Questions on marlin 336 micro groove OAL

[Tripplebeards]

I loaded up my first batch of or group by MP 200 grain HP boolots today. I checked my OAL. I seared a boolit in a case abs chambered it about a half dozen times and the shortest measurement was 2.462”. I figured I’d load at 2.420” so my case mouth would line up with the crimp groove. I ended spinning the die in a hair further by accident and ended up seating it a little deeper at 2.415”. I used my lee factory crimp collet die and used a little lighter crimp than I normally do. I cycled a round through it a5 2.415” and it chambered and ejected perfectly. Just like the lees I loaded about .04” shorter than my chamber measurement I but I still noticed microgroove rifling marks on my boolit that chambered and cycled fine. Just want to make sure this isn’t to excessive and I don’t get pressure spikes.

Hers a pic. Is this ok?

https://i.imgur.com/bCzuzKR.jpg


Here’s my OAL checker and where the boolit stopped to measure the max chamber length so you can see I’m a bit further back from where my boolit stopped but I still have microgroove markings.

https://i.imgur.com/EDnRXNO.jpg

[dakotashooter2]

I'll assume that being your first loading of this bullet you are at starting charge correct?.. if so it is unlikely you will have a pressure issue..

Sent from my KYOCERA-E6920 using Tapatalk

[725]

+ 1 w/ dakotashooter2. Starting w/ the lightest book load and working up should tell you all you need to know. I wouldn't be leary of the chambering. Just work up 'till accuracy is there.

[popper]

Light jamming of the lands - better accuracy. I've run max loads, no problem. It is a problem as chambering can be difficult and removing a loaded round isn't always easy. I don't crimp (just remove bell at mouth) and don't use the crimp groove.

[Tripplebeards]

Yes it’s my first loading for this rifle.

No resistance when chambering at this length. I also could not feel any resistance when cycling out this loaded round as well. This round is loaded .047” shorter max chamber length so it should have plenty of clearance. Sound like this is the norm for marlin 336’s and microgroove rifling the more I read on past posts here. This is a soft alloy. I mix of 16:1 pure lead and pewter mix clear PC and GC. It has a tested BH of 7.8 with my lee tester. I also casted up some 50/50 with a BH of 10.4 that barely leaves marks from the microgrooves loaded at the same length. My bore slugged at .357” and my boolits are sized at .3595”.

[unclemikeinct]

Show us the on target results

[Tripplebeards]

Show us the on target results


The whole reason I posted is to find out if this was safe to shoot. Now that I know it is I’ll try to get to the range next week to load test after turkey hunting is over. I know this soft 7.8 Bh alloy(16:1 pure lead and pewter mix) PCd and GCd will hold up at max 44 mag rife Velocities without leading. The best groups came from a slower 1600 FPS load. I’m guessing max was around 1850 FPS. I’ll see how it dose on a ladder test all the way to 2000 FPS to see if it leads and also to see how good or horrible the accuracy is. I also loaded up some 50/50 10.4 Bh alloy boolits to try a well. The microgrooves don’t show up as noticeable on the harder alloy when test chambering. The purple 50/50 boolit I used above to measure my chamber length really didn’t leave any marks on it. My guess is the softer 16:1 will probably will slump at higher velocities and groups will suffer? I have a 1/16” twist. Range time will give me answers.

[Tripplebeards]

Here are the on range results from today from my first try with cast in 35 remington.
My best 100 yard groups came from the 200 grain group buy HP with 40 grains of Varget and 50/50 alloy. Just about as good of a group was with the lee 200 grainer using 36.2 grains of imr3031.

https://i.imgur.com/uv6NGaO.jpg

[Tripplebeards]

I lightened my trigger pull to 2 & 1/4 pounds and re tested My 40 grain varget load at 100 yards. Here’s my first three shot group today...

https://i.imgur.com/uVbAZ73.jpg

I also had just enough H 4895 left to try one loading of three. I rolled the dice and loaded up a max j word book load for it...

https://i.imgur.com/yby2coi.jpg