.243 Ladder

Thread starter #1

Jester896

Senior Member
boy! did I learn a few things today. Federal GMM AR primers have a little AR stamped on them...it sure makes checking primers difficult...looks like there is something wrong with all of them.

The other thing was a consistent 4.5# trigger pull is way more than twice what a 2.5# is...I sure made some shooting errors. Every time my right thumb gets on top of the stock I will make a left error...and I kept finding it almost on top...not a good day.

Here is and image of the ladder...
#1 that ES and SD looks great on the first one doesn't it!...velocity just not there.

#2 The error on the target (didn't record shot) threw that ES and SD out a good bit....but that one round sure spiked.

#3 We got a spike in that one too and it has the worse ES and SD

with the 20" barrel I am figuring I am going to be about 80 fps off published speeds but I am way more than that off.

Ladder.jpg

case (2).jpg
Top case:
primer is backed out of the case maybe .001 and the shoulders are still at 0. Not enough pressure to make the head come back to the bolt face after the firing pin hit I am guessing. Primer edges still rounded.
Middle case:
primer flush with case and the shoulders are pushed out about .001 from where they started. Primer edges still rounded.
Bottom case:
primer flush with case bottom and shoulder are pushed out .003 from where they started. Primer edges still rounded....this may be filling the chamber.

I did let it cool between each 5 shot group. I kept feeling at the chamber and half way down to see if the barrel was hot and it wasn't. After the 3rd group, when I turned the radar off I noticed the heated portion of the barrel was from 1/2 way down and to the muzzle.

I think I am going to bump it up .2gr and see what I get....what are your thoughts? Maybe by then I can get that trigger adjusted better.
 
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chuckdog

Senior Member
Get rid of that hook and target C shows real promise.

My experience with a chronograph has taught me some barrels just aren't as fast as others of the same length.

I have a 16.5" Ruger .243 Win that I remember being pleasantly surprised with the velocities achieved from a 34gr Varget 95gr Nosler combo. I'll see if I can find my range notes.
 
Thread starter #3

Jester896

Senior Member
Thanks! @chuckdog the hook does need to go :) slightly over .5MOA for a new Remington might be good

yeah...my 700P 308 is 26" and 100fps slower than others

Target C is at Sierra max load for the bullet and I feel like it is just starting to come into where it needs to be. That is why I thought I would run a couple of more with .2 increases and reduce the trigger pull.
 
Thread starter #6

Jester896

Senior Member
I agree with both of you if that is possible. I started with the IMR4198 for speed in the short barrel. It is clear from the heat pattern of the barrel it can be much slower than it is now. By comparison Varget and 4198 are very close if not the same burn rate. My buddy uses 760 in his loads. I do believe I need a slower powder to get the velocity up. I have 760 and both 4350s as well as RL-15 and plenty of the 2 4831s...I'll get there eventually :) if I don't run outta those bullets.
 
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I use faster burning powders for carbine/shorter barrel .243.

That’s why I chose Varget over the usual 4831 class powders for the Ruger Compact.
The powder that gives you the most velocity out of a 24" barrel ....Will also give you the most velocity out of a shorter barrel .....

The fast powder short barrel is a myth that keeps getting passed around ...

Prove it for Yourself ....get out your chronograph and do the test.... I have many times !!!

Powder burns in the first 7" to 11" of a barrel (Probably shorter) ...gas expansion after that provides velocity...
 
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chuckdog

Senior Member
Muzzle flash is my driving force for shorter barrel weapons.

It may not make that much difference, but after being temporarily blinded with H4831 at around 6pm this time of year I decided to go for something a bit faster in the shorter .243.

The velocity loss wasn’t that bad with Varget. It was much better than I ever expected.
 
Muzzle flash is another factor ..... that is also not powder burning..... but the super heated gases igniting in the presence of oxygen in the air .....

It can be a bother at darker periods during the day ....

Pistol/revolver muzzle flash is more concerning for me in self defense situations....
 
The powder that gives you the most velocity out of a 24" barrel ....Will also give you the most velocity out of a shorter barrel .....

The fast powder short barrel is a myth that keeps getting passed around ...

Prove it for Yourself ....get out your chronograph and do the test.... I have many times !!!

Powder burns in the first 7" to 11" of a barrel (Probably shorter) ...gas expansion after that provides velocity...
Just educated me !!! Thank you.


I always assumed there was validity towards customizing powders to barrel lengths for mitigation of velocity loss in short barrels.

Won’t waste the time, primers or powder trying now. Good info. (y)
 
Dub .... It all about "pressure under the curve" .... If you would view a pressure graph of a bullet in a barrel .... It would probably be easier to comprehend ....

When a cartridge is fired .... Peak pressure is the first milliseconds ...usually the first inch of the barrel .... after that powder burns completely in the next few milliseconds and inches of the barrel .....once the burn is complete this produces high pressure gases .... these gases push the bullet out of the barrel .... the whole time this is happening the volume of the chamber and bore area is increasing..... but the gases continue to expand ....until the bullet exits....which release the hot gas which ignite in the oxygen in the air producing flash ....

Here is where we get to "under the curve" part .... faster burning powder usually reach peak pressure earlier than a slower burning powder .... once the peak is reach .... the pressure starts dropping until bullet exit....

Slower powders reach the peak pressure slower and normally build greater volumes of gas over faster powder ....

Pressure goes from zero to peak pressure ....then the longer you can keep the pressure up behind the bullet(gases) the faster it will travel.... Slower powders can maintain that pressure longer ....thus the pressure(time)under the curve .....

There is such as too fast powders (over pressure) and too slow powders (never reach the needed velocity) ....

Generally the slowest useable powder in that cartridge yields the highest velocity...
 
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Example ....300 WBY 180 grain bullet my chart would not line up correct ....Maybe it will be readable ...

Bullet Ballistics Chart
Time (seconds) Pressure (psi) Velocity (fps) Distance (inches)
0 0 0 0
.0001 12,000 60 .02
.0003 36,000 500 .60
.0005 60,000 (near peak)1,400 2.80
.0007 42,000 2,350 7.40
.0009 24,000 2,970 13.80
.0011 6,000 3,250 21.30
.0013 100 3,300 26.00
 
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Super thread, gentlemen.

Overpressure signs, extreme spreads, standard deviations, powder dynamics.....great reading.

Looking forward to seeing your .243 Win load development work continue @Jester896
 
Thread starter #16

Jester896

Senior Member
I remember playing with my 18" .30-30 and the flash it produced with load I was using...748 under 175 gr boolits. It sent a flame out of the end of the barrel that looked over 2' long. When I increased the load I got the flame with some chaff to go with it. I changed to the faster RL-7 and it stopped...I no longer lost sight of the target.

I made an error in my statement and data above...I am using IMR4198. I think I have it corrected everywhere. One of the reasons I chose it over some of the others is a) being faster b) most velocity with the least pressure.

Again, it looks like 760 or 780 is going to give the strongest velocity. Probably why my friend uses it in loads he does for other people. I found out how temp sensitive 760 can be at warmer temps and was trying to stay away from it.

We will do something different on the next one. At least I have more data on the chamber now....the shoulders only need to be pushed back to +.003 when I am sizing brass instead of the SAAMI zero number.
 
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W780 is recommended for top velocity.... never seen any shelves at local gun store. It is a slow burning powder close to IMR 7828 in burn speed maybe between IMR 4831 & IMR 7828 .... I am out away from my burn chart..

Side note .first trip to town since I got hit by Covid!

Dangitman......first trip to town.

Let’s see.....trying to think of what changes you may see.

You’ll be happy to know some of the rioting idjits are staying holed up and playing video games and getting high....only gonna see them when they sent a representative out on a food run.

Conservatives, while on edge, are behaving professionally and going about their business and handling their responsibilities. Imagine that.

The so called moderate dems won’t even look you in the eye. Even they are embarrassed over the hijinks their team pulled thus far.

Glad you are getting out and about. Hoping in the truck and riding around is good for the soul. (y)
 
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