30 cal 230gr Sierra matchking .8bc

smoked

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Going to try these new Matchkings out. First thing I noticed is they arent much longer than the 230 hybrid but they do appear pointier. Second thing is where my coal is 3.72 with a 230 Berger hybrid and these I had at 4.0 inches and were not touching the lands. I pulled them down to 3.72 and will go shoot them and see what happens then I will do the .1 jump each set until I find length. Then try h1000, Retumbo, AND RL33. My first set is starting load of 90gr Retumbo cci250 primer and Nosler brass out of a 300RUM plus p. Has anyone verified the .8 bc. If so I should be able to safely crank these out at 3200fps.
 

NEMTHunter

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Howdy The bullet intrigues me a lot. As far as BC Sierra gives stepped BC. .8 is on the top end of the FPS scale. Try taking all three of the BC number and averaging them out. That would put you right around a BC of .773 . Another thing with doing that is depending on how far you shoot them and what the FPS is at the target.
 

smoked

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These are out of a 30 inch hart 9 twist. Loaded the first five at mag length and it wasnt very promising. If I can get them to shoot at 100 yds I will start verifying bc through the average. Fist group was right at 1inch. Didnt hit the chrono yet until I get something to work with.
 

smoked

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First solid test. 90gr Retumbo coal 4.08 resulted in .6. Outside to outside then subtract .308. Will keep messing with them. If I get them below .500 then I will start chronograpgh and long range testing.
 

smoked

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Ok still in the .6s but hit the chrono. 90gr retumbo at 3060fps about 60fps slower than a 230 otm. Either way set my math at .8 down to 2k and .7 below that for testing. Fist shot hit on about a 1moa rock at 950. Second shot 1760 steel plate that is 2 moa. First shot hit. Last shot left in the box I dialed 72.25 moa and 9 minutes wind for the 2250 plate and shot just over the top right edge. As far as groups I dont care so much but they fly pretty **** good down range. I will start loading up until I get pressure and see what happens.
 

NEMTHunter

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Looks like they are working out good for you. I have a feeling the shorter bearing surface is keeping the pressure down so it might take more powder to hit the same speeds. But I would guess at the same pressure they should be faster.

Another thing setting the 2000 and below fps BC to .700 will make you hit high. For under 1600 they call for a BC of .740

Here is what sierra calls for 1880 fps and above BC of .800 Between 1600 and 1880 a BC of .780 and Under 1600 a BC of .740.

So by calling for a BC of .700 under 2000, you will be hitting high when you hit the range where the bullet hits 2000fps and below.

add the BC up and the average is about .773 But it looks like you have the ability to do stepped BC in your program. If thats the case I would go with what Sierra calls for. You should then be dead on the 2250 plate next time.
 
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smoked

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Looks like they are working out good for you. I have a feeling the shorter bearing surface is keeping the pressure down so it might take more powder to hit the same speeds. But I would guess at the same pressure they should be faster.

Another thing setting the 2000 and below fps BC to .700 will make you hit high. For under 1600 they call for a BC of .740

Here is what sierra calls for 1880 fps and above BC of .800 Between 1600 and 1880 a BC of .780 and Under 1600 a BC of .740.

So by calling for a BC of .700 under 2000, you will be hitting high when you hit the range where the bullet hits 2000fps and below.

add the BC up and the average is about .773 But it looks like you have the ability to do stepped BC in your program. If thats the case I would go with what Sierra calls for. You should then be dead on the 2250 plate next time.
For sure. I was going off a guess at the range just for plinking. I will mess with them a little more and up the velocity. 30 inch hart with plus p throat.
 

smoked

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Got these out to play with again. Full length sized some worn out rem brass with cci 250 primer and 91 gr Retumbo. It was most likely a fluke but I shot a .04 3 shot group at .023 off the lands. The other length That looks promising is 4.010-.010 off the lands. It was consistent .46 inch groups and beats the sub 1/2 moa I wanted. I will start adding powder and maybe a primer swap and see if these get better or worse with velocity.
 

NEMTHunter

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That looks very promising. If the groups stay that small or shrink the bullet should work very good for you.
 

Rum Man

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Any chance these will work in a Sendero 26" 1/10 twist or am I wasting time and money ? Thanks
 

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