapua brass with a JLK 180 VLD LBT. That's 2740fps with a (verified, not advertised) .580BC bullet.

It runs 2.925 OAL, so you need to take the spacers out of your AICS mags, but they fit just fine in AW mags.

Thank you. I will be feeding a gas gun, however, from an FAL Magazine so will be limited to around 2.80" Have to find one that works reliably in that area of length.