Rather than start a new thread with my question, I'd like to resurrect this old thread because of all the good related info it has in it. The 7mm Rolling Blocks are surprisingly accurate even with very worn bores. So I neck size cases during reloading so that I do not size any farther than bullets are seated. I've settled on seating the bullet so the base is approx.
I seat bullets out so that they can get closer to the rifling. I have used bullets from 140-175gr what ever the cheapest bullets I can find when I need more (Camp Perry is not in the picture). If you don't anneal you will get case mouth splits after several firings due to the brass getting brittle. It will be necessary to anneal case necks periodically (I do mine after every 2nd shooting). This causes the case mouth to fairly greatly expand on firing. Also, I have found that most of my 7mm Rolling Blocks have chamber throats that have been eroded due to repeated firing from corrosive primers. After firing it will be necessary to trim your cases to uniform case mouths. Clean cases and reload using the starting load listed in modern reloading manuals. Lock your 7mm die at this location and repeat the process for all cases you plan on shooting thru this rifle. You have now removed all excessive head space. It is best if there is very slight resistance of the face of the hammer against the breech block. In small increments, repeat above until the case will chamber, the breech block will close AND the hammer can be lowered to where it would strike the primer. Next, using a 7mm Mauser sizer die, screw it down until it only slightly sizes the neck. A successful way to fire form 7mm cases for the rolling block is to 1st expand the case mouth of an unprimed case with a. It is difficult to fire form rimless cases as there is nothing holding the base of the case against the breech block. The distance from the base of the case to the start of the shoulder is shorter. This results in a modern 7mm Mauser cartridge having excessive head space (being too short) in the rolling block chamber. When SAMMI standardized the cartridge in the 20th century they settled on a case length that was slightly shorter than the original 7mm cartridge that rolling blocks are chambered for. The 7mm Mauser cartridge dates from 1892.
0 kommentar(er)
