Calculating Nodes

[Bill Daniel]

Just back from testing some loads with 175 grain SMK's and R15 power. My best group was with 43.6 grains at 0.75 inches for a 5 shot group at 100 yards. 43.4 yielded 1.19 inches/ 43.8 yielded 1.01 inches/ 44 yielded 1.15 inches and 44.2 yielded 1.36 inches. This is from a Savage FCP in 308 at 0.01 inch from the lands. Should I try 43.5 and 43.7 to fine tune or does 0.1 grain change make that much difference in a 308? My goal is a 1000 yard round. My plan is to find my most accurate load and then chronograf to see if the muzzle velocity will keep the 175 SMK supersonic at 1000 yards. Once there I will work out the distance in stages. Any advice is appreciated.
Thanks

[mehavey]

1/10 grain will make little (if any) difference, and is the usual margin of error in even the most consistent of reloading processes. Some suggest 2/10ths as the least rung on the ladder. I have settled on 3/10th for the most part.

As to velocities/pressures for your 175SMK/43.6gr Varget/2.800 OAL: QL tells me you are running 56,500psi (in a 60,000psi max cartridge) for 2,640fps in a 24" barrel. The usual match (M118) standard is 2,550, so you're G2G for 1,000 yards.

Incidentally, ±1/10th grain yield ± 6fps ..... totally in the statistical noise; and seating out another 50 thousands (or wherever the lands might be in your rifle) only loses you 20fps.

[black mamba]

Seating closer to the lands (farther out) in a bottleneck cartridge will INCREASE pressure and velocity, not lose it, unless you have a 1/4" or more of freebore.

[edward5759]

With the 175 grain bullet I have found most loads will be sonic out to about 1000 yards after that they drop off fast.
I got key holes at 1200 on paper. Computer programs are just that, programs they will give you an idea but that's about it. Shooting is the best way to tell.
Shooting here in Arizona I have had good luck with BLC powder even when it's 115 degrees outside.
My best was with 172 B.T. Government pull downs.
I do shoot with a + 20 mount for the scope to give enough clicks for the distance. I have had no luck shooting longer distance with the 308. but I have had a little with the 30-06 "A little better"
Good luck
Edward5759

[mehavey]

Seating closer to the lands (farther out) in a bottleneck cartridge will INCREASE pressure and velocity,

I have not found that to be the case experimentally. Pressure may initially peak slightly higher,
but it's the total area under the 24" curve that finally matters. I generally give it a wash.

[Bill Daniel]

Thanks to all for your replies. Thanks, mehavey, for checking the ballistics on your Quick Load calculator for me. edward 5759 new glass and mounts will be in the works as I increase my ranges.

[mehavey]

I have not found that to be the case experimentally. Pressure may initially peak slightly higher,
but it's the total area under the 24" curve that finally matters. I generally give it a wash.

Supplying mere corroborative detail to add verisimilitude to an otherwise bald and unconvincing narrative... ( )*
here is the data/experience I had mentioned earlier.

http://thefiringline.com/forums/show...58&postcount=1





* Poo-Bah in The Mikado

[Brian Pfleuger]

UncleNick has several times posted a graph of seating depth versus pressure in 30-06.... Here is one such example:




Were I to hazard a guess, I would say that pressure and velocity BOTH increase as the bullet is seated closer to the lands but at some point, probably very close to the lands, the force of engraving the rifling without the bullet getting a headstart "uses up" the extra pressure and velocity no longer increases. That theory seems more or less in line with Mehavey's graph.

Note that there's not a whole lot of change in pressure based on UncleNicks chart. A full quarter inch change in distance changes the pressure only 6,000 psi, about 9.6%.

Along more common distance (say 0 to .10), the change is only 2,500 pounds.

It would be very interesting to see a velocity graph overlay of that pressure graph.

[frank_1947]

Bill

Save your self alot of time, if your going to shoot 1000 yards load to max of what ever book your useing best is go to manufacurer website and see what they tested bullet placement at lands will be what your looking far, all of the data books out there have been tasted if your gun is in good shape it should be no problem the worst that could happen is bolt may be harder at max to open then back off about.5 gr I shoot all competitions and most folks go for it all to max and then some. I have loaded for many 308 savage savage uses the same reamer on all their actions and same action quality no fear with savage I use Varget , i use Hogdon data from web and go max on any bullet hogdon shows that max is compressing powder not a problem bolt a little sticky on the palma gun back it off .5 it goes good.

With any savage out of box right load good rest shouls shoot 1/2 inch at 100 and a constant 1/2 moa out to 200 from there on its the shooter.

[Brian Pfleuger]

I know you did not just tell an inexperienced reloader to load some max charges and back off half a grain if the bolt sticks!

Surely, you mean to work up those loads from the suggested starting load?

Surely, by "worst that could happen", you meant "as you work up the loads" not "slap in that max load and all you might get is a sticky bolt".... right?

[frank_1947]

that is correct all mfg do intence testing before releaseing data , as i said if it is in good condition there should be no problem I load wildcat 30BR all the way to the top and compress the load a good 1/8 inch enuff for brass to hold bullet on a jam, I start out a max, and go backwards, most folks just have a fear of that after 35 years of loading I have never seen a problem with MFG data being to hot they would never take that chance.

Good example I shoot USPSA in open class to make a power factor that is required in a 9mm pistol you must go way above any known data running a 124 gr bullet 1400 fps in a 5 inch gun , worst I seen case head seperation thousands load that round like that.

In 600 yard Benchrest alot of folks go for 99% case capacity thats beyond any data with rem 700s or savage actions.

I should add one more thing if bolt closes easily when loading round your good to go if not dont load ck headspace.

This is just my opinion over the years what I have learned.

[mehavey]

[highvel]

Shocking turn of events dear Watson

[Bill Daniel]

frank_1947, Thanks for your suggestions but I noticed that my groups began getting larger the further I got from my 43.6 load so I would figure it would be worse at an over max load. Any thoughts?

[frank_1947]

what tool or method did you use to contact lands, Hornady modified case or on a jam, you said you are.010 out of lands try at touch or on a jam and back .005 at a time try 5 of each this is the most important part of finding the right load, just in case Hornady makes a tool #C1000 overall gauge and case #A308 are the part numbers. if you want you can neck size put a bullet just started in case no primer of coarse and slide bolt forward and jam till bolt closes then take it out measure and load from there going .005 out each time.

I never use Rl powders but go in the middle if you dont care to go close to max bullet position is far more important then powder in the begining one you get the best group on position to lands then work on powder amounts if once you find something good and you go from 100 to 200 yards , if it is shooting for example 1/2 inch at 100 you should be 1 inch at 200 if it opens up go up .5 or better until it closes up.

I do a set up thing for people at the indoor range i do classes far I go to their house set up dies and teach them to reload take them to the range and get them from 1 1/2 to 1/2 in just a couple outing by doing just what i said, also some barrels shoot better with other bullets, recently I did a savage palma gun in .308 it liked Hornady Amax over sierra and end result was 155gr amax at 46.5 grs of varget that was .5 from max it stayed constant at all ranges from 100 yards to 300 all at 1/2 moa , personnally I would never start with 175 gr one reason recoil less recoil you can shoot alot more comfortable without anticipating recoil try some 155 and 168 if your not satified with the 175 just because you have a 1/10 twist doesnt mean there going to shoot the best every barrel has its own personallity, it is alot of time , money and work to find the best load I will buy Breger , hornady and Sierra when I build a new gun, have you been cleaning it well ?

Keep it going let us all know your results might wanna try Varget

go here http://www.accurateshooter.com/cartridge-guides/308win/

[Bill Daniel]

I measured the distance to the lands with Hornady's LNL tool. The brass is fireformed Lapua. I have a nice load with 168 SMK's with 43.8 of Varget (also works well with A-Maxes. The books seemed to indicate I would get greater velocity with R15 and since my goal was a 1000 yard load I was testing the 175 SMKs with R15. As Pete noted I have less than 300 rounds of rifle reloading experience and so will tend to be cautious. I reload 45 ACP also and have for many years but aside from a double charge there is not so much you can screw up reloading that cartridge. I use Wipe Out and keep the bore squeeky clean. I also will fire three to four fouling shots prior to beginning my measured groups. I will try 0.005 inches off the lands to see how that changes the groups.
Thanks again to all. I have learned most of what I know from reading your posts over the years.

[frank_1947]

Causious is good, you will need all you can get to hit at 1000 keep in mind Palma shooters use only a 155gr bullet for 1000 yard competition and F class shoots 1000 also, I can tell you this the Military uses a 175gr for some long range kills but they are running at 2700 fps + none of the books I have show data for that but Hogdon shows 2690 fps with 45 grs Varget, also a Mil Spec 308 that is 7.62x51 has a really long throat I have a Mil Spec gun and you can just touch the lands with a 175 and have enuff brass to hold the bullet you can not touch with any other lighter bullet , so long gives greater case capacity in a normal out of box gun that amount of powder is being compressed so you have more pressure you can reach 1000 no problem with any bullet, but how effectively?

The gun I have is not a catalog gun and only one distributor carries it, it is a Rem 700 R4 Mil Spec SS I have won 1st and 2nd place with it this year, you can find then on the internet $1000 plus under $1000 is good.

Sounds like you may be really getting into long range so keep in mind with your Savage action down the road you can have a barrel made just for 1000 yards + You would take a 175GR bullet set it in your case just so the brass grabs good maybe 1/4 inch then y6ou send that round no powder or primer to Shilen ask for no freebore a .330 neck 1/10 twist R4 or R5 not sure if they have R5 someone does just cant remember , Krieger will do the same but you save money with shilen because you can set barrel up your self with a few tools and a GO gage, I am thinking of doing this now but with a 155gr bullet.

Good luck
Frank