Picture of chamber slug

[mroliver77]

This is a chamber neck/throat slug from my Marlin 336 30-30. I was playing with camers and was amazed how well this came out. I thought some of yous might like to see what we are talking about when we lok at the throat. The Marlin has no lead or throat as such. Just basicly a "funnel". Interesting how much longer the chamber is than the brass. I did not realise the factory crimp marks were there until I looked at pic. This was taken with the Macro setting.
J
http://i38.photobucket.com/albums/e145/oliver77/Resized_Marlin30-30chamberslug3.jpg

[mooman76]

Nice picture. Very informative. Always wondered what the throat area looked like!

[LeadThrower]

mroliver,
An 1894C followed me home yesterday, and I was pondering doing just what you've done here. If I can pull off anything so loverly, I'll post pics as well. Did you use the "pound a Pb slug down onto a Pb-filled case" method, or is that cerrosafe poured in through some tubing (looks like lead in the pic)?

I've got the cerro, so am leaning in that direction. Your thoughts, or anyone else's, for that matter?
Thanks,

[mroliver77]

Actually there is a piece of steel rod in the case. I rolled a .30 boolit tween two pieces of plate to size it to .300 and just pushed it down to case. I then upset it with a 2 lb sledge with a few smart taps. You want to be careful as you can lock up the gun by upsetting the slug too much. It took three tries to get it "just right". Bolt guns have a strong camming action to open them and are therefor more forgiving of over doing it. The lead does not grow or shrink as the cerrosafe does. Once you have the slug it stays the same size. For throat/lead I see no reason to use cerro.
J

[LeadThrower]

Thanks for the news. I'll cast some pure lead slugs and give 'em a whack and post a photo. Probably not until this weekend, but I'll make a go of it asap.

[VTDW]

I hope you do not mind. I put that pic in my PhotoBucket account and posted it as a sticky on Marlin Owners in our Reloading Forum. Good stuff and thanks for sharing the pic and information.

Dave

[35remington]

Reinforces what I've been saying for years and looks like my own chamber castings.

That the guns shoot lead at all is remarkable when they're cursed with throats like this.

[DrJay1st]

Ok, educate me. If one seats the boolit out and into the riflings, what difference does the throat in question make?

Jerry

[LeadThrower]

Well, I couldn't get a slug as pretty as yours, mroliver, so I won't post a pic. I did see the "funnel", and it doesn't look significantly different. After the slug didn't turn out pretty I used a fired case (for slip-fit of boolit) and a clean boolit (sized to 358 -- Lee's 358-158RF) to get some dimensions. Best I can measure, my "throat" is 0.075" (room enough for a front driving band, though perhaps not as big as a Keith-style swc). I can get away with a COL as long as 1.614" with finicky action, or 1.608 reliably. At 0.170" from a 1.284" case mouth, the max boolit diameter is 0.350", so now one can get an idea of the "funnel". The slug showed the groove dia is 356, bore 348, so 004 groove depth. All measurements were made carefully with calipers, I don't yet have a mic.

[45 2.1]

Very good work........... Should make a nice throat for paper patched slugs.

To elaborate on the PP slug, ideally, you would want a slug whose body had a length from the base of neck to the leade shown in the picture. A plain base, loverin style body would be ideal here with a shorter nose at land diameter. The body diameter should be about 0.0085" smaller than the throat diameter if patched with 9 lb. onionskin. Cast of pure lead, this would be a very effective slug up to about 2200 fps, at which point it should be hardened by addition of tin to the alloy. Patch over the front band and seat so the front band will mark the throat up to the lands if possible. The loaded cartridge should be removable with no damage to the patch noted except for dirty land or throat marks showing on the patch. Lube the patched boolit also. It is nice if you can place a moderate crimp into one of the groove locations. Take care not to tear the patch in any way.

[Morgan Astorbilt]

I find that photo very interesting, in that there is almost no freebore. Wouldn't a round loaded with a long round nose hudson-style bullet run into the rifling before the cartridge is chambered? I can't even see a jacketed factory 200gr. RN chambering in it.

Morgan

[Morgan Astorbilt]

Sorry, Must have been havng a "brain fart", when I mentioned a 200gr. slug, I was thinking of .35Rem. cal.
Morgan

[Morgan Astorbilt]

In stark contrast to mroliver's Marlin chamber, below are the type of reamers I used, back when I was building Schuetzen rifles.( These are lead bullet target rifles, for those of you living in Rio Linda):mrgreen:

The top reamer is a SAAMI spec. .32-40 finish reamer, and the one below it is a 1-1/2º throating reamer, which was run in after the chamber was cut. This long throat is necessary to get the most accuracy out of lead bullets, especially if breech seating. In Schuetzen, almost all bullets are tapered, custom moulds are made according to a chamber casting, with the forward portion riding on the lands, and the rear portion bore diameter or .001 over.

Morgan

http://i201.photobucket.com/albums/aa159/pgfaini/reamer1.jpg

[mroliver77]

Sorry, Must have been havng a "brain fart", when I mentioned a 200gr. slug, I was thinking of .35Rem. cal.
Morgan
Morgan,
If you look at factory 30-30 there is very little bullet at .308 in front of the case mouth. Oh and , nice reamers!
J

[Morgan Astorbilt]

J,
You're right regarding the 170gr. factory bullet. My main concern was with the type of cast bullets we use when looking for accuracy.

I posted photos of the reamers, hoping someone would notice that the throat on the .32-40 SAAMI reamer, was just about as abrupt as the Marlin's .30-30. I was going to suggest that the long throating reamer, could be used to improve the throat of any factory chamber, for use with lead bullets. These reamers aren't "caliber specific" except in the pure meaning of "caliber" ie: the diameter of the bore, and if they're ordered with replaceable pilot bushings, as I do, bushings could be turned to closely match any bore dia., allowing the reamer to be used for any bore within a thou. or two of the given size.
A bushing to align the rear of the reamer with the bore, can be fashioned by drilling a hole in an empty cartridge case, held in a lathe as I described on pgs.403-404 of Brownells' "Gunsmith Kinks 4". The accuracy improvement should be significant, depending upon the condition of the barrel.
Morgan

[mroliver77]

That is my plan Morgan, I only shoot cast in most of my guns and use very few bore rider designs. This Marlin will shoot cast but is very finicky. I bet with a cast friendly throat/lead it would shoot cast easier. Most will tell you the MG needs a hard bullet. I think it is because most MG have this "funnel" instead of a gentle lead.
I was pointed to a "Uni-Reamer" set up as you described with floating pilot and a tapered center for the rear of the reamer. $99 for the "kit".
J

[PatMarlin]

Ok, educate me. If one seats the boolit out and into the riflings, what difference does the throat in question make?

Jerry

Very good question.

Now I see why the original Fat-30 shoots so well out of my 336.

[Morgan Astorbilt]

Ok, educate me. If one seats the boolit out and into the riflings, what difference does the throat in question make?

Jerry

What do you mean by "Out and into the riflings'? Just seated out so that the bullet doesn't jump(as is done with jacketed bullets when looking for optimum accuracy), or actually breech seating?

Accuracy improves as the area of support increases when the bullet starts down the barrel.
Optimum accuracy with lead bullets, is achieved when the bullet is completely supported for the length of its trip down the barrel. A long tapered throat achieves this by aligning the bullet in the bore without undue deformation as it jumps forward. A tapered bullet (multi-diameter), one which has the forward portion (bore diameter) riding on the lands, and the rear (groove diameter) sealing the bore without undue upsetting(deformation)

These tapered bullets are almost universally used, unsized, in Schuetzen shooting, and require either pan lubing, or a Pope-style lubricator.

Morgan

[PatMarlin]

Is that a fired formed case? Which it probably is, but even since the Marlin doesn't have a long tapered "Lead" the boolit and brass is supported by the chamber correct?

So how can it deform unduly more than a tapered lead? It may deform differently due to the short funnel shape then on it's way, but why would this be worse than deforming to a longer tapered shape? If it's supported by the chamber, the same result would happen wouldn't it?

Obviously many folks feel this may not be considered optimum, but we do get some pretty decent accuracy from a marlin micro groove. My 30'30 is very accurate specially for a lever gun.

There maybe a blessing in disguise also with that throat. Does the lead erode over the years of shooting, or does the chamber erode in diameter also? If it was just the lead, then you may get your taper and since we shoot cast we can compensate and adjust for it.

Lord I'm trying to think this through, and put my thoughts down on only a half cup of coffee.. :roll:

[PatMarlin]

Reading back through, I see if the chamber diameter right near the throat lead is larger than the boolit diameter, then I guess there would be no support there for that space between the brass and the lead.

I know most of you guys know this stuff, but I'm trying get a grasp on exactly what goes on there. A quest for knowledge kind of thang.. :mrgreen:

[montana_charlie]

Is that a fired formed case? Which it probably is, but even since the Marlin doesn't have a long tapered "Lead" the boolit and brass is supported by the chamber correct?
Nope.
The bullet lying in the chamber will have a space of about ten thousandths between the lead and the steel. At firing, the bullet will 'bump' (like the test slug did) to fill the empty space...causing a sudden, small, modification of the bullet design. Then that 'fatter' bullet is mashed down while passing through the 'funnel' (getting modified again) and further reshaped to conform to the rifled bore.

With all of that going on at the moment of firing, it seems like being careful to cast a 'perfect' bullet (for that chamber) is pretty much a waste of effort.

CM

[45 2.1]

The bullet lying in the chamber will have a space of about ten thousandths between the lead and the steel. Not everyone has that much space. At firing, the bullet will 'bump' (like the test slug did) to fill the empty space...causing a sudden, small, modification of the bullet design. Not necessarily, with that much space, as you say, the boolit will probably missalign, if hard enough and go into the bore crooked and shoot a normal 2 MOA group that is reported regularly. Then that 'fatter' bullet is mashed down while passing through the 'funnel' (getting modified again) and further reshaped to conform to the rifled bore.

With all of that going on at the moment of firing, it seems like being careful to cast a 'perfect' bullet (for that chamber) is pretty much a waste of effort. With proper methodology, it isn't.

[Morgan Astorbilt]

I GIVE UP!!! I won't even go into the contribution the proper bullet lube makes to accuracy.
Morgan

[PatMarlin]

I GIVE UP!!! I won't even go into the contribution the proper bullet lube makes to accuracy.
Morgan

:confused: ....what no time for us commoners? . . ...:roll:

[Nrut]

That is my plan Morgan, I only shoot cast in most of my guns and use very few bore rider designs. This Marlin will shoot cast but is very finicky. I bet with a cast friendly throat/lead it would shoot cast easier. Most will tell you the MG needs a hard bullet. I think it is because most MG have this "funnel" instead of a gentle lead.
I was pointed to a "Uni-Reamer" set up as you described with floating pilot and a tapered center for the rear of the reamer. $99 for the "kit".
J
mroliver...would you please give a link or info as to where one might buy one of these "Uni-Reamers"....Can they be hand turned?
In making your throat slug what size rod did you use down the bore to upset the slug?
Thanks,
Mike

[Morgan Astorbilt]

:confused: ....what no time for us commoners? . . ...:roll:
No, Pat, I'm just not as articulate as I'd like to be. It's frustrating sometimes, when people don't see, what to me, is obvious.
It's my shortcoming, not yours.:-?
Morgan

[mroliver77]

mroliver...would you please give a link or info as to where one might buy one of these "Uni-Reamers"....Can they be hand turned?
In making your throat slug what size rod did you use down the bore to upset the slug?
Thanks,
Mike
Sorry Mike,
Uni Throater it is.
http://www.pacifictoolandgauge.com/throating_reamers.asp
I think it was 1/4 rod I used. I heated and bumped the end up to vey close to barrel bore diameter and files smooth. Use some tape to keep steel off of bore.
J

[Nrut]

Sorry Mike,
Uni Throater it is.
http://www.pacifictoolandgauge.com/throating_reamers.asp
I think it was 1/4 rod I used. I heated and bumped the end up to vey close to barrel bore diameter and files smooth. Use some tape to keep steel off of bore.
J
Thanks mroliver77...just found some 1/4" rod I had used in the distant past....got to thinking another trick if you are using undersized rod in relation to bore you could cut a small length of bolt that is closer to bore size (taped up of course) and use the 1/4" rod taped like an extension....I have found if the rod is to undersized it embeds itself into the slug and makes things difficult...

[calkar]

I just puchased a marlin 30a 30-30 for cowboy sillywet and had problems right away. lee's 150 would not chamber and was heavily engraved. Lymans 311291 chambers great do to the .300 nose, but I cant get it to shoot. I have tried basic accurate loads like 10g of unique, 14 to 16g of 2400. my alloy is lyman #2. I have even tryed Ranch dogs version of 311041 which engraves heavily but closes. what was marlin thinking, some factory rounds will not even close. the micro groove rifleing looks spankin new. I realize it has a throat like mroliver"s. Is there a way around this problem or does is just need more money thrown at it?

[STP22]

mroliver77,

45 2.1 nailed it...

Your pic speaks volumes about trim length and our carefully assembled CB loads.