I originally posted this under the firearms form but decided it might be better here...

Last Friday I purchased a NEF/H&R Super Light Handi-Rifle in .243 Win. I now need to work up a load for it. I believe most .243 Win load data is based on a 22-24" barrel. My barrel length is 20". Has any one come across load data for a shorter barrel? My instincts tell me to pick a faster burning power for the shorter barrel. However, I have no experience in this area and would like input from the group. I also am interested in how accuracy might be affected by the shorter barrel. I expect a slight reduction in bullet speed but I hope the accuracy will not be affected. Have any of you come up against this problem?

The idea that a faster powder (for the same caliber) will work better in a shorter rifle barrel is a myth. Check the loading manuals and pick the powder that looks like the best choice, regardless of barrel length.
As to accuracy, barrel length has little to do with mechanical accuracy- most bench rest rifles that are the ultimate in accuracy use 20 inch barrels.
What a shorter barrel will often do, compared to a longer barrel, is give you lower muzzle velocity. But you already know that.
So, go ahead and work up a load using what looks like the best powder, and have fun shooting.

+1 on what Jack described.

When the powder is ignited, the peak pressure occurs before the bullet strikes the lands. At that point, all the powder that can usefully be burned has been consumed. If there are traces of unburned powder, it is of little consequence and has no bearing on whether powder is of the proper burn rate.

The valid point about the WSM and WSSM cartridges was that the peak pressure would occur before the bullet began to move forward from the neck and, theoretically, offer more efficient and uniform pressure. Likewise the 6PPC. Now, the 5X35 Savage adds to the short/fat powder column and type of shoulder that supposedly reflects some of the primer energy for even better burn.

Let me stray a little further from the subject to add that this type of cartridge shape experimentation, with all the attendant claims, has been going on for a long time. It was the claim of Weatherby, Gibbs and Ackley, among others. The advent of inexpensive chronographs and trace pressure gauges (not so inexpensive) have given us tools that put the theories to test, some substantiated, others not. In the same manner, the issue of using the same proper powder regardless of barrel length has been verified.

ok but if i didnt see this i apologise, the accuracy only suffers or gets better at 18 inches, so if it is over 18 its no "real" matter of 20 inches or 24 inch also a faster or slower burning powder does a lot for accuracy with a fast burn it "cracks" spends its propusion and thats it. a slower burning powder will push and will continue to push the length of the barrel, i do have chronos of this for proof, working up loads for a .357 and a .44 you can lower the pressure, raise the fps and gain accuracy

Morax: my understanding is that it doesn't matter the barrel length. Period.

As an example, I have three firearms in 243 winchester, a 10" T/C, a 16" Compact and a 26" Ruger No1. They have been developed individually for load data, but, by comparison of results all use the same powder, when using the same bullet weight, which gives the best velocity in each of these firearms.

ok it accually does, the same powder at different weights for the correct burn time for said barrel length. the same powder charge for the 26 inch ruger, will more than likely dump unburnt powder out the end of the 10 inch t/c. thus you will not get a full burn and will not get full pressure or fps. if barrel length didnt matter then why are we loading down the snipers with long barreled rifles and not just tossing them a bunch of carbines? barrel length does matter when you are going the distance, also due to stabilizing the bullet as well, if its longer it has the chance to stabilize before being acted on by outside forces (wind) you take a .357 rifle and a .357 colt with a 8 inch barrel, you will get different pressure,different velocity, different accuracy out of both using the same cartridge

I will tell someting 22Horn Caliper. I have T/C Contender 10" bull barrel. When I shoot it with carbine stock and rifle scoup, it is moore accurate than Brno 110 24" barrel withn same loads, because barrel vibration. I must look off better load for Brno and maybe make its barrel to 20" long. K.W.

Morax: My understanding is that longer barrels give higher velocity, they don't stablize bullets better nor do they provide for better powder burn. The amount of powder that will be burned occurs as the bullet enters and passes the front of the lands and the resultant pressure continues to allow the bullet to accelerate as those gases expand. Powder doesn't continue to burn as the bullet travels down the barrel, except for the first few inches.

Longer barrels do not impart greater stability. Stability is a process of reaching the optimum spin rate which is determined by the velocity and twist rate. Regardless of barrel length once the correct spin rate is achieved, going faster isn't going to improve stablity. To the contrary, a bullet can spin too fast and cause structural problems leading to disintegration or accentuating any yaw in the bullet and degrade accuracy as a result. Too, the spin rate doesn't really slow down as the velocity of the bullet decreases. Spin rates remain reasonably constant.

You, however, have arrived at different conclusions. It would be nice if we had some "authority" on board to 'splain it all to us.

a bullet cant spin faster than the lands and groves, it can however be pushed through them. and what i am basing it on is info from the chronos sight seen and shot, and also from the basic fbi ballistic courses that teach the trajectory, velocity, stability of shot etc. so i donno what to tell ya big guy wasnt trying to get into a peein contest, just stating what is taught and learned and all that fun stuff. its a known fact a longer barrel gives better stability, when you get a old kentucky rifle with slower speeds thats why they are a mile long, with newer powders etc, the barrel length shrank, it is a known fact of 18 is the break point.. anything longer dont really help, and anything shorter you got to play with the load for optimal burn and or speed to get the best of all worlds possable.

Morax: and that's what makes it all so interesting.

Onward

Morax,
longer barrels give the shooter more stability not the bullet. If a bullet "slides" throueven 2" of a 1 in 10 twist it is too small in diameter to ever get hold of the rifling. The bullet is engraved in the rifling before it gets any speed up. The powder is all burnt up before a bullet travels more than a couple of inches and the same powders that give the highest velocities in a 26 in barrel will give the highest velocity in an 18 inch barrel. The best powder for the capacity of the cartridge and the weight of the bullet at a given pressure will be the same whether it is fired in a 30 inch barrel or a 10 inch barrel. Otherwise we would be using pistol powders in those 7mm-08 in Contenders instead of the same powders that we use in our rifles.
On the extreme end of things you can't put enough bullseye into a 30-06 to make it as fast in a five inch barrel as you can by using the normal charge of 4350. The bullet goes faster from a long barrel because the powder continues to heat the gasses until they expand enough to start cooling. The basics of physics and the tests that I have done over the last 33 years shows that all the tests that different folks have done are right. Even the NRA did a test that they published in the National Rifleman. They took a TC Contender with a 24 inch barrel and shot a wide range of powders through it. they used the same loads throughout the test as they cut two inches off that barrel at a time. They got it down to 6 inches and the powders that had the highest velocities always had the highest velocities from 24 inches down to six inches. The cartridges that they loaded for the test were the 30-06, 30-30 and the 357 magnum. Each barrel started at 24 inches and was cut two inches at a time. Each barrel length the same range of powders (specific to the cartridge) were used and the results from the chronograph were recorded. In the 357 H110 gave the highest velocity at all barrel lengths. In the 30-30it was much the same with the powder that gave the highest velocity at 24 inches kept right on giving the highest velocities all the way down to 6 inches. The '-06 was the same story. The thing is that there is a small range of powders that will fill the case while giving a near maximum pressure for the cartridge. Those are the powders that yield the highest speeds because they have the greatest mass at the highest allowable pressure to move the bullet through its acceleration. You have to use less of a faster burning powder so the mass that is pushing against the bullet is less even though it is at the same peak preasure - the pressure drops off sooner and the hot gasses are less dense than the slower powders. If you use too slow of a powder then it can't get hot enough to produce maximum pressure and the bullet speed drops from that "ideal" powder.

PaulS wrote:

The thing is that there is a small range of powders that will fill the case while giving a near maximum pressure for the cartridge. Those are the powders that yield the highest speeds because they have the greatest mass at the highest allowable pressure to move the bullet through its acceleration. You have to use less of a faster burning powder so the mass that is pushing against the bullet is less even though it is at the same peak preasure - the pressure drops off sooner and the hot gasses are less dense than the slower powders. If you use too slow of a powder then it can't get hot enough to produce maximum pressure and the bullet speed drops from that "ideal" powder.

WHA ????? HUH ????? :wtf:



Cheers, Vince

What Vince? You don't understand? What is there that you don't understand...Me neither....Must be good though. PaulS wrote it...That makes it right...

A-men! they asked for an authority and they got one.

While still off the subject from "Need help with load for a short barrel .243 Win", Morax,Handloader and PaulS what are your relevant opinions of the muzzle blast (flame) seen from some rifles that is visible at nigh or in the dark?