Marlin 336 chamber 30-30

[kfd518]

I have a marlin 336 sn indicates 2002 manufacture. The measurements of slug are shown in pictures attached.
Lands 0.3025
145198
grooves 0.307
145199

Bullets cast from rd 311-165 drop at 0.3125
when chambered it takes a fair amount of force to close lever, but bullets are not pulled from case on extracting dummy rounds.


last pictures show rounds as extracted.
145200
145201

In the general opinion should I size back to .310? Or will I be fine to run these as cast?

I have thought about shortening Cartridge length by trimming cases, what length have any of you that have shortened cases trimmed to? what overall length have you decided to use?

I guess my general impression is that the marlin bbls are oversized all the way around (land and groove), possibly just a brand new tool when rifling this one?

[Outpost75]

I would try sizing bullets to .311 or .310. It looks like rounds enter forcefully.

A bit of engraving that doesn't cause hard bolt closure is OK.

[Scharfschuetze]

By the amount of lead displaced in the engraved boolits, I don't think further sizing is going to help as the beginning of the boolit's ogive is what is touching the rifling at the throat/lead. Shortening your case about .01" would help, but then you probably would not be able to properly crimp your rounds for magazine use.

I think that your slugging measurements are about right for Marlins with Micro-Groove rifling. That style reportedly shoots well with slightly oversize boolits anyway so I'm guessing that your boolit's body diameter is probably OK where you're at although I think Outpost's advice for a .310 or .311 diameter is good advice depending on the diameter of your rifle's chamber's neck. The extra pressure to close your action is probably the force required to engrave the boolit's nose and not the boolit's diameter as loaded, although it could be the sum of both. You can confirm that by just seating the boolit down deeper and see what force is required when you're not forcing the boolit into the lead/throat. Personally, i like to engrave a cast boolit a bit, but your examples look a bit excessive and thus my guess as to the reason for your hard chambering.

Options? Have the rifle's throat moved forward .01" or so, but that might be a bit pricey depending on the gunsmith. Perhaps a mould with a smaller nose diameter would be the cheapest option. You might also try reducing the amount of tin in your alloy as the boolit will shrink a bit more on solidification in the mould. Given your photos though, I don't think that would be enough to matter.

Let us know what the diameter of one of your boolits is at the point just forward of the driving band above the crimp groove where the lead is displaced and we can compare that with examples from similar rifles and moulds. My SWAG is that it'll be in the vicinity of .3035" or so. My 311041 mould for my 30/30s throws a boolit with a diamater at that point of .3000" give or take a 10,000th or two. That most likely would not engrave to any extent in your rifle and would probably solve your problem.

Good looking the boolits by the way.

[kfd518]

Diameter just in front of front driving band = 0.03050 front driving band = 0.03125 base= 0.03110.
using Lyman m die for neck expansion

[Larry Gibson]

Your rifles chamber has a typical throat common in 30-30s. The problem is exasperated by the large diameter nose of your cast bullet. As Scharfschuetze says further sizing of the bullet will not solve the problem. Best solution is tho have the leade slightly lengthened (throated) longer). Or y can get another mould with a nose more friendly to the 30-30 such as a 311041. Or you can trim the cases back for a shorter oal. As mentioned also, you may not be able to then crimp with the dies as they are. You might try that with just one or two cases and see as that would be the simplest solution.

Larry Gibson

[Scharfschuetze]

.305" does seem awfully large and no wonder so much lead is getting displaced.

My guess or suggestion? I'd try the classic Lyman 311041 or a similar mould. As you can see in my post, mine throws a boolit at .3000 just above the driving band v. your .3050.

Most of my 30 calibre moulds (311332, 311334, 311299) all throw boolits between .2995 and .3010 diameters so your mould is definitely throwing a larger than normal boolit at that dimension.

Update: Hey Larry. You must have been posting while I was typing. Good idea to try a few shortened rounds.

Try crimping over the driving band. Might just be the solution, although with stiff loads, you might have the rounds in the magazine setting back their boolits from recoil if shooting full power loads and also how much neck tension you have on the boolits. If loading single shot, that would be the easy solution and you really wouldn't need to crimp in that situation.

[kfd518]

Already can't crimp with 2007 manufactured lee dies unless doing a LIGHT factory crimp with said die set. Spoke with them yesterday, seating die does not go over the front driving band… send to them with some bullets to re lap to oversize, if going to shorter case length could I simply lap the bottom surface of die enough to make up for the shortened cases after getting crimp ring lapped by them? How much shorter can I safely trim cases, if 0.01 does not get it where it needs to be?

[Mk42gunner]

The first thing I would do is to make up a dummy round (no powder or primer) with the bullet seated so the front driving band is inside the case mouth. Try to chamber it, this will tell you if your present sizing diameter will work for your chamber, or not.

You can then make a more informed decision as to weather to modify things or to try a different mold.

Robert

[kfd518]

The first thing I would do is to make up a dummy round (no powder or primer) with the bullet seated so the front driving band is inside the case mouth. Try to chamber it, this will tell you if your present sizing diameter will work for your chamber, or not.

You can then make a more informed decision as to weather to modify things or to try a different mold.

Robert
Alright, done as cast seated to top of driving band was about like when the ogive was touching rifling.
sized to 0.311 seated even with top of front driving band chambered
nice and easy straight in chamber just dropping it in the chamber no pressure to close lever.
Dummy sized to 0.311, seated to crimp groove with brass @2.030" you guessed it!
chambered as before same amount of cart. Head sticking out of chamber as ammount of rifling engraving.

[whisler]

What alloy are you using? If the alloy is hard, adding pure lead would reduce your boolit/nose diameter but I'm not experienced enough to know by how much.

[kfd518]

Straight ww, kind of in a quandary I know now that I need to size to 0.311 which fixes part of hard lever but now there is the serious engraving. Mold was fathers day gift from wife… I know some people trim quite short. Sami spec says trim length of 2.039 -0.020 (2.019). That puts COL at around 2.44 I imagin I can figure a way to shim the backstop of the carrier to help with this issue if it prevents feeding reliably. With the wide me plat it has to be a rapid upstroke on the lever to pop it up anyways. Which can be fixed with simple shimming as well same as with the marlin 94 jam.

Is it possible that the hollow point might be making the fat diameter bullet? Too late to fire up and cast anything FP tonite
this gun isn't going anywhere any time soon for anyone else to have to be aware of anything.

[popper]

I seated the RD where it worked, then FCD as normal. Crimp was in front of the groove, no problem.

[runfiverun]

look at where your engraving is.

the drive band diameter is not your problem.
the nose diameter is where you have the issue.

either move the nose back, or make it smaller.

[sparky45]

I would simply have a gunsmith ream the throat a tad, problem solved.

[kfd518]

look at where your engraving is.

the drive band diameter is not your problem.
the nose diameter is where you have the issue.

either move the nose back, or make it smaller.
finding of post #9 did address some problems with difficulty but most is seating depth.

[kfd518]

I seated the RD where it worked, then FCD as normal. Crimp was in front of the groove, no problem.
What was you C.O.L.
did you have any bullet hanging in case below the neck? Any ill effects from this.

[kfd518]

Alright after some reading and researching, I have decided to have it reamed a tad deeper. After talking with smith he feels the drive band diameter will work sized to 0.311, and saami case length. Reamer should be here next week sometime, with another 2-3 week lead time for the work. Thanks for the help and advice gentlemen!

[popper]

Sorry, just got back in town. Yes, base was below the shoulder, just the GC part, no problem. I sized 311, set OAL to fit without engraving, IIRC, my 336 is ~ 2006 vintage. Same accuracy as far as I could tell. I sold the 3x by 3x (RD/Lee) mould as I couldn't get the PB ones to shoot well. Still have a bucket of them cast & coated. If I get another mould for the 30/30 I'd get a 041 (or RD clone) slick sided with the nose ~ 0.003 smaller for coating. The 31-165C is 170gr with GC and works well for me but doesn't have the huge meplat. I don't trim my 30/30 brass, never had a problem with setback in the tube when FCD over a full load of LEverE powder. I did find my barrel was slightly tight at both ends, seems common. This wasn't bad @ ~ 40yds, freehand resting elbow on a cooler. Yes, full load, loaded in the tube.
145501

[kfd518]

Thanks for the info, these will be PB loads in mine. Apparently I grabbed the updated version he designed for the win 94's.... Doesn't have the straight nose like the first gen did. Owell, will do what I can go get it to work.

[Firearm Nut]

Is the Marlin 336 an older model with the Ballard rifling or a newer one with the micro-grooving. I have both and size the bullets for the older one to .308, the chamber throat being extremely tight. If you have a newer one with the micro-grooving the chambers has much more lee-way. The recommendation is to size to .310, however I'm still playing with mine to get better consistency, it may just be a matter of finding the right powder combination.