.45ACP oal effect on pressure

[Bama Drifter]

Hey fellas, 1.235" is what I run for all of my 230gr loads regardless of powder as it "plunks" well in several 1911s. I noticed the hodgdon data lists 1.20 oal with 5.3gr of w231 max charge. If I go with 1.24 to 1.26 oal, does the extra space allow 5.5gr (GI load) to burn at standard pressure? I know my Kimber Custom digests +P loads, but I don't want to run my Colts too hot!

Projectiles of choice are Xtreme plated, and MBC Softball coated.


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[Blue68f100]

Increasing the OAL will decrease pressure. As for what the internal pressures are doing you would need test equipment to find that out. Some +P loads do not produce higher velocities, just higher pressure over std.

Powder selection normally gives you choices to get higher velocities without increasing the pressures much. I would stick with std pressure loads, no need in beating the gun up.

 

[Jim Watson]

Your numbers make no sense.
SAAMI maximum for .45 ACP is 1.275" and even that won't fit all magazines except with the elliptical hardball bullet ogive.

 

[Walkalong]

I noticed the hodgdon data lists 1.2 oal with 5.3gr of w231 max charge.

That is for a flat point.

If I go with 1.4 to 1.6 oal, does the extra space allow 5.5gr (GI load) to burn at standard pressure?

Who knows, but the pressure will be probably be greater. I would stick with the 5.2 Grs W231.

 

[Bama Drifter]

Edit: Oops, I left out a 2! 1.235 and later 1.24 to 1.26.... that happens when relying solely on memory and not notes

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[Jim Watson]

Which is why I avoid posting "recipes" especially in cases of shopping for heavier loads.
But I will hint that Lyman shows heavier loads than Hodgdon, probably because they use a roundnose bullet instead of the deep seated flatpoint.

 

[ArchAngelCD]

I can't tell you what will be safe in your guns, I can only tell you what I do. I load 5.5gr W231 under any 230gr bullet in my 45 ACP ammo and call it good. I do however use an OAL of 1.255" with a FMJ bullet and 1.265" with a LRN bullet.

Only you can decide what is safe for you but I will add, the older Winchester load data used a charge much higher than 5.3gr W231 without listing excessively high pressures. A charge of 5.5gr W231 has been standard for many years and millions of rounds lol.

 

[Bama Drifter]

Thanks ArchAngel... you got what I was thinking. I suppose running 1.25" and using a case gage would be the safest way, if not most expedient.

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[rg1]

What I've read about seating depth in 45 ACP:
The 45 ACP with large case volume and a low pressure round has minimal pressure increases with shorter seating depths. Not much change in velocity and pressure until 50-60 thousandths shorter seating depth. But with a maximum load I would be careful changing seating depth without lowering powder charges. Unlike 9MM and 40 S&W which are very pressure sensitive due to smaller case volume and higher pressures than 45 ACP seating depth is not as critical in 45 ACP. I would definitely do the plunk test with 45 ACP as different bullet profiles can change the distance to the rifling. I've read that you should try to have bullets at least 10 thousandths from the rifling in 45 ACP. Here's a good article on plunk testing:
http://www.shootingtimes.com/reloading/reloading-tips-the-plunk-test/
I recommend using bullet manufacturers overall lengths as a guide and doing plunk tests in your pistols. This is totally unscientific and just what I've read about 45 ACP.

 

[Bama Drifter]

Thanks rg1, great article!

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[Rule3]

As Walkalong posted, the data on Hodgdon for the 230 gr Hdy FMJ is a flat nose which will be shorter COL than a RN. That said they load a 230 gr LRN to the same 1.20 but the pressure is a tad higher due to the shorter length but it is lead which will not be the same as a FMJ.(pressure would be more if it was a FMJ

Two different shapes and material.

So you can not compare it to YOUR bullet.

Look at some different manuals for data for a similar bullet. It will vary say between Hornady and Speer.