300 RUM and 230 Berger Hybrid project

[ajridgedell]

Got a chance to shoot my ladder test this evening. Was so hot and humid this morning I didn't know if I was gunna get a chance to shoot. Finally the mirage settled down and slightly overcast sky helped me get good chrono readings. Took an hour and 20 minutes to shoot 21 shots. I've never had a ladder test go so high! After the first 10 shots I had to add more cardboard and paper to make sure they all made it on there. The colored bullets worked out good and I only made two trips down there while shooting; one to make sure my sighter was at the bottom of target and then to add more paper to target. Tell me what Yall think, but it looks like the possible nodes are the ones I marked on the notebook according to velocity and vertical dispersion. Also I used a cold wet rag to rub down the barrel to keep it at a manageable temp; not to get it all the way cool but just to keep from getting too hot; thoughts on that? Worked well for me in the past.

 

[jwall3d11]

When did you start seeing pressure marks?

 

[ajridgedell]

Started getting primer flow around 87 and light ejector circle at 93.5, but no swipes and bolt never was hard lift.

 

[ajridgedell]

I was going to shoot groups in node areas but I think since I've gone this far I might as well shoot another ladder test over the node areas. After looking closer, there is another node area I would like to test too. My plan is to shoot 86.4 to 87.6 by .4; 88.4 to 89.6 by .4 and 92.3 to 93.6 by .4. Twelve more shots I plan to pump out one evening this week.

 

[barefooter56]

I was going to shoot groups in node areas but I think since I've gone this far I might as well shoot another ladder test over the node areas. After looking closer, there is another node area I would like to test too. My plan is to shoot 86.4 to 87.6 by .4; 88.4 to 89.6 by .4 and 92.3 to 93.6 by .4. Twelve more shots I plan to pump out one evening this week.

ajridgedell,
If you are seeing primer flow and a "lite" ejector circle at 87 and 93.5 now. Just remember that when it gets warmer you MAY be really over pressure !!! What temps are you load testing in?

 

[ajridgedell]

I'm in south Louisiana, it was high 80's when I shot on Sunday.

 

[barefooter56]

I'm in south Louisiana, it was high 80's when I shot on Sunday.

ajridgedell,
Send some of that up here will ya! Good to know it was hot when you tested. Have you done any bullet seating depth testing yet? That will impact your case capacity and pressure.

 

[ajridgedell]

ajridgedell,
Send some of that up here will ya! Good to know it was hot when you tested. Have you done any bullet seating depth testing yet? That will impact your case capacity and pressure.

bottom of page 2 shows my seating depth test, I used .060 for my powder charge test and after I finish that I may go back and find the longest oal that works good so as my throat wears i don't have to "chase the lands". Since I first measured when the gun only had about 40 rounds through it, they appear to have worn about .020 after about 300 rounds.

 

[barefooter56]

bottom of page 2 shows my seating depth test, I used .060 for my powder charge test and after I finish that I may go back and find the longest oal that works good so as my throat wears i don't have to "chase the lands". Since I first measured when the gun only had about 40 rounds through it, they appear to have worn about .020 after about 300 rounds.

ajridgedell,
Wow! .020 in 300 rounds. It took a years worth of practice and competition for my .308 to move out .010! One thing I found was that if my rifle liked the bullet .010 off the lands ( just an example). Keeping the bullet .010 off the lands as I chased the throat kept me in my seating depth "sweet spot. At a certain point though I did have to tweak the powder charge to keep me on the velocity accuracy node as the bullet moved out and resulted in more room in the cartridge case that affected the pressure/velocity. The only problem is that sooner or later you run out of bearing on the bullet in the case neck and have to screw another barrel on and start all over. Its a vicious cycle.

 

[4xforfun]

Just out of curiosity.......why such a big aiming circle? I use the smallest possible aim point I can see at a given distance. Aim small, miss small!!

 

[ajridgedell]

Just out of curiosity.......why such a big aiming circle? I use the smallest possible aim point I can see at a given distance. Aim small, miss small!!

I was hoping someone would ask about my fancy targets I printed in paint! Haha, I like to put my crosshairs in the center of the circle and pay close attention to the four sections it makes, making sure they all look even when I touch it off. As you can see with the ffp viper pst scope the reticle is pretty thick at 24x so at 585 yards the circle is about 1 Moa on the outside I think. This picture is pretty crappy but you get an idea of what I see. And obviously I didn't have it centered up when I took the pic. I would like to hear haw other pick out the most precise aiming point. This is just something I came up with that works for me, definitly open to suggestions.

 

[4xforfun]

Yep...different strokes. I make a solid square box and aim at a corner of the box so that the vertical cross hair rides the side of the box and the horizontal rides the top (or bottom) of the box. If I make a 5 inch box at 300 I now have 4 aim points....kinda like having 4 bulls to shoot 4 groups.

Otherwise I make as small a dot/square as possible and take dead aim.

 

[rem338um]

Hey,,,dont rule out H1000 powder...I was shooting 89.5 gr@2925 fps out of a 30" tube....040 jump....just my input

 

[ajridgedell]

Did my second ladder test yesterday evening. After these 12 shots, made about 63 shots fired since the barrel was cleaned. I started seeing some ejector swipes in the 92.8 to 93.6 range. I guess this pressure is coming from the barrel getting fouled? I can see a noticeable difference in the bore of the barrel from before this last test to after it. The temperature was around 70 and overcast with a steady 3-7 mph wind from my 10 o'clock getting up to 10 mph at one time i'm guessing. This kept the barrel at a good temp without me having to cool it much at all. I dialed left 1 minute for most of the test and 1.5 when the wind got a little stiffer to keep them all on paper which turned out pretty good since I was just guessing wind speed and hold and never having feedback on my correction till all 12 shots were fired. After my first two 4 shot ladders I dialed down 1 minute to get my last four shots on the target because the wind folded the top half of my target over. I was just glad all 12 shots made it on there lol. Right now I'm thinking of going with 89.2g and shooting that some to see how it does. I can't help but like the very top three shots and their velocity, but being as I was having some pressure signs there I would like to stay away if I can reach one mile without it. The results: