250-7 Blaser (0.340 G7 @ 3400-3500 fps)

[Romulus]

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.

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.



---

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

 

[B23]

I have a 7mm Blaser mag built on a LA Rem 700 and it wears a Hart barrel finished at 26in less brake. Been shooting the 180 Bergers w/RL26 at 3088-3100 and it stacks them up into some pretty small goups.

Norma makes the brass for Blaser and it's been great so far.

I think the 7mm Blaser mag case is well designed and would make for a great case to wildcat off of.

I'm not that big of a 1/4 bore fan so a 25-7mm Blaser mag has never interested me a whole lot but I've often thought a 270-7mm Blaser mag shooting the 170 Bergers would make for an excellent 270 wildcat and would be an easy peasy straight neck down.

 

[Romulus]

I have a 7mm Blaser mag built on a LA Rem 700 and it wears a Hart barrel finished at 26in less brake. Been shooting the 180 Bergers w/RL26 at 3088-3100 and it stacks them up into some pretty small goups.

Norma makes the brass for Blaser and it's been great so far.

I think the 7mm Blaser mag case is well designed and would make for a great case to wildcat off of.

I'm not that big of a 1/4 bore fan so a 25-7mm Blaser mag has never interested me a whole lot but I've often thought a 270-7mm Blaser mag shooting the 170 Bergers would make for an excellent 270 wildcat and would be an easy peasy straight neck down.

Our 131 ACE has the same BC as that 170 Berger and will offer a few hundred more feet per second MV and better wind deflection with 1400 ft/lbs energy at 1000 yds compared to 1580 of the heavier bullet which produces 23% more recoil. In this comparison I only ran the 257 WBY at 3400 although it will run 3470 too which is only 80 ft lbs less energy than the 270 WBY at 1000 yards.

I used to run 270 WBY at 3200 fps with the 170 EOL - the cartridge and bullet work very well together. Many 3-5" 3 shot groups at 3/4 mile.



--- 270 WBY - 3200 fps -


Both setups are more than enough for any task in NA.

 

[Zero333]

Ran the #'s in QL...

Reduced case capacity to 81 gr because you're gonna loose it when shrinking the neck.

Upped the MAX PSI to 63,000 psi (from 60,000 for the 7 BlaserMag), but used 62,000 PSI as to get the results..

3.400" COAL (0.218" bearing surface in the neck / 0.343" total bullet in the neck).

N-570 is the king of velocity for this and all other magnums.

30" barrel.

3,426 fps.

Here is a screenshot...




N-570 = 73.2 gr = 62,000 psi

RL-33 = 76.7 gr = 62,000 psi (3,410 fps)

If you want any QL data, powder specific, or multi-powder readouts or anything you can think of... you can PM me any time.

Sharing Quickload in the open forums is a....

 

[Romulus]

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.

 

[Zero333]

Very good looking cartridge !

 

[Romulus]

26 Nosler necked down to. 25 cal. ?? Why not

Our customers have asked us to make reamers for that but we recommend against it due to the seriously poor barrel life.

AT 93.5 gr H2O the 25-26 Nosler has about 11% more capacity than a 257 WBY, 264 Win Mag, or 250-7 Blaser which is already on the poor barrel life side of things. We have customers running 257 STW and power to them, but we aren't going to push things that far. With a good bullet 3400 fps is about 200 fps more than anyone needs more high hit %'s at long ranges, and ethical hunting beyond most shooters' capabilities or access.

 

[Romulus]

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.

 

[B23]

In those cartridges, like the 26 and 28 Nosler, they are so overbore, they really do need at least a 28 or better yet 30+ inch tube before they can take advantage of all that case capacity.

My 7mm Blaser, pronounced blahzer not blazer, shoots 180's from a 26in tube 3088-3100 which is the same as what the 28 Nosler does with a 26in tube, but with about 15gr less powder.

A 25-7mm Blaser should make for a great combination without having to hang an extremely long barrel on it and have a relatively very short barrel life.

 

[Romulus]

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!

Front of Shirt:

Back of Shirt:

Shirt Previews:

 

[NC308]

Why not jut AI the 257 weatherby? Gets rid of the double radius and a little more case capacity?

 

[std7mag]

Hmmm,
I'm thinking i see litigation from Lazzeroni in the future...

Mayhaps you should consider a name change.

Just say'n....

 

[LoanHarvey]

Ordered reamer!! Need some brass..

 

[std7mag]

Personally i'm looking forward to building a 25-350 Rem Mag some day.

Looking at the cartridge vs WSM, RSAUM, you end up with more capacity than either of those.
WAY more than a 25-284!
And seeing as to how the 6.5-284 got a reputation as a barrel burner, i'm taking a stab and going with about 900 rounds before your barrel is toast.

Cool design! And personally i like the idea!
But for longer barrel life a 25 RSAUM, 25 WSM, or 25 RCM would work better.

 

[Romulus]

Why not jut AI the 257 weatherby? Gets rid of the double radius and a little more case capacity?

Fireforming can be useful, BUT the vast majority of shooters and customers want to load ammo and shoot. 257 Blackbird was an answer to our customers requesting this speed without belts or radius shoulders - most active competitors don't want belts on their cartridges.

84 gr H2O should be fast enough for about anything at 0.340 G7.

Hmmm,
I'm thinking i see litigation from Lazzeroni in the future...

Mayhaps you should consider a name change.

Just say'n....

It does not appear the Lazzeroni cartridge is still active at all in rifles chambered, brass offered, etc. Even if it were we could add a space to make it Black Bird. The way they denote bore/groove apart from the rest of the industry is enough. Their search function shows no return when seraching for Blackbird. Google does show some necked-down brass in Cartridge Collector. If Laz wants to talk we can have a good conversation. I've reached out to them in the past to discuss our 131 ACE and their platforms.

Personally i'm looking forward to building a 25-350 Rem Mag some day.

Looking at the cartridge vs WSM, RSAUM, you end up with more capacity than either of those.
WAY more than a 25-284!
And seeing as to how the 6.5-284 got a reputation as a barrel burner, i'm taking a stab and going with about 900 rounds before your barrel is toast.

Cool design! And personally i like the idea!
But for longer barrel life a 25 RSAUM, 25 WSM, or 25 RCM would work better.

Yes, the 25 SAUM is a much more practical cartridge with the many of them out there in the wild running 3250-3385 fps. They are extremely competitive in 2000 yard matches with anything guys could and do bring to the firing line.

We have customers who want to shoot 257 WBY or 257-264 Win Mag speeds without the belt.

250-7 Blaser is about the most direct route with great geometry and it fits in the magazines like a dream.

 

[Romulus]

Due to stronger interest than anticipated we added more reamers to the initial order!

As orders come in please let us know what Call Sign you want for the back design of the shirts we will print in September.

 

[Edd]

I like it, I have a 6.5-7mm Blaser. I originally drew a print for a 6.5 and a 257 but I never ordered the 257 reamers. Now If I decide I want a 257, I can use your design.

 

[std7mag]

What would happen with a 375 Ruger necked to 25 caliber?
Should give you about same or better than the 257 Weatherby without the belt.
Would still be a long action, but with slightly greater case capacity.

I like these threads!
They get me thinking!

 

[Zero333]

What would happen with a 375 Ruger necked to 25 caliber?
Should give you about same or better than the 257 Weatherby without the belt.
Would still be a long action, but with slightly greater case capacity.

I like these threads!
They get me thinking!

Once you neck down the 375 Rug. to 25 cal., the case capacity will be in the 96 gr range. So yeah it could be faster than the 257 Blackbird, but it would also require a 3.600" COAL with the 131 BJ bullet to have it seated at the same depth as the 257 BB.

So in theory, the 25-375 Rug would give you 60 fps ? more over the 257 BB.
12% more powder burned for 2 % more velocity is not enough to justify the difference.

 

[Romulus]

Once you neck down the 375 Rug. to 25 cal., the case capacity will be in the 96 gr range. So yeah it could be faster than the 257 Blackbird, but it would also require a 3.600" COAL with the 131 BJ bullet to have it seated at the same depth as the 257 BB.

So in theory, the 25-375 Rug would give you 60 fps ? more over the 257 BB.
12% more powder burned for 2 % more velocity is not enough to justify the difference.

Not worth it in our estimation as well.

257 WBY feeds perfectly out of LA PMAGs and AI LA mags but the 257 Blackbird will feed even better a 3.314".

Usually 3200 fps I call plenty, but I have to admit 3400 fps is very fun. After that the powder to performance ratio gets out of whack and there is more material and opportunity cost to shoot above 93 grain H2O until you get in to heavy 7mm and 30 cal in my opinion.

This 84 gr H2O is the useful top end for 0.257 in our estimation.