| DarylS |
| (.700 member) |
| 02/10/10 12:29 PM |
|
Re: 20 ga DR build progress.
|
Quote:
Hey guy's.
I thought the limitation on shotgun actions had to do with the strength of the underlugs, and at higher pressure the action trying to unhinge itself.
Wall or chamber thickness, with modern steels is not the limiting factor.
Without the locking shoulders of a bolt or lever action design, all the thrust is rearward on the standing breech, hinge pin and underlugs.
This is where the third bite helps ( Greener cross bolt, Rising Bite etc )
I would think a 3rd bite and side clips add more than just picking a 10 ga action.
Are the 10 ga lugs that much larger and stronger than a 16 or 12 ga ?
If my hypothesis is flawed please educate me.
Nitro
Exactly - with modern limited taper rounds, there is very much reduced bolt or thrust against the standing block, therefore less of the pressure is trying to unhinge the action.
The 10 bore action is larger than the smaller cases to contain the larger cartridge, but also for added strength due to the larger case head. The pressure against a 10 bore's standing breech at 11,000PSI, would be the same as a smaller ctg.'s pressure at perhaps 15,000PSI would be against the same block in the same action. This is why when people can use shotgun actions which are chambered for 12 bore cases, but chamber the rifled barrel for a .450 #2 (smaller rin size) which produces 38,000PSI - the action doesn't spring open & the pressure is contained by the action. The difference is the area over which the pressure is spread.
Now, that .450 #2 might fit perfectly and the barrel would be plenty heavy enough if done on a .410 double shotgun, but the action wouldn't take the strain, whereas the larger action can, even though both shotgun rounds are loaded to the same pressure- of 11,500PSI max- or thereabouts.
I am not explaining this sitation well - sorry.