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

 

[Sea Green Thrilling Turtle]

I have been looking at the 183 smk for my 7SWC, curious how they would do here. Watching for updates

 

[6.5SH]

Given the burn rate of the powders OP's tried, StaBALL Match will likely be a good fit.

 

[Simia Dei]

Try MR2000, I had a 7SAW hitting over 2900fps with Berger 175s out of a 26” barrel

 

[iceng]

7mm is best mm.. Unless its pistol, then its 10mm.

In believe the 7mm is underrated for lots of styles of shooting, and I built a 7 superLR a few years ago which was amazing. I'm a huge 7mm fan.

Well done on having a go.

 

[45-90]

I like the 6 dasher,... but a 7 Dasher with almost twice the bullet weight?

Its Your project, but...Looks to me like ya need more case capacity then the Dasher has to offer.

My 22" 9 twist 308 will do a bit over 2500 with 230s, being tested here.

 

[Kickin45]

@Cz455guru what’s your charge weights?

 

[Sea Green Thrilling Turtle]

My 22" 9 twist 308 will do a bit over 2500 with 230s, being tested here.

What is the COAL though? I suspect one of the goals here was to stay under 2.96”. Regarding larger case capacity, it seems like the 7SWC is about as big as you can good for 0.284 with 190s, unless you go to tiny necks like the 7 Moses. However, I suspect the OP was looking for maximum efficiency to push heavy 0.284 bullets and not highest velocity.

 

[45-90]

What is the COAL though? I suspect one of the goals here was to stay under 2.96”. Regarding larger case capacity, it seems like the 7SWC is about as big as you can good for 0.284 with 190s, unless you go to tiny necks like the 7 Moses. However, I suspect the OP was looking for maximum efficiency to push heavy 0.284 bullets and not highest velocity.

The COAL really doesn't matter in a bolt gun. There are intermediate actions and long actions...and custom machined actions.
That's always an excuse for those who's short actions calibers do not measure up in velocity, then they themselves run the COAL over length to cram in more powder to get a bit more velocity.

The 308 Winchester is not a speed deamon and is beaten by every cartridge in these pages, as the slow dog.
But when you can not beat the speed of a 308 with your new 7 mm dasher ya probably need more case capacity or even longer action.
My 6 dasher runs .6 g1 BC bullets 110 SMK to 3085 fps in a 28" barrel.
So 2400 fps to a maybe 2500 fps appears too slow to be of any advantage at 1000 yds over the orginial...a hopped up 6 dasher, and the accuracy isn't there with the 7.

Preliminary test tell me ya need more case capacity.
Why build a less performance cartridge when you want a better performing cartridge with super high BC bullets?
Ya still need "enough" velocity to accomplish that.

It should be better than a 308 Win regardless of the COAL ...everything beats a 308.

 

[fdkay]

The COAL really doesn't matter in a bolt gun. There are intermediate actions and long actions...and custom machined actions.
That's always an excuse for those who's short actions calibers do not measure up in velocity, then they themselves run the COAL over length to cram in more powder to get a bit more velocity.

The 308 Winchester is not a speed deamon and is beaten by every cartridge in these pages, as the slow dog.
But when you can not beat the speed of a 308 with your new 7 mm dasher ya probably need more case capacity or even longer action.
My 6 dasher runs .6 g1 BC bullets 110 SMK to 3085 fps in a 28" barrel.
So 2400 fps to a maybe 2500 fps appears too slow to be of any advantage at 1000 yds over the orginial...a hopped up 6 dasher, and the accuracy isn't there with the 7.

Preliminary test tell me ya need more case capacity.
Why build a less performance cartridge when you want a better performing cartridge with super high BC bullets?
Ya still need "enough" velocity to accomplish that.

It should be better than a 308 Win regardless of the COAL ...everything beats a 308.

Are you the arbiter of what is worthwhile?
Some folks with the expendable income like to play with stuff and try new things.
With the Atip at 2500, he's got 9.6 mils of drop at 1000 and is still supersonic at 1500 (Per JBM).

 

[Sea Green Thrilling Turtle]

If the OP is shooting in matches, I doubt they care alot about drop (i suspect that is also why they care about SA mags). Either way, the appeal is an increased wind budget. His wind budget at 600 yards is better than a 6 dasher and a 308 if he can shoot 190 atips at 2500 fps.

 

[45-90]

Are you the arbiter of what is worthwhile?
Some folks with the expendable income like to play with stuff and try new things.
With the Atip at 2500, he's got 9.6 mils of drop at 1000 and is still supersonic at 1500 (Per JBM).

So using the same jbm ballistics app at sea level etc
The 308 Win with 230s and only s 22" barrel has the same ballistics 9.7 Mil at 1000 yds with the 1500 yds available too.

Put the brass 308 load in my 30" and it would surpass the 7 dasher in the 28".
Plus the 30" LA will shoot 230 Atip over 2700 fps with hybrid cases...that's efficient.

My 6 Dasher 28" barrel with 110gr at 3085 fps only has 7.0 mil drop and goes 1500 yds.
And he's struggling to get the 2500 fps with a 28" barrel without pressure, I see more in the low to mid 2400s for velocities.

But if the Idea was to make a cartridge more effective than something that is not already available...this doesn't appear to have succeeded. Ya need more case capacity....or hybrid cases.
No one cares what cartridge ya choose, or if it has an advantage...if you like it shoot it.

But if you going for an advantage as suggested, it should surpass the others, not be equal or lesser.

So one could improve the 7 dasher with hybrid cases where the brass isn't holding up at 2500 fps.
Here is some 6 dasher hybrid cases, 7 dasher would be easier. But it requires dies to produce...
There are alot of brass cases to choose from these days, if ya don't like hybrid cases.

 

[45-90]

If the OP is shooting in matches, I doubt they care alot about drop (i suspect that is also why they care about SA mags). Either way, the appeal is an increased wind budget. His wind budget at 600 yards is better than a 6 dasher and a 308 if he can shoot 190 atips at 2500 fps.

If the OP can get 2500 fps out of it ...he has gained nothing over the other calibers at the stated speeds.
Especially at a measly 600 yds....they are all the Same ...1 mil wind deflexion at 600 yds in a 10 mph cross wind...
Break it down less than 1" difference at 600 yds....and the 308 230 Atip comes out ahead by .2" ...you can not shoot the difference at 600 yds....if the OP can get it to 2500 fps accurately.
I'd just shoot the 6 dasher its just .7 inch wider in 10 mph at 600 yds with my load (and it's accurate), then his 190 Atip that "might" reach 2500 fps.
That's without the hybrid cases to bump up the velocity on the little 110 ATip or SMK.

Just the facts ...they all have 1 mil of wind deflection at 600 yds...and you can't shoot the difference.

 

[diggler1833]

Are you the arbiter of what is worthwhile?
Some folks with the expendable income like to play with stuff and try new things.
With the Atip at 2500, he's got 9.6 mils of drop at 1000 and is still supersonic at 1500 (Per JBM).

+1

Why worry what someone else is building and shooting when you don't have to fund it?

We do this because it's fun, not because we're making money at it.

 

[fdkay]

So using the same jbm ballistics app at sea level etc
The 308 Win with 230s and only s 22" barrel has the same ballistics 9.7 Mil at 1000 yds with the 1500 yds available too.

Put the brass 308 load in my 30" and it would surpass the 7 dasher in the 28".
Plus the 30" LA will shoot 230 Atip over 2700 fps with hybrid cases...that's efficient.

My 6 Dasher 28" barrel with 110gr at 3085 fps only has 7.0 mil drop and goes 1500 yds.
And he's struggling to get the 2500 fps with a 28" barrel without pressure, I see more in the low to mid 2400s for velocities.

But if the Idea was to make a cartridge more effective than something that is not already available...this doesn't appear to have succeeded. Ya need more case capacity....or hybrid cases.
No one cares what cartridge ya choose, or if it has an advantage...if you like it shoot it.

But if you going for an advantage as suggested, it should surpass the others, not be equal or lesser.

So one could improve the 7 dasher with hybrid cases where the brass isn't holding up at 2500 fps.
Here is some 6 dasher hybrid cases, 7 dasher would be easier. But it requires dies to produce...
There are alot of brass cases to choose from these days, if ya don't like hybrid cases.

So?
What's your point?
My 7-08 AI with a 22" barrel drives the 162 eld x to 2800 with room to spare as far as case capacity goes. Gets me to 1000 with only 8.3 mils.
Big deal. It's not what the OP is looking for.
I do agree with you in regards to case capacity, let alone the increased recoil. If he wants to be competitive in PRS, and really wants to use a 7mm bullets, he'd probably be better off with a lighter bullet.
But, he wants to experiment. That's how you learn shit. Shitting on his thread, telling him how you and your ideas are far superior is poor form.
If you want to brag on your experiment, start your own thread.

 

[45-90]

So?
What's your point?
My 7-08 AI with a 22" barrel drives the 162 eld x to 2800 with room to spare as far as case capacity goes. Gets me to 1000 with only 8.3 mils.
Big deal. It's not what the OP is looking for.
I do agree with you in regards to case capacity, let alone the increased recoil. If he wants to be competitive in PRS, and really wants to use a 7mm bullets, he'd probably be better off with a lighter bullet.
But, he wants to experiment. That's how you learn shit. Shitting on his thread, telling him how you and your ideas are far superior is poor form.
If you want to brag on your experiment, start your own thread.

We mostly agree here, except for shitting all over his project.

He appears to be swimming upstream, and struggling making the needed velocities to have an advantage against "normal calibers" as used in the examples.

Showing him he could accomplish his project with more case capacity or try hybrid cases, is a suggestion for improvement, not shitting on someone's project.

I also said, "noone cares what rifle you shoot, if you like it, shoot it... it's your rifle, I don't care."

 

[Cz455guru]

@Cz455guru what’s your charge weights?

Cfe 223 36
Rl 15 34
H4895 33.3
Rl15.5 34
Varget 33.8
Currently considering these as max from the preasure testing ive done. Lapua brass BTW.

 

[Cz455guru]

We mostly agree here, except for shitting all over his project.

He appears to be swimming upstream, and struggling making the needed velocities to have an advantage against "normal calibers" as used in the examples.

Showing him he could accomplish his project with more case capacity or try hybrid cases, is a suggestion for improvement, not shitting on someone's project.

I also said, "noone cares what rifle you shoot, if you like it, shoot it... it's your rifle, I don't care."

Im not gonna dive into the weeds of a debate on this thread. Pm me if you want to debate. I will tell you my thought process behind this build.
1. Fun!!!!
2. Long flight time for more recover time at shorter ranges, I blink under recoil, it sucks!! I have tried to train myself out of it but my eyes just dont do right. Longer flight time at short range may help me see better. This is a experiment to see if it will overcome the additional recoil.
3. All I spent on the project is a new barrel and a bushing.
4. Getting into a different cartridge I would need new sac dies, brass and I already had this for this cartridge.
5. According to my calculations its a 7mph rifle at 2400 vs my 22 dasher and 6 dasher being a 6-6.5 mph rifle.
6. Its gonna make awsome trainer with slightly more recoil and long barrel life. I got tired of .223 consistency in es and sd, so I sold all that stuff. Shooting factory-second-bullets is just as cheap as a.223. Hence why I got the 197 smk.
7. About forgot, lead on a mover is exactly 2 mil. I sometimes have problems finding my 1.6 hash quick on the clock. Personal issues I know but kinda cool also.

Nobody has to like what im doing or do they have to understand the practicality side of it. I do not believe this has the potential to be the new hotness, so if im coming across that way I didn't mean to.