Follow my 7 dumbo project aka 7 dasher!!
- Thread starter Cz455guru
- Start date
Since I have the 6 Dasher with hybrid cases I mocked up some with the 7 mm dasher and 180 gr Berger bullets, I have on hand.
It appears the loads you have are already over pressure for brass cases.
I ran the hybrid cases to 65,000 psi.
Most loads with the 180 gr Berger at 2.620" COAL will reach 2500 fps plus in a 30" barrel.
RL 17 will reach 2600 fps...with hybrid cases...according to QL.
It's a big chore for such a small case.
The 166 gr Atip might be the best bet.
It appears the loads you have are already over pressure for brass cases.
I ran the hybrid cases to 65,000 psi.
Most loads with the 180 gr Berger at 2.620" COAL will reach 2500 fps plus in a 30" barrel.
RL 17 will reach 2600 fps...with hybrid cases...according to QL.
It's a big chore for such a small case.
The 166 gr Atip might be the best bet.
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All good stuff and thoughts guys, I have gotten to the point that I dont ever trust box bc values but generally they are closer then im experiencing with this project. So that would point me towards something going on with the lower velocity. I was under the impression that hornady 4dof and ab cdm calculated in the muzzle velocity bc variation but I could be wrong on that, either way they have similar drop numbers to what published bc was. Ab cdm was the closest but still .3 off.
Like has been stated i bet a 7.5 twist would help. Mine is a 8 twist.
Like has been stated i bet a 7.5 twist would help. Mine is a 8 twist.
As close as I can tell with my specs im under max preasure still at 64193, this is gotten by trueing ql up with the ba.
Maybe you dont view the dasher max at 65000,
I am also using fireformed lapua brass that has about .5-.75 gr more h2o capacity then alpha or peterson.
That being said, I use ql preasure as a guideline for ladders, after that as long as I dont see preasure signs and dont have any issues I'll shoot as hot as the rifle likes to shoot, if ql shows its 75000 and im ok with decreased brass life I'll shoot a hunting rifle there as long as it likes it and bolt lift is compromised.
The 180 berger is gonna have to be on the list to try tho. Also would love to find some Rl17 again but for now that experiment will have to be on hold.
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I think hornady app has a a few issues with the group analysis. 6 inches at 1000 isn't .05 mil it should be about .16 - .17 mil
I was quietly thinking the same thing.
We were running 7BR out of some XP-100s in the 80's to shoot the Long Range portion of the the MASTERS national competition. It was stupid easy to get 1MOA accuracy out of with Nosler BTs and had plenty of energy to down steel with even at long distance with shitty hits.
I know you want to shoot the heavies but have you considered some of the lighter solids like senecas?
Ya I certainly have, wish they were cheaper, my curiosity may get the best of me tho sometime. I wasn't able to get the 95 Seneca to shoot very good out of my 6 dasher so thats also causing some hesitation.
I Been thinking about it and my only hesitation is that its a little short, I would love it if somebody would confirm this but it appears like peterson 7 br case is 1.520. Lapua 6 br is 1.555. I really want to get as much neck as possible for this long bullet, my reamer is 1.555.
Maybe they would both be similar after being fireformed to 7 dumbo.
Homework done on the front end to choose reamer, brass and dies as compatible as possible will always minimize headaches and foul language!
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