load development question, need some advice.

[zeke]

LC brass is some of the heaviest 308 brass available, and Win one of, if not the lightest brass available. LC has more than "a touch less" capacity. Combined with using a magnum primer would echo Uncle Nick's advise. Whenever there is a flat spot in velocity curve, am getting very wary, especially if your velocity's are up there beyond load manuals. Instead on relying on pressure signs, would be putting the money on recorded velocity comparisons for load limits, and group size over es readings.

Depending on your purpose for the rifle, may influence how you test for accuracy. If it is a hunting rifle and you expect to use both hands on it, might consider testing it that way and 3 shot groups are plenty.

 

[Shadow9mm]

it is a hunting rifle. but at the moment I am working up precision match type loads with some hornady 168g OTM bullets. These it will be shot off a bench and for the moment my range is shut down to 200yds for berm work. but once they open up they have paper out to 500.

After I get this load dialed in I will be switching over to Hornady 150g interlock soft points to work up a hunting load. But since I have a while until season opens I figured I would see what the rifle is capable of and have some fun and refine my methodology for working up loads before I switch over to my hunting bullets.

 

[hounddawg]

Whenever there is a flat spot in velocity curve, am getting very wary, especially if your velocity's are up there beyond load manuals.

great advice.

That load test pic I posted is a good example. Velocities between 43.9 and 44.2 are flat as a pancake and I was approaching max velocity as per Barnes load published data. I believe it was Uncle Nick who posted several years ago that this was caused by the case stretching and expanding. I stopped testing at 44.2 even though Barnes maximum for that bullet and powder was 44.6 and the primers were still nice and rounded and bolt lift was normal. Sometimes you just have to apply common sense.

 

[Metal god]

I believe it was Uncle Nick who posted several years ago that this was caused by the case stretching and expanding.

I'd like a little more context to this theory . The case always expands and stretches on just about every charge past start loads so there must be more to this idea ? My thinking is the chamber and bore them selves are stretching/expanding ?

 

[hounddawg]

I'd like a little more context to this theory . The case always expands and stretches on just about every charge past start loads so there must be more to this idea ? My thinking is the chamber and bore them selves are stretching/expanding ?
__________________

No idea, I may even have gotten it wrong with my oldfartitus syndrome. Might not have even been UN, maybe he will chime in

edit - I did a lot of searching and cannot find anything to back that up. Regardless since I was approaching max velocity I stopped testing at that point. Not only for safety but because the velocity had flattened nicely and I can live with velocities around 2675 FPS.

For further tuning I want to keep this load magazine length so I have two options. Either go with the 43.9 and load some @ 44.0 44.1 etc to try and bring that vertical string into a more round group or load up a bunch at 44.2 and bring the bullet back into the case .03 at a time ( 2.797, 2.794, 2.791 etc etc) to get the groups to tighten. I will probably go with option 2

@ Shadow9mm

no reason a hunting rifle cannot be accurate. The rifle above is just 7.5 pounds without that target scope. The new barrel is the same length and taper but without the fluting and threaded muzzle. Not exactly a featherweight, but add a small 1 - 4 x scope and it would be usable for hunting. There is a 90% chance I will be able to get it into the high 4's or low 5's with the Shilen barrel. Checked the throat on the Savage barrel today, at 2.80 OAL I was doing a .157 jump on that load test

A buddy of mine has his beanfield guns smithed by some of the best smiths in the region. He never shoots in competitions but I saw him line up some clay pigeons on the 800 yard berm and nail in 5 a row with his pencil barreled deer rifle one calm evening.

 

[jetinteriorguy]

Bi-pod off the bench...I use a rear CrossTac bag (they have a heavy and light, I use heavy for bench) and load the bi-pod. That is usually just a wood board clamped to the bench.

If I can't do that, then with either my left hand if shooting close, or with a paracord loop around either my arm or foot, put downward force on the bi-pod sufficient to lock the rubber feet to the benchtop. Got to stop the hop.

Great ideas. I only use a bipod off a bench, although these benches have a rubber surface which seems to grip the legs enough that they seem to preload fine. With my loads, shooting sub MOA regularly generally isn’t a problem I may try these methods to see if any improvement can be detected. Of course this will require a lot more shooting to gather enough data so I guess I better get busy.

 

[RaySendero]

Shadow9mm
Was able to get the 65guys excel sheet. here's how the graphs came out.

Attached ImagesFile Type:
png graph 1.png (43.9 KB, 131 views)
png GRAPH 2.png (52.2 KB, 131 views)

Shaddow9mm,

Sorry late to your party! Just saw those graphs.

I think its possible that you have 2 errs in the measurements or reload quality control of the 40 rounds.

1) The high velocity point at 45.2 grains and
2) The low velocity point at 47.0 grains

Re-figure the stats and re-plot the graphs without those 2 points and you will get an entirely different picture of the results!

 

[Don Fischer]

I got an inexpensive little Cauldwell tripod for shooting off a bench. Nice little tripod but about all I shoot off of is a 6x6 about a foot long with a large sand bag I made on it. I think the broad flat surface across the bag helps hold the rifle steadier. Have a small sand bag, home made, I use in my left hand under the butt of the stock.

 

[kilotanker22]

Shadow,

Coincidentally, I recently bought some Hornady 165 gr BTSP and tried them with BLC-(2). I ended up finding a decent hunting load using Nosler's published most accurate load with a 165 and that powder. Not sure how your brass will fair, I am using Lapua large primer brass.

I tested that laid at .015" off lands and then seated to the canelure. The cartridges with the bullets seated to the canelure shot pretty well(.6 moa). My velocity from a 22" barrel was like 2740. Es was 24. I figure that is plenty for hunting here in Northern PA.