Reloading 101 Question

[mmc45414]

4. Groups got smaller, then larger, then smaller, then larger. But my inaccuracies again come into play. I had 3 loadings in a row with what started as sub 1inch groups, but then 1 pulled shot taking it to a 1.5 inch group.

Years ago I watched something (I think it was a video, couldn't find it...) where Bryan Litz talked about over stability, and the importance of matching up twist with velocity. The Cliff Notes would be that the bullet obviously needs to be stable, but more is not always better. Once stability is achieved additional bullet RPM only would exacerbate any potential (miniscule) flaw. You obviously have great bullets, but I mention this since you are shooting lighter bullets in what might be a factory rifle twisted for stabilizing something a little heavier?

[Dov]

I've only reloaded small amounts, primarily practice loads for revolvers.

So just asking for my own clarification, changing seating depth while keeping powder load the same has impact on pressure doesn't it? Shorter COAL would increase pressure and longer COAL would decrease it right?

Maybe not a lot if nowhere near max pressure or Case OAL?

Also aren't monolithic bullets more sensitive to dirty bores?

[mmc45414]

Shorter COAL would increase pressure and longer COAL would decrease it right?

Not exactly, my understanding has always been:
If the bullet is out against the lands it will take more pressure to initially get it moving, overcoming both the inertia of the stationary bullet and the swaging into the rifling has to take place at the same time.
A deeper seated bullet will increase pressure, but this (IMO) is mostly a pistol thing where the bullet is shoved back.

[Dov]

Not exactly, my understanding has always been:
If the bullet is out against the lands it will take more pressure to initially get it moving, overcoming both the inertia of the stationary bullet and the swaging into the rifling has to take place at the same time.
A deeper seated bullet will increase pressure, but this (IMO) is mostly a pistol thing where the bullet is shoved back.

Thanks

[Rick R]

I no longer own a 7mm-08 and didn’t use Barnes bullets in the ones I had. But my thoughts are:

1) Did you actually chrono the factory ammunition in your gun? Your upper load is close to the 3,050 to 3,120fps that Barnes and Hodgdon show with Varget both with 24” barrels.

2) Varget seems “happiest” with some compression in every cartridge that I’ve used it in. I’m not sure where your loads are in that respect. I seem to remember W760/H414 giving better accuracy in my 7mm-08 rifles. But that was with cup and core bullets.

3) 0.05” off the lands is the suggested best seating depth with Barnes bullets, barrels are a law unto themselves and you probably need to tweak seating depth to see if there’s a preference, which hurts at $1/bullet. Also, Barnes bullets don’t play well with bore fouling from other brand bullets in my experience.

[ccmdfd]

A few issues:

• Pressure nodes are largely irrelevant if you don’t have pressure-testing equipment. Forget about them and focus on accuracy. It’s possible to work with Overall Length but the Hornady comparator will let you look at Cartridge Base To Ogive (CBTO) length, which tends to be more consistent.
• Seating depth matters. See details at https://bergerbullets.com/getting-th...in-your-rifle/
• Barnes need speed. Don’t try to outrun factory loads but move it as fast as it will go, then adjust CBTO to tighten groups.
• The shape of groups matters. You adjust that with seating depth. A group with 2+1 means seat them deeper. Three shots evenly spaced in an equilateral triangle means seat out further.
• Varget is a good choice. It works best at top pressures. Look at TAC and CFE 223 for 120-grain bullets and Big Game for 140s and heavier.
• As soon as you get decent groups at 100, push it out to 200 or 300 and continue your tests.

Let me know if you have questions.


Okie John

Thanks for the info!

1. Do you use the seating depth method outlined in the Berger article? Barnes recommends starting at 0.05 off the lands and then working to shorter OAL/BTO. Can go to 0.2 or shorter! Most YT reloaders vary the depth by 0.003, and if we're going to do 20 rounds at each depth, that's going to chew up a lot of ammo fast.

2. Do you have any references to look at regarding the shape of the group as it relates to whether or not the bullet needs to be seated deeper or shallower? I might take some pictures of my groups and post them sometime later but at the maximum powder load I had a small triangle but then two stringing low shots, straight vertically down about 1 to 1 1/2 in away.

Thanks again!

[ccmdfd]

I no longer own a 7mm-08 and didn’t use Barnes bullets in the ones I had. But my thoughts are:

1) Did you actually chrono the factory ammunition in your gun? Your upper load is close to the 3,050 to 3,120fps that Barnes and Hodgdon show with Varget both with 24” barrels.

2) Varget seems “happiest” with some compression in every cartridge that I’ve used it in. I’m not sure where your loads are in that respect. I seem to remember W760/H414 giving better accuracy in my 7mm-08 rifles. But that was with cup and core bullets.

3) 0.05” off the lands is the suggested best seating depth with Barnes bullets, barrels are a law unto themselves and you probably need to tweak seating depth to see if there’s a preference, which hurts at $1/bullet. Also, Barnes bullets don’t play well with bore fouling from other brand bullets in my experience.

Yes I did chronograph the factory ammo. I don't have the numbers in front of me right now at work but they were basically exactly what the max load minus 0.4 velocities were. The max load was like 20 to 30 ft per second faster. That would put it around 293X fps for the factory loads.

I didn't feel like I was doing any compressing with the powder even at Max load. However that might change if I start seating further away off the lands.

Thanks!

[ccmdfd]

That bullet at any of those speeds will absolutely slay deer. They open more reliably at faster speeds, but even your ~2600fps load won’t have dropped below 2000fps before 300 yards, and that’s usually considered a safe threshold for TTSX to open up on impact. Pick the speed and recoil you want, then tune for accuracy.

FWIW, I’m running an LRX in my .270 this year at about 2950 or so. In the .270, that is very much not a max load, but it doesn’t need to be to blow a good hole through a Coues whitetail out farther than I will shoot at one.

Thanks for the info. I have read there's a lot of confusion regarding what velocity a TSX needs to expand and it may even be very different for each caliber and weight of bullet. But all that seems to be conjecture. Since I am only shooting out to 300 yards I've wondered if the slightly slower velocities would bother this at all.

I might try LRX in another rifle in the future.

[okie john]

1. Do you use the seating depth method outlined in the Berger article? Barnes recommends starting at 0.05 off the lands and then working to shorter OAL/BTO. Can go to 0.2 or shorter! Most YT reloaders vary the depth by 0.003, and if we're going to do 20 rounds at each depth, that's going to chew up a lot of ammo fast.

Yes, I use the Berger method. It radically reduces the time and components required to identify good loads because it isolates seating depth as the variable. If you can call your shots reliably, then it's the ticket.

Here's a target where I varied seating depth in 0.004" increments. Firing order was center, lower right, upper right, upper left, and lower left.



None of those are bad groups for a hunting rifle, but which one is best? Why? Are you sure? The last group is interesting. Relative to POA, the shot to the right is farther to the right than any other shot on the paper. Is that a fluke? Was that depth better than the others but I just timed my trigger press wrong against my heartbeat? Or is it because of barrel heat? Or did the weasel with a 300 RUM and a muzzle brake on the next bench touch one off in the middle of my trigger press on the shot that went out to the right? I have no idea. What matters is that these groups just aren't that different.

The Berger method will give you maybe one group like those on the target above and three that are either much larger triangles with evenly spaced shots or with two shots touching and one way out. Then you bracket down from there.

Also, why are you shooting 20 at each depth when Berger specifies six?

2. Do you have any references to look at regarding the shape of the group as it relates to whether or not the bullet needs to be seated deeper or shallower? I might take some pictures of my groups and post them sometime later but at the maximum powder load I had a small triangle but then two stringing low shots, straight vertically down about 1 to 1 1/2 in away.

Same rifle, different loads. The 155 Scenar group is evenly spaced. I'd seat that one deeper. The CoreLokt, Hornady, and Barnes groups show 2+1. I'd seat them longer if they were handloads. All of this is way more pronounced at ranges beyond 100 yards.

Shoot three-shot groups for now. What you're seeing could be marksmanship, barrel heat, eye strain, bedding issues, or something else.


Okie John

[ccmdfd]

Also, why are you shooting 20 at each depth


Okie John

Sorry, must have misunderstood your original post. Was thinking you said 20 shot groups was better for better statistical validity.

Then again I was up all night last night with a sick wife so my brain isn't quite in full gear right now.