very fast twist too much ?

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Last Post 10 November 2023

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Ken Campbell Iowa posted this 05 November 2023

against my better judgement i was browsing some you-tube gun videos and happened upon a test of light mj bullets in a very fast .... 6.5 twist ... barrel . i heard short bullets don't do well shot fast in a fast twist ... oh well ...

since cast seem to do better the longer they are ... hey, its harder to bend ALL of a longer bullet ... maybe we should all be ordering custom 6.5 twist barrels ... of course this is for our usual 1750 fps loads ....

oh, yep, he wasn't shooting zeros but this is a commercially available plastic gun ... testing relative to longer bullets ...

maybe it would be a sweet spot to choose a very fast twist barrel but chamber/throat it for a desired shorter bullet ... as maybe a 165 instead of a 225 gr. cast in a 30 cal ... hey, lighter recoil for the 8,9, and 10 th shot ....

ken

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MP1886 posted this 10 November 2023

Larry, when they come apart in flight, think of thems as "FLAK"!! LOL

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Larry Gibson posted this 10 November 2023

MP 1886

Yes, most al varmint bullets are built to rapidly expand, explode, come apart, etc. on impact. The thinner jacketed ones especially. However, other than those mentioned and perhaps a couple others, all the varmint 224 cal bullets these days are built to withstand the higher velocities and centrifugal forces of faster twists used in rifles today.

There is little if any correlation between what causes a bullet to "explode" on impact and what causes the bullet to come apart inflight.

LMG

Concealment is not cover.........

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MP1886 posted this 10 November 2023

I know all that, but some of those bullets like the V Max are built to explode. The A Max is that way too. I shot a milk jug full of water with a 7 twist AR14, the bullet was a 65 grain A Max. It never made it through the jug. There were particles of the jacket and the lead alloy core and none were any larger than a #6 shot. I mention this because a broadside lung shot coyote went 1/2 mile before he collapsed. That's why I shot the water jug to see what the bullet might have done. Now I know, it blew up. The jug was at 80 yards and a 65 grain .224 bullet isn't exactly a light weight bullet.

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Larry Gibson posted this 09 November 2023

MP 1886

Larry would not say that because Larry knows better. If you'd bother to read my previous post you'd find I referred to "thin jacketed" bullets and gave examples of those that blow up. The Sierra 50 gr Blitz, the Speer 52 gr HP, the Hornady 50 and 55 gr SXs and the Hornady 45 gr Hornet bullet Hornet mentions are examples. Those were all made for 12 to 16" twists with velocities upwards of 3400 fps. Put any of them in faster twists at 3000 + fps and they begin to come apart as mentioned.

All the older manuals had plenty of data for their thinner jacketed bullets for use with those slower twists for which the bullets were made. Hornady 4th Edition, Vol I, page 114 states; "When using a 223 with rapid twist barrels (as in Ruger Mini-14s,or Colt AR15A2) do not use SX bullets. The rapid twist can cause these fragile bullets to come apart in flight, especially at maximum velocities."

The question was; "Why do bullets wait until 40-50 yards to blow up?" It is not asking what makes them blow up but why they "wait until 40-50 yards before they "blow up". As I mentioned in answering that actual question; "In the microseconds it takes for the bullet to spin apart (i.e. "blow up") the bullet, at 3000 +/- fps has traveled the 40 - 50 +/- yards. Simple as that." Indeed, it is that simple.

LMG

Concealment is not cover.........

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Hornet posted this 09 November 2023

Some of the jackets are much thinner than others. Try pushing a Hornady #2230 45 grain Hornet bullet at the 3808 fps speed of that V-max and bad things will happen. I seem to recall that the jacket on them is about 0.007" thick. Throw in some stress risers from the rifling making grooves and the material gets thinner. Add the material strength reduction from the frictional heat and you pass the stress to failure limit. It happened with the original cup-and-core bullets in the .30 Newton and with the original 0.007" thick jackets tried for the .303 British at even lower velocities. Newton went to a paper-wrapped core to help keep it from melting and the brits went to a 0.014" thick jacket to increase the stress to failure. This isn't a new development. It's both heat and rpms and the rifling form may also have an effect.

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MP1886 posted this 09 November 2023

Larry would say a 40 grain Hornady V Max bullet doing 3803 fps spun at 391,166 rpm would blow up? Well it doesn't. Hodgdon's reloading data has lots of bullets in the 30 to 40 grain bracket loading data. If they blow up that easily why would they provide data and not mention that? They have 30 and 35 grain loads exceeding that velocity above, albeit some are copper bullet with a tin/copper alloy. I think there is more to bullets blowing up such as a combination of extreme heat, velocity, and rpm, not excluding air damage from friction heat and stress force.

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Larry Gibson posted this 09 November 2023

RicinYakima is correct. In the microseconds it takes for the bullet to spin apart the bullet, at 3000 +/- fps has traveled the 40 - 50 +/- yards. Simple as that.

LMG

Concealment is not cover.........

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RicinYakima posted this 09 November 2023

The time it takes to get to 40/50 yards.

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MP1886 posted this 09 November 2023

Question was asked why does it take a bullet so many yards to blowup. Well there is a lot of heat from air friction. Maybe some of you airforce boy can tell me if this is true or not, but I was told or read where the wings, possibley the fuselage, can get up to a 1000 degree and they are supposed cooled some how.

What the twist does, or more accurately, the rifling cuts into the jacket and weakens it.

Ricin the bullets main source of high heat is the friction of it going down the bore in conjunction with heat from the powder burn.

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RicinYakima posted this 09 November 2023

My guess, for what it is worth, is that it takes that long for the heat to get through the guilding metal jacket.

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Eutectic posted this 09 November 2023

Why do bullets wait until 40-50 yards to blow up?

It seems to me if rotational speed was too great they ought to come apart at the muzzle.

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Ken Campbell Iowa posted this 08 November 2023

Bud .. in 1960 we loaded up those Norma 93 gr 30-06 loads for a friends Rem 760 as a jump-em-up jackrabbit gun .. 1.5 groups ... oh, about 60 gr. BallC ... heh ... worked outstanding at up to 100 yards ... never tried them at longer range.

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muley posted this 08 November 2023

Ed, what is WC820 compared with ??

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MP1886 posted this 07 November 2023

Bud I have a similar story. About a farmer up northeast. He had a huge groundhog problem. Called this gentleman that was suppose to be very good at clearing your farm of groundhogs. This old ruddy guy shows up with an old 1903 Springfield. He done almot the same thing as you mentioned on loading the 93 grain 30 Mauser bullets, except his were 90 grain FMJ 30 Luger bullets. They didn't blow up at any distance, but the groundhogs sure did!!

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Bud Hyett posted this 07 November 2023

I apologize but I've got to tell a tale on bullets blowing up.

In the 1950's, a Western Illinois varmint shooter was looking for a ground squirrel bullet for his .30-'06. He happened on some Norma 93 grain .30 Mauser soft-points. He loaded them to a maximum velocity and shot at 100 yards getting 1 1/2 inch five-shot groups that were adequate. Testing them at 200 yards, they did not hit the paper. But there was a strange rough surface to the paper. He surmised the bullets were blowing up and put a five-gallon bucket at 175 yards. The bucket had slight dings and paint scratched off. These made a devastating ground squirrel load.

The Rivoli Rifle Club at New Windsor, Illinois has a fun Turkey Shoot every November. One event is five shots at 200 yards, offhand, unsupported at five balloons each on a three foot string. In the Fall winds, this was a very competitive target. Two balloons often won a turkey and three balloons were almost guaranteed to win.

Knowing of Loren's load, I purchased and loaded some 93 grain Norma .30 Mauser bullets. The day of the match, my first shot burst a balloon. My second shot burst a balloon. The scorekeeper said I was well on the way to getting a turkey. My third shot burst two balloons. The scorekeeper asked to see my loads. Unfortunately, I had bought the bullets from him and he instantly surmised the scenario.

The next year, the club added the phrase "No Specialty Loads" to the event.

Farm boy from Illinois, living in the magical Pacific Northwest

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MP1886 posted this 07 November 2023

That's the way I heard it Ed, but I'll try go one step further. When they were developing 844, and they just didn't hit the nail on the head the first time, They had a batch that was better then the other batches. The two were very similar, but the better batch went on to become 748. The other batch become 335. 748 was 846. What I had read said that 748 was better powder. Most all my 5.56/.223 loads are loading with 748 except when I'm shooting match bullets. Just my two cents and that doesn't make it right!

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Ed Harris posted this 07 November 2023

H335 is milsurp WC844.

BLC2 was originally milsurp WC846 but now may be newly manufactured.

H322 was originally milsurp IMR8208M and now is newly manufactured.

H380 was originally WC852. Now is newly manufactured.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Larry Gibson posted this 07 November 2023

&48 is a completely different ball powder developed by Winchester in conjunction with 76 and 780 powders. the line of powders intended for loading into all Winchester commercial cartridges. H335 was a milsurp powder produced for loading the 5.56 cartridges (M193) and then was produced commercially. Winchester 748, even the original 748BR, was always a bit slower than H335, even a tudge slower than BLC2.

In pressure testing both powders (H335 & 748) it takes about 1.5 gr to 2 gr +/- more of 748 in the 223/5.56 under 55 gr bullets to achieve the same velocity and psi as with H335.

LMG.

Concealment is not cover.........

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MP1886 posted this 07 November 2023

That is what I've always though and I also believe, the two being very close in their early initial manufacture, that 748 was better or a better grade then 335.

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Larry Gibson posted this 07 November 2023

No, 748 and H335 are not the same. H335 is a tudge faster in burn rate than 4895 whereas 748 is about the same burn rate as Varget or 4064.

LMG

Concealment is not cover.........

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