Thread: Pressure / barrel speeds?

Ok guys im trying to get my head around a few things.

Firstly pressure. Why is it lighter pills in the same cal can use more of the same powder than heavier pills. Is it to do with resistance?
How can this effect the case differently (pressure wise) ?

Secondly barrel speed?? If someone has told me my barrel is slow (tikka) how could a magnum of same cal same (tikka) go any faster?

Just getting my head around the basics of reloading so keen to learn. Hope these even make sense: D

For the same charge a lighter projectile will move more easily and build less pressure.

I think a "fast" or"slow" barrel is probably more to do with variations in chamber and how it shows pressure in the ways we normally read it..... but I really have no idea

Originally Posted by veitnamcam

For the same charge a lighter projectile will move more easily and build less pressure.

I think a "fast" or"slow" barrel is probably more to do with variations in chamber and how it shows pressure in the ways we normally read it..... but I really have no idea

Thanks.

Could barrel speed be purely down to twist rate ?

The lighter projectile will accelerate faster and will have moved further down the barrel when max pressure is reached. Same pressure but more volume = more powder.

Dont know

Originally Posted by Banana

The lighter projectile will accelerate faster and will have moved further down the barrel when max pressure is reached. Same pressure but more volume = more powder.

Mmm starting to get that bit. Thanks

Originally Posted by Pengy

Could barrel speed be purely down to twist rate ?

Slower twist should be faster as not using up as much energy to rotate mass,but the term is usually used to compare otherwise identical barrels.

Another question. What are the common pressure signs and does anyone have photos with explanations?
Maybe a thread from one of you gurus for us newbies to reloading?

Originally Posted by Gibo

Another question. What are the common pressure signs and does anyone have photos with explanations?
Maybe a thread from one of you gurus for us newbies to reloading?

when you blow a primer............. you know youve hit pressure

Originally Posted by Smiddy

when you blow a primer............. you know youve hit pressure

So i keep going till then?

Originally Posted by Gibo

So i keep going till then?

jeues christ that was a joke

There was a thread somewhere with some examples. But making a new one as a sticky is a good idea.

I have a picture somewhere of ejector marks on my 6.5ai brass

Every barrel made is different. Some tighter tolerance than others, different internal finish, due to the manufacturing process. A 'tight', or slow barrel will grip the projectile more and therefore give lower velocities for the same pressures.

the first sign of pressure is usually sticky bolt lift, this is when you feel resistance when lifting the handle to extract the round