- Thread starter kaskin
- Start date
44.8 as long as there’s no signs of pressure.
Did not check the velocity. I will next time out . Didn’t want the magneto speed to throw off the harmonics. I was also leaning somewhere around 44.8. It’s for a hunting bullet (nosler 168 BT Hunting). Weird thing is, that’s almost a whole grain over what my 168 BTHP uses. 43.9 grn...
43.6 also looked good but I’m sure it’s lacking in velocity...
43.6 also looked good but I’m sure it’s lacking in velocity...
Im curious on the velocity too, whats the bthp velocity? and whats your barrel length. Ive never used the nosler 168 BT but with the 168 amax compared to the the nosler 168 bthp with the same powder charge the Amax runs 40fps more
The BTHP is running 2620 FPS, Lapua brass, 43.9 gr Varget and a 20” factory tube.
I may try this. The rifle pressures out at 46. This test was shot at 41*F. Not sure how much seating depth will change since the throat in this barrel is a country mile long. If memory serves me right, the BTHP’s jump 136 thou....
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@kaskin or anyone else,
Are y'all using a ladder test at 350 because you may not have access to a chronograph? Or do you do a ladder at distance to confirm what a chronograph is giving you? I understand where the nodes are based on your target, took me a second though and reading as I am used to seeing chronograph data.
I ask because I am going to start my process for my .308 (1/12", 20") barrel this week (hope to shoot Sunday) and may not have access to a chronograph, but will have access to 375 yards with a paper target board at 300. Obviously your reloads need to be consistent as to produce a good result, something I need to work on...
I estimate my velocity with 155 TMKs will be around 2810fps. Do you start with an estimated velocity and dial for the estimate or what is your process?
Basically, what is your process for finding a load without a chronograph? If this is too much of a thread drift, let me know and I'll make a separate topic.
Thanks!
Are y'all using a ladder test at 350 because you may not have access to a chronograph? Or do you do a ladder at distance to confirm what a chronograph is giving you? I understand where the nodes are based on your target, took me a second though and reading as I am used to seeing chronograph data.
I ask because I am going to start my process for my .308 (1/12", 20") barrel this week (hope to shoot Sunday) and may not have access to a chronograph, but will have access to 375 yards with a paper target board at 300. Obviously your reloads need to be consistent as to produce a good result, something I need to work on...
I estimate my velocity with 155 TMKs will be around 2810fps. Do you start with an estimated velocity and dial for the estimate or what is your process?
Basically, what is your process for finding a load without a chronograph? If this is too much of a thread drift, let me know and I'll make a separate topic.
Thanks!
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There are a few ways of identifying your nodes. One is a ladder test, another is OCW, and the last is using your chrono to identify flat spots in MV as charge weights increase. I've done all three and for S&G, I did all three developing the same load. I found ladder and OCW identified the same node and they corresponded with the flat spot in MV (I didn't have my MS mounted since I was doing a ladder and OCW). Take your pick and run with it.
I don't ever go in with a "this is where my MV should be". Too many variables for that. Some barrels are just slower than others. Or you're going from Hornady, let's say, to Alpha or Lapua brass.
I don't ever go in with a "this is where my MV should be". Too many variables for that. Some barrels are just slower than others. Or you're going from Hornady, let's say, to Alpha or Lapua brass.
If you have an ES of 20 which is common using a chrony can be misleading. Hard to tell a flat spot when a chrony accuracy is 10-20 fps and your ES is 20 fps. The paper doesn't lie if you do your part in shooting.
In that case you can still shoot groups at 300 but I'd probably just load a bunch at 45 and roll with it.
You have two obvious nodes. A high and a low. In my opinion the high node is hot in Lapua brass unless you’re running a big chamber. More importantly, even if it’s not over max, the hot load will be less receptive to OAL tuning and 100 FPS won’t improve performance that much. The low node will be more receptive to tuning and more forgiving of charge weight and oal variance. That has been my experience.
The BTHP speed sounds a little fast for the powder charge and barrel length. This can be due to the Lapua brass having less capacity than Win brass which is what I use. Just watch for pressure signs substituting the Nosler BT It may have a different bearing surface ratio, The amax does for sure. I would be worried with the 168 if your velocity is over 2700fps in a 20" tube unless someone else chimes in and thinks thats safe? In the long term keep an eye on the primer pockets
Agreed, I will know more on the next test with a chronograph. Side note: I saw a thread about a contraption that allows us, Magneto Speed users, to use the chrono without it having to be attached to the barrel... Promising. Got supplies ordered and will be putting it together soon.
This is a hunting bullet, so i plan to tune as such. IF the difference between high and low node is 100 fps, I will probably choose the low node. Easier on brass and not to have to worry about temperature changes... If there is a substantial difference in FPS, I will have to regroup...
PBWalsh,
I have used all 3 processes... Ladder, OCW and Chrono.
OCW - Pro: Lot's of data. Con: Lot's of ammo to shoot (hot day=Long wait times)
Chrono: Pro: Hard numbers to look at. Cons: Sometimes not easy to decipher
Ladder: Quick, Not much ammo used, Simple to interpret Con: No extra rounds in case of shooter error.
Bottom line: The target doesn't lie.
I have settled on using the ladder test. It gives me all the data I need without wasting components and barrel life.
In my opinion, If you can keep track of every shot fired on paper, Ladder test is the way to go.
What's that they say? Different ways to skin a cat?
So I’m guessing you just mark your shots on target with a shot caller target paper in your data book, or are you going to the physical target and marking them every time?
If you’re shooting somewhere with a pit and a target puller then that works to pull and mark each shot.
I used to run to the target each shot or I would shoot a low charge and then a middle high charge so that I could tell the difference between the two shots based on elevation to cut my trips there in half. I actually did that twice. But after two times of two miles ran each time I found a better way.
I bought a 10 pack of different colored sharpies. Color the bullets and shoot on white paper, leaves a ring of color around the bullet hole. Normal paper, no waxy stuff, something that will suck up the sharpie ink.
I will color it to where colors that are close to one another are spaced as far apart as I can. Aka orange doesn’t go next to yellow and red, put a light blue then orange, then green, then a red, then a purple, then a light blue, then a yellow, then a light green. That way if you have closly matching colors they are at least spaced apart from each other. A qtip with a bit of alcohol pressed to the outside around the hole will also leach some color out into the paper to make it easier to see, only needed to do that once in some poster board. Butcher paper works great. Computer paper works great.
If you shoot it far enough away the slows won’t ever be higher than the faster charges so you can just read their color order up the board.
Several ways you can do it. In my opinion, it varies with the amount of bullets you plan to shoot. Driving down after every shot is one way. Coloring bullets another way. I do it on a home made Shoot N See target and match the shots on my data book. 90% of the time i can see my shots with the scope. If i can't find the impact, i break out the spotting scope.
You are going to have to figure out which way you prefer. Just remember, you must shoot all bullets from same spot. If you decide to mark on the target after every shot, something is staying behind... Truck, table, rifle... You get my drift...
