Smaller 30 cal. case questions

[RU shooter]

Is there anything to be gained by using a smaller case for 30 caliber cast bullet shooting? I shoot mainly 30-06 in my rifle matches but I dont need velocity over 1800 fps. with boolits in the 150-185 gr. range. shooting at 100 and 200 yds.I use mainly Unique , 2400 and similar powders. With my loads theres an awful lot of extra space in that big case. I was thinking/dreaming of an ideal new match rifle and cartridge that goes with it that fits the above needs as far velocity with boolits I use .I thought about the 300 whisper and the 7.62 Soviet but I just can get used to that short neck and deep seating bullets would something like a 222 necked to .30 cal. sorta a long neck 300 whisper with more capacity be an option? as a plus the 700 rem holds 5 rds of that size case which is the rules in the matches I compete in. What about pressures in a case that small could it be loaded to my needs and stay low enough not to cause issues with cast? So lets hear it,Pea brained idea(Ive been know to have a few of these)? is there something better or something already available in a smaller case?


Thanks,Tim

[felix]

Always use as little case capacity as needed for your favorite boolit to shoot the speed desired with a case filling powder appropriate for the speed desired. If you need versatility, choose another gun for the new parameters desired and treat it the same way. ... felix

[bearcove]

30-30 would be closer to the vol you want. Or 30-30 ackley imp if you want better shoulder for headspacing.

[felix]

For cast, I prefer a more gentle slope as is standard. Sharper shoulders make NORMALLY appropriate powders ignite faster which can be a surprise if not compensated for by shooting a slower powder than book normal. The pressure curve WILL be different. ... felix

[lylejb]

I think ideas like that was the birth of the .308 x 1.5

A 308 (or 06) case shortened to 1.5 inches. I've seen them, but never owned one.

A gunsmith I used to go to had one for match shooting. I'm not sure of the exact velocity, but 1800 is probably do-able.

[CENTEX BILL]

Try the 300/221 case (300 Whisper) for cast bullets. It works well.

Centex Bill

[Chapped Lips]

I think ideas like that was the birth of the .308 x 1.5 A 308 (or 06) case shortened to 1.5 inches. I've seen them, but never owned one. A gunsmith I used to go to had one for match shooting. I'm not sure of the exact velocity, but 1800 is probably do-able.
......30BR,i believe it's called now....love those shortened cases & their small rifle primer pockets....have a couple of 22BR's,a 6BR and a 25BR....but only shoot jacketed stuff thru'em....

[nicholst55]

......30BR,i believe it's called now....love those shortened cases & their small rifle primer pockets....have a couple of 22BR's,a 6BR and a 25BR....but only shoot jacketed stuff thru'em....

That's what I was going top suggest, the .30 BR. You could do the same thing with either the 7.62X39 or 6PPC case - just set the shoulder back and form a longer neck, if that's what you want. Of course, you're into custom dies (and reamer) there, if that expense matters.

[Echo]

I have an XP-100 in 30/223 - simply the .223 case necked up and fire-formed. Ballistic equivalent to the 30 Herret/308/1.5/8mmKurz et al. But seldom with lead boolits, in fact, haven't shot it with anything in years. BUT.

A tack-driver with 110-125 gr condom bullets.

[Houndog]

I'll second the 30BR for a proven match winning chambering! Reamers, dies, and everything else you will need are readily available and they just plain SHOOT!

[Trifocals]

There are a number of cases suitable for your needs, .30-30, .30-40, .308X1 1/2, .30 Herrett, .30 Remington (obsolete), .303 Savage (obsolete) plus a number of shortened .308 Win. cases as used by bench rest shooters including the .30BR, plus many others. Don't forget the .308 Win.. For simplicity, put a quality barrel and trigger on a P-17 Enfield (originally chambered for the .303 British cartridge) and chamber it for the .30-40 Krag cartridge. The .30-40 Krag originally was loaded with bullets in the weight range you specify. Better yet, find yourself a .30-40 Krag rifle with a pristine barrel. They are wonderful shooters. I hope this helps. LOL

[missionary5155]

Good morning
+1 with that fine little 7.62x39 Rusky... Biggest deer I ever ate was 250 pounds after gutting. He fell victin to my 52 pound recurve at 12 yards. Any 155 caliber .30 boolit would have made that shot at any velocity over 900 fps... maybe a lot less.
Those Rusky´s may have political problems but they sure do not lack on the practicle side of life. Poor economies do give rise to completley thought out no waste solutions.
But then our culture has always been driven by magnumitis ...

[runfiverun]

the new 30 ar case from remington looks to have some potential as a cast boolit shooter.

i'm with felix on the sharp shoulder issue at least thats the impression i get with my ackley cases.
i have learned to pick the slow powders for it and cases just fall from the chamber.
the quicker powders seem a bit squirrelly in it, i'd chalked it up to a volumetric issue but the shoulder thing seems very plausible.
especially since i shoot the non ackleyed round too.
and have made direct comparisons.

[Pat I.]

If you like a longer neck and a shallower shoulder angle when I built my first BR rifle the only decent reamer I had was a 30/06 so what I did was shorten an 06 die, use some 35 Rem cases to form the brass, and use a formed case with the neck cut off to head space the rifle. The hardest part about forming the case was that you had to remove a lot of neck with a tubing cutter and after that trim to length. It shot good but no better than a 30 BR or any of the other small 30 caliber cartridges out there. I never tried shooting it through a magazine and wouldn't be surprised if I had run into problems if I did.

You're best bet in my opinion if you're going to shoot from a magazine would be to go with a .308 or .300 Savage and get it throated with a .310 x 1 1/2 degree reamer so you're able to use all available magazine box length. You'll also probably more than likely have to start using rifle powders to get the most out of the gun. Somewhere around 28 grs. of Varget usually works pretty well with the 308.

I think I was calling the case I was talking about the 30/35 when I was using it in matches but that was a while ago and don't remember for sure. Case length is 1.700.

[GabbyM]

http://www.6mmbr.com/30BR.html

[Larry Gibson]

RU Shooter

I went through this dilemma about 28 years ago with regards to .30 cal. I was shooting '06, 7.65, .303, 7.62x54, .308W and 30-30. With the exception of the 30-30 all shot the same bullets (311359, RCBS 150 gr, 311466, 311921, 311041, 311284 and 311299) with best accuracy in the 1800 - 1950 fps range. Even with medium burning powders the loading density was still at 50 - 66%. The 30-30 and could shoot the same bullets with the exception of 311284 & 311299 with best accuracy up into the 2100+ fps range. One .308W could shoot all of the bullets with best accuracy up into the 2100+ fps range. There was a clue there but I did not see it at the time.

I reasoned at the time that the accuracy at increased velocity must be because of the more efficient case capacity of the 30-30. The accepted thought at the time was that a certain chamber pressure was the limit to accuracy at higher velocity with cast bullets. Thus I thought if I could decrease case capacity to that of 100% loading density with 4895 under the 311299 (my favorite .30 cal bullet for shooting to 600 yards) giving 2100 fps at perhaps the same psi as the 30-30 then I would have an ideal cast bullet cartridge.

I wanted the cartridge to be useful in a bolt action repeater so the case was designed off the standard '06, etc. size case. The Powley computer was used to guestimate the case capacity given a 22" barrel to dive the 311299 at 21-2200 fps with 4895 using reformed 7.62 cases. I used those cases because they are thicker than commercial cases leaving a thicker neck even after neck turning. Using a shortened .308W FL die the shoulder was set back until the case capacity to the base of the neck was correct according to the Powley Computer. I then shortened the neck to '06 case neck length. The OAL turned out to be exactly 2.0". I had, I thought, come up with the perfect .308CBC (Cast Bullet Cartridge).

I had a brand new 2 groove '03 barrel. The 2 groove barrels were also then touted as "best" for cast bullets. The barrel was installed on an extensively modified M1916 action that had already proven it's accuracy ability with the shooting out of two .308W barrels. The chambering was done with a match '06 reamer to initially provide a tight neck. A neck less .308W match reamer then was used to finish ream the chamber body and headspace with a tight fit on the formed cases. The rifle as finished works and functions perfectly with one exception; accuracy remains the same as I get with any of the other cartridges. I.E. best accuracy with all of the bullets is in the 1800 – 1950 fps range. That was a very perplexing situation and I tried all sorts of variables to no avail; best accuracy remains in the 1800 – 1950 fps range.

I also have had a bolt action Mini MK X 7.62x39 for many years. Regardless of the cast bullet used if it can attain the velocity best accuracy is in the 1800 – 1950 fps range. I was perplexed. If it was pressure then why was I able to shoot cast bullets at full throttle 40,000 psi with exception accuracy out of my M1 Carbine yet the same bullets loaded to the same pressure in the 30-30, .308W or ’06 shot horribly? Pressure did not seem to be the answer. I then picked up another .308W, this time a target M70. It shot all the cast bullets mentioned with best accuracy up into the 2100+ fps range. So what was the difference? Why does the M94 30-30 and two M70 .308Ws shoot all the cast bullets well up into 2100+ fps and the other rifles don’t? I didn’t think it could simple be the name “Winchester” so I looked over everything else.

I then remembered an old article I read some time ago where an individual questioned psi as the limiting factor and thought it was RPM. He was pooh poohed for such and abstract idea. I also noticed about then that some cast bullet bench resters were going to slower twists with excellent accuracy at higher velocity. Looking back over my records I found all the cartridge/rifles that had the best accuracy in the 1800 – 1950 fps range had 9 ½ or 10” twists including my .308CBC. The M94 and the 2 M70 .308Ws had 12” twists. Computations showed the RPM, where best accuracy occurred, to be same for the 9 ½”, the 10” and the 12” twist barrels. Obviously it is RPM that plays a big role on where accuracy will begin to deteriorate with cast bullet.

Now, before some begin to moan and groan it is a fact that RPM is a major player as to where accuracy will go south. There are some things that can be done lowers the velocity level (faster burning powders is the obvious) and there are things that can be done to raise the velocity (slower burning powders again being the obvious) level where RPM adversely affects accuracy. RPM is not a “limit” as some here have misconstrued it to be. It is “limiting” to best accuracy however because where it causes accuracy to deteriorate is influences by many things. Acceptable accuracy (not best accuracy) can be had at higher velocity. When the expansion of groups at longer ranges is not linear then you have really exceeded the RPM tolerance for that bullet/load/rifle.

To answer the question; is there any benefit to a smaller case? The answer is yeas and no. Yes in that you will have fewer problems with powder sensitivity in the smaller case or will not have to use a filler. Keeping the same twist of barrel the accuracy potential will remain the same as you’ve mentioned. However, If you do intend to build a cast bullet rifle for those bullet weights using a shorter more efficient cartridge as several have mentioned then I would suggest a barrel with a minimum of a 12” twist and preferably a 14” twist. I have 10”, 12” and 14” twist .308Ws and can shoot the same accuracy at 2400 fps with the 14” twist that I get at 1850 fps with the 10” twist. The 12” twist gets the same accuracy at 2100+ fps, all with the same bullets. The same holds true for my .223s (7, 9, 12 and 14” twist barrels) I get accuracy with cast bullets at 2300 – 2400 fps that is not probable with the 7 and 9” twists, all with the same cast bullets. I also suggest a cartridge with a longer ’06 length neck as it is easier to fit most cast bullets to the leade without the base of the bullet extending below the neck. For strictly target work a .308W with a 12” twist that is throated for the most useful and used cast bullet would be a good choice also.

Photo shows the 308CBC to the left of a 308W.

Larry Gibson

[Char-Gar]

My interest has always focused on rifles first. Accuracy while interesting is often very relative and rifle specific. My goal has always been to get multiple rifles to do their best with cast bullets. Soem times that is 3 moa, sometimes 2 moa and sometimes 1 moa and smaller. I am a happy camper when a rifle does it best.

My favorite case is the 30-40 Krag round. The capacity is all you can use with cast bullets, and that long neck is wonderful. In terms of case capacity is is almost identical with the .308 Winchester.

The Krag rifle handles the rimmed 30-40 round very well, but they are now getting quite old and are not of the best design to produce top end accuracy. Bolt action rifles can be made to feed rimmed rounds like the P14 in .303 Brit.

If a stray P14 action wandered into my shop, I would barrel it to 30-40 so quick it would make your head swim.

[onesonek]

Always use as little case capacity as needed for your favorite boolit to shoot the speed desired with a case filling powder appropriate for the speed desired. If you need versatility, choose another gun for the new parameters desired and treat it the same way. ... felix


I agree totally!!

Dave

[Frank46]

For a small case for 30 caliber cast boolit shooting would be the 6.5 japanese or the
7.35 appropiatly sized for 30 caliber boolits. I have a 6.5 jap case by norma that was modified by a benchrest shooter to shoot jacketed bullets cut down and necked to 6mm. Frank

[runfiverun]

i like the way you said that larry.
to add to it some.
iv'e proved the same over and over with different powders targeting the same velocity.
odd that 2400,1680,aa-2230 [with pistol primers] at 1900
and h-322,4895 and 4064 [with fillers]at 1900
and slower powders like h-4831 and rl-19 [rifle primers and sometimes fillers] at 1900
and even a case full of 5010
all achieve the same accuracy out to 300 yds.
as long as the boolit is a good fit to your rifle it will do it with those powders and others also.

what's optimum is what felix outlined, find a case with sloping shoulders that holds @ 28 grs 4895 and make sure the throat fit's a good boolit.
add in a 12 twist bbl and life should be easy.

[Pat I.]

Considering what the 30 BR is doing with it's 30 degree shoulder what's gained by going to a shallower angle?

[missionary5155]

Good morning
Back to RPM... Sorry but I had a thought..
We know that cast boolits can have are bubbles.. not all but some may and some bubbles can be largish. Also impurities.. that is why I weigh my boolits when absolutel accuracy is desired.
But yet some type of cavities may exist.. some may be nearer the outside diameter than others..
So we begin to spin that and like it or not there is a wobble factor. Increase that spin lets say 10 %... 20 %.. would not the wooble increase...
Yea this may have been rehashed 212 times.. but it is still there... and questions still pop up.
Mr. Roberts wrote the BEST boolit was acast slug that was then swaged to remove any air pockets. Also slow twist rates were used in comparrison to today...
Just some thoughts rolling about... and when you get to 60 any thought is great... especially at 8000 feet.

[Larry Gibson]

missionary5155

Also consider that most cast bullets are slightly out of round, some more than others This can readily be observed after sizing. If the driving bands are not of equal width all the way around then more mass is in one spot on one side of the cast bullet to imbalance the bullet. The imbalance is going to be there whether the bullet is sized or shot as cast. This imbalance has the same adverse affect as the bubbles because there is more mass where the driving bands are thickest. This imbalance at the circumference of the bullet is where it will also have the greatest effect as the centrafugal force increases with increased RPM. The bullet can be the best "fit" we could make but those imbalances are still going to take their toll as we increase the RPM above a certain threshold for whatever bullet/alloy/lube/load we are using.

Larry Gibson

[RU shooter]

Thanks all for the replies ,Its certianly food for thought on the issue with alot of options mentioned.The matches I compete in are reduced course(200yd.) NRA Highpower I was just thinking of something better than my 03A3 ,while it does alright scoring in the high SS/low expert class I though I would have more of an advantage shooting a more modern rifle and more and accurate cast boolit ctg.


Again, Thank you.Tim