Seating Depth Q in 7mm-08

[modoc]

Good evening,

I was working on some loads this evening for my 7mm-08 and after finishing the funny projectiles, was starting on the boolits that I had been given and ran into an issiue. The boolits look like the RCBS 7mm-145-SIL with a gas check and weigh about 147gr+/-. After seating one to 2.75" OAL like the J words, I tested the unprimed case in my 660 for function:-?. After a stiff closing of the bolt, I removed the cartridge and inspected the boolit. It had been pushed back into the case so that the OAL is now 2.605" and shows rifling marks going back almost .125" on the ogive. By comparing this to a free boolit, the bottom of the front driving band is at the bottom of the neck. Will this cause any problems? I am actually in new territory with this both the boolit and seating so deep. BTW, I have about 400 of these and plan on driving them ahead of H335.

Thanks.

[leftiye]

I would guess yes! You won't have much grip on that boolit (might even get knocked back loose inside the case). This might also affect accuracy- variable boolit pull and ignition. And it will cause higher pressures due to less case volume when seated that deep. Might even be some problems with alignment when chambered - affecting accuracy.

[GooseGestapo]

You'll probably have to get a different mould to get decent results from the 7mm08.

My Rem. Mod7 in 7mm08 has a very short throat. This is because it was designed for jacketed bullets and was at the time it was commercialized being heavily used for long range metallic silhoutte matches. Most competitors were using 162-168gr BTHP match bullets, in Remington 700 Short actions so dimensions are tailored around that. My rifle will accept a round up to about 2.850" in the magazine, but most jacketed bullets such as the Sierra 140gr and Nosler 140gr bullets need to be seated to 2,795" to touch the rifling, and best accuracy comes at 2.775 with the Nosler B.T.,down to 2.750" oal for the Sierra Game King and Pro-hunters.


A bullet with a long nose shank of bore-riding dimensions such as the Lee .285-130-R will be called for. However, if your bore is on the tight side even that might not work well with any cast bullets.

Most if not all of the bullet moulds are designed/intended for use in the 7x57 Mauser chambers which typically have long to very long throats.

I suggest putting as much crimp as possible on the bullet seated to the depth you got and try it.

Push comes to shove; you may have to do something like get a gunsmith to use the throat reamer for a 7x57 to lengthen the throat to allow use of the cast bullets. If done well, it probably won't much affect the accuracy of the jacketed bullets.

Good luck...........