[mattamus1987]

Brand new to reloading here just got a RCBS press set up and put together my first batch of 30-06. My question is what is a satisfactory way to determine bullet seating depth for my rifle and how far off the grooves should I seat it, preferably a way without buying one of those chamber gauges.

Did some searches and could get a good answer other then just "feeling it" as I chamber a dummy round, also dont really know what I should be feeling for anyhow.

[Strykervet]

You load a bullet long and keep seating it deeper until it just chambers. With a black marker, you can color the bullet and you'll see the rifling contact the bullet. Provided it isn't seated too deep. Then you can measure how far off the rifling you want to be with your calipers and then figure your case overall length from that. How far off the rifling depends on the rifle and the calibre, and to some degree, your particular rifle and the loads you load. Typically you want them close but not touching, how close depends. Different COL loads can be one of the variables you work with in loading. You may need a benchrest to see the differences though. I mostly load for autos, so mag length usually gets in the way first, except with the Grendel and 100gr. AMAX --I can seat them close to the grooves and they are the most accurate bullets I've used yet. How close? Don't know yet, but I'm seating so close 1 in 100 won't chamber, and I'm getting sub-MOA in an AR using a sandbag under the folded bipod and a sock filled with rice under the stock.

Make sure to adjust your powder accordingly and work up. Changing your COL changes pressure. Good luck, stay safe, and focus on the fundamentals in your book to begin with. Weigh each load, every one. When you get a feel for a certain powder or measure over time, you may just dispense and check now and again, but to begin with, "treat every gun as if it were loaded" is a good way to put it --treat every step as suspect to error.

[cfullgraf]

If your rifle has a magazine, and you wish to use the magazine, then usually the length of the cartridge that fits in the magazine will be well short of the rifling.

But you can load the round longer than the magazine and single load it in the rifle.

Skrykervet's method works for determining the maximum possible overall length.

[mattamus1987]

Awesome thats for that trick Skrykervet. Im sure Im going to be spamming this board for a while with all my questions Im sure im going to come up with.

[kludge]

I make a dummy round for each rifle/bullet combination. I start 0.015"-0.020" off the lands, using the check and measure method similar to the above method, and I am almost never tempted to change the seating depth beyond that. The actual dimension is not critical at first, however, I double check the load data for that bullet to make sure I'm not below COL listed in the manual. The dummy round also lets you set up your dies for that rifle/bullet combination without any thought. It can also be used to check that the round will go into the magazine and feed into the chamber.

Then work up the load without changing the seating depth. Be warned that the pratice that some benchrest shooters use of "jamming the bullet into the leads" can raise chamber pressure, and should be left to expert loaders. Don't be afraid to back off and work up again if you change seating depth, but I've found that seating depth is one of the last things to chase in the quest for accuracy... The shooter, the scope, the rifle, the bullet, the powder, the case preparation all have much more effect.

[mattamus1987]

Thanks guys, also how often should it be expected to have to trim a case like 30-06. I trimmed each one to about .010 under max case length, am I going to be over after every shot? every third shot? what should I expect?

And what's the specific harm in trimming a case too short?

[James2]

How often to trim? Best to just measure some of the batch to see if they need it. You can be over the spec length some and not cause a problem. If they are too long though they hit bottom in your chamber. Then you have a problem. Brass will stretch some every time you size it. The 30-06 brass is specified to be 2.494. That is where I would size it. As for overall cartridge length, my manuals give a OAL length for each recipe. That is a good place to start.

[SASS#23149]

be sure to brush the case necks before re sizing,and some folks use a dab of lube in the necks so that the expander ball does not drag,they can really drag depending on...well,I"m not sure what,but i'fve had some rifle dies REALLLY drag when retracting the case.brush,lube,size,measure. Do expect to do some trimming,it's a fact of life with bottle necked brass.