Faster powders for shorter barrels - say 1680 for a 16 inch 308

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So what you are saying is that if;

303 british case

Powder X gives you 2400fps from a 24" barrel ( slower powder)
Powder Y gives you 2200fps from a 24" barrel (faster powder)

If you cut the barrel to 16" there is a good chance that

Powder X may only be 2000fps whilst powder Y gives say 2100fps

Both powders use the same load data in 24" and 16" barrels
 
steelgray said:
Once again the part of the curve after the bullet leaves the barrel is meaningless. It does, indeed, matter whether the bullet is in the bore for 1 Ms. or 5.

After the bullet leaves the bore the remaining part is curve is theoretical. That is, the "nonsense part" of the curve, representing what would have been if the bullet had still been in the bore and still subject to those pressures.... which it is not.

The theoretical part of the curve, instead, adds-up to useless muzzle blast/ report and lost energy. Besides that, you are also assuming the goal is max power. You don't actually get that per the testing in the video above - where a faster burning powder, in the 308 would, have coped better with the shortened barrel time, in the 16" gun.

In any case the objective is to have a balanced shooter - where the load is properly matched to the gun. No huge, useless fireballs please.

Do any of you guys actually have Quickload or are just not into that ballistic sciences thing?
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steelgray said:
Not so. This example shows that even using 1680, in .300 Blkout, in a 16.5" barrel with a 220 grain bullet leaves 16.2% unburned powder (ie., amount of burnt propellant = 84.8%).

Follow this link to load data results (click here)

The suggestion made here stunning.

You self proclaimed "experts here" are asserting, universally, that "The softer curve of a slower burning powder will obviously have more area beneath it, regardless of whether the bullet is in the barrel for one millisecond or five".

If so, why isn't 4350 the World's best pistol powder?

The World of reloading revolves around matching burn rates and powder volumes to cartridges sizes, bullets diameters weights and BARREL lengths.
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That's because you are looking at a suppressed loading, 30,000psi at 1200fps.
Try a proper load with the cartridges you listed (308/223) that are running at 60,000psi and see how much powder is burned.
 
Yes that's pretty well it - and while this is unfortunately a pretty blabby video, that is the main takeaway.




A 7.62x39 round delivers about the same performance whether you go with a 20 barrel (as with an SKS) or a 16" barrel (as with an AK) or an 8" barrel (as with a shorty AK) BECAUSE the round uses a faster powder (equivalent to 1680)

A conventionally-loaded 308 round uses a slower powder and looses a huge amount of ballistic performance when you go from a 24" barrel to an 16 incher - so much so that the 16 inch AK will actually out performed a 16 inch 308 - in ballistic performance. However, the 308 16 inch gun will definitely outperform the 16" AK in the muzzle concussion department - so much so that you don't even want to be near that shooter. This is really the meaningless/ "theoretical" part of the pressure curve after 1.2 Ms expressing itself as wasted external energy.

It doesn't have to work that way though. A 16" 308 loaded with a faster powder could out-perform that 16" AK. It seems that armchair folks are just universally stuck on the idea that a slower powder is always better, regardless of barrel length. Err ... no.


Evanguy said:
So what you are saying is that if;

303 british case

Powder X gives you 2400fps from a 24" barrel ( slower powder)
Powder Y gives you 2200fps from a 24" barrel (faster powder)

If you cut the barrel to 16" there is a good chance that

Powder X may only be 2000fps whilst powder Y gives say 2100fps

Both powders use the same load data in 24" and 16" barrels
Click to expand...
 
steelgray said:
Yes that's pretty well it - and while this is unfortunately a pretty blabby video, that is the main takeaway.




A 7.62x39 round delivers about the same performance whether you go with a 20 barrel (as with an SKS) or a 16" barrel (as with an AK) or an 8" barrel (as with a shorty AK) BECAUSE the round uses a faster powder (equivalent to 1680)

A conventionally-loaded 308 round uses a slower powder and looses a huge amount of ballistic performance when you go from a 24" barrel to an 16 incher - so much so that the 16 inch AK will actually out performed a 16 inch 308 - in ballistic performance. However, the 308 16 inch gun will definitely outperform the 16" AK in the muzzle concussion department - so much so that you don't even want to be near that shooter. This is really the meaningless/ "theoretical" part of the pressure curve after 1.2 Ms expressing itself as wasted external energy.

It doesn't have to work that way though. A 16" 308 loaded with a faster powder could out-perform that 16" AK. It seems that armchair folks are just universally stuck on the idea that a slower powder is always better, regardless of barrel length. Err ... no.
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Literally this entire post is completely incorrect...
 
My experience with Re 19 and 208 Amax ogive in my 19 inch Steyr Scout 308 or my KAC SR25 20 inch barrel is the best possible velocity with the max load.

The same powder and ogive will give me the best velocity in my SSG3000 24 inch barrel.
 
Tell me what powders to use, i have a barrel i can cut from 28" to what ever is legal.

Ill test it using 180gr jacketed in a 303 case over a croni


I want the slow powder to be the most common powder that gives the highest velocity in most manuals

You can pick the fast powder, you can go as fast as you want really. ( tightgroup) but remember out of a 18" barrel it needs to be moving faster then the slow powder pushing the same bullet
 
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this is a real cold weather thread
QL is a great tool to understand that in some cartridge cases all the powder that is going to burn is burnt and the rest makes you your impressive fireball leaving the barrel .
some cartridge cases have to have unburnt powder left over due to volume otherwise you have the infamous pipe bomb
the charts and graphs are again a tool to help understand what is going on in the load ,but changing the perimeters during the discussion from 308 to using a 22 V .
so my take on this thread is very confusing at best ..Also in quick load it states to use caution with the data
one more thing forgot to mention was that those with the experience in the industry and trade are a valuable asset when the right questions are asked
 
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Great suggestion. If you have a 303 British gun that you are willing to experiment with then why don't you go ahead and pick your favorite slow powder for that cartridge, based on published data in manuals etc. Then, if you are willing, just do a chrono test with the original, stock (24 inch) barrel and then cut it down to the minimum legal; which I suppose is 18 ½ - not 16). Otherwise, you could just borrow a jungle carbine from somebody and use the same load, since they already have legal 18-inch barrels.

In the next part of the test you could use 1680 for a 24” 303 barrel – but you won’t find load data for that. I can give you the load data from Quickload. Then try the same 1680 load in the 24 inch gun versus a borrowed Jungle carbine or your proposed cut-down 18 ½ inch 303 Brit gun. The resulting data should confirm what you’ve suggested with Powder X and Powder Y.

Meantime, you might be interested to know that there are a few guys who have already experimented with just pulling the bullets off 7.62x39 ammo, dumping the 1680-equivalent original powder load into a 303 Brit cases and re-seating the original AK bullet in that ol’ timer 303 brit case. People who do that seem pleasantly surprised by the outcome.

Here is a link that you can click on to see the comments of one CGNer who has done that recently

He wouldn’t be getting the 2500-2600 fps of the original 7.62x39 round because of the case capacity difference – but probably at least the 2100-2300 you are talking about.

Others do the same thing BUT add about 20-25% more of the original powder (from a second decapped cartridge) and they get great results – including no issues with ignition. I’m pretty sure that such a 120-125% (of original AK powder, plus original boolit) load would do 2500-2800 fps from a 24 inch 303 brit gun the same performance (or just a bit less) in an 18” jungle carbine. On the other hand, I'm guessing that your 45 gr of H4985 behind a 125 grained would do around 2930 FPS in a 24 inch gun and less than 2,500 in a 18" gun.

Furthermore, people like Caramel don't get it. It isn't just about velocity. It is about having a load that is balanced for your gun. That H4985 in a shorter-barreled 303 will be a really unpleasant gun to shoot. The 1680 load in a shortened 303 Brit will have less drama and more results.

Evanguy said:
Tell me what powders to use, i have a barrel i can cut from 28" to what ever is legal.

Ill test it using 180gr jacketed in a 303 case over a croni


I want the slow powder to be the most common powder that gives the highest velocity in most manuals

You can pick the fast powder, you can go as fast as you want really. ( tightgroup) but remember out of a 18" barrel it needs to be moving faster then the slow powder pushing the same bullet
Click to expand...
 
Well i must do something good, most of my pet loads are MOA or better, I wonder what i could achieve if i was to ….GET IT….
 
I don't get this but I do get it that people who aren't comfortable with addressing the facts of a discussion usually just lower themselves to making personal attacks ... sad

nowarningshot said:
I see pirate costumes, 365 days/ year for the OP.

What is this , the return of Sunray. Son of Sunray.

Its like watching the Acme truck deliver packages for Wily E Coyote.
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steelgray said:
Great suggestion. If you have a 303 British gun that you are willing to experiment with then why don't you go ahead and pick your favorite slow powder for that cartridge, based on published data in manuals etc. Then, if you are willing, just do a chrono test with the original, stock (24 inch) barrel and then cut it down to the minimum legal; which I suppose is 18 ½ - not 16). Otherwise, you could just borrow a jungle carbine from somebody and use the same load, since they already have legal 18-inch barrels.

In the next part of the test you could use 1680 for a 24” 303 barrel – but you won’t find load data for that. I can give you the load data from Quickload. Then try the same 1680 load in the 24 inch gun versus a borrowed Jungle carbine or your proposed cut-down 18 ½ inch 303 Brit gun. The resulting data should confirm what you’ve suggested with Powder X and Powder Y.

Meantime, you might be interested to know that there are a few guys who have already experimented with just pulling the bullets off 7.62x39 ammo, dumping the 1680-equivalent original powder load into a 303 Brit cases and re-seating the original AK bullet in that ol’ timer 303 brit case. People who do that seem pleasantly surprised by the outcome.

Here is a link that you can click on to see the comments of one CGNer who has done that recently

He wouldn’t be getting the 2500-2600 fps of the original 7.62x39 round because of the case capacity difference – but probably at least the 2100-2300 you are talking about.

Others do the same thing BUT add about 20-25% more of the original powder (from a second decapped cartridge) and they get great results – including no issues with ignition. I’m pretty sure that such a 120-125% (of original AK powder, plus original boolit) load would do 2500-2800 fps from a 24 inch 303 brit gun the same performance (or just a bit less) in an 18” jungle carbine. On the other hand, I'm guessing that your 45 gr of H4985 behind a 125 grained would do around 2930 FPS in a 24 inch gun and less than 2,500 in a 18" gun.

Furthermore, people like Caramel don't get it. It isn't just about velocity. It is about having a load that is balanced for your gun. That H4985 in a shorter-barreled 303 will be a really unpleasant gun to shoot. The 1680 load in a shortened 303 Brit will have less drama and more results.
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I have lots of parts guns and barrels ranging from 30 to 18" ill use the exact same barrel and cut it down to make all things even

And yeah ive been making x39 ammo into 303 plinking loads for a while. So i can use that powder if you want

Give me a quick load load for 180gr bullet, 40k psi using the x39 powder. Ill use it in both length barrels.

And ill take a look at what to use for the slow powder ( im just going to look at velocitys at min load to pick it) (40k psi ish)


I dont mind cutting the barrel. Its a shotout long lee barrel thats already been shortened.


Just to be clear. I personally believe what ever gives the best velocity from a 28 will also be the best from 18,
 
Two thumbs up! But could you use 125 gr boolits from AK ammo for both the fast and slow burn loads?

Evanguy said:
I have lots of parts guns and barrels ranging from 30 to 18" ill use the exact same barrel and cut it down to make all things even

And yeah ive been making x39 ammo into 303 plinking loads for a while. So i can use that powder if you want

Give me a quick load load for 180gr bullet, 40k psi using the x39 powder. Ill use it in both length barrels.

And ill take a look at what to use for the slow powder ( im just going to look at velocitys at min load to pick it) (40k psi ish)


I dont mind cutting the barrel. Its a shotout long lee barrel thats already been shortened.


Just to be clear. I personally believe what ever gives the best velocity from a 28 will also be the best from 18,
Click to expand...
 
Well i can but that not normal weight for the 303 case ( too light for the slow powder)..it will favor the faster powder.

Il use both 180 and 123

5 rounds of each
20 rounds total
2 barrel lengths
 
steelgray said:
People will tell you that Accurate 1680 is to fast for a .308 etc. BUT I say the faster stuff makes total sense for short barrel guns like a 16" 308.

I figure people should match the burn rate to the barrel length. You got a 7" AR? Go with a faster powder or you'll have a huge fireball going on at your muzzle every time you touch-off a round. Got a 9mm carbine? Think of using a slower powder than you would use for your handgun.

IMO, one of the reasons to reload is so you can make these kind of adjustments to suit your situation. Reloading manuals won't help. Use Quickl*ad.
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Did you run a model in QL where you compare powder suggestions for a 24" 308 barrel to a 16" barrel 308 and see how they differ?
 
Awesome. I'll get back to you in a few days with the QL suggested loads for 1680 with an 18 and 24 inch barrel - 125 and 180 gr boolits.

FYI I'm waiting for my new copy of QL to arrive since I upgraded to Win 10 and have recently ordered the required "new" QL version for Win 10. Believe it or not, you can only get QL by physical delivery (not download) due to ITAR.

If anyone else has QL going for them now maybe the could supply the load data. Otherwise, I'll be back on this shortly.

Evanguy said:
Well i can but that not normal weight for the 303 case ( too light for the slow powder)..it will favor the faster powder.

Il use both 180 and 123

5 rounds of each
20 rounds total
2 barrel lengths
Click to expand...
 
I wonder how Quickload deals with situations where the tail end of the work integral has dropped to a pressure level that cannot overcome the force of friction in the barrel?
 
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