Marlin Firearms Forum banner
1 - 20 of 41 Posts

·
Registered
Joined
·
427 Posts
Discussion Starter · #1 · (Edited)
Don't often try hotter loads at the paper range in my 30-30, but I tried a 170-grain RNFP Lee with gas check and lubed with Ben's Red

In my lino alloy, the heads weighed in at 160 grains, hardness was BHN 21

Powder charge was 22.0 grains of 5744. New R-P brass.

In the event, at the 100-yard point they proved very accurate indeed, extremely so, and on cleaning I found not a trace of leading (micro groove barrel).

I found 3 cases that had a spiraling gouge appearing near the head. I enclose an image of a typical one, and a primer shot.

Appreciate comments from the more experienced on this. Yes this is accurate and clean, but is it too hot for my particular barrel?

edit - when I use my 'normal' target load in new brass (10 grains Trail Boss) fired cases measure 2.028" - these from the 22.0 grains of 5744 measure at 2.037")



 

·
Premium Member
Joined
·
8,595 Posts
I'm new'ish to handloading so will wait to see what other people have to say here, BUT
Something ain't right that's for sure!

Looks like primer flow to me. And is that crack completely through the case?.?

You said "New Starline" Brass, but those are Rem Brass. Are you Sure it's new brass?

BloodGroove4570
 

·
Premium Member
Joined
·
8,595 Posts
I'm new'ish to handloading so will wait to see what other people have to say here, BUT
Something ain't right that's for sure!

Looks like primer flow to me. And is that crack completely through the case?.?

You said "New Starline" Brass, but those are Rem Brass. Are you Sure it's new brass?

BloodGroove4570

Is your load data from a Good Reputable source? I'm not familiar with 5744 that's why I asked!
 

·
Registered
Joined
·
5,954 Posts
Like he said that's remington brass not starline. But primer isn't flattened like you would see with case head extreme stretching and the cratering is very slight. Nothing that would say to me this is too much pressure. I also don't see a ring around the case head. The load isn't that hot according to my data 23 grains is max with a 170 grain lead bullet. Did you shoot through a chrony to verify velocity. In my opinion if you reload you really should have a chrony to assist you with staying safe with your loads. Did the brass extract hard?
 

·
Registered
Joined
·
427 Posts
Discussion Starter · #5 ·
Hey Blood'

Yep, corrected the error, it's new R-P brass, I just got 5 of the zip-locked green bags.

I did wonder if it's partial head seperation. The waving, spiraling track is present of much of the brass from this firing.
 

·
Registered
Joined
·
427 Posts
Discussion Starter · #6 · (Edited)
hey Bryan,

No chrony at that session. All cases extracted easily.

Edit-

here's another image of another case, can you see the spiraling grooves I am describing? Not the 'normal' chamber marks that you can see that go around concentrically, but those that spiral up along the length of the case near the Head end.

 

·
Registered
Joined
·
5,954 Posts
In my opinion then you got some bad brass. Toss them and keep going with that load if it shoots good for you. But get a chrony to assist you with velocity and that can help with the ballistics end. Have fun and stay safe!
 

·
Registered
Joined
·
5,954 Posts
Case head seperation will happen right wear the brass goes from shiny to dull. It should happen in a perfect line all the way around. I can't see any stretching there so it doesn't look like that. If there is a crack going through the web like it is I'm guessing bad brass it should never ever fail there first. That should be the thickest part of your brass and the last spot to fail. And for me when you start to get sticky extraction tells me when I'm getting to hot for my particular gun and I'll back off.
 

·
Registered
Joined
·
5,954 Posts
Load data was from the Lee insert that came with the dies. It lists 22.0 grains for the 170 grain lead, so with mine at 160 grains I felt it was safe.
The weight doesn't matter as much the mass does. Densities in lead differs and the load data for the 170 grain projectile is for how far it seats into the case which will affect pressure

Best I can compare it to is a jacketed lead bullet at 150 grains and a pure copper bullet at 150 grains. The copper bullet will be longer than the jacketed lead bullet but OAL would be the same. If you put the same amount of powder in both cases the copper bullet will have higher pressure because it is seated deeper.

So in this case stick with 170 grain data.
 
  • Like
Reactions: EDR

·
Registered
Joined
·
5,954 Posts
I saw the second picture and the spiraling marks are tooling marks from when the chamber was reamed.
 
  • Like
Reactions: dpe.ahoy

·
Registered
Joined
·
5,954 Posts
You should put a side view picture of some brass that looks fine to you that you fired with that load.
 

·
Registered
Joined
·
1,005 Posts
I think your load and brass are ok but that chamber is a mess. Is this a Remlin? For what it is worth, the primer flow around the firing pin is pretty typical of Marlin and other rifles chambered for .30-30 class cartridges. The hole is a bit big for the pin.
 
  • Like
Reactions: dpe.ahoy

·
Registered
Joined
·
788 Posts
I think this a chamber machining problem. Normally the short section of the case just in front of the rim is not supported around the outside by the chamber and expands slightly more than than brass in the chamber so it flexes more on firing and resizing. Thus the more unsupported expansion especially in very high pressure cartridges the faster case head separation occurs. Your photos seem to indicate that the chamber supported case section is larger than the unsupported rear end of the case when the opposite would be expected. If so, this would say that your chamber is quite a bit oversized and that might be supported by the appearance of the heavy machining marks. A chamber cast measured against SAAMI specs would tell the truth. If this is a Remlin maybe this wouldn't surprise us but if a JM Marlin of dubious history maybe someone reamed rust etc out of the chamber with the wrong tool. A chamber cast compared to specs would tell the tale.
 

·
Registered
Joined
·
427 Posts
Discussion Starter · #17 ·
It's a 1974 JM build, and is near mint all over. Hard to think the chamber would been bad when the rest is so good.

here's a side-by-side lined up to the same tool marks. One that has the 'gouge', the other that didn't.

 

·
Registered
Joined
·
1,706 Posts
I'm lost on the gouge...It may be a sharp protrusion somewhere else that is cutting the brass when cycling into the chamber...

But the 'spirals' are clearly tooling marks in the chamber...
 

·
Registered
Joined
·
5,954 Posts
I still think that yes the chamber is rough but that brass was bad in the first place. If the chamber is out of spec that is the thinkest part of the brass and the last place that should split. The case head should not be expanding and it never did touch the chamber wall because it is still a dull finish. If it were me I would use some factory round fire them and examine the cases.
 

·
Premium Member
Joined
·
2,912 Posts
hey Bryan,

No chrony at that session. All cases extracted easily.

Edit-

here's another image of another case, can you see the spiraling grooves I am describing? Not the 'normal' chamber marks that you can see that go around concentrically, but those that spiral up along the length of the case near the Head end.

Now I am still gathering stuff for reloading so I am no expert but does anyone else see the bulge where the spiraling begins? I mean maybe it is the way the picture was taken,
 
1 - 20 of 41 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top