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Discussion Starter #1 (Edited)
I couldn't find the original thread that I owed a response to, so I'm creating a new one.

The original question was how much velocity is lost with shorter barrels, but then we got into whether slower-burning powders lost more or less velocity.

Today I tried four loads of H4895 with 95 gr SST in a 243 Ruger M77 Compact 16.5" barrel.

I found that there was a big jump in velocity going from 32.0 grs to 32.5 grs, but much shorter jumps after that. It appears that 32.5 or 33 grs is about what can be burned in that short narrow barrel. 33.0 grs is the published starting load in the Hodgdon manual. I have the same rifle in 260 REM, and the velocity peaks out at about .5 grs below published max.

Anyway, here are the averages and velocity spreads. Remember, these are from just 5 shots with each load, so more testing would be required for a good stats. This was just to give me an idea of what charge to load for the kids' hunting season starting in a month. Mission accomplished! (My goal was approx 2600 fps with a 95 gr bullet and decent accuracy for 50-100 yard shots. Group sizes below are 5 shot 100 yard groups. Last group was probably worst because I was getting a little tired and didn't let the barrel cool as much between shots.)


32.0 grs avg 2569 fps spread 88 fps group= 3.2"

32.5 grs avg 2651 fps spread 41 fps group= 1.9"

33.0 grs avg 2656 fps spread 60 fps group= 1.5"

33.5 grs avg 2679 fps spread 12 fps group= 3.5"


The published velocity for the 33.0 gr charge is 2865, from a 24" barrel, so my gun dropped about 28 fps per inch. Right on our other estimates of 25 fps per inch. Since the velocity with this slow powder peaks well below the max charge, I suspect the loss per inch when comparing the max load woiul;d be a lot more than 28 fps per inch.
 

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Interesting that you should bring up this topic. I was just discussing this the other day with a friend. We went over some of our reloading data for .308 and found that every inch past 20" yielded about 50fps out to 24 inches (we didn't have any data on a 26"). For example his savage in .308 pushes the 150 gr nosler BT right at 2900fps out of a 22" barrel. My remington pushes the same bullet at 3000fps out of 24". He also has a remington 700 sps tactical that gets right at 2800fps out of a 20" barrel. Perhaps there is some difference depending on the caliber, shape of the case, and powder capacity. I know my uncle was a little disappointed in his 1903 enfield that he had "sporterized" and now has an 18" barrel. The 30-06 just can't reach it's potential out of a barrel that short. We were able to get some more velocity out of the 06 by changing to a faster burning powder but had to be careful because of the 06's low pressure limits. The simple truth of his gun is simply that the gun will never use the full powder capability of the cartridge because of the short barrel. Then again, if the hunting situation benefits from a short barrel, ie heavy woods, you don't really need the extra push as your shots will be short range. I guess it all boils down to asking what you need your gun to do and can it do that job. Good luck on the load development and good hunting!
 

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Discussion Starter #3
I found the original thread in the Ballistics forum...look there if you're interested in this topic.
 

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