LRB luodit

[MJ]

Moi,



noista luodeista oli keskustelua heti, kun uudet TA-killan sivut saatiin kuntoon. Mielenkiintoinen aihealue.



LRB:n ja vastaavat solidit luodit vaativat tosiaan tiukan rihlannousun vakavoitumiseen, johtuen juuri luotien pituudesta, valmistusmateriaalista ja korkeasta BC:stä.



TM:llä ja varmaan JPu:llakin on kokemusta solideista ja niiden nopeuksista yms...



Joten kannattaa kysellä lisätietoja TM:ltä ja JPu:lta.



Carpe Diem,



MJ

[john]

Sain todellakin tilattua pienen määrän LRB:n J 40 luoteja .308 kaliperissa.



Luodit ovat 200 grainisia eli n. 13 grammaisia. Pituutta luodille tulee 43,3 mm. Olin aluksi siinä uskossa, että luodit olisi sorvaamisen jälkeen työnnetty jonkinlaisen kalibrointiholkin läpi mutta näin ei ole asia. Myös Lapualta kerrottiin, että nykyiset CNC sorvit tekevät niin tarkkaa työtä, ettei erilliselle työvaiheelle ole tarvetta.



Kyseiset luodit vaativat 10 tuuman rihlannousun vakautuakseen. En ole vielä päässyt kokeilemaan luoteja, mutta .300 winmag:sta ammuttaessa luodilla tulee teorian mukaan olemaan 1000 metrin etäisyydellä vielä n. 525 sekuntimetrin nopeus. 1400 metrissä alitetaan 400 m/s. BC:n väitetään olevan peräti .785.



Luodilla saadaan aikaan melko laakea lentorata mutta todellisen "paremmuutensa" luoti kuitenkin näyttää kyvyssä vastustaa sivutuulta mikä mielestäni onkin tarkkuuden lisäksi ensisijaisesti huomioon otettava seikka luodin valinnassa.



Luodin pituuden takia ei patruunoita voida ladata sellaiseen pituuteen, että ne mahtuisivat normaaliin lippaaseen. Patruunoista tulee väkisinkin 6-8 mm normaalia pitempiä ja on näin ollen syötettävä patruunapesään yksitellen.



Mikäli luoti on tarkka, tulee se olemaan varteenotettava kisaluoti. Normaaliin harjoitteluun sitä ei kannata ostaa suolaisen 1,2 euron kappalehintaan.



Pyrin kirjaamaan testitulokset mahdollisimman tarkkaan, kunhan kerkeän radalle uusien patruunoiden kanssa.

[MJ]

Moi,



alla lainausta erään amerikkalaisen arvostetun testiampujan kokemuksista yli 35 vuoden ajalta. Hän on ampunut mm. useita 1000 yardin kilpailun ennätyksiä.



Sopinee tämän otsikon alle.



Miellyttäviä lukuhetkiä.



Carpe Diem,



MJ

When I was six years old I had rifle maintence, optic care and MOA drilled into my head.



At 10 years old I was consistantly making 500 yd shots with his old "scoped 1903 Springfield". He pasted away my 10 month in Nam. He always asked to pass the skill on, and I have. I've helped shooters from the FBI, DEA,state and local LEO, even duty snipers, all for free. Passing it on.



...I joined up with Jimmy Knox of JLK custom bullets. I was the first to test his 180 grain VLD's. Now must all custom bullets are made on J4 Jackets. Very thin, meaning you just can't push them to fast, 2850/2950 fps is tops. Unless you want the jacket to tear off and bullet blow up. Now you can push them faster in a new barrel up to about 400 rounds.



JLK, Bergers most all have the J4 jackets. I believe even Delta bullets. I tested bullets for them before he got the military contract, 6mm VLD's 105,106,108, and 115 grain bullets.



...175 gr SMK 7mm at about 2950/3000 fps. Well lets see, NO RECOIL, high BC, fast, but not a real barrel burner and should be extremely accurate. I feel a shooter could kick this round out at 3100 possible 3200 without any trouble.



The 6.5/284, BC is .595 with a 142 gr bullet at 2950/3000 fps; 175 gr BC of 608 at 2950/3000 fps. Higher BC, more wieght, bucks the wind alot better....



...here's what I found in testing many wildcats over the last 35 years.



1) Bullets will only fly at a certain RPM and stay together.

2) Bullets like a certain twist and speed in order to go to sleep.



If a bullet likes a 1 in 10 twist @ 2950 fps and thats where it goes to sleep, why not use the smallest case to do this?



In other words, if a 300wsm will push a 190 SMK @ 2940. Why feed a Ultra mag 80.0 grains of powder to do the same thing?



If 2940 fps is the speed @ 195,000 rpms is where the bullets see's the most extreme accuracy. Why try to push it faster? Larger cases means less rounds a SS, can carry. Larger cases means more felt recoil.



Now if your using a 240 grain SMK with a BC of 711, from the Ultra mag, then yes, now you have a round capable of extreme ranges. Well beyond a WSM.



I also looked at Remingtons new, 300 SA UM, this cases is shorter than the 300 WSM. I don't think this case will give you the FPS and RPM needed to put both the 30 cal and the 7mm to sleep.



Sleep?



Barrels have a right hand twist, bullets spin clockwise. Moving down the barrel a bullet causes vibration. At certain speeds, when leaving the barrel it will pitch the bullet. Thus causing bullet "yaw", a small spiral motion for 80/100 feet. Although sometimes lasting well past 100 yds depending on the speed.



Putting the bullet to sleep is where you tune the load @ a speed and rpm where the barrel has little or no vibration and the bullet exits the barrel smooth and free of Yaw. Thus the wind and conditions have less effect on the bullet on it's way to the target.



Thats why I believe certain case design and bullet designs are made for one another. Getting the maximum speed, RPM, sleep of the bullet, with the least amount of powder and cases damage.



In the early 90's while testing the 7mm, we saw a phenomenon, unlike any other bullets of any other cal. When I tuned the load so that the bullet went to sleep and I was able to obtain .5 MOA of accuracy @ 1000 yds, the groups got tighter at 1700 yds! Why? I'm not sure, but I have an idea that it reach the lower accuracy node (reduced speed and RPM).



There appears to be three to four levels of accuracy in any round, lets take a 300 wm for example.



Using a 190 smk, the bullet might go to sleep at these speeds,



1) 2550 fps

2) 2750 fps

3) 2950 fps

again @ 3050 fps, now problem here is @ 3050 fps you find case damage. So you try to find the highest accuracy node where there is no case, stretching or primer pocket expansion.



It's just my opion, but a who's, who's list and top of the heap is usually decided by World Record accuracy. Not the number of rifles built. Both Mr. Baer and Mr. Spencer hold that honor, of building the most world record setting 1000 yd rifles in the country. I've set 4 records using their weapons at 1000 yds myself.