257 BLACKBIRD (250-7 Blaser) for 131 ACE (0.340 G7 @ 3400-3500+ fps)

Dollarhyde

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Gentlemen,

I have had quite a few customers want to run 257 WBY speeds but not run double-radius brass. The results of 257 WBY have been excellent with the 131 ACE but I understand their concerns and want to accommodate.

In this case capacity the easy options are 257-264 Win Mag (perhaps Arnold Magnum iirc - didn't see it mentioned in either of PO Ackley's books), the 257-7 WSM, and then perhaps one with a better brass option, a 257-7 Blaser or 250-7 Blaser for an easier to say name.

82.0 gr H2O case capacity new (84 fired) - practically identical to 257 WBY but should still yield 3400-3470+ fps in a decent barrel. The case is 0.200" shorter than a WBY case so this will work in magazines very well - the 257 WBY runs perfectly from LA Pmags with 131 ACEs anyway.

I've had the 131 ACE up to 3670 fps and did not have bullets come apart (340954 RPMs) but this was in a premium barrel from Blake Barrels so YMMV if you run the ACE that fast. At any rate 3400-3470 should be fast enough for most any use.

I earned 16th place of 191 competitors at the NF ELR Steel Challenge in Wyoming a few weeks ago (700-2091 yards) shooting against many magnum 7s, 30s, 338s, 375s, etc.

If someone is so inclined could you cook up this recipe in QL? 131 ACE (1.440") 1:8" twist with the usual suspects for powder.

I will probably order 6 reamers from JGS in a one-time project. Most of these rifles will be built as long range Mulie rifles and/or for the Nightforce ELR Match.

1593324014817.png


COAL = 3.300" - 0.126" FB - 0.275" BSL seated in neck - 0.042" clear of Neck-Shoulder junction.
--- Seated according to common preferred jump distances (0.005, 0.018, 0.035).
--- 3.295 COAL - 0.280" BSL in neck - 0.037" clear of NSJ.
--- 3.282 COAL - 0.293 BSL in neck - 0.024" clear of NSJ.
--- 3.265 COAL - 0.300 BSL in neck - 0.007" clear of NSJ.

or

COAL = 3.314" - 0.140 FB - 0.261" BSL seated in neck - 0.056 clear of Neck-Shoulder junction.
--- 3.309" - 0.266" BSL in neck - 0.051" clear of NSJ
--- 3.296" - 0.279" BSL in neck - 0.038" clear of NSJ
--- 3.279" - 0.296" BSL in neck - 0.021" clear of NSJ

Since the 131 ACE likes 0.005 off, 0.018" off, and 0.035" off both of these setups will work well with the brass, mags, bullet, and barrel life/chasing lands if end-user wanted to for the duration of the barrel wear.

1593364619725.png


---

Please share any experiences if you have used 7 Blaser brass or want to get on the list for 250-7 Blaser reamer.
 
Last edited:

Dollarhyde

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Sending off dummies for the JGS reamers tomorrow!

250-7 Blaser (a few friends call it 257 Black Maxx) and the 257 WBY shown below. The youtube vid shows the magazine lengths of both in PMAG and in AI mags.

250-7 Blaser Revision 0 will COAL right at 3.314" on the lands and have plenty of room in magazines. She's a beaut.

1594089447447.png


 

Dollarhyde

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JGS has the dummy rounds and we will be comparing them to the modified standardized 7 Blaser print today.

After discussions with a few of the 250-7 Blaser supporters regarding an updated name, the early 6-12 guys who buy first reamers for the project will get to cast their vote for the name from a short list of 5 options.

257 Black Maxx
257 Blackbird - after the SR71 Mach 3+ plane
257 Jackpot
257 High Roller
257 Pit Boss - this was the original name of the 257 Blackjack cartridge but a few MFG's wanted a more standard name when we were heading toward full commercialization.

Should be a fair and fun way to set it in stone.

I'll post the reamer print on LRH tomorrow and the reamer-preorder slots on BJB tomorrow too.
 

highdrum

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Love it! Will be a speedy lil sucker. Long neck to boot. The blaser case should have been much more successful than it was.
 

Left Hand Dave

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Am I correct that with your 257 Weatherby reamer the 131 Ace will run fine in a Rem long action BDL?
 

GoosePilot

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Is this simply a necked down 7 blaser? I have an improved 37 deg 7 blaser and really like it. Have thought about a .277 Blaser, but maybe this would be a more interesting route.
 

Dollarhyde

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Messages
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BFE, OK
Love it! Will be a speedy lil sucker. Long neck to boot. The blaser case should have been much more successful than it was.
Yes it's sad that it is a deserving geometry and quality design, but people went with what was marketed on TV when the 7 Blaser was released. Thankfully there is a hoard of affordable and high quality brass for wildcatting! It's a perfect 257 and 6.5 parent case.

Am I correct that with your 257 Weatherby reamer the 131 Ace will run fine in a Rem long action BDL?
Yes it will. It will feed out of PMAGs, AI mags or internal box well.

Is this simply a necked down 7 blaser? I have an improved 37 deg 7 blaser and really like it. Have thought about a .277 Blaser, but maybe this would be a more interesting route.
Yes this is a non-improved version. I don't think we will need more velocity than the 3350-3470 this will yield, but after a while of shooting if the guys want a 257 Blaser Improved we can do that.

I just got the prints back from JGS today, so the order will go in tonight for 6-12 reamers and 1-2 resize reamers.
 

Dollarhyde

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BFE, OK
The voting from the buyers and social media fans has been nearly unanimous. 250-7 Blaser will become 257 Blackbird in honor of the SR71 spy plane.

We have a couple reamers left and since the plane and cartridge match so well, we are going to do a limited run of T-Shirts for September.

The "Test Pilots" who purchase the first batch of reamers will have their names, initials, or call sign on the back of the shirt which is shown in rough draft below. Should be a fun way to commemorate a wildcat based on such a good design that is under-utilized.

We have two reamers left out of the initial batch - two Test Pilot spots left!

Airframe-SR-71-Blackbird-017.jpg


Front of Shirt:

blackbird front.png


Back of Shirt:

257 Blackbird back large forum.png


Shirt Previews:

Screen Shot 2020-07-18 at 11.14.05 PM.png




Screen Shot 2020-07-18 at 11.14.43 PM.png
 

Dollarhyde

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Messages
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BFE, OK
Dang.....I'm weak....you don't need, you don't need, you don't need....i have wanted to do the 7mm blaser for some time--always thought the Blaser was a great cart design...and I'm a 257 WBY freak..

Ok we need to talk
I'll be looking forward to hearing your Call Sign soon.

Remember, 12 mils to a mile at 3KDA!
 

highdrum

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Montana
I'll be looking forward to hearing your Call Sign soon.

Remember, 12 mils to a mile at 3KDA!
What's a guy got to do be put on the list Miles? Also curious who a guy needs talk to getting a resize reamer cut bushing style? I think I just might have to do one these in a 28" barrel.
 

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