SmallCaliberCentral

I recently grabbed a bottle of ADI TrailBoss (pretty sure it's the same as IMR TB) to work up some reduced loads for plinking and bunny shooting.
Filled a case with TB to where I've been loading BM2 at 28.7gn behind the 26VGs, and the TB weighed in at 9.7 grains!
Loaded 3 each (just over a week ago) at 0.2 intervals from 8.0 up to 9.8 and tested them at 50yds. Accuracy was pretty poor (best was 0.8" - remember 50yds) and most were 1.5-2" And plenty of evidence (about 90% keyholed) to suggest they weren't flying straight (off axis).
Also, the 2 lower charges gave around 2400fps, then everything above 28.4gn gave about 2500fps. 29.8gn still gave 2500.
So today I loaded a few more at the lower end from 6.8-7.7 - best group 3", worst >5" Don't reckon I can settle for 10moa.

Thing is - the first loads were at 2.266" OAL, and for some stupid reason I ASSUMED I was seating at 2.262" so that's where the last loads ended up (been at sea for a week between loads - lesson learned - ALWAYS check data).

Seems clear enough evidence, even though they were different charges, that small seating depth changes can make big differences.

Before I put this powder to the back of the safe and forget about it, I'd like a few opinions.

I know the obvious alternative is to buy a .22lr, (or .17hmr for similar speeds), but convincing the finance minister is an issue there. Besides, there's a bit of the 'taming the beast' feeling of accomplishment hovering around this if I can get a good consistent group.

-The OAL for the 26VG touching the lands in my rifle is 2.275" so the first loads are 9 thou off.
-Obviously seating deeper isn't working, and although working closer to the lands MAY shrink the groups, is it likely to stabilize the bullet any better? Or is it simply a matter of RPM (bullets built for higher speed) and they won't stabilize at lower velocity?

***I have contacted ADI and received confirmation that it is safe to use this powder in .204
It isn't listed in their .204 data, but they sent instructions on how to safely work up a load.

the only thing i can think of is that you have a light weight bullet and it is going transsonic at maybe 35 yards ? have you tried a heavier bullet like 39 sbk with tb? keyholes when it goes transsonic ?

I'm not too familiar with the effects of the trans-sonic zone other than a few brief readings on long range bullets hitting that speed becoming unpredictable.
I assumed this was the 1st sound barrier/mk1/1125fps

Just punching numbers into my ballistic calculator, the 26VG exiting the muzzle at 2400fps hits mk1 around 250 yds
At 50yds it's just under mk2

It's also possible that I'm mistaken, and not seeing keyholes. Perhaps the bullet is expanding so rapidly as to cause the irregular tear in the paper?

I'll give it another try with the bullets touching the lands, and seated maybe 5 thou out. If it works I've got the .204 and .17HMR areas covered with one rifle. If not, I guess I've just learned a few more lessons, and gained some trigger time

Meanwhile - My darling girlfriend has given in to my NEED for a .22lr
She nearly gave the tick of approval for a new Sako 85 Varmint in .260 - until I showed her the AUS$2500 price tag - Bugga
So I made sure I didn't let 24 hours pass before signing up for a Savage Mark II, just in case she changed her mind

with paper i always got nice round holes with the vg. then again i was using 10x . i had a wood backing but it was thin.

250 yards till mach 1 wow i was way off. i know the less they weigh the quicker they loose velo.

congradulations on the appoval for the new toy. i would play with the trailboss load bofore purchasing the new toy. then maybe the new toy will not be needed.

204cat wrote:...maybe the new toy will not be needed.

I always need a new gun
Even with the TB and lower velocities, the noise comes nowhere near matching the quiet of a .22lr. Same with ammo costs.
So, for busting bunnies close to houses, and shooting paper with a few mates and some prawns on the Barby, the new toy will be pretty handy.

Had a little more luck yesterday. Still not seeing screamer groups, but I've got something to work with now as they didn't spray all over the target.
I (thought I did) seated the bullets so they were kissing the lands. So my next move was to seat out a touch further and see what jamming them did.

Then I measured the jam O.A.L. again, and realised I still have plenty of room to move. So much that I thought it was worth starting a new thread about in General Reloading.

Weather's perfect for testing today too, but I've run out of primers
Is it worth the trip into town just for a pack of primers? - probably, but I'm sure there's other jobs I was meant to do