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I just loaded some 7mm08 in new Nosler Brass. I loaded both 120G Ballistic Tips (red tips) and 120G TTSX (blue tips) at the same time. I full lengthed sized all the cases before using them and seated them with a Redding Competition seater. Both bullets were seated 50 thousands off the lands. All bullets fit easily in the detachable magazine. The BTs are actually a hair shorter (technical term).

Just got back from the range. The TTSXs loaded and worked fine. The BTs would chamber, but I could not lower the bolt knob (Tikka T3X) on them. What am I doing wrong?

Ogive?



Mark a BT with sharpie, try loading it.
Are there marks from the lands?


Or,

Carefully a BT into to muzzle. Gently.
Use the depth gage on your calipers to measure how much sticks out.

Do the same with a TTSX.

I'm guessing the BT ogive is more rounded and is hitting the lands.

Obviously you didn't measure the ogives on both bullets, relative to the lands.

How did you determine that both bullets would be .050" off?

MM

The dreaded Ogive. Seat the bts in further. Always chamber a few before going to the range.

Ogive variable is the issue.

I approach this differently. My standard objective is .015” off the lands for determining COAL. Different action guns may require a different approach, but the first step is to insert a cleaning rod with blunt tip in the muzzle with action closed. Bit of tape on the rod allows me to mark the rod at the muzzle junction. Next step is to open the action, drop a bullet into the chamber and gently hold it in place with a pencil or small dowel. Move the cleaning rod to contact the bullet point, mark and remove. Calipers measure marks on the rod, and I subtract .015” from that. Presto! This approach has not failed me.

When using cast bullets I do not subtract, but load to have the bullet in contact with the lands.

Always a good idea.


I got burned this summer. Loaded some Nosler 2nds from SPS. Used the same COAL as firsts. Wouldn't chamber. Turns out the ogive length was 0.080" different. Maybe why they were seconds?

You’re right. I measured the TTSX because I’ve had good luck with them 50 thousands off the lands (measured with a Hornady gauge). Then I set the seating gauge the same for both of them (my mistake) - but usually BTs have shot better for me closer to the lands. I should have measured the BTs as well- didn’t think that was necessary.

So, they knew that, but didn't bother to let the buyer know?

Does any company, when they change dimensions?

Been there; done that, seen it before...... Except I always try a few in the chamber before going out to shoot 'em; as DLSguide already mentioned.

Rarely do 2 different bullets from different manufacturers have the same ogive contour, so each really has to be measured individually................but being .050" off with the Branes, it's a little surprising that the NBT's jammed.

I start everything .010" - .015" off, even Barnes, never seen a reason to jump Barnes any more than anything else. But lots of people insist they shoot better off. Makes me wonder if they even tried them close.

MM

He said they are both "seated .050" off the lands". The question that needs to be asked, is are you sure they are loaded off the lands and what was your method for finding the lands, to be sure? The ogive means schidt in this case.

There are many ways to find the lands with the bullet. Some are easy, some more complicated. Some require no tools. That's how I do it. Use a fired case, and soot the bullets. No extra gizmos needed. Keep it as simple as possible, applies here.

There in lies your problem. You should always measure your OAL, for every bullet you intend to load, then write it down somewhere. If you change lots, recheck just to be sure it is the same. If not, make correction in your OAL book.

I wonder the exact same thing. I've tested them, and find I get excellent accuracy even at .020-.025" off the lands. Often times getting better precision that far off the lands than .050-.120" off the lands. Barnes recommends .050" as a starting point, but f that if .020" works well.

Sinclair and PTG both make a Ogive tool that is a hex and will work for different calibers. You use it with a standard dial caliper and it will seat different bullets to the same CBTO.

The approach I use is to get a short section of barrel and run the same chamber reamer in until the shoulder of the case will go in about .100 or so. Then test a round by putting it in that section of barrel. Its easy to get the length that way.
But, in a factory barrel, that wont work.
Charlie

Takin' Care of Business with the Sinclair nut is a good idea . . . .

Those steel comparator nuts are Not Fragile

I would add that have found the "same" bullets, made by several companies, to vary a little in dimensions from lot-to-lot. This occurs because the bullet-forming dies or, in the case of monolithics, the lathe-work varies a little as the tooling wears. (Was even informed during a factory tour of a bullet company known for their accurate match bullets that they typically change forming dies every 40,000 rounds, due to wear.) Have seen those dimensional changes in other brands of bullets over the decades--which is why we should check dimensions when working with a new lot #.

Might also mention that Nosler "seconds" are not picked by dimensional changes, but cosmetic flaws. Sometimes I have not been able to see those flaws, but sometimes I have--yet the seconds shot just as well as the "firsts." The last such 2nds were some 200-grain .30s--which grouped just as well as 1sts in my ULA Model 24 .30-06, three shots in a little over half an inch.

I’m one of habit that has always started them .050 off. I’ll have to try them closer the next time I work with them. You all could be learning me some new habits.