CAST IN MICROGROOVE BBLS

[swany]

I've seen this subject in many threads this one I'm going to make a sticky. Hopefully it will avoid new threads on the same subject in the future. Hopefully all the answers will be here.

YES CAST WORKS WELL IN MICROGROOVE BBLS


Okay we'll start with a 30-30 for an example

First to get a proper fitting cast bullet you should slug your bbl. Instructions for this are in our Reference Library.

Once your groove diameter is known then you are ready to order cast bullets or buy a proper mold to cast your own.

Let's say your groove diameter for you 30-30 is a little larger than the .308 we all buy jacket bullets for.


Say yours is .3095 then your cast should be at least .002 larger or .3115 round it up to .312

Okay now you know what you need for yours. Order your mold and sizer or cast already to load lube and all.

You gents with cast in 30-30 Microgroove Marlins please chime in here and help me finish this thread.

[Husker Leverman]

Thank you Swany.

I was just thinking about this very subject as I have a 30.30 with microgrooved barrel.  I'll check the reference section on slugging, hopefully there is a method that does not require melting lead, as at this time I have no equipment for that process.

One question if have is; Is there any real difference between a Silver Alloy bullet and a Lead Bullet? I would be using gas checked bullets for the most part in all my loads.

Thanks again for bringing this up and making it a sticky.

[swany]

Silver alloy makes them a little harder. Just water quenching a wheel weight makes them harder. Gas checked while more expensive is still way cheaper than jacketed most often. They can be driven to normal velocities easily.

[Hank Stone]

How severe is the problem of barrel leading with microgroove barrels,I know reduced loads help but when it comes to microgroove barrels I have no experience?

[Dr. A]

How severe is the problem of barrel leading with microgroove barrels,I know reduced loads help but when it comes to microgroove barrels I have no experience?

Leading is primarily a problem with inadequate lube or improper sizing.  I've dealt with serveral 30-30's, and if you are not up to slugging (which you really should do), I find that most Marlins will use a .311 bullet just fine.  I like the gas checks for this caliber if you are going to shoot over 1100fps.  Just doesn't seem to perform too well with these undersized bevel based crayon lubed bullets.

[Hank Stone]

Dr.A,Thanks for the comeback,I have time on my hands and will give casting bullets a try.

[Bob A]

Swany,
Thanks for starting up this sticky. I've been working with cast bullets in my microgroove 30-30 for a few months now. I decided to shoot nothing but cast in one 336 and nothing but jacketed in the other.  I slugged my barrel first thing, just about .309. So I started looking for .311 bullets. There aren't a lot of people selling cast over .310 but I have found a few. My latest test is on bullets from Illinois Bullet, sold on the Reloaders Auction site. They have a custom 180 gr bullet that looks a lot like a Lyman 173 GCFN but has a bore riding nose that engraves slightly into the rifling when you chamber the cartridge. This design is not appropriate for Cowboy Action cause it can be a little slow to chamber that last fraction of an inch but it looks to be very accurate. I've been working with SR4759 and Reloader 7. Full power RE 7 is looking real good. First two shots into an inch at 50 yards with iron sights almost every time at about 1750 fps. Third shot is giving me trouble but I figure thats my rifle, not the load. Next I plan to try a slower powder, maybe Varget. I would like to get to 1900 fps.
I think this is going to be a legit hunting load.
I am also working on a plinking load with a 165 BB bullet from Magnus Bullets. Really nice people. They did a custom sizing to .311 for me and sent me free samples to try them out. I am working with pistol powders trying to find a good tin can load with very little recoil. Hopefully about 1100 fps. Blue Dot and Bullseye are doing OK but too many flyers. Next week I'm going to load up some Trail Boss for this bullet.
Anyone having success with Trail Boss?
There a lot to learn about this cast business but I am having fun - and thats the whole idea.

Bob A

[Dr. A]

http://www.gmdr.com/lever/lowveldata.htm

Here is all the low velocity data you could want.

I like H4198 believe it or not for 1900fps loads.  Start at 19gr. with a 170gr. Lyman 311041 and work up from there.  Casting your own with a softer alloy is the way to go for hunting. RCBS 180gr. probably is the best 30-30 bullet for hunting. These store bought super hard bullets pencil right through an animal, and although they are fine for the smaller animals, we owe it to the animal to get some expansion.  The only time I will ignore this is with a bigger caliber bullet (444 or 45-70).  With a softer alloy, the 35 Rem. is about as small as I go.  I have shot several animals with 30-30 and 32 special, and have come to prefer jacketed bullets for them.  There is a reason that we switched from the cast to jacketed.  Increased velocity and increased predictable expansion. Everybody needs to do their own research.  Look into the above data and go over to Cast boolit forum for the complete story.  Its an evolution.  I've got well over 75 molds, and have moved on basically to archery.  Primitive in the way I do it by far, but just as deadly.

http://castboolits.gunloads.com/index.php

Incidentally, the number one way to get rid of any leading is to smooth the bore.  I usually do this with lapping the bore.  Information is available on the Beartooth sight as well as a few others.  Remember to clean the copper out with a good copper solvent, and don't break over to using copper and go back to lead without that good cleaning!

[Yellowhouse]

Super hard bullets that expand little are not necessarily inappropriate for game.  You just need to change your mentality about the "right behind the shoulder" aim point and go for the shoulder areas to break the animal down.  Then a finishiing shot.  There was a helluva lot of African plains and dangerous game kiled with FMJ out of 303 and mauser rifles.  Not because the animals are tougher....you just half to apply your equipment differently to meet the occasion.  In this case, all the Boers, etc. had were FMJ and they found the best way to utilize that style of bullet.

[30wcf]

Swany, thank you for making this a sticky.
 
As we know, the myth about cast bullets don't shoot well from micro-groove barrels, is just that, a myth, which continues on in the minds of arm chair experts.

Just how the myth got started, is anyone's guess, but I am thinking that it goes back to the 1950's when micro-groove came into exsistance. In the beginning, .30-30 micro-groove rifling was somewhat shallower than it is presently with a larger bore diameter. A lot less was known about bullet alloys & fitting the bullet to the barrel back in those days as compared to today.

Thus, back in the late 1950's, good results would not be forthcoming if one used a too soft bullet that did not fit the larger bore diameter barrel properly. Perhaps that is how this whole mistruth started....
 
According to Brophy there have been three different types of .30-30 micro-groove rifling.  We’ll call them a., b., & c. These are Marlin specifications but individual rifles may vary slightly due to tolerances:

  a.) 1955 to 1957 - 16 grooves - .304” bore diameter / .308” groove diameter
  b.) 1958 to 1968 - 22 grooves - .304” bore diameter / .308” groove diameter
  c.) 1969 to present-12 grooves -.302” bore diameter / .308” groove diameter

Back in the late 1980's I purchased a used  Marlin 336A rifle with c.) rifling, and back in 2001, I had been able to test two earlier Marlins with the a.) & b.) rifling.

Fortunately,  I have found that by applying the same principles used for successful cast bullet shooting in conventional rifled barrels ( bullet hardness / design /  bullet diameters correct to fit the barrel ), one can attain equal results in micro-groove barrels  to over 2,400 f.p.s.!! 

Let’s dispel one myth  which I have seen in print many times, and  which goes something like this - ”The shallow micro-groove rifling does not grip the bullet as well as ballard or conventional rifling and can strip.”  A typical .30 caliber conventional barrel has  6 grooves with a bore dia. of .300”  and a groove diameter of .308”. So doing a little calculation, we find that the rifling is .004“ deep x 6 grooves = .024“ of  bearing surface depth (b.s.d.). By  comparison we find that, in fact, all three forms of micro-groove rifling have more b.s.d. … 
    a.) .002” deep x 16 grooves = .032” b.s.d.  or  33% more than ballard rifling
    b.) .002” deep  x 22 grooves = .044” b.s.d.  or  83% more than ballard rifling
    c.) .003” deep  x 12 grooves = .036” b.s.d.  or  50% more than ballard rifling

As we can see, the bearing surface on the bullet is not a problem. A problem does exist in that on a.)& b.) type rifling, if you use a .30 caliber cast bullet designed with the  standard .300“- .301 “ bore ride portion that is longer than ½ the bullet length,  the .304” bore diameter  is too big to provide support to the front of the bullet.  In this situation, when pushed too fast,  the  bullet will yaw in the barrel, destroying accuracy.  The bullet must fit the barrel. 

Bullets that are .001 -.002 over barrel groove diameter on the driving bands will give the best results just as they do in barrels with standard rifling.

In all three types of micro-groove barrels, Lyman’s 311041 g.c. bullet  made from 20 b.h.n. alloy gave fine accuracy  to 2,000 f.p.s. using 36 grs. of H414 powder.  Over that velocity,  the c.) rifling gave better results since the smaller bore diameter provided better support on the bore riding portion of the bullet.   

Lyman’s 150 gr. Loverin style bullet works well in all three types right up to 2,400 f.p.s. since my mold drops bullets that are .002” over bore diameter  for most of its length. Once again, bullet hardness, bullet design and a  bullet that fits the barrel well are the keys.
 
Another myth: “Micro-Groove barrels are more prone to leading.”  That  is also false.
Contributors to leading are rough barrel finishes and incorrect alloy hardness  for the
load being used, not the type of rifling.   I will say though that my 336A had a rough spot a few inches in front of the chamber when I purchased it and it did pick up leading  there.  50 lapping rounds later and that took care of the problem.

They also shoot plain based bullets extremely well, dispelling another myth....

w30wcf

[swany]

This was long overdue for a stickey and I see there is some interest to it. 30wcf nice read appreciate it.

Not to stomp on any toes boardwise, but we do have an excellent cast bullets section and paper patched section. Both for the caster a good place on Marlin Owners to visit.

Do keep the data coming.

[Murphy]

Swany, Today I recieved my sample of pewter and have been busy casting bullets. With a bit of luck I may get a chance to shoot some tomorrow. My mould is a lee 120g 30 caliber but with the pewter they weigh 85grns. Will be doing most of my testing out of a 308, but could not resist loading a few up for my 336 30/30 as well. They seem plenty hard, dropped one on the concrete and it was not even marked. Will be working my way up to about 40g of Reloder 15 in the 30/30 for 2800+ fps so we should really find out what these micro groove barrels are made of! 

[riley]

    I've been loading 173gr wheel weight lead bullets in my Marlin up to about 1800fps with good accuracy and very little leading. The bullet is "water quenched" and "gas checked". I've been contemplating driving lead bullets faster in my "Microgrove" barrel, but haven't been able to obtain information on the subject until now (thank you Swany).
   Lee Precision makes a 185gr. bullet that is .312 diameter for the .303 British, which should work for the 30/30 Marlin. I purchased one recently to use in my Mosin Nygant 7.62X54R.  With the new data provided, I will try it in my '50's, 336 "Texan" as well.
    After reading the "posts" and comparing the results most have had with the 444 with a Microgrove barrel, I would expect that an "oversized" bullet could be driven faster (accurately) in the microgrove than a "non-microgrove" rifle. I believe Ranch Dog has at least proven this "theory" to be true in the larger calibers.
     I would be curious to know if there is an "optimum" bullet weight and design that seems to work best for the Microgrove Marlin's?

[Edward Teach]

Just yesterday I had my 30-30 out and I had some .309 cast bullet loads that at 25 yds made a pattern on the target not unlike a shotgun blast!  Now I know why.
So if one wanted .311s is there anyone that is making them or is it a do-it yourself thing?  Midway's out...they won't ship anything to Canada now.

[Murphy]

Swanny, Tested pewter bullets in my Marlin microgroove today. My main concern was that they would fly to pieces at hi speed, but this did not happen, even though I could drive these 85g 30 caliber marvels at better than 2800fps. Accuracy was only so so at 50yds at about 2.6" for a 3 shot group, but that was only a first attempt and there is plenty of room for refinement. The good thing is that they shoot to the same point of impact as regular bullets and no barrel fouling problems. I really do not want to hijack this very excellent thread so I will continue my rant in the Bigbore and other related topics column. Reguards Murphy.