Best NBT COAL

[Hoot]

...snip... Have you tried IMR 4007 SSC in your 25 WSSM?

Actually it's .25 WSSM brass necked up to 30 caliber. Not sure how the dynamics transfer to the larger bullet. RL-17 has been working out nicely though.

Hoot

Edit: Next time I need powder, I'll give 4007 a try.

[steel89]

Nice tool! I particularly like using the screw to lift the cartrige out of the chamber. My 120 AMAX averaged 2.265. The 125 NP around 2.245. And the NBT 2.225??? I ran different bullets in the tool to be sure, and keep getting the same reading. I went back to the 125's and it gives me the previous setting 2.245, but the NBT's are strange. My last range day I shot 120 NBT's set at the AA COAL of 2.245 and had no problems at all. I chambered a round I had loaded recently to 2.260 and it did jam the bullet into the lands and pulled it when I extracted the cartrige (not good, powder every where).
Is it better to seat the bullet deep first and screw it till it seats, or seat it long and tap it in to get the best read?

[steel89]

Ok, back to the basics.
120NBT:
COAL 2.260 - Bullet jams
2.550 - Bullet jams
2.250 - no jam- smooth eject by hand
2.245 - Ditto
So my max COAL is somewhere between 2.250 and 2.255 and at my last range the 120NBT's shot with TAC (27.7-28.4g) at a COAL of 2.245 were not real tight groups 1.5" at 100yds. Should I drop my COAL back a little? Would 2.240 or 2.235 give me a better jump for accuracy?

[Hoot]

...snip
Is it better to seat the bullet deep first and screw it till it seats, or seat it long and tap it in to get the best read?

As long as you don't have too much neck tension, either way will work. I used the start short and screw it in approach. If the neck is too tight, it will be hard immobilizing the case while you turn the screw. Also, it will be hard to tell wehn you first kiss up against the lands. It you start long and have a lot of neck tension, it will actually drive the bullet into the lands a certain amount and give you a longer reading than is true. That was what I experienced. I had made my slit neck case a while back, with a lot of emphasis on neck tension so that the bullet didn't move when I removed it from the chamber. With the screw drive, I loosened the neck tension so that the bullet almost falls out when tipped downward. That way, I have the greatest tactile sense of resistance the bullet encounters as it is screwed into the throat and contacts the lands.

WRT how your load groups for a given COL, the amount of powder affects the group as well. It's kind of a cut-and-try approach as you juggle the powder charge against the COL. That's where range notes are essential. My personal experience has been that the closer I get to the lands with the bullet, the greater the impact of different charge weights upon my groups. That's just the process you go through reaching an optimum load. Hopefully, you're not doing workup with an expensive bullet like some of the Barnes.

Edit: As for where to load a particular bullet WRT the lands, that is different for each bullet. The Amax 123 likes a different location than the NBT 120. Be wary of folks who tell you always set the bullet in the same place as they use. It has to be arrived at experimentally by you with your setup. With a few rare exceptions, you can not rely upon a manufacturer making any two chambers perfectly the same. You can pay for that attention to detail, but it's not cheap.

Hoot

[steel89]

I had really good success loading 120 SierraPH, 123SMK and may yet revisit the BarnsTTSX. So far I've had no bad experiances and want to keep it that way. That is why it is important to understand how to 1) Know the Max Coal for each bullet I load and 2) What is a good 'Jump" for the rounds I load. So far my best reloads have been more 'Luck' using the reload tables. But I want to shoot my reloads knowing that although the powder charges may vary, the COAL I use is going to suit my rifle the best. Does that make sense?

[bwaites]

My best NBT accuracy was 2.25-2.26 also. It likes to be almost fully mag length, at least in my rifles.

One note: Many of us, including Bill Alexander, myself, Variable, and others, have noted that if you shoot Noslers it takes a while for the barrel to settle down and shoot other bullets well. In fact, if I am accuracy testing and have shot a fair number of Noslers, I will clean the barrel before shooting anything else.

I usually try to shoot the Noslers last and then clean.

Don't ask me why....we discussed it ad nauseum on the old board and the only thing we agreed on was that it occurred!

We have not noted the same with other bullets, so it may be some unique property of the copper alloy that Nosler uses, but it has been noticed by quite a few of us.

[sneaky one]

Bill, I don't want to drag this on & on,, but my Entry rifle never had bad groupings after shooting Nosler BT's. In fact, I shot 5 Nos. then my best group ever with my own creation, the 100 grn. GMX. My buddy that witnessed the 1 hole group is convinced my upper came with an upgraded bbl. by mistake. Is that possible from AA?

[bwaites]

Bill, I don't want to drag this on & on,, but my Entry rifle never had bad groupings after shooting Nosler BT's. In fact, I shot 5 Nos. then my best group ever with my own creation, the 100 grn. GMX. My buddy that witnessed the 1 hole group is convinced my upper came with an upgraded bbl. by mistake. Is that possible from AA?

Sometimes even less expensive barrels shoot great. I've said it before, but I think the Grendel chamber does what it was designed to do, shoot most bullets well, and sometimes one or two spectacularly, even from barrels where it isn't expected to do so.

[steel89]

My gun shoots them like a dream at 2.250. Get a hornady oal meas. tool so you know where the bullet contacts rifling in YOUR gun. Then back off and work up Seems like most of us have a decent-Normal chamber-. For the 100 nos. I have an oal of 2.3015,, and for the 120 nos. an oal of 2.2705. I use a pacific tool and gage comparator, to find the true contact area oal. that will add to these numbers. With my gage the 100 nos. reads 2.7120. It looks cheezy, like a giant nut with no threads but full of holes. The unit is dead nuts on tho, I trust it as do many others, and it's reasonably priced,, a must have unit.

I picked up a comparator for the 6.5mm and am doing a few measurements with different bullets to see the relationship. Hey, I ran across this article on using the tools you are talking about on the 6mmBR website (link: http://www.6mmbr.com/catalog/item/1433308/977259.htm ).... I still need the OAL gauge.