Is this too much variance in boolit length?

[ghh3rd]

I took a sample of ten boolits from some .40 cal that I loaded to check the length. They were
1.105
1.102
1.098
1.103
1.103
1.103
1.098
1.107
1.104
1.100

Is this much of a spread unusual? They all fed well.

Thanks,


Randy

[felix]

No, Randy. ... felix

[Jumping Frog]

A range from 0.98 to 1.107 is a spread of 0.009", which says your process is perfectly acceptable in terms of repeatability. If you take 10 samples from 2 or 3 boxes of commercial ammo, you'll see that their spread is even higher.

However, your lengths seem awful short to me for .40 S&W. Heck, my 9mm rounds are longer than that. The maximum length for .40 S&W is 1.135. Both Hornady and Hodgdon list 1.125 as the minimum length for all of their loads.

What kind of boolit are you reloading?

Do you understand that most load data shows the minimum allowable overall length, with it being implicitly understood that the SAAMI maximum cartridge length is the maximum. Basically, you want to find a length that will chamber well in your gun, feed correctly, and be between the minimum and maximum lengths.

Please tell us your load data, because I am concerned you may be too short. The .40 S&W is a relatively high pressure cartridge, and it isn't one to make this kind of mistake with.

[ghh3rd]

I appreciate your help.

Boolit: LEE #90431 TL401-175-SWC 40 S&W 175 Grain Tumble Lube Semi-Wadcutter
Load: 5.5 gr of Accurate #5.

By the way, am I thinking too hard... if the difference between min and max len is .010, and my spread is .009, it seems like it would be easy to wander outside the limits a bit at times.

Thanks,


Randy

[sagacious]

You didn't specify your reloading routine, but if you seat and crimp in separate steps, your OAL range will usually be appreciably smaller.

Just a suggestion. Hope this helps. Keep up the good work. :drinks:

[helg]

1. This is how the TL401-175-SWC bullet should look when seated to 1.135", which is max SAAMI OAL for the caliber.
http://castboolits.gunloads.com/showpost.php?p=673826&postcount=8

2. QuickLoad program shows that the load, which you use with your bullet and powder, is light enough not to worry of overpressure.

Seating to 1.137" calculates to 763fps muzzle speed and 13600 PSI max pressure, which is just 39% of the max pressure for the caliber.

Seating to 1.100" is 800 fps, 16300 PSI and 47% respectively.

Needless to say that .009" variations of the length give way less differences in the above parameters.

3. Only 65-70% of the powder burns while bullet is in a barrel - i.e. muzzle flash should be visible for the load.

[ghh3rd]

Thanks for all of the help with this. I am going to pull one of my boolits and measure the ID of the neck to see if the crimp I used is sizing them -- I suppose that I could measure the boolit as well.

Of everything that I've learned about reloading, CRIMPING IS MY WEAKEST LINK. It's hard for me to tell how much crimp I really have. I start at none, and keep turning the knob slightly until I begin to see it, and stop. After crimping my .40's, I notice just a slight curve of the edge of the brass. I read somewhere that auto load boolits don't require as much crimp as revolver boolits.

Helg - my boolits are seated so the top 'band' is just above the case, significantly deeper than the pic that you provided. I think I'll move them up as close to max OAL, while still have good feed through the gun.

By the way Helg, I like the method of measuring the diamater of a boolit without a caliper/micrometer that you provided in your other post.

What is that 'Quickload' program that you have? It sure seems handy.



Randy

[snaggdit]

+1 on making them a bit longer. I load this boolit in 40 S&W with 4.7gr Red Dot to 1.125 and it feeds well and gives me good accuracy.

[fredj338]

Yep. I load all my 40s to 1.125" regardless of bullet wt. & design. Aslong as it will chamber, you are good to go. As saga noted, seating & crimping in separate steps is more uniform. You'll also get a slight variation using mixed range brass vs brass being all of the same headstamp & number of times fired. The 0.009" variation is not worth worrying about.

[helg]

What is that 'Quickload' program that you have?

Here is the link.

http://www.neconos.com/details3.htm

This is commercial program. It solves 'internal ballistics' problem: you supply caliber, bullet weight/length/type, powder charge, OAL and barrel length, and the program calculates max pressure, muzzle speed, %powder burned, with useful tables/graphs.

QuickTarget is 'external ballistics' program. There are other programs of this type. You provide muzzle speed and bullet parameters, and it draws bullet drop, speed, wind deflection graphs and other parameters of the flight.

It is very handy for estimates. Say, you cast bullets of some hardness. With Lee or some other chart, you know what is optimal pressure for the hardness. Then you can calculate a load for this pressure. Of course, the program shows what is the maximum for chosen caliber, and warns you with many reds, if you are close or exceeding the max. Another example of the use is above in the thread.