Marlin 336 30-30 throat...

[kd7kmp]

Howdy,

I have been working more with cast boolits lately for my 336 30-30 in stainless. The thing that is bothering me is that on nearly all the boolits I am using, I have to crimp above (sometimes substantially) the crimp groove or the bolt won't close. I have heard/read that Marlins of the past few years have short throats/leades. Is there a way to increase this dimension so that I can crimp in the crimp groove? What effect might this have on overall accuracy? How much might it cost? Or, am I off my rocker for even considering this? Thanks for all the help.

Kevin

[stubshaft]

Have you checked the overall length of your brass? Could the brass be too long for the chamber?

[Jon K]

Unless you already have a reamer, it is cheaper to shorten the brass to be able to crimp in the groove, and keep the OAL.

Jon

[Lead melter]

Can't help with the chamber issue, but the Lee Factory Crimp die is a must have. You can make a good crimp anywhere along the length of the boolit with one of those jokers.

[marlinman93]

This is usually not a case of chamber length with cast bullets in newer Marlins, it's actually more of a neck diameter/bullet problem. The cast bullets are expanding the necks of your brass enough that they fit too tightly in the chamber, so it restricts the bolt. Take it to any good gunsmith, along with one loaded round and have him check the cartridge dimensions, vs. chamber casting. Probably just ream the neck of the chamber and you'll be ready to go.

[kd7kmp]

Thanks for all the replies.

Stubshaft: I use a Lee case length trimmer, so none of my brass is too long. In fact, most of it doesn't get close to being touched by the case length trimmer.

JonK: without an adjustable trimmer, I can't shorten the brass. Beside that, I don't want to maintain different brass for different applications for the same rifle.

Lead Metler: I have a LFC die. In fact, all my dies are Lee. I have crimped farther up on the boolit, but it just bothers me for some reason.

Marlinman93: Hmmm, I never thought of what you brought up. I will have to measure the neck diameter of a cast and jacketed round. On thing though, I have a modified case that I use to check for maximum length with any bullet/boolit I use. With cast projectiles it is very easy to see where rifling engraves the boolit. It's that engraving that I has me thinking its a throat/leade problem. But, I don't know a lot about it. Just what I have read from other posts with a similar issue.

If anybody can provide further explanation or advice, I would love to listen. Thanks.

Kevin

[Chuck 100 yd]

Kevin , I have had the same problem with several leverguns and not all of them are Marlins.
If you crimp into the crimp groove and load a round, are there rifling marks on the bullet if you eject without firing?
I have this problem with a new (1967) Winchester 94 .30-30 using the Lyman 311041 and the Ranch Dog .30 cal. bullet. The RCBS 150gr. chambers with ease. Marlins and some Winchesters have little or no lead. the chamber ends and the rifling begins. A bullet cast of softer alloy was the answer for my Marlin 336 in .35 Rem. It engraves the bullet into the rifling when a round is chambered but the effort to chamber is not going to put undue stress/wear on my rifle. Try another bullet or a softer alloy.

[kd7kmp]

Chuck,

That is exactly what is happening. I guess I didn't say that with my first post. The rifling is engraving the boolit. Isn't chambering a round so the rifling engages the boolit bad as start pressure can be very high? I have always thought the small jump from chamber to rifling was important to control start pressure.

Kevin

[Slow Elk 45/70]

Kevin, some rise in pressure may result, it should not be significant. I like to load my cast boolits to touch the lands when ever I can, depending on the boolit/chamber /action ETC.

The pressures that most cast boolit loads produce are not usually at the Red Line on pressure like a lot of people use with J projectiles. The "Start Pressure" should not be a problem.

IMHO, I would load a few and try them with the load I wanted to use, if you are concerned, back the load off 10% and work up, watching for excessive pressure signs.

Or you can do as suggested, change boolit molds, or ream the throat to fit the boolit you like. [smilie=1:

[Chuck 100 yd]

What Slow Elk said. I could not have said it better.

[MtGun44]

Need a smaller front section on the boolit. Might be able to change alloy or casting
temp to improve this. Biggest issue is will you leave a boolit stuck in the rifling if you
eject the round unfired. If not, work up with this situation and make sure you don't get
over pressure and you will probably have good accy, assuming the lever closing forces
are not unreasonable.

Bill

[Slowpoke]

You really should know the diameter's of your barrel (Bore and groove) as well as your bullets nose and body. That's part of the fun -- knowing not guessing.

You shouldn't take anything for granted with cast bullets.

If you use a lube sizer you can have a nose first die made that will size your bullets to whatever internal dimensions you need like 309 body x 300 nose, or.310 x .301, .308 x .302 etc.

Buckshot made mine they are sure handy.

A couple of those dies can sure cut down a guys mould inventory if he so chooses.

Some engraving is desirable but it's real easy to get to much of a good thing.

good luck

[dubber123]

If the throat is indeed too short, a throating remer will fix it in about a minute. I did 3 45-70's a few weeks back, and it was very easy. If you only lack a little bit, you may try firelapping. My Marlin Cowboy wouldn't chamber my hunting boolit without a bit of engraving. 50 rounds of firelapping boolits later, and it chambers them just fine.

[kd7kmp]

Thanks to all of you for the great tips and advice.

dubber123: I ordered a lapping kit from Beartooth Bullets. I will report back on it when I get it run through my 336.

Kevin

[jimkim]

This was discussed last year on the CBA forum.

linoww wrote: "I am loading for a Marlin 336 CS 30-30 with Microgroove barrel.Its been about 10 years since I played with one like it.It seems like my last one preferred rather big(.312) bullets.I cannot chamber anything over .310 in this chamber.I haven't shot it yet,but was surprised by the "tight" neck in the rifle.Are others similar to mine?

George
"

Many are. You will need to cast the chamber, but .330-.332 is normal for a .30-30. That limits you to .310 bullets unless you turn necks VERY thin, less than 0.010 which makes them too fragile to be practical. Use a .32 H&R Mag. reamer and run it in just enough to enlarge the neck to .337-.339 and rethroat the existing forcing SAAMI cone. That enables .313 bullets and 0.012 case neck wall thickness. Ed Harris

http://www.castbulletassoc.org/forum/view_topic.php?id=2460&forum_id=18

[Griff]

Howdy,
I have been working more with cast boolits lately for my 336 30-30 in stainless. The thing that is bothering me is that on nearly all the boolits I am using, I have to crimp above (sometimes substantially) the crimp groove or the bolt won't close. I have heard/read that Marlins of the past few years have short throats/leades. Is there a way to increase this dimension so that I can crimp in the crimp groove? What effect might this have on overall accuracy? How much might it cost? Or, am I off my rocker for even considering this? Thanks for all the help.
KevinSometimes, we run onto a boolit mold or supplier that's a little too generous with their calipers... resulting in boolits that won't chamber in a particular rifle or a 100. If your rifle chambers factory ammo as well as your jacketed reloads... I suspect you have have either a cast boolit supplier or a mold that doesn't have the correct dimensions, nose shape or a combination of those.

As others have said, you CAN modify your rifle to fit that boolit... however, you will then have a gun that may not like a lot of other boolits. That'd be fine if you're dead set on shooting THAT boolit, possibly to the exclusion of a host of others... or at least are willing to accept that you might be removing any potential for accuracy with other boolits.

Without doing a chamber cast, including the leade and even partially into the rifling, you (and we) are just guessing as to the problem. If you're casting your own, you can change the alloy you're using and change the finished product's dimensions, thereby it's chamberability.

T'were it me... I wouldn't dream of altering the gun until after you have the chamber cast and compare it to SAAMI specs and a variety of boolits appropriate to the .30-30. I ain't altering the chamber of a x$ gun that provides a known level of acceptable accuracy with a variety of jacketed bullets just to accomodate ONE cast bullet when I could have a mold custom made for about what the chamber reaming might cost ya.

YMMV. But, that's the view from my saddle.

[matm0702]

I would not do anything to the gun. I would do a chamber cast and compare to your loaded ammo. Deeper seating may help as long as the bullet base stays in the neck.

Mike

[btroj]

I've run into the same problem with my 336. I have to trim the cases a bit shorter than the normal "trim to length" and this gets the bullet off the lands. I also have the tight neck problem. I've been turning necks to eliminate that problem and allow me to use .311 bullets.
I have the Lee factory crimp die but it only made things worse as with anything but a minimal crimp it bulged the neck just enough to make chambering a big problem. Only takes .001 in bulge to make it a no go situation for my rifle. Getting a Redding taper crimp die stopped this problem.
This darn rifle has fought me all along since I got it last fall. I've finally gotten it to shoot well without having to pull extremely hard to get the action open as these problems make it harder to extract the empty also. Nothing like having people at the range be certain you are shooting way too hot a load because of how hard it is to open the action but these rounds are just as hard to extract if you don't even fire them.
Keep messing with things and measure the diameter of a loaded round or two. I also took a fired cases and a .312 bullet would not fit into the unsized neck. This is a sign to me of how tight the neck on my rifle is. Just don't give up- once I got mine figured out it shoots very well with a 165 Ranch Dog sized 0.311 over 17 grains of 2400.
Brad