Follow my 7 dumbo project aka 7 dasher!!

[Cz455guru]

Hey guys, I got a wild hair brained idea about 6 months ago to neck the dasher up to 7mm, to be called the 7 Dumbo lol. Going into it with few expectations and viewing it as a experiment, hoping its a success.
I worked together with manson reamers to get a reamer built and sent it off the #620riflewerks to get the chambering done. (By the way he is a jam up gunsmith if somebody is looking for a guy to do your work with good turnaround time.) I opted to use a 8 twist crb comp barrel, finished at 28 inches.
I want to get it to shoot 2400+ with the 180+ bullets, preferably the 190 atip or 190 bergers. If it all works out I will certainly be shooting it in a few matches to see how it handles that vs the 22 dasher and 6 dasher that I normally use.
Follow this thread for updates!!!!

 

[diggler1833]

I applaud your willingness to experiment man. Obviously, you're going into this understanding that you aren't going to break any performance records... but if you get good accuracy (and have fun), then I'm down to read your results. If you can put up side-by-side wind results at distance between this and your 6 Dasher, that would be awesome to see too.

I did similar with the 7-300 PRC over last winter. It probably is a touch behind the 28 Nosler, and definitely the 28 Sherman Mag... but it is something that I wanted to mess with, and I'm very content with my results.

Best of luck!

 

[XP1K]

I mean, there is a 30BR, why not a 7 ? I'd have probably shot for the 160 class of bullet but hey, sounds fun. Do keep us posted.

Is a 180/190 7mm longer than a dasher case ?

 

[4O6shootist]

Is a 180/190 7mm longer than a dasher case ?

A 190 Berger is about 0.040-0.050 longer than the dasher case length depending on the trim.

 

[Cz455guru]

Here's a picture of some dummy rounds from when I was designing the reamer. Left to right, 190 atip, 190 berger, 180 eldm. I may end up shooting the 180 eldm yet.
I have been working on finding max charges with multiple powders with atips while fireforming brass. Powders I have tried, 8208, cfe223, RL15, RL15.5, varget.
The 8208 velocity was lower then I wanted, cfe223 yields the highest velocity at 2510. I think h4895 might be the perfect powder for this but I dont have any at the moment.

 

[Cz455guru]

Rl 15 numbers, slight ejector mark if I use my imagination.

 

[Cz455guru]

Shots 4-6 with 197 smk with Rl 15.5 group was about .7.

 

[Cz455guru]

Cfe223 190 Atips at pressure.

 

[Cz455guru]

Sorry im not organized, I should have clarified the build earlier, so here it is.

Impact 737r
Foundation Samson
Crb comp 8 twist
Botnia maxi
Nf atacr 7-35
Bix'n and tacsport pro x, gator shoe
Warne precision mount
Sg pulse level

 

[fdkay]

Maybe staball 6.5? Slower than the powders you're using, but it's a ball powder, so you might be able to get enough powder in there to make a difference.
Staball does like heavy bullets and high pressure

 

[Cz455guru]

Maybe staball 6.5? Slower than the powders you're using, but it's a ball powder, so you might be able to get enough powder in there to make a difference.
Staball does like heavy bullets and high pressure

Good idea!! Ill have to see if i can find some. Found a place locally with some h4895 I'll be able to try that also.

 

[XP1K]

Cfe223 190 Atips at pressure.

Im actually pretty impressed by this. I didn't think it would push it that fast.

 

[Mike Casselton]

BL-C2 might also be a contender in your powder search.
Like Staball, it likes full pressure for velocity and clean burn