bullet seating issues

[holfeldian]

hey guys... i've got a remington model 700 sps ss in 7mm rem mag. i'm starting load development on it and i have run into an issue. I'm trying to figure out where the lands are on my rifle by making a dummy cartridge and (with some modifications to the brass) pushing the brass cartirdge into my rifle with a bullet lightly seated in it. the idea is that the bullet will touch the lands and push the bullet to the exact depth. I was then planning on seating the bullet .002- .005 of an inch further in so i'm just off the lands. however, when i did this i came to a length of 3.322" so i figured i put the bullet at 3.318- 3.320". then i looked at my loading manual and noticed that the maximum overall length for my bullet and powder is 3.290"... is this an issue? I also tried cyclng my dummy round a couple of times( the one set to 3.320" ) and found that it came out at 3.270" after a couple cycles. It was also harder to close the action than i think it should have been... compared to factory ammo. and while looking at a few different reloading manuals i noticed some discrepencies... some say maximum overall length is 3.290" while some say MINIMUM overall length is 3.290"... what the $%@#? it also might be important to note that i'm loading 162 gr hornady spbt with imr7828 powder.

 

[cosmic]

You're going to have trouble holding that small of a clearance to the lands, from shell to shell. Bear in mind:
a) You cant be assured your trial was accurate.
b) For a hunting rifle, your better off having more "margin" for reliability.

3.29 is the max dimension, for the production of commercial cartridges. If your trial was correct, loading to that length would give you a margin of about 30 thou, which is good. Bear in mind that I have been using 30 thou clearance for years, and I can easily develop loads that shoot better than I do.
In my mind, bullet jump is a "least" variable for sporting rifles. Suggest you focus on major variables like bullet weight/spec and powder - you'll get more fruitful results.

 

[Lead Loader]

I would say, like i always do, .020 off the lands seems to work best, and dont need to worry about oal, as long as it fits in your chamber and mag its ok, thats just a general guide, every gun is different. I have a gun with a heavy bullet thats 0.070 longer then max oal, but thats where it likes it.

 

[aheppner]

to find out what your max oal is,

make sure you don't have too much neck tension on your dummy round, if there is too much it will push the bullet a little way into the lands and give you a bad measurement

I make sure I can move the bullet in and out with my fingers, should be snug ish, then after I measure I pull the bullet out a bit and check it again, sometimes up to 10 times just to make sure then eliminate the longest and shortest then average the rest

low tech but it works for me


Alex

 

[Cleftwynd]

I do the same thing and use several attempts, after I have at least ten measurements, using 2 casings and bullets, I then average the numbers and record it for that rifle.

 

[holfeldian]

ya i've used a few methods now... i found my lands at 3.305... i made a pretty stupid mistake the first time i was trying it...but i'm good now! so i'm going to seat my bullets between 3.280 and 3.290 and see if these work