What is happening with this boolit?

[Copper75]

Shot some new boolits today. They were keyholing at 25 yards. Was only able to recover one and it seems to be stretched. Longer and thinner than it started. Using boolits made with lee tl309-220-5r roto metals 1/40 alloy in 300 Blackout with 8gr of Unique. Didn't have the chrono today so no velocity but I'm pretty shure they were subsonic. 6901469015.

[Copper75]

BTW I'm powder coating them. This is what it looked like before I shot it.
69016

[joesig]

Quick load says 8gr Unique is 45776 PSI! You are over driving it!!! Start at 3-4gr and see what happens.

[RickinTN]

Quick load says 8gr Unique is 45776 PSI! You are over driving it!!! Start at 3-4gr and see what happens.

Agreed. I also think your probably fast-twist barrel is imparting it's twist on the bullet to an extreme!

[Copper75]

I'm was hoping someone would quick load it for me. I shoot 6 gr w 147 grain pulls and started there with my 230s. Since they didn't stabilize I went up.
Guess I should have gone down.
Ill try 4 and go from there.
Thanks for the help guys!!
Copper

[BBQJOE]

Whatever it is you're doing, I'd suggest you stop it, and start all over.
In all my berm digging, I've never seen a thing like it.

[303Guy]

Someone posted a picture like that before. Not quite the same but an elongated boolit just the same. "They were keyholing at 25 yards." I'm wondering whether it went sideways close to the muzzle and stretched itself by virtue of the high sideways spin induced forces. If that were the case then that boolit might have lost a lot of its forward velocity and struck the berm at a modest speed so that it survived the impact.

[Copper75]

Struck sideways.
Made a hell of a hole in the paper/cardboard target.
Too much rotational torque caused by
too much energy sounds like the problem to me.
I'm gonna back WAY off and start again.
Sound good to you guys?

Copper75

[303Guy]

I re-read your first post and edited mine. Before you 'solve' the problem, that there is a mighty interesting phenomenon. It has happened before and left folks scratching there heads I'm sure. If you could find someone with the necessary photographic equipment you could make history with that one. Well, a great youtube shot anyway. Maybe some lab boys would like to study that. There are some high speed bullet photographers out there - why not try contact them? They would love to capture that event.

What I think is happening is the boolit is beginning to bend as it exits the muzzle so loses its stability right away and takes on that interesting spiral which grows as it progresses downrange then probably loses energy and stops distorting.

Oh, the powder coating looks great! I just forgot about it in the moment with the weird boolit distortion. Was it you who did a thread on powder coating?

[Jupiter7]

8grs is hot! I run my 245's at 5.5grs. I don't know how that was subsonic...

[btroj]

That is a very soft alloy for that hot a load. 1/40 may work with 20,000 PSI loads but not much more.

You are exceeding the limits of what that alloy can handle. The bending may well beging when bullet begins to exits the case mouth. It will bend and expand under pressure to fill any voids in case neck/throat area. This will destroy accuracy and can give leading too.

Talk about a great example of a need to A- read a manual, B- match the alloy to the pressure/velocity window, C- make observations and say, hmmmmm, this may not be the road I want to be going down.

If they need to go faster than 4 gr of Unique will give then go to a better powder for the increased velocity. Try some 2400 or something like that.

[huntrick64]

That is not your bullet! Be on the lookout for a jake turkey that drops lead. If you find him, I will buy him off ya, cause lead is getting harder and harder to find.

[detox]

Linotype may work better with the fast twist. BTW what type of rifle and twist rate?

[andrew375]

Strangely I've actually seen this once before, but with a 147 gr. .30 jacketed bullet that I picked up in the butts at Bisley.

The cause is mentioned in my copy of Text Book of Small Arms, 1928. Basically the issue, referred to in the book, was with the fact that even jacketed bullets set in the throat to obturate but this may not happen in a barrel with excessive wear. When the bullet does not seal the gas behind it then the gasses can form a layer between the bullet and bore, effectively floating the bullet off the bore surface. The sideways pressure of this gas is enough to compress the bullet radially which makes it longer and thinner. The helical shape is due to the fact that clearence between bullet and land is less than between bullet and bottom of the rifling groove.

I suggest either the bullet was too small to start with or you are driving it too hard which is letting gas blow by occur before the bullet can obturate.

[felix]

The latter, especially with an exposed boat tail. ... felix

[44man]

I had to laugh----WAY too soft a boolit.
Good snake shot stuff though! [smilie=w: