Reloading first for me.

J

jerrya

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I have been reloading for about 6 years now. I went through the learning curve, so I thought, and had it figured out for the few I load for.
Was loading up some for my sons 270 today with 130 accubonds, same load for a few years now that was extremely accurate. Primed and charges cases the same as always and starting seating the bullets with the same dedicated Forster micrometer die. I roughly checked the first few for coal and they were way off. This threw me for a loop. I piddled around checking everything but finally checked the bullets. Between the 2 boxes I used for this session there was .020" difference in overall length of the bullet itself.
Is this a common thing or I am just the lucky one? I have more new boxes here that I am going to check bullet length tomorrow.
 
not uncommon, had a hummer of a load with Berger bullets, next lot of bullets I got were 57 thou longer, and didn't group worth beans, had to keep buying bullets until I found a lot number that was as short as my original ones. I got lucky and found some, but that was serious luck of the draw. Most of Berger's bullets got longer and they updated their required twist rates to reflect the change in bullet shape
 
6MT said:
Ogive is more important.
Click to expand...

I understand that, and checked that when developing this load. Didn't feel the need to do that since seating die is only used for this rifle. I will check tomorrow but these longer bullets may have had problems in the mag box, not sure yet.
 
The way a bullet is made, the nose section flows and becomes whatever it is. The Ogive position tends to be very accurate, but measuring to the tip of the bullet is not good.

Sierra tells me the variation can be 20thou. Hornady claims to be about half that.

I use a tool like this to measure the loaded length off the ogive.

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Bullet length variation of several thou is not unusual in my experience, although 20 thou is quite alot!

As others have mentioned, cartridge base to ogive is best to use for determining your seating depth. If mag length is an issue, you would tune that CBTO measure to a common value that accommodates the longest bullet you would encounter. With your micrometer seater and a bullet comparator tool, that should be straight forward to determine.

I use the Hornady bullet comparator and insert set with calipers. Works good. There are other brands of this same type of tool that fits on your calipers and are excellent.

Beware of donuts forming inside case necks. These can push back against the bullet and cause huge seating variations. Your micrometer seater will not be able to correct for the springy push back as you crank it down until it overshoots and seats it too deep. So an inside case neck reamer is a handy tool to have to cut out that donut after several firings on the brass, if necessary.
 
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