Over-spinning bullet…until they come apart

FireFlyFishing · Saturday at 3:49 PM

I plan on running heavy for caliber under most circumstances; 69 and up. However, I have many 50-55 grain bullets on hand and would mind making a laser load with those.

It certainly occurred to me to test out velocities with the thread protector instead of the suppressor.

I figured contacting the manufacture of the bullet would also be a good place to start.

It was said above, modern bullets shouldn't have an issue. I have a large stockpile of 52 gr SMKs I inherited from my dad. They're pretty old…with the old style Sierra boxes. That's where my concern lies.

Anyway, I thought I'd do my homework prior to shelling out a can.

muledeerhntr · Saturday at 3:55 PM

FireFlyFishing said:
I plan on running heavy for caliber under most circumstances 69 and up. However, I have many 50-55 grain bullets on hand and would mind making a laser load with those.

It certainly occurred to me to test out velocities with the thread protector instead of the suppressor.

I figured contacting the manufacture of the bullet would also be a good place to start.

It was said above, modern bullets shouldn't have an issue. I have a large stockpile of 52 gr SMKs I inherited from my dad. They're pretty old…with the old style Sierra boxes. That's where my concern lies.

Anyway, I thought I'd do my homework prior to shelling out a can.

My Tikka loves 69 SMKs and 75 eldm! I have shot milk jugs at 1200 yards with the 75's.

memtb · Saturday at 4:00 PM

just_jon said:
If you are running a mono, RPM is not a consideration. I am running the 35HH in a 22-250AI over 4850 fps (>350,000 rpm) without issue. The 35 Berger FB at similar speeds never made it to the 100-yard target.

Certainly……you're not suggesting that some Bergers are a little thin in the jacket! Tell me it ain't so!

memtb

Justice1327 · Saturday at 5:51 PM

I have had .20 cal (39g SBK/40g VMx/55g Bgr) all above 4k fps…1:8.5 tw
No blow ups.

Lapuatom · Saturday at 6:01 PM

Quintus said:
If you want be sure load and shoot em without the can and see what hits the paper. Calling the manufacturer will get you most of the way there before you make the investment. As Petey said, when they do spin open it's usually 10 to 20 feet past the muzzle, that you notice it's done, but I can't say where they actually start to come open.

They start to come apart the instant they leave the muzzle. After that point, they are slowing down .

243winxb · Saturday at 10:30 PM

memtb said:
Bergers are a little thin in the jacket!

Berger bullet failure test. As others have said, condition of barrel may cause excessive heat from friction.

Varmint bullets may have thinner jackets?
Sierra uses 4 different lead/antimony cores for their bullets. Harder alloys may be better? Dont know.

Hornady - 2020

Every bullet manufacturer's tips begin to melt and deform depending on their specific material properties.

https://www.hornady.com/support/faqs/at-what-temperature-do-standard-tips-melt#:~:text=In general, standard acetals and,to melt and badly deform.&text=This generally begins to occur,the bullet leaving the muzzle.

A lead nose spitzer bullet may leave a lead trail, marking the target. My first used 243 with a bad barrel, did this @ 100 yards. No bullets blew up. Berger has said the lead core becomes liquid as bullet leaves the barrel. Two things are the cause of bullet blowup. 1. A 28, 30 inch hot rough barrel. Extra friction over barrel time. 2. Bad bullet when core and jacket are spinning at different speeds.

Internet photos. Lead on target & mid-air blowup.

Seabeeken · 2025-01-26T00:35:12-0600

The bullet maker should know. I contacted Barnes about there varmint grenades and found out I was 3,000 rpms over their spin limit and shredding them.

Rflshootr · 2025-01-26T05:02:55-0600

I chambered a Lilja 8 twist 3 groove for a 22x6mm Rem.
Didn't matter what bullet brand or weight, everything from 80 grain to 55 grain, they all came apart when I started to push them. The original 14 twist barrel had no problem pushing a 55 ballistic tip to 4020 fps.
Even when it went south, the bullets stayed together. Other than the twist, the other difference was a 3 groove vs a 6 groove. Don't know if it was the twist or the wider land of the 3 groove or a combination of both.
I think you'll be ok with the 52 Sierra's and a 22-250. But, like you mentioned, to be sure, work the load up without the can.
With 10 rounds you should be able to hit max pressure and velocity. If there are no problems, go to the can from there.

ncwg2boatguy · 2025-01-26T05:16:21-0600

Never seen it happen at the muzzle but seen them come apart in flight "puff" 162Amax from my 28" 7mm STW running 3400+ fps

M118LR · 2025-01-26T05:45:44-0600

Now at long range most projectiles lose enough spin rate that explosive impact isn't really relevant. Yet spin drift calculations and predictions can become palm pilot only projections as excessive spin due to barrel twist vs Projectile weight + bearing surface increase. The goal is to match barrel twist, barrel length, and the Projectile so that the most predictable repeatable conclusion is attained.

M118LR · 2025-01-26T05:51:13-0600

Let's just say matching all the pre shot parameters is supposed to be as predictable as shots within the supersonic range of the Projectile?

Tiny Tim · 2025-01-26T06:57:26-0600

As others have stated, barrel throat and rifling type will come into play. A 5R will be easier on jackets than a 3 groove. Also, if you run them just below the failure point, as your throat becomes rougher over time, they may start failing at reduced speeds.

M118LR · 2025-01-26T07:02:48-0600

Throat erosion has a tendency to increase Freeplay which increases smoothbore vs roughness?

Rflshootr · 2025-01-26T07:02:53-0600

No sense in having a thoroughbred racehorse and letting him trot.

Over-spinning bullet…until they come apart

FireFlyFishing

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muledeerhntr

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memtb

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Justice1327

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Lapuatom

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243winxb

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Seabeeken

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Rflshootr

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ncwg2boatguy

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M118LR

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M118LR

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