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Comet tails

Canuckenstein

What the hell are those and why do they happen?

Testing a load for a 1913 M96(all matching serial#’s) Trying to replicate the original 140gr load.
Powder:43.7gr of RL-22
Bullet: 142gr SMK
Primer: S&B LR
Case: Win 3rd firing

That target is at 50yds. Don’t know what that little smear is. Powder?I know RL-22 is a really slow burning. However it is also the most recommended for factory duplication. From what I have read the factory 140gr spitzer has a MV of 2635fps. Which is am a shade over.

I noticed that RL powders are like carbon fouling machines 10x leaves my 22-250 looking like a chimney on a coal stove.


See the picks below. The SD is phenomal. I shot one round at another target (insert curse words) above the one the picture.
 

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I've seen those several times over the years. The jackets are failing and what you see on the target is indeed lead. Next time you shoot that rifle aim at the target then raise your head and focus about 30 to 40 yards down range as you squeeze the trigger. Sometimes you will see the beginnings of the lead escaping the jacket in the form of a blue/grey 'smoke trail'. It really kinda cool to watch it. What amazes me is how accurate a rifle can be when the bullets are coming apart.
 
Dave, do you think that the diameter of the first inch or 2 of the barrel is allowing the jacket to expand excessively? I had a .17 Mach IV that started doing that about 1 out of 4 shots at 3500 rounds and by 4000 rounds every shot would 'smoke'. The leade of that barrel was an inch long at least and I'm sure the diameter was large as well. I should have slugged that barrel ahead of the chamber and measured it. I may have learned something.
 
Could I be over driving these bullets? My buddy who has a .260 reports 2800fps with the same bullet. I also imagine fellas with a skookum .264 win mag launch these at crazy speeds.

Not that IMO this matters but... The disc reports a groove diameter of .261. And the brass was starting to flow into the ejector groove(slot?). Nothing I would call serious seen way worse with my AR. The primers were not flattened no other signs of over pressure. The necks and mouths however had quite a bit of carbon or soot on them.

I am gonna go back tomorrow with some factory rounds and see if the same thing happens. I would hope it’s not the barrel this rifle as beautiful as it is, was bought to shoot (periodically) not look at. Also would like to take her on a deer/elk hunt.
 
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DaveTooley said:
You're losing lead. They are feet away from blowing up. I've got target after target that looks like that. It's a barrel/jacket problem.
Click to expand...

What were the solutions? Different bullet? Powder? JB Bore paste down the barrel? Recrown? As much as it would kill me to do it a new Barrel? (Walther makes a mil profile replacement). Suggestions?

Jon
 
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My 243 M70, 1965 had a large groove diameter allowing blow by of hot gas. The lead tip spitzer left the lead smears on target like OP photo. Replaced the factory barrel.

Clean the barrel well. Mine always took 10 shots till it would group after cleaning.
 
Looks like they are being driven too fast for your twist and bullet jacket...some Swedes have very tight bores also.

Simple enough to test the theory by trying a mild load .
 
This was done in multiple 1K BR rifles. 1-8 and 1-9 twist barrels. After the success of BIB 187 gr. 30 cal. FB bullets we got a set of 6.5 bullet dies. We made 140 gr. FB bullets and loved them. With the next lot of jackets we started to have problems. Loosing bullets in a string. We tried just about everything. New lot of jackets etc. Nothing helped. It was heat/friction related in combination with a jacket issue. I shot through angled plywood and got one bullet to turn sideways on a target. The tail appeared to be coming off at the junction of the body and ogive. I'm surprised you're having issues with Sierra's. They're pretty tough.
 
STS said:
Dave, do you think that the diameter of the first inch or 2 of the barrel is allowing the jacket to expand excessively? I had a .17 Mach IV that started doing that about 1 out of 4 shots at 3500 rounds and by 4000 rounds every shot would 'smoke'. The leade of that barrel was an inch long at least and I'm sure the diameter was large as well. I should have slugged that barrel ahead of the chamber and measured it. I may have learned something.
Click to expand...
I think it's all about heat. A rough bore contributes to friction. What we'll never determine is at what point does an increase in friction, which melts the core, start to compromise jacket integrity. The end result is the same. I have a thermal image of a bullet just after leaving the muzzle. The contact patch where the rifling engraved the bullet is more than hot enough to melt the core in that area.
 
I have one in full military dress. Been a long time since I shot any jacketed through it. It is a slick barrel but has a large throat and neck. Never had it do what yours is with surplus or factory.
 
DaveTooley said:
I think it's all about heat. A rough bore contributes to friction. What we'll never determine is at what point does an increase in friction, which melts the core, start to compromise jacket integrity. The end result is the same. I have a thermal image of a bullet just after leaving the muzzle. The contact patch where the rifling engraved the bullet is more than hot enough to melt the core in that area.
Click to expand...
Are you saying that you think that just some cores are liquified due to increased friction of a rough bore, or all cores are in that condition?
 
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