Breech thrust question

[jason045]

I know Tim can answer this for me.  When calculating breech thrust you use the head diameter not the rim diameter, correct?  Also, how much is the handi good for?  Seem like I remember reading the .500 has 13k+ lbs.

[Spanky]

Lots of people can answer your question... it's been discussed about a million times. Do a search for it and all will be revealed.
FYI nobody will give you a straight answer about what the frames can handle.
 
 
 
Spanky

[trotterlg]

Total breach thrust is just one part of the problem.  Breach thrust of a small diameter cartridge with the thrust consentrated in a small area of the breach face is a lot different than the thrust applied across the entire breach face, so comparing the breach thrust  of a .223 against the breach thrust of a 12 gague is like comparing apples and oranges, the .223 case head can cause a failure in the breach face because it's force is applied against a very small area.  Then you have the forward thrust on the hinge pin, this would be calculated by multipling the area of the sholder of a bottle neck case by the chamber pressure, this is a seperate force from the breach thrust, this is the reason that the magnum rounds do not do well in the H&R's.  Lots of things going on when the thing goes bang.  I think H&R tried some of the mag rounds and failed to make them work.  Larry

[quickdtoo]

You can get a ball park breech thrust figure using this simple calculator, plug the case head diameter into the cylinder bore field and the SAAMI MAP in PSI into the PSI field, leave the rod diameter blank. The results will be high because actual breech thrust is dependent on the internal case head area, but it will give you an idea for comparison purposes with factory chamberings offered on the frame in question.

http://www.baumhydraulics.com/calculators/cyl_calc.htm

http://stevespages.com/page8d.htm

http://www.leverguns.com/articles/saami_pressures.htm

http://www.riflebarrels.com/articles/custom_actions/bolt_lug_strength.htm

H&R had plans for Handi-mags with an all new frame and possibly stronger underlug design, but they never got enough distributor pre-orders to warrant the $20k to R&D to make them, so they cancelled them. 

Tim