reloading for shorter barrel rifle---faster powder?

[hipshot300]

I am about to start reloading for the win 308. The rifle (ruger 77 rsi)  has a short 18" barrel. I have some experience in reloading. Is there a powder better suited for this short barrel that anyone can recomend for hunting? Or should I just stick with win 748?

[dw06]

I have a remington 600 in 308win with a 18.5 barrel.Shoots ww748 well,also imr 4064.Its favorite loads are with imr 3031 and 150gr partitions.So i would say use the powder that shoots best,it is a very efficient round even in short barrels.

[dave375hh]

Hipshot,

The same powders that give the highest vel. in a long bbl will also be fastest in your short bbl. Powder is burned in the first 4-5 inches of the barrel the expanding gases still push the bullet more untill they get to the muzzle. The powder is consumed and has already produced it's gas volume in that first 4-5". The higher vel in a longer bbl comes from the expanding gases pushing for a longer time on the bullet. That's why the short bbls blast is much louder it's venting more expanding gas at a higher pressure. An example is the 22lr, if you put too long a bbl on a .22 it will actually show a reduced vel, because it runs out of gas pressure to push the bullet and drag starts to slow it down.

[PaulS]

748 was designed for the 308. I can't think of any powder better suited to that case with 150 grain bullets.

[hipshot300]

Thanks for the replies. My on hand choices are imr 4320 and win 748. Will give the 748 a try. 

[Ron T.]

You might try some Hodgdon Varget.  Varget was developed with the .308 Winchester cartridge in mind.

On a Powder Burning Rate Chart I copied from the AMERICAN HANGUNNER magazine (July/Aug. 1993) which I found on line, here's the relative positions of the powders that were mentioned here in this thread.

Out of 107 powders listed with #1 having the fastest burning rate and #107 having the slowest burning rate, the following powders and their postion on the chart are as follows:
#65. - IMR3031
#76. - Winchester 748
#79. - IMR4064
#80. - Hodgdon Varget
#84 - IMR4320

The actual burning rate of a powder does not necessarily qualify it for use as a substitute for powders with similar burning rates.  You should always look at a well-known reloading manual for the powders and their amounts which are suitable for a given caliber and bullet-weight.

Good luck...   


Strength &  Honor...

Ron T.

[trotterlg]

I think the bit about the powder being burned in the first 4 inches of the barrel is plain wrong.  If it were all burned in that space then you would never get unburned powder and a big muzzel flash from using powder that is too slow.  If it were all burned in the first short distance there would not be any need for different speeds of powder.  I can tell you that with slow powder and light bullets the powder is still burning when the bullet exits a 24 inch barrel of a 22-250.  Larry

[dave375hh]

trotterlg,

You don't have to believe me read it for yourself in the latest issue of Handloader mag. The only time unburned powder is expellled from the muzzle is when the powder used is too slow for the cartridge, and dosen't generate adiquate pressure to burn properly. The flash at the muzzle is the high pressure gases hitting the air where the added oxygen allows it to flash. Stand to the side sometime and notice the ball of flame starts a couple of inches beyond the barrel, after it has picked up the extra oxygen. Not at the muzzle.

The article is by John Barsness and is about long vs short barrels.

Yes one of us is "plain wrong" but it isn't me. I don't try to answer someones question unless I know the answer is right. If I'm not sure I don't post.

[PaulS]

I think the bit about the powder being burned in the first 4 inches of the barrel is plain wrong.  If it were all burned in that space then you would never get unburned powder and a big muzzel flash from using powder that is too slow.  If it were all burned in the first short distance there would not be any need for different speeds of powder.  I can tell you that with slow powder and light bullets the powder is still burning when the bullet exits a 24 inch barrel of a 22-250.  Larry

Trotterlg,
there are studdies that span the last thirty years (at least) and they all agree that the muzzle flash is not unburned powder. It is the carbon residue and super heated gases that glow because of the temperature. The pressure / time curve is what gives the range of powders that are usable in any given cartridge. A fast powder reaches a peak preasure very fast and then loses its pressure fast where a slower powder takes more time to reach its peak preasure but cools more slowly providing a higher total impulse to the bullet because the pressure is higher over a greater length of time. Even though the powder is burned in the first few inches of barrel the pressure in the barrel can continue to rise for most or all of the barrel time. (the length of time the bullet is in the barrel). A fast powder cools faster and the pressure starts to drop part way down the barrel and the slower powdes can have higher pressure all the way to the time that the bullet exits the muzzle. That causes bigger blast and a large flash.
To get the highest velocity from any gun you must build a maximum pressure for as long as possible as the bullet travels down the barrel. If a powder is too slow for the bullet or case then the pressure will never get to maximum and the bullet will suffer from slow accelleration and it velocity will be lower than it would be with a powder with a more appropriate burn rate.

A further note on those burn rate charts and why they all aren't the same:
The burn rate is determined in a closed bomb test which always allows the maximum pressure and fastest burn of the powder. Your gun is an open combustion device that changes the burn rate and pressure levels of powders. So while the burn rate charts can provide an idea of what powder to use in what case remember that different bullet weights and extremely small differences in barrel diameter and chamber sizes can and do affect the pressure levels achieved in the normal use of powders in any given gun.

That is why the manufacturers test their loads and ask that we remain within those tested loads. Always consult several loading manuals to arrive at a safe starting load and watch for signs of excessive pressure as you increase your load toward the maximum listed load. Never exceed the maximum listed loads. That last bit won't guarantee that your loads are at safe pressure levels but you can be sure that if you do exceed the maximum listed loads you will have excessive pressures in your loads.(whether or not those signs of excessive pressure are apparent)
Paul

[dw06]

I agree with Paul,who buy the way exp;ained that very well.

[Davemuzz]

Hipshot,

I reload for my Winchester Model 88 and a Stevens 200, both in .308 caliber. The Model 88 seems to like Varget the best with a 150 grain Hornady SST bullet. The Stevens however, seems to like IMR powders. I load IMR 4198 with Hornady 110 grain bullets and they will cloverleaf at 100 yards. For the 150 grain bullets, I have tried Win 748, Hodgdon 4895, and Hodgdon BL-C2 with not too good success. Just last week I loaded up the Hornady 150gr SST's with IMR 4895 and the Stevens was shooting MOA at 100 yards.

So, if your gun isn't shooting well with the Win 748, you may need to try some other options.

Good luck.

Dave

[trotterlg]

If there is unburned powder still in the barrel and the case it clearly wasn't "all burned" in the first 4 inches of bullet travel.  A verg good example is the Russian 7.62X54 rifles, the long barreled ones burn nice and clean and the short carbine length have a huge muzzel flash and leave un-burned powder in the barrel, all with the same ammo. Don't believe everything you read in the magazines.  Larry

[dave375hh]

Trotter I appologize it's obvious you know much more about "PLAIN WRONG" than I thought. Did you even bother to read Paul S post? (Well done by the way Paul) Oh, By the way I knew what I was talking about years before the article I wasted my time pointing out to you. It just happened to be where you could have learned something in a current publication. I'll not waste my time again.

[jack19512]

This thread may pertain to a question I have.  I am working up a load for my B/C 45/70.  I shot it today using IMR 4895 powder which gives me pretty good groups but there was a lot of residue left in the barrel after firing each shot.  So much that I actually blew the residue out from the chamber end.

Now, I assume I should be using a faster burning powder to prevent this, or should I ignore the residue and just go with the powder that gives me good groups?

I have the following powders that should be quicker burning than the IMR 4895, RE-7,IMR-4198.

Ron T.  According to the chart I have the  IMR 4320 is a faster burning powder than Varget.  Unless I have made a mistake or my chart is wrong, which is certainly possible.

[Jerry Lester]

OH BOY! Another heated debate!

I'm not even going to put my thoughts into this one simply because it always turns out to be a waste of time, but I will toss this in for the sake of pondering this subject.

This isn't the only time this has happened during my vast amount of load testing over the years, but it's a good example that can be repeated by anyone else.

I was working up a load in a Browning A-Bolt II Varmint 223 with 40g Balistic Tips, CCI BR-4 primers, Federal cases, and varying weights of AA 2015 BR powder. My velocities were running in the expected ranges, and absolutely zero signs(yes I know how to check the right ways) of high, or even maximum pressure with these combinations. Being the eternal experimenter I am, I decided to increase charge weights 1/10 grain at a time, and see how it went. I'm not going to list here exactly my charge weights, but I've repeated this same thing in a couple other 223's, at slightly different charge weight ranges so I'm sure you can repeat it too if you choose.

I, as expected, gained a slight but definate increase in velocity(5 shot averages) with each increase in charge weight to a point, and then with only one more 1/10 grain increase, I lost about 15-20 fps. I then shot 5 more at that level, and got the same results. This is with Federal cases, and there's no doubt that if I was running high in pressure, it'd easily start to show when I miked the cases heads. I then increased another 1/10, and lost another 30 fps or so for a total decline in velocity of around 50 fps. Again, I tried that charge with identical results.

I scratched my head for a while, and literally gave myself a headache trying to figure this thing out at the time. I dismissed it that day as a fluke, or chrono glitches, but I ended up going through it again a few days later just to double check myself. Sure enough, exactly the same results. I decided that the only possible reason for this was unburned powder being pushed down the barrel behind the bullet, so I rigged up a back stop with plywood, and a cardboard layer taped solidly to the front. What I saw convinced me that my theory was right. With every shot at those charge levels there was a bullet hole with a little shotgun pattern around it. Once I dropped back to the charge weight where the last velocity "increase" was measured, this stopped. I imediately called the tech at Sierra to ask his opinion, and he confirmed my findings as something Sierra already knew.

You can draw your own conclusions from this... 

[JBMauser]

Lots of good data in this thread.  I just wanted to point out that a load that does in fact leave powder in the barrel may still yield the best results.  The fact that all of the powder is burned has zero relavance to the performance of the load.  A faster powder will yield a different vibration which is what will effect the harmonics of the barrel in a different way.  If you have a load that leaves some powder unburned and you reduce the charge you will change the volume and burn.  There are guys getting great results with cast bullets and 50 cal powder.  you fill the case to the neck and stuff a bullet in and when you fire and take the spent case out of the chamber you shake out the excess unburned powder on the ground.  Still, it shoots.... JB

[trotterlg]

I've seen the light now!  It now seems clear to me that if there is powder left in the barrel that either one of the following is true:  (1) All of the powder did not burn before the bullet left the barrel, therefore the powder was burning all of the time the bullet was traveling down the barrel.  (2) The barrel was less than 4 inches long so the powder could not all burn in the first 5 inches because the barrel was an inch short of the required length to burn it all.  Glad I finally understand this highly technical issue.  Larry

[R.W.Dale]

 It's more like this. All of the powder that is going to be "burnt" is going to do it in the first 4 inches. After that if there are unburnt powder granules they will stay that way. Bullets aren't driven down the bore like a rocket they are pushed down the bore by pressure like those pumpkin chukin guns you see on the Discovery channel.

[hipshot300]

Thanks to everyone for the information. Will hopefully find out how the 748 loads do next week. I am looking for hunting accuracy and not necessarily the highest velocity. In my mind I thought that the slower powders would give a larger extreme spread in fps between shots in a short barrel. It is my ignorance as I do not own a chrnograph.

[PaulS]

If there is unburned powder still in the barrel and the case it clearly wasn't "all burned" in the first 4 inches of bullet travel.  A verg good example is the Russian 7.62X54 rifles, the long barreled ones burn nice and clean and the short carbine length have a huge muzzel flash and leave un-burned powder in the barrel, all with the same ammo. Don't believe everything you read in the magazines.  Larry

Trotter,
Take a wooden dowel and put your "unburned powder" on a piece of tin foil and light it.
The reason it doesn't burn is because it is ash. A residue from the burned powder that was not allowed time to be completely consumed.

[PaulS]

This thread may pertain to a question I have.  I am working up a load for my B/C 45/70.  I shot it today using IMR 4895 powder which gives me pretty good groups but there was a lot of residue left in the barrel after firing each shot.  So much that I actually blew the residue out from the chamber end.

Now, I assume I should be using a faster burning powder to prevent this, or should I ignore the residue and just go with the powder that gives me good groups?

I have the following powders that should be quicker burning than the IMR 4895, RE-7,IMR-4198.

Ron T.  According to the chart I have the  IMR 4320 is a faster burning powder than Varget.  Unless I have made a mistake or my chart is wrong, which is certainly possible.

Keep using the 4895, its a great powder for the 45-70. The ash won't bother anything but you can continue to blow it out if you are so inclined.