Boolit Bumping?

[chuebner]

What is meant by "bumping up a bullet" and how is it accomplished? I have often seen reference to the term but am still in the dark.

Charlie

[waksupi]

Hi Charlie,
I've done it with a couple different calibers. It generally entails putting a bit of extra pressure on the bullet nose, when using the lubrisizer. Various methods can be used to limit the travel of the ram, to get consistent sizes. I'm sure someone will chime in with better details.

[felix]

It is far better to reshape (bump) the boolit with a press designed specifically for swaging. The intent is to reshape the boolit to match EXACTLY the throat of a gun. The reason you would do this is for the utmost accuracy out of a bench gun (BR gun). The boolit so formed will have maximum concentric resistance for the hope of more consistent ignition from shot to shot. In general, the dies and press so designed is completely out of the question for lesser, non-competitive, sports using our typical guns used on this board. ... felix

[Bullshop]

That aint the only game for bumping Brother Felix. I use a regular old green RCBS, only I aint tryin ta do what you are talkin about. I use it to bump a flat nose on a round nose boolit either for better terminal balistic performance or use in a tubular magazine.
My procedure is to first size/lube the boolit in the normal fashon, then using a flat punch invert the boolit to nose firse in the die. Set the depth adjuster as low as it will go and push the boolit into the die until the top punch contacts the die and stops the downward travel of the ram. At this point hold the ram down and begin to adjust the depth adjuster upward until it contacts the boolit and stops. Now raise the ram and give the depth adjuster about a 1/8 upward. Then press down the op handle and you will feel the boolit swage. Raise it out of the die and check to see how much flat you have. If you need more turn the depth adjuster up about 1/8 turn at a time until you get what you want. If you want les flat then of cource you would adjust it down a might. This works good with ACWW but I sure wouldnt try it with anything quenched. Enjoy!
Blessings!
BIC/BS

[Antietamgw]

I bump slightly in my RCBS lubrisizer exactly as Bullshop mentioned, usually in an attempt to bring an undersize nose up to size a couple thousands. I generally use flat top punches with the same results and benefits that Bullshop noted. My goal is not to drastically change the configuration of the bullet, just increase the size slightly. If I need the base increased a little I lube first in the die I want to bump up to: i.e .310 bullet in a .312 die. I'm cheap and the bulk of my casting is with soft ACWW. Go gently and learn the feel. Many thousands of boolits have been bumped this way in my green sizer without any problem. I doubt it would last long with a harder alloy. Prior to recieving the recent 360 220 group buy mold I was bored and bumped a handfull of 358315 with a flat punch in an attempt to bring the nose up about .0045. That was too much and the nose was left with a .300 meplat - looked like a long 2 diameter wadcutter. It shot well and was impressive on a couple water jugs but wouldn't feed in my BLR and was really more than the lubrisizer should be subjected to. I'd surely like to find a swaging press around somewhere but until then this will do fine. I did make a nose bump die with 7/8 X 14 threads for use in my loading press and it works well but is slow.

[beagle]

I agree with Felix. Bumping is useful and I use it ocasionally...BUT....the results are always inconsistent due to the equipment that we try and use.

You turn out bullets that will shoot better but if you do some fairly close measurements on them, you'll find that they don't bump consistently.

BUT...if that's the only means you have to change the dimensions on a bullet nose/body then use it. Just be aware that with our primative equipment that noses will be bent, not to the same tolerance and generally not look "nice". If you don't mind that and want success, give it a try./beagle

[WBH]

Another answer perhaps..........Soft bullets (20:1) and softer will "naturally" bump up upon firing. This is mostly usefull in BPCR shooting where the bore might be oversized by wear and age. That's why most BPCR shooters load their bullets to chamber into the rifling. Just another viewpoint.

[smokemjoe]

I get a throating reamer made, Like 1/2 deg. per side or a total of 1 Deg., I throat the rifle, Then I make a 7/8x14 die and throat that also. Make up kick out pins to fit and use a RCBS Rockchucker press. A bullet is put in the die and pushed in to bump down to fit the same dem. as whats in the rifles throat. That way you have a perfect match, I have done this on a 308, 30 Brs, and 5 -35 rem. barrels.

[felix]

Acceleration Results and COSTS..........

* One Top Fuel dragster 500 cubic-inch Hemi engine makes more horsepower than the first 4 rows at the Daytona 500 .

* Under full throttle, a dragster engine consumes 11.2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

* A stock Dodge Hemi V8 engine cannot produce enough power to merely drive the dragster's supercharger.

* With 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. Cylinders run on the verge of hydraulic lock at full throttle.

* At the stoichiometric 1.7:1 air/fuel mixture for nitro methane the flame front temperature measures 7050 degrees F.

* Nitro methane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

* Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.

* Spark plug electrodes are totally consumed during a pass. After 1/2 way, the engine is dieseling from compression plus the glow of exhaust valves at 1400 degrees F. The engine can only be shut down by cutting the fuel flow.

* If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half.

* Dragsters reach over 300 MPH before you have completed reading this sentence.

* In order to exceed 300 MPH in 4.5 seconds, dragsters must accelerate an average of over 4 G's. In order to reach 200 MPH well before half-track, the launch acceleration approaches 8 G's.

* Top Fuel engines turn approximately 540 revolutions from light to light!

* Including the burnout, the engine must only survive 900 revolutions under load.

* The redline is actually quite high at 9500 RPM.

* THE BOTTOM LINE: Assuming all the equipment is paid off, the crew worked for free, & for once, NOTHING BLOWS UP, each run costs an estimated $1,000 per second.

The current Top Fuel dragster elapsed time record is 4.441 seconds for the quarter-mile (10/05/03, Tony Schumacher). The top speed record is 333.00 MPH (533 km/h) as measured over the last 66' of the run (09/28/03, Doug Kalitta).

Putting this all into perspective:

You are driving the average $140,000 Lingenfelter twin-turbo powered Corvette Z06. Over a mile up the road, a Top Fuel dragster is staged & ready to launch down a quarter-mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line & pass the dragster at an honest 200 MPH. The 'tree' goes green for both of you at that moment.

The dragster launches & starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums & within 3 seconds the dragster catches & passes you. He beats you to the finish line, a quarter-mile away from where you just passed him. Think about it - from a standing start, the dragster had spotted you 200 MPH & not only caught, but nearly blasted you off the road when he passed you within a mere 1320 foot long race!

That, is acceleration!

[NVcurmudgeon]

Gently leaning on the Lyman 450's handle does help with some of the regrettably exact specification moulds available. My Lilja .35 Whelen barrel has a groove diameter of .3595", and the RCBS .35 200 gr. boolits I bum from Cobb Mountain Mac are .3582" as cast. (Gotta get one of those moulds of my own.) A calibrated left arm and an exact .360" Lyman sizing die makes everything fit. Notice this is with ACWW and a less than .002" size increase. Wouldn't like to try it with much larger size increases or harder alloy lest there be crooked boolits and/or a broken lubrisizer.

[Bullshop]

felix
That is way kewl!!! But what I want to know is at the 8g's acceleration will I look thinner?
BIC/BS

[Nueces]

Maybe you will look thinner, but you also can't puke 'til you slow down. :mrgreen:

[kodiak1]

Try that with a hangover!!!!!!
Ken.

[Nueces]

You have to wear astronaut wings to do that.....:drinks:

Mark

[WBH]

I have an Outlaw drag car that has only 875rwhp from it's 327ci engine running 116 octane, and a hard launch will almost black you out if you have an inner ear thing going on. I can't even imagine what 8000hp can do.

Actually more damage is done in the form of detached retinas from the chute than the launch. Slowing down from 300+ mph is a shock. It's bad enough from 150+.

[waksupi]

Felix, those are some great, eye opening facts! Thanks!

[felix]

Yeah, they even include the SEE description quite well. Also, 900 rounds is about right for any ballstothewall BR gun. The common parameter for that is the flame temp. Wonder if that mo-sheen is working 65K psi/cup per barrel, errrr, cylinder? ... felix