266 grain cast bullet, the Dolomite special

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armedferret
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Re: 266 grain cast bullet, the Dolomite special

Post by armedferret » Thu Oct 03, 2019 1:28 pm

dellet wrote:
Thu Oct 03, 2019 8:57 am
armedferret wrote:
Thu Oct 03, 2019 5:41 am
Sounds like I may be done with these then. It already takes nearly 2 hours for 50 rounds, and thats without adding another handful of steps. I don't have that kind of time.
I would suggest you give up all cast and coated bullets then, or get used to shooting patterns rather than groups. Most people are pretty happy to add a single step and shrink their groups from 3-4 MOA to 1.

The only step you are adding is belling the case. Almost all seating dies can be set to remove the bell and if you are dropping powder on a press instead of by hand you can bell it case then.

It would also probably help with the stability issue you are having.

Giving them "all" up would be fairly easy since these sre the sum total of all I've ever bought.

Not everyone has progressive reloading presses. Adding yet ANOTHER die into the mix just for one single projectile that hasnt even shown a willingness to work properly isn't something I'm keen on.

Then having to buy a new set of dies just so i can get a specific expander ball...and do I then size normally, trim, chamfer/deburr, then run it through the sizing die again this time with the x39 expander ball? The projectile won't drop straight through the neck if it's that far oversized?

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ShootNstuff
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Re: 266 grain cast bullet, the Dolomite special

Post by ShootNstuff » Sat Aug 06, 2022 12:06 pm

I have some of these on the way. Will be shooting in a BA 10.3” 1/7, a Bison Armory 8” 1/7, Uintah bolt action 8” 1/7 upper, Faxon 6” 1/5, and a KAK “Baby Blonde” 6.25” 1/5… so a decent variety… may throw a Wilson Combat 10.5” 1:7 barrel together just to add another data point.

I would like to use N110. Was thinking of maybe starting at 9.0 and working down. Does that sound right charge wise? I also have CFE BLk, SW BLK, H110 and Lil Gun on hand if needed.

Objective is just a reliable functional (cycles to BHO) sub load for the AR’s that’s decently priced and at most 2 MOA.

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Bob the nailer
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Re: 266 grain cast bullet, the Dolomite special

Post by Bob the nailer » Mon Aug 08, 2022 6:30 am

CFE Blk will work good, starting at 9 grains then working down should get you there. The designer of the bullet recemonds IMR 4227 as a choice powder for this bore rider.
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ShootNstuff
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Re: 266 grain cast bullet, the Dolomite special

Post by ShootNstuff » Sun Aug 14, 2022 10:39 pm

I shot some today. I did 9 grs of N110 out of a 6.25” 1/5 twist.

1022 five shot average.

Image

Testing stability no can on test upper (same barrel, primary upper has a tucked can so I build a second upper for this purpose). 10ft to poster board.

Top shot showed some wobble, second shot didn’t.

Shot one round through can on primary upper. Paper looked like clean hole but pulled off can to check. Noticed some obstruction so took out the baffles and baffles two and three had some lead deposits on the edge of the baffle bores. The lead popped right off with a pocket knife. It almost looked like it was molten then solidified.

Shot the rest of the rounds with just empty tube (baffles and end cap removed) on the rifle (again, it’s a tucked can) and it grouped terribly.

I had three rounds remaining so I shot those through an 8” 1/7 Uintah bolt action upper. Those punched holes, great group.

I am using a NOE .310 -.307 sizer plug with a VLD chamfer. I’m not scraping lead or coating during loading.

What I think is happening in the standard upper, is the coating is scraping upon feeding causing irregular flight. The coating is super easy to scrape off the bullet. I’m not too happy about that. I can use these in the bolt action upper since it’s feeding is much more gentle as it is not only manually operated, but has different feedramp geometry.

It’s my first experience with HyTek coating. Is it typical to scratch off so easy? This would totally fail the “hammer test” used for powder coating.

That said, any recommended powder coated bullets?

@Dellet

Your thoughts?

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Re: 266 grain cast bullet, the Dolomite special

Post by BJK » Mon Aug 15, 2022 12:14 pm

Did you test the adhesion of the coating by smashing the coated bullet with a hammer repeatedly? Another test is to use a rag with solvent on it and rub, rub, rub, to see if it comes off.

The tests begin at the 11:30ish point, but of course you can watch the entire video.
https://youtu.be/k6MoF8u4rHk

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dellet
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Re: 266 grain cast bullet, the Dolomite special

Post by dellet » Mon Aug 15, 2022 12:35 pm

ShootNstuff wrote:
Sun Aug 14, 2022 10:39 pm
I shot some today. I did 9 grs of N110 out of a 6.25” 1/5 twist.

1022 five shot average.

Image

Testing stability no can on test upper (same barrel, primary upper has a tucked can so I build a second upper for this purpose). 10ft to poster board.

Top shot showed some wobble, second shot didn’t.

Shot one round through can on primary upper. Paper looked like clean hole but pulled off can to check. Noticed some obstruction so took out the baffles and baffles two and three had some lead deposits on the edge of the baffle bores. The lead popped right off with a pocket knife. It almost looked like it was molten then solidified.

Shot the rest of the rounds with just empty tube (baffles and end cap removed) on the rifle (again, it’s a tucked can) and it grouped terribly.

I had three rounds remaining so I shot those through an 8” 1/7 Uintah bolt action upper. Those punched holes, great group.

I am using a NOE .310 -.307 sizer plug with a VLD chamfer. I’m not scraping lead or coating during loading.

What I think is happening in the standard upper, is the coating is scraping upon feeding causing irregular flight. The coating is super easy to scrape off the bullet. I’m not too happy about that. I can use these in the bolt action upper since it’s feeding is much more gentle as it is not only manually operated, but has different feedramp geometry.

It’s my first experience with HyTek coating. Is it typical to scratch off so easy? This would totally fail the “hammer test” used for powder coating.

That said, any recommended powder coated bullets?

@Dellet

Your thoughts?
A 1/5 twist is hard an jacketed bullets, more so on cast with a long bearing surface. I’ll see if I can dig up some photos I have where I pushed cast bullet to the point of being driven straight through the rifling. You can see where the groove from the lands is straight, before the bullet starts to spin.

The other thing is that most consider 140,000 the upper rpm limit for cast bullets. In a 1/5 it’s spinning 144,000 at 1000 fps.

The sharpness of the transition from the throat into the lands and grooves can be another factor, sharp leading edges will. If the lead instead of compress it. Chambers designed for lead are completely different in the taper than than those designed for jacketed.

Then there is the question of compromising the coating when sizing. You might do a smash test and compare sized and unsized results.

Since the problem is only with the fast twist barrel you need to figure out if it’s just the twist or possible the chamber itself that is causing the problem. One indicator might be a lead ring forming at the leading edge of the rifling. May need a bore scope for that.
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Re: 266 grain cast bullet, the Dolomite special

Post by ShootNstuff » Mon Aug 15, 2022 2:01 pm

BJK wrote:
Mon Aug 15, 2022 12:14 pm
Did you test the adhesion of the coating by smashing the coated bullet with a hammer repeatedly? Another test is to use a rag with solvent on it and rub, rub, rub, to see if it comes off.

The tests begin at the 11:30ish point, but of course you can watch the entire video.
https://youtu.be/k6MoF8u4rHk
Thanks. I’ll test a couple.

ShootNstuff
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Re: 266 grain cast bullet, the Dolomite special

Post by ShootNstuff » Mon Aug 15, 2022 2:04 pm

I understand the potential consequences of excessive centrifugal force on jacketed bullets, but how would that effect a coated lead bullet since there is no jacket to separate?

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Re: 266 grain cast bullet, the Dolomite special

Post by 2manyToys » Mon Aug 15, 2022 2:33 pm

The coating and lead are so soft the the bullet will "strip" and deform in the rifling. I've seen this happen will plated bullets as well. It's not pretty. Your target will look like a shotgun blast from a single shot.

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dellet
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Re: 266 grain cast bullet, the Dolomite special

Post by dellet » Mon Aug 15, 2022 3:22 pm

My instructions were “see if you can make this bullet and coating fail”

Image

viewtopic.php?f=128&t=102326&p=985663&h ... ed#p985663

Too much pressure, too soon causing too much acceleration. It’s easier to compress the bullet and push it over the lands, than to spin it. Note the 1900 fps. Bullet, the engraving starts straight.

There is a reason a lot of cast shooters use a gain twist barrel if they want a fast twist like a 8 or 9.
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