george20042007 wrote:

Handloader, in your quest for 5000 fps, I'd be interested in knowing the shooting details, i.e. are you allowing the barrel to cool between shots, barrel prep., how often do you clean the barrel, etc. Other threads have addressed such issues, but, I'd like to know more about your shooting considerations as opposed to bullet type, powder, primer, and brass used. Keep it coming...

Howdy George

At this point no extraordinary proceedures have been incorporated, although, some may be needed to reach goal. One impediment is the 1 -12 twist. If it were a 1 in 14, velocities would be higher with each of the loads tested thus far.

The barrel is given two minutes between shots. No cleaning is done except as needed or if their is a change in components*. As much as possible, I try to time my sessions with temperatures in the 68 to 75 degree range which means trips to Prescott this time of year. I fire lapped the barrel on the first session and, then, treated it with Microlon, a standard proceedure I use with all new rifles.

* Most factory barrels are fairly rough when new and some may have tight spots along the bore. Looking at a new barrel through a 25X borescope is almost frightening! I use the NECO fire lap process which removes the feathered edges on button rifled bores and polishes, or laps, the barrel to where it is significantly smoother and more uniform. After this process, cleaning is done only as a factor of deteriorated accuracy. I have several Swifts and on one of them I can go just over 100 rounds before cleaning is needed. Most other fire lapped centerfires will go 40 to 70 rounds before any deterioration of accuracy is noted. Because fire lapping makes the bore smoother, cleaning is easier, too. On high quality cut rifled barrels (for example, Krieger) no fire lapping is needed as the barrels have been carefully lapped before shipment. On hammer forged barrels, rifling is often smoother than button rifled barrels in my experience. Finely lapped barrels will yield lower SDs, increase accuracy and will clean up much faster.

Might be worth noting that the M1A Abrams uses a smoothbore cannon- the stabilizing spin is imparted by fins on the projectile, not rifling.
Far less bore friction than a rifled barrel, FWIW.

Hi

Jack wrote:

Might be worth noting that the M1A Abrams uses a smoothbore cannon- the stabilizing spin is imparted by fins on the projectile, not rifling. Far less bore friction than a rifled barrel, FWIW.

The main advantage of the smooth bore gun is that you don't have to precompensate for stabilizing spin when you manufacture a High Explosive Anti Tank (HEAT) round.

The stabilizing spin of a rifled-barrel fired round screws up the formation of the high pressure jet in the HEAT round, decreasing the thickness of the armor it will defeat. The only way to UNscrew-it-up is to machine an Unscrewing-it-up counter-rifling in the metal cone that forms the jet. The counter-rifling of that cone is mathmatics, physics, terminal ballistics and engineering gone MAD! Take out the rifling, though, and you're back to plain, un-counter-rifled cones and un-screwed-up high pressure jets.

For what it's worth: You can fire MISSLES out of a smooth bore gun, as well. Not that I'm saying that I think that they ARE, or that they WILL, or even that they MIGHT; Just that they CAN.

Al_Sohlstrom wrote:

For what it's worth: You can fire MISSLES out of a smooth bore gun, as well. Not that I'm saying that I think that they ARE, or that they WILL, or even that they MIGHT; Just that they CAN.

They have been firing Rocket Assist Projectiles from artillery pieces for some years...I suppose they could be classified as a missile of sorts.

Cheers, Vince

Hi

Vince wrote:

Al_Sohlstrom wrote: For what it's worth: You can fire MISSLES out of a smooth bore gun, as well. Not that I'm saying that I think that they ARE, or that they WILL, or even that they MIGHT; Just that they CAN. They have been firing Rocket Assist Projectiles from artillery pieces for some years...I suppose they could be classified as a missile of sorts. Cheers, Vince

Naw - RAP's a whole 'nother thing. It's just an effective way to get more propellant behind the projectile, and thus greater range, and not over-pressure the barrel and breech of the howitzer. Somone, somewhere, saw the RPG-7's setup - with the expulsion charge and the sustaining motor - and thought, "you know - if that were just 155 millimeter or so...".

The Shillelagh was a real wire-guided missle, and, at the time, had the highest homogenous-steel penetration of any American shaped-charge munition. The TOW missile beats it (at a vaguely-remember around-13-feet of homogenous steel), hands down, now, and I believe that the later model Dragons matched it while being smaller and lighter.

I just find if very interesting that ALL the new fire-and-forget anti-tank stuff clocks in at right about 5 inches in diameter, and the M1A has a right-about-5-inch-diameter smooth bore gun....

Hello guys! Again I will bring to your attention that "yes" there is a gun fired round that exceedes 5000 fps. the only one that matches it is our Abrahms tank gun, but not by much.
It is the MECAR 105mm TPDS-T Practice shot M724 made in Belgium. Otherwise known as a submunition, It is a Target Practice Discarding Sabot-Tracer. Made for the British 105mm Tank guns made in the Mecar plant in Belgium.
Complete round weight is 29.5LBS
Projectile weight is 6.8LBS
Muzzel velocity "IS" 5,035 FPS
It's range is in excess of 7,650 yds.
It is not a rocket assisted projectile.

Crackshot wrote:

It's range is in excess of 7,650 yds.

AND BEFORE SOMEONE ASKS, NO I WILL NOT ADD IN THE EFFECT OF THE EARTHS ROTATION ON PROJECTILS FIRED AT THAT RANGE INTO THE NEXT VERSION OF POINTBLANK!!!




-DallanC

AWWWWWW..... Why not? :):):)

Programming for the Earths spin must be a nightmare.

You'd need to:

Know your Latitude to get the EXACT diameter of the earth where you are, the angel diffence between true north or south and where your aiming, then you need to calculate the diameter of the earth divided by the time it will take the projectile to reach the target then you'd calculate how much is the "corrected" amount based on the angel your shooting.

Dimitri

mc223, your point is well taken, but, most gun writers use the rpm term as most walks of life identify with the term. Now for us suffisticated folks here
Keep it coming...

a trick navy question

what is the velocity of a 12 inch gun at the target.

As fast as It needs to go to get the job done.:)
I have some info here on the 16 inch naval gun, but none on the 12 inch naval gun. sorry.

Arnt the original battle ship guns accurate to under 1 MOA ?? I thought I read that somewhere

As for them firing, I wouldnt want to be anywhere within 20 milies (their max range) from it

But seriously though Bushmaster would have this answered properly

Dimitri

The newer 16 inch guns that were on the Iowa Class Battle ships were in fact accurate to 26 miles and could keep all nine guns fire inside a football field at that distance. pretty impressive while rocking and floating and bobbing up and down in the ocean....

Crackshot,

I didnt know that they were accurate to 26 miles thanks for the correction. Still pretty far. That would really require doing math for the Earths spin.

Also if I did the math right I guess they arnt Sub-MOA accurate. At 26 miles 1MOA is 13.3 yards. That means the battleships guns at that extreme range are accurate to 7.5MOA

Dimitri