Over All Cartridge Length

[PA BEN]

OK, you guy's who shoot a lot, this question is for you. I'm reloading new Win. brass. 7mm REM. MAG. I trimmed each one. But, I'm getting 3.32 to 3.29 w/my die. I saved my 3.32 rounds and they group very will. Will the 3.29 to 3.30 be off by much? I am talking about hunting rounds.

[JackOfAllTrades]

No.  When I reload for hunting, I set an amount of tollerance/range that I'll accept for an amount of accuracy that I expect. You're not trying to develope cartridges that put bullets in the same hole at 100yds, you're trying to hit an 8-12" kill zone at a given range. Now... If you're shooting game at more than 500yds, then you're going to build cartridges with tighter tollerances that should provide better accuracy. But then.. You're playing with many different variables that mother nature dishes out.

-Steve

[hunterofelk]

The overall cartridge length is more important when you're considering whether the rounds will fit nicely in the magazine or cycle without any jams.  Accuracy will depend on how close or far away the ogive of the bullet is from the start of the lands in the barrel.  I try to get the gap of ogive to rifling to be between .030-.025 inches.  In some cases the rifling starts farther down the barrel to keep chamber pressures down.  If I loaded my .300 Weatherby so the bullets ogive was to my specs., the rounds would not fit in the magazine.  So there is quite a gap there.  Still, the rifle puts out tight groups and I can't complain.  Your longer rounds probably have the bullets ogive closer to the sweet spot, whatever the gap is, but the shorter ones will be more reliable in a hunting situation where a quick followup is needed.

[PA BEN]

So, if the ones at 3.32 shoot groups at a 1/2" then the ones between 3.32 and 3.29 should be ok too? (In hunting situations.) I'm not a paper shooter just looking for good hunting rounds. Also, is this a normal spread for a die to seat bullets?

[tlbradford]

Are your bullets seated deeper or are your cases not trimmed to the same length?  By saying it was caused by your die I'm guessing some are seated deeper.  I think this is too much of a tolerance to accept from your dies.  They will still shoot fine, but you shouldn't have more than .01 difference when seating.  Are you making sure you're getting the arm completely down when seating bullets?  Any wiggle in your mount when seating bullets?

[PA BEN]

New brass. I trimmed each one. And use the same pressure on each one. It's a Lee die.

[hunterofelk]

Are your bullets lead tip exposed?  Are they premium bullets?  Some of the tips may have been dulled during packaging.  A few hundreds of an inch range might be normal for bullets with lead tips.  The overall length might vary a little, but as long as you can feed the rounds into the magazine or clip and cycle them through and hit the target in a fashion you are satisfied with, then no worries.

[PA BEN]

Nosler AccuBonds. Palmer tip. I never miked the bullets them selves. I'll give that a try, I assumed they should be the same.

[JackOfAllTrades]

You're talking .03" variable. Yes, this is normal without competition dies and components. A more precise measurement would be from the forward ogive of the bullet instead of the tip. If I remember right, you're using a semi-progressive press. ?? There are minute flexes in the turret/mounting that could also account for some varied seating depths.  A heavy single stage press can reduce much of this. As for the demmensions of the bullets themselves, there will be some variables. -Even Noslers. 

-Steve

[Rob]

Two things I noticed...

1.  Make sure your primers are seated FLAT.  I was getting some odd readings once, and found that I had a batch of primers that were not quite seated flat.

2.  Measure length to the Ojive, not the tip.  Even polymer tips can vary a bit and lead are really bad.

That said, I don't know that I cannot shoot well enough to tell a .03 OAL difference!

[tlbradford]

If I remember right, you're using a semi-progressive press. ?? There are minute flexes in the turret/mounting that could also account for some varied seating depths.  A heavy single stage press can reduce much of this.-Steve

That was my guess too.  A little flex at some part of the press when seating bullets.

[PA BEN]

Signal stage press, one die at a time.

[Jamieb]

Your never going to notice 1/100'th of a inch.

[tlbradford]

 

[JackOfAllTrades]

If you're not reaming the inside of the case necks, then I'll bet that your neck brass does not have a uniform thickness across brass lots. What happens is that when the bullet is seated, sliding into the case, there's less friction with one or the next. The one that has more friction exerts more pressure on the seating cone of the die. The cone cuts into the copper jacket just a tad and the case actually flexes a tad. If the bullet set is also 'not perfect'; Combined, this results in an inconsistant seating depth across a set of loaded cartridges. Each with a variable of hundredths of inches. Without a fixed accuracy testing barrel, you're never going to notice this in your paper or hunting shooting.  Does that mean you should never set everything consistantly? Never measure the final cartridges you produce? Certainly not. Again.. Set what you feel is an acceptable tollerance that provides the accuracy you desire.

Side note-  From the most resent result targets you posted in another thread, Accuracy wise, I think that you're loading just fine. Inspecting your brass after firing, looking for any signs of over pressure is still suggested. Asking questions is good though.

-Steve