"Optimum" barrel length

[renaissance]

Ok
I've been playing around without reliable facts for long enough.
Time to ask for help from those who know more than I ( I would hope).

I have a TC Contender in carbine configuration.
I shoot at an indoor range which is limited to 25 Yards and "Pistol" ammunition calibers.

I reload and am trying to "simulate/emulate?" bench rest reloading and shooting for accuracy.
( At age 71 it is getting too hard to "stand up and shoot like a man" with consistently satisfactory results )

I have already gathered the following barrels for my Contender:
16 1/2 " .45 Winchester Magnum
and
18 " .357 Maximum

Adjustable Objective Scopes (3x-12x) mounted on each.

I've got both these printing three shots basically into one hole at my maximum 25 yards ( on a bad day at worst a "tight" cloverleaf )
I load 230 FMJ in the 45 and "was" using 180 FMJ in the 357, but I think I will go to 158 FMJ on the 357 to "standardize" my 357 bullets for bulk buys ( I shoot 357 Magnum in other pistols and levers )

Question is:
What are the guidelines for optimum Barrel lengths when shooting .45 Win Mag and 357 Max.

I need to keep the length over 16" to make the "carbine" "legal" ....
but what am I doing to the ballistics and accuracy by getting barrels longer that this.

I have been searching for a used 16+ barrel in 44 Magnum and can't find one.
Are there none out there
or
Are they soo good that people hang on to them?

As an aside:
Trying various loads with the 45 Win Mag
I found that 23 g of H110 with a 230 FMJ seems to give the best Accuracy, but the recoil was driving the scope dangerously close to my shooting glasses.
I found the 10 g of HP38 was very near as accurate and a lot less punishing.

Also
Shooting regular 357 MAGNUM rounds out of the 357 MAXIMUM barrel printed ( at 25 Yards ) EIGHT (8) Inches ABOVE the POI of my 357 MAXIMUM Loads.


I'm guessing > Longer barrel + lower velocity of 357 Magnum = Longer time in Barrel - Gives more "lift" to bullet -resulting in higher POI.
but
EIGHT INCHES ???

This leads me back to my original quiestion.

What is the "Optimum" barrel length for a Contender in Carbine Configuration - for accuracy ( I'm not hunting and trying to kill) at 25 Yards.

Why are there not more 44 Magnum Barrels in 16" + length
Is it a "Bad" idea ???

What other "Calebers" should I consider for my goals ( accuracy at 25 Yards in a "pistol" caliber.

I have been using H110 and HP38 because I found recepies for these and I had them on hand
Are there better choices?

I believe I will standardize on 230 and 158 grain Jacketed (semi or full)for 45 and 357 respectively.ads.

 

[Idano]

renaissance,

I am not sure that there is a straight forward answer to your question. Optimum barrel length is dependent upon the burn rate of the powder for the cartridge you are loading ,the twist, and the bullet. Since you have already spelled out that you want to use a 230 grain FMJ in the 45 and a180 grain FMJ in the 357 you just need to decide on the powder. Most likely you will want to lean toward a fast burning powder like Unique or HP-38 since you are dealing with such a short barrel there no need to be burning powder after the bullet leaves the barrel. I would recommend getting a chronograph if you don't already have one then you can find the optimum powder and load for each barrel.