velocity and pressure?

[Charlie Tango]

Well I bought a Lyman shotshell reload manual like a couple of you guys requested and it is an great book. I have a couple questions that I could not find in the book.
What kind of pressure am I looking for with my reloads?  Is there too much pressure?  How should I choose velocity and pressure?
Thanks for all the help!
Charlie Tango

[Ka6otm]

How to choose pressure/velocity...good question.

All of the loads in the Lyman manual are supposed to be safe for use in the gauge they are listed for.  Notice I said "supposed to be safe".  I have found a few of their loads for Activ 20 Gauge hulls are hot enough to blow gases out above the basewad section after the second loading.  After checking the loads against an old Activ loading manual, I found the amount of powder in the Lyman manual was about 15% higher than Activ stated for the same hull, wad, primer and powder.  Dropping down 15% on the powder charge completely cured the problem.  So pay attention to what your empty hulls look like after shooting them.

What you're looking for is kind of a personal thing.  If you pattern the shotgun on paper, you're looking for the pressure/velocity that gives you the best patterns on paper.

If you're recoil sensitive, you're looking for the least amount of shot that will do what you want to do combined with the least pressure/velocity.

If you're shooting sporting clays, you may be looking for more velocity in the hope that it will reduce the lead required to hit the clay.  By the way, I don't buy this theory after looking at the external ballistics charts in the Lyman manual...it just doesn't make that much difference to me.  I think this would just give you a mental edge if you believe in it.

If you're shooting trap competitively, you're probably looking for a load that won't beat you up when shooting 300-500 in a day, which is probably a combination of the amount of shot you want to use and 1150 fps or so.

If you're shooting handicap trap at longer yardages, you might want 1200 fps...and if you're like me, you might not.

So....what do you intend to do with your loads?  That would help with the selection.

Came back to add SAAMI maximum pressure levels for shotguns:
10 Gauge        11,000 PSI
12 Gauge 3.5" 14,000 PSI
12 Gauge 3.0" 11,500 PSI
12 Gauge 2.75" 11,500 PSI
16 Gauge          11,500 PSI
20 Gauge 3.0"   12,000 PSI
20 Gauge 2.75" 12,000 PSI
28 Gauge          12,500 PSI
410 Bore 2.5"    12,500 PSI
410 Bore 3.0"    13,500 PSI

This is from the Hodgdon Shotshell Data Manual Pg. 15

Ka6otm

[Bob_K]

When selecting loads, I tend to look for the lowest pressure that achieves my desired velocity.  Generally the lowest pressure for a velocity will give the more uniform patterns.  Still, you must pattern the load with your shotgun and choke to confirm the pattern meets your requirements.

An interesting article I read indicated you can tighten or open a pattern just by the powder you select.  This could be useful if you are shooting a fixed choke shotgun.

Lastly, I select a load based on components I have on hand.  If I don't have the primer specified, for instance, I keep looking for a load that does use the primer I have.  There is less flexibility in mixing and matching components in shotshell reloading than there is in metallic cartridge reloading.  Not only are there pressure considerations, the stack up of components must be right in order to achieve the correct crimp, and a correct crimp is required for the shell to perform properly.  If I was willing to put up will poor performance, I'd be better off just buying cheap promotional shells rather than invest time and money into shotshell reloading.