> Now I'm trying my first 30-30 reloads for the Thompson.

I thought (since I have a .35 Rem) I would load the 30-30s with a 110g hollow point (Sierra) to make a pretty quick heavy varmint load for my > TC. The Sierra loading manual calls for an OAL of 2.715. When I seat a bullet to that length, only about .1 inch of the bullet is in the case > neck. Seems to be really unstable with that little seating depth. Also, the bullet hits the lands and grooves?.. I slowly worked a bullet in till it chambered without any resistance then added an additional 10 thousandths. The OAL of this bullet is 2.680. I figure the dead space will be a little over 10 thousandths. More than I would like but I want to get the bullet into the case as far as possible. This gives me a bullet seating depth of about .135. 

From njohnson@nosc.mil

Short bullets do result in this problem. I have not ever found the very shallow seating depths to be a problem and would be curious to know what you mean by "Seems to be really unstable with that little seating depth.". Unless you carry them in your pocket in the field, they should be OK. Perhaps your expander plug is a little too large to provide a good grip by your case neck. You might try Lee's Factory Crimp Die to further tighten things up if that is really necessary. My 7mm Remington Rolling Block has rifling worn so badly at its origin that I seat my 175 gr. bullets only 1/16" into the mouth. That has caused me no problems.

Seating against the lands is not usually a disadvantage (to the contrary) as long as powder charges are adjusted so that excessive pressures do not result. Our police range allows a maximum of 900 fps and I load my .357 Herrett down to this velocity. I use .357 HBWC bullets started into the case mouth just enough to allow the action to close. The bullet is seated by the closing of the action. This makes for loads that shoot far better than I can and are more accurate than any revolver that I have ever fired. If I can not keep all in the 10 ring, I cannot blame it on the gun/load.

Incidentally, my boys and I use 110 gr. Soft Point .30 Carbine bullets for all of our .30 caliber varmint loads. They are FAR less expensive when bought in bulk than the Sierra HP's. Black Hills has them for $58.50/1000. We stocked up a lifetime supply at $42/1000 a couple of years ago.

God Bless!