believe it or not?

Following on from the 30mm scope tube and light transmission discusion what other myths /wives tales are floating around?

Heres one to start off the discussion:

If you shorten your barrel you can regain the lost velocity by changing to a powder with a faster burn rate.... fact or fiction?

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Originally Posted by sneeze

Following on from the 30mm scope tube and light transmission discusion what other myths /wives tales are floating around?

Heres one to start off the discussion:

If you shorten your barrel you can regain the lost velocity by changing to a powder with a faster burn rate.... fact or fiction?

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I need to know this :)

Firearm manufactures all over the world spend mega dollars on engineers and their reports before they build a rifle and yet there are DIY's who attack these rifles with hacksaws at every opportunity because they know best.

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Originally Posted by Spook

Firearm manufactures all over the world spend mega dollars on engineers and their reports before they build a rifle and yet there are DIY's who attack these rifles with hacksaws at every opportunity because they know best.

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Yup Spook. I could never figure it out either. Every one of my firearms is exactly as the manufacturer built it and although I can't explain it, for some reason they seem to work.

In my mind barrel lengths on most hunting rifles are dictated by custom as much as anything else,and them factory ammo is built around that length barrel.

Eg my main hunting rifle is a browning blr takedown in .308 and it had a 20" barrel-it now has a 15" barrel and with reloads and a suppresser I'm getting a few fps more than I did with factory ammo.

Quote:

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Originally Posted by sneeze

Following on from the 30mm scope tube and light transmission discusion what other myths /wives tales are floating around?

Heres one to start off the discussion:

If you shorten your barrel you can regain the lost velocity by changing to a powder with a faster burn rate.... fact or fiction?

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Negligible imo

Play with quickload and the fastest load with a 12 inch barrel will still be the fastest from a 24 inch

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Originally Posted by res

In my mind barrel lengths on most hunting rifles are dictated by custom as much as anything else,and them factory ammo is built around that length barrel.

Eg my main hunting rifle is a browning blr takedown in .308 and it had a 20" barrel-it now has a 15" barrel and with reloads and a suppresser I'm getting a few fps more than I did with factory ammo.

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Yep

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Originally Posted by gimp

Negligible imo

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Yes you can fiddle around the edges a bit but best velocity burn rate is dictated by the chamber bullet relationship, barrel length is mostly irrelevant.
Often see the " chop it and get the speed back with a faster powder" quoted though.

Could be other reasons to use a slightly faster burn though like reduced muzzle flash?

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Originally Posted by Rushy

Yup Spook. I could never figure it out either. Every one of my firearms is exactly as the manufacturer built it and although I can't explain it, for some reason they seem to work.

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Yes, well, they will all perform better if you were to cut a piece off the end...or weld a piece on.

If it were the case Im sure all the competitive shooters would have the shortest barrel they could for stiffness less leverage on action etc
But they don't seem to.

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Originally Posted by veitnamcam

If it were the case Im sure all the competitive shooters would have the shortest barrel they could for stiffness less leverage on action etc
But they don't seem to.

Sent from my GT-S5360T using Tapatalk 2

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Funny thing, my target rifle has a short barrel with a tube extending out past it to extend the sight radius. It's a factory anschutz set up so hardly a buba job

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Originally Posted by res

Funny thing, my target rifle has a short barrel with a tube extending out past it to extend the sight radius. It's a factory anschutz set up so hardly a buba job

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Rimfire?

There will be an optimum length for velocity for any given cartridge.
While i think you can get SOME speed back with faster powder in your normal big game cals your always goin to loose over factory length and optimum charge of optimum powder.

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Typed a long reply but lost it :(

.22

But work out the energy you need and go from there. That's my short answer

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Originally Posted by Spook

Firearm manufactures all over the world spend mega dollars on engineers and their reports before they build a rifle and yet there are DIY's who attack these rifles with hacksaws at every opportunity because they know best.

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You need to remember that these manufacturers are there to make a profit (a big one) not neccesarily to create the best performing firearm.

I think there are improvements to be made to pretty much any off the shelf firearm.

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Originally Posted by veitnamcam

Rimfire?

i think you can get SOME speed back with faster powder optimum powder.

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. The problem with verifying this is identifying max pressure with either powder. While someone may appear to get some velocity back its most likely they are just running at a higher pressure. Or didnt have the best powder to begin with

In my experience I have been able to gain some velocity back by changing to a faster powder after shortening the barrel but I have never gained it all back. Close in a couple of instances although, whether thats increased pressure or a real gain for same pressure I couldnt say.

However, the longest barrel will pretty much always win the velocity battle. Unless of course you go stupid long and friction comes into play.

I personally have never measured pressure,only projectile speed. And have kept things safe.

To me it's just about wether it works as needed,or not

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Originally Posted by Proudkiwi

In my experience I have been able to gain some velocity back by changing to a faster powder after shortening the barrel but I have never gained it all back. Close in a couple of instances although, whether thats increased pressure or a real gain for same pressure I couldnt say.

However, the longest barrel will pretty much always win the velocity battle. Unless of course you go stupid long and friction comes into play.

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No debate about velocity and barrel length. The longer the barrel the longer the bullet is exposed to the pressure so the longer it will keep accelerating.
the discussion is really about optimum burn rate and barrel length.

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Originally Posted by sneeze

. The problem with verifying this is identifying max pressure with either powder. While someone may appear to get some velocity back its most likely they are just running at a higher pressure. Or didnt have the best powder to begin with

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Quote:

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Originally Posted by sneeze

No debate about velocity and barrel length. The longer the barrel the longer the bullet is exposed to the pressure so the longer it will keep accelerating.
the discussion is really about optimum burn rate and barrel length.

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Both good points.

If you think of a pistol length barrel at one extreme and a 30 inch in something a bit over bore like 243AI with 105s requiring a slower powder like N165 or whatever.

With the slow powder in lets say a 4" barrel with the same load as the optimum 30'', that optimum powder for the long barell may not even reach peak pressure until the projectile is 6" down the bore.(a figure plucked out of my arse)

So in this made up situation, faster powder would almost certainly yield more velocity for the same peak pressure in the 4'' barrel but still be a long way short of 30'' velocity.

The best speed will always be from whatever powder has the highest average pressure for the projectiles full travel of the bore while staying under max pressure.

What is max? Well that is entirely up to the individual re loader but with the same components other than powder a reasonable comparison should be able to be made( 1 pound vs 6pound hammer to open bolt:D)

So If you are already getting the best velocity possible from "X" length and whack 6 inches of the barrel faster powder will not get back your velocity,but it may minimize your losses.

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Originally Posted by veitnamcam

Both good points.

If you think of a pistol length barrel at one extreme and a 30 inch in something a bit over bore like 243AI with 105s requiring a slower powder like N165 or whatever.

With the slow powder in lets say a 4" barrel with the same load as the optimum 30'', that optimum powder for the long barell may not even reach peak pressure until the projectile is 6" down the bore.(a figure plucked out of my arse)

So in this made up situation, faster powder would almost certainly yield more velocity for the same peak pressure in the 4'' barrel but still be a long way short of 30'' velocity.

The best speed will always be from whatever powder has the highest average pressure for the projectiles full travel of the bore while staying under max pressure.

What is max? Well that is entirely up to the individual re loader but with the same components other than powder a reasonable comparison should be able to be made( 1 pound vs 6pound hammer to open bolt:D)

So If you are already getting the best velocity possible from "X" length and whack 6 inches of the barrel faster powder will not get back your velocity,but it may minimize your losses.

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Thats pretty close. If its graphed then its area under curve that will increase velocity. Area under cure is usually best with the slowest powder that can give max pressure for the longest time ( flattest curve peak) but when the bullet is 4(ave) inches down the barrel the pressure is already dropping and acceleration is slowing. Using your pistol/ rifle example if you check reloading data given same chamber and bullet its powders from a similar burn rate recommended for both.

Graphs please

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Originally Posted by veitnamcam

Graphs please

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Dammit, .....searches for the dont like button..

Ill see if I can pull one off QL

:D
Everyone likes graphs.

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Originally Posted by veitnamcam

:D
Everyone likes graphs.

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Not pro 1080 people :D opps thats Grafs :P

Hopefully below is a chamber pressure graph for a 7mmsaum . All things being equal if a faster powder was used the curve would be more of a spike and the area under curve would decrease

Attachment 23922

Quote:

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Originally Posted by Spook

Firearm manufactures all over the world spend mega dollars on engineers and their reports before they build a rifle and yet there are DIY's who attack these rifles with hacksaws at every opportunity because they know best.

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Hi all , there is a good article which appeared some time a go about a guy that built a huge warehouse and did a lot of rifle and ammo testing in it he found that the best accuracy in all of the guns that he tested came from 21 and 3/4 inch lond tubes and as these were all custom guns it would seem that the manufactures dont know it all . 22 rimfire guns suffer from friction slowing the bullet down in long barrels the 30 odd inch target guns just use the extra length for more precise aiming .with a scope they could get the same results from 16 inch barrels the length needed to properly burn the current standard rimfire load

So, the point of the thread is......?I am easily confused

I have a 700 Rem tac (or it started out that way once upon a time), 20" barrel, just for shots and giggles, at the range friday arvo gone, loaded up some 165 SST's, got them doing 2980 average at the point I was blowing the primers clean out.Was shooting half inch doing it too!(certain precautions had been taken by the way)

Clearly not recommended, but, that is faster than factory? yes?. Got there using a really fast powder, so, fast powder and stiff load, and the bullet goes faster. There is a point at which a barrel is too short, but you can get velocity back if you are prepared to raise pressure, safe or not.

Yikes!

yep each to their own........was that a 1 pound or 6 pound hammer to open the bolt?:D

Quote:

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Originally Posted by sneeze

Hopefully below is a chamber pressure graph for a 7mmsaum . All things being equal if a faster powder was used the curve would be more of a spike and the area under curve would decrease

Attachment 23922

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Would be interesting to compare quick load to strain gauge graphs.
Especially in a few different rifles.

Quote:

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Originally Posted by veitnamcam

Would be interesting to compare quick load to strain gauge graphs.
Especially in a few different rifles.

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There would be some differences no doubt. I find the QL outputs very close with most Iv tried but way out on a few. I dont think it would change the basics though.

Quote:

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Originally Posted by veitnamcam

Yikes!

yep each to their own........was that a 1 pound or 6 pound hammer to open the bolt?:D

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Bolt was stiff, but opened by hand, best extractor marks I have ever seen. Elected to stop right there, was trying to get to 3k with usefull accuracy to win a bet. Replacing the extractor then building a 270-08 or 270 Redding on the action to make a short light hard hitting bush rifle that will be usefull in open country as well, will be looking to get close to standard pressure 270 velocity. Not so fast I'll net to open the bolt with a hammer though, to heavy to lug around all the time!

Myth: cratered primers are " over pressure".

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Originally Posted by Tahr-Bound

Myth: cratered primers are " over pressure".

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depends on the gun

myth: almost all "conventional wisdom" re: guns/shooting to some degree depending on context

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Originally Posted by gimp

depends on the gun

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And the primer

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Quote:

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Originally Posted by gimp

depends on the gun

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Of course. When I am at a starting load and showing no other signs of pressure but have cratered primers, I could almost say one hundred percent that it is not an over pressure load though.

Like you say, some rifles just crater primers no matter the load.

Anyone got a pic of a cratered primer?

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Originally Posted by Gibo

Anyone got a pic of a cratered primer?

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From a .270 R700, factory Federal on the left, reasonable pressure handload with WLR primer on the right.

http://i58.photobucket.com/albums/g2...s/PB080181.jpg

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Originally Posted by gimp

From a .270 R700, factory Federal on the left, reasonable pressure handload with WLR primer on the right.

http://i58.photobucket.com/albums/g2...s/PB080181.jpg

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Cheers Gimp