Need some schooling, AR platform

[tigris99]

Ok so I know there is alot that can effect things, trying to put the pieces together.

Bullet weight, twist, barrel length, powder burn rate and so on. Have 2 constants, primers and brass.

Here is what I have done.

10.5" pistol carbine gas (less concerned about this one as I haven't really worked loads, just tested loads worked up in carbine)
16" carbine mid gas

Both 1:7 twist IIRC

H335, carbine loves 24-24.5 with 62gr BT

2230, seems lighter loads are going over better for same bullet. Just started playing with this powder today as h335 is gone and got my hands on a lot of 2230.

Trying to break down the basics of how burn rates effected by twist rates, effected by barrel length and so on. Trying to tune loads so they aren't far off from each other down range (or move to specific powder etc for each specific gun, barrel etc).

Thanks





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[Holland]

Ok so I know there is alot that can effect things, trying to put the pieces together.

Bullet weight, twist, barrel length, powder burn rate and so on. Have 2 constants, primers and brass.

Here is what I have done.

10.5" pistol carbine gas (less concerned about this one as I haven't really worked loads, just tested loads worked up in carbine)
16" carbine mid gas

Both 1:7 twist IIRC

H335, carbine loves 24-24.5 with 62gr BT

2230, seems lighter loads are going over better for same bullet. Just started playing with this powder today as h335 is gone and got my hands on a lot of 2230.

Trying to break down the basics of how burn rates effected by twist rates, effected by barrel length and so on. Trying to tune loads so they aren't far off from each other down range (or move to specific powder etc for each specific gun, barrel etc).

Thanks





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I guess I’m just confused what you’re asking

[tigris99]

Trying to understand effects of burn rates, twist rates, bullet weights and how they all effect each other.

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[JeffreyDeGraff]

Powder burn rate has no correlation with twist rate. Burn rate is something that is considered for bullet weight. Typically, heavier bullets perform better with slower burning powders, lighter bullets with faster powders for lighter weight bullets. Short barrels may not allow all of the powder to burn.

I hope I’m hitting on some of what you are looking for.


JTD

[tigris99]

Ya there we go, moving that direction

My understanding is bullet weight, twist rate and velocity all effect how a bullet comes out. So would a fast burn or slow burn rate change velocity? So mess with things in the end.

There is a ton of science to this that I'm trying to grasp since ar platform is something insanely customizable with twist rates and so on. Trying to gain an understanding so I can figure out less wasteful starting points for tuning loads.

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[JeffreyDeGraff]

Ya there we go, moving that direction

My understanding is bullet weight, twist rate and velocity all effect how a bullet comes out. So would a fast burn or slow burn rate change velocity? So mess with things in the end.

There is a ton of science to this that I'm trying to grasp since ar platform is something insanely customizable with twist rates and so on. Trying to gain an understanding so I can figure out less wasteful starting points for tuning loads.

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Slower powders will push heavier bullets faster. You cannot fit enough of the slower burning powders in a case to get enough pressure to push lighter bullets faster. So you have to use a faster burning powder, which reaches pressure, with less, to get the higher velocities with lighter projectiles.


JTD

[72Camaro]

Also something I was wondering but read somewhere is that if a certain powder give the best velocity with a longer barrel, it will also be the highest velocity with a shorter barrel. That seemed a bit wrong to me since I would think a faster powder burning up instead of blowing a flame out of unburnt powder would give a higher velocity, but evidently it does not.

[JeffreyDeGraff]

It’s been my experience that the slower burning powder is faster irregardless of barrel length, but there is less difference the shorter the barrel gets.


JTD