Cast bullets for Mannlicher M95 in original 8x50R - keyholing!!

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cohenmj660 posted this 05 June 2023

Hi out there. I’m looking for some help with a very specific question and I have a lot of background, so my question is going to be fairly lengthy. In summary, I’m looking for why my bullets seem to be keyholing, and what can I do about it. Now the background: The firearm I’m using is a Steyr-Mannlicher M1895. It is chambered in the original 8x50R and still has the original 30” barrel. The bore looks fairly good, although it does show some minor pitting. Nevertheless, the muzzle end seems ok since a vintage military bullet only goes in part way.

First, what ammo doesn’t keyhole? I have about 40 rounds of vintage military ammo for this rifle. The headstamp shows the Bulgarian lion and indicates that they’re from 1936. The bullet is a steel-jacketed round nose and weighs in at 244 grains. There’s a cannelure near the base of the bullet into which the case mouth is crimped. I don’t know what weight or type of powder is inside. I recently went to the range and shot a 4-5” group (5 shots) at 50 yards. The hits were about 12” above the point of aim, even though I had the rear sight set as low it could go (300 Schritt). No keyholing.

Second, I have other ammo that I purchased from Gad Custom Cartridges. These are reloads made from reformed PPU 8x56R cases and have what appears to be 205 gr spire point bullets. Once again, I don’t know the weight or type of powder used. These seem to print pretty close to the point of aim using the same rear sight setting. Similar group size but no keyholing.

I measured the diameter of both of these bullets (i.e., the vintage military and the reloads) and they both measure 0.323”.

OK, now the problem. I made some reloads of my own. The cases are leftover vintage military (1936) that I decapped (Berdan) and reamed out the primer pockets to fit CCI 250 Magnum large rifle primers (I was not able to find any CCI 200 primers anywhere). The cases were full-length resized and I guessed at a charge of 45 grains of IMR-3031. The bullets are ones that I cast myself from a Lyman 323378 mould, using homemade #2 alloy (hardness measures 15) and 8mm gas checks. The bullets were sized to 0.323” (i.e., to match the other bullets that I described above). When I shot these at the range, I could barely find the holes until I saw a couple that were quite far away from the point of aim and totally keyholed.

OK, now, let’s talk about the diameter of the bullets, because this is a very common cause of keyholing. From what I’m able to read, the bore of these old M95 Mannlichers is 0.329 or 0.330”. I have read that even though the original 244 grain bullets measured 0.323” they were expected to obdurate during the firing process, thereby grabbing the grooves and stabilizing the trajectory. I have no way of knowing how much, if any, obduration either my vintage military or my Gad Custom reloads experienced. All I know is that for those two cartridge types, there was no keyholing. I haven’t yet had a chance to slug my bore.

So, even though a very common cause of keyholing is bullets that are too small for the bore, this didn’t happen with 0.323” bullets in the first two cases, only in my reloads.

So, my next question, is it possible that my own reloads are overcharged and forcing the bullet down the bore too fast for it to obdurate and grab the grooves? Does anyone have any powder data for this cartridge with a 240 grain long round nose bullet?

8x50r m95 steyr

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Eutectic posted this 05 June 2023

Sounds like my first adventure with cast bullets in a 8mm Mauser.

First: you need to slug the bore. The major diameter on your bullets should be at least 0.001" larger than the groove diameter. As-cast bullets might work if their diameter is large enough.
Second: your charge is much too heavy. I would start about 23 grains of 3031 and work up.
Third: 323378 is a long nose bore rider. The nose MUST be supported by the lands. Drop a bullet nose first into the muzzle. If it drops in up to the bands the nose diameter is too small. Lyman 323471 has worked for me, but it might cast too small depending on your barrel.

Cast bullets are different from jacketed. Sounds like a fun project.

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John Alexander posted this 05 June 2023

Guessing at a load of  45 grains of 3031 is the biggest problem. Very bad guess.  Try about half as Eutectic suggests. You may have to so do serious deluding of your bore before trying cast again.

John

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Hornet posted this 05 June 2023

I think your sized diameter is way too small. For reference, Lee makes a C329-205-1R mold and 0.329 push-through sizer specifically intended for these rifles. I have heard of other people using them with sized-down 0.338 designs. I'd tend to agree with a load around 23 grains of 3031 and work up as needed.

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45 2.1 posted this 05 June 2023

 You are getting keyholing because your bullets are undersize. Measure the inside diameter of one of the cases you've fired in the rifle. It probably will take anything up to that size. I've worked with the remake of that rifle into the 8x56 and that rifle should take 0.329" bullets, but accepts 0.338" loaded and fired in it. You need larger bullets and try a milder load with Unique to see if you can get it running.

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cohenmj660 posted this 05 June 2023

Wow - thanks everyone for the quick advice. Lemme see if I can address a few of the comments.

First, re: John Alexander. Yeah, I was being a bit flippant with my post when I said that the charge of 45 gr of IMR-3031 was a guess. In fact, I took that right out of a post that I saw from, I believe, Cartridges of the World, Chapter 7, Military Rifle Cartridges in which a charge of 45 gr of 3031 was recommended for a 244 gr bullet as one that approximates the military load.

Second, re: Eutectic. I think my mistake is assuming that the charge for a cast bullet would be about the same as the one for a jacketed bullet of the same weight and shape. Apparently this isn't true, which is why you suggest starting at 23 gr. And, yes, I still need to slug my bore one day. However, I will say that the Lyman 323378 bullet that I made only goes into the muzzle end of the bore a short distance, so that's a good sign. In addition, remember that I was able to shoot two other bullets, both measuring 0.323", through that bore without keyholing. I think that means that there's something special about undersize cast bullets vs. jacketed ones.

I'll keep everyone posted once I slug the bore.

 

Mike

 

And thanks again for all your help.

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John Alexander posted this 06 June 2023

 Taking recommended charges for jacketed bullets out of any source, no matter how reliable, and using them a cast bullet won't work.

The difference between shooting jacketed bullets and cast is huge.

The fact that the two jacketed bullet cartridges shot reasonable and a cast bullet of similar diameters and Way to much powder is no mystery.

Bullet size is probably a factor as point out, but the perfect size cast bullet of #2 alloy will not work with full charge loads.

John

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cohenmj660 posted this 06 June 2023

Hi John,

Yup, a rookie mistake on my part. I've reloaded many a cartridge in the past, both with cast bullets (9 mm, .45 Long Colt and 357) as well as jacketed 30/40 Krag and .30 Remington, but never without the appropriate references in my Lyman manual. Now that I look at some of the entries (e.g., 8 x 57 mauser), I see that not only are the charges different for cast bullets but they also recommend different powders altogether.

Is there a reason why? I'm curious about the mechanism of the difference between cast and jacketed.

Thanks,

Mike

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delmarskid posted this 06 June 2023

Gas checked cast bullets work best for me at between 1600 and 2000 fps with a bullet that is a couple thousandths groove diameter. When cast bullets are undersized or driven too hard they won’t take on the spin they need to fly straight away. They just fly over the tops of the grooves I believe.

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longhunter posted this 07 June 2023

Ok,

So this has worked for me. I have had a couple of 8mm's that were over sized.  Early 8mm usually do. Go to 

Mid South Shooters supply.  8mm karabiner, It an over size mold of 215 gr. Lee mold #006-8mmKAR

or Mid South #006-8mmKAR. Size will help they run about .330. Hand  lube and gas check shoot as castor size and lube .330 

16 gr of 4227 or 2400 will work.

Jon

 

Jon Welda CW5 USA Ret.

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cohenmj660 posted this 07 June 2023

Thanks for the additional information. I'm going to slug my barrel as soon as i get a chance. This seems to be the critical piece of data that I need.

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cohenmj660 posted this 08 June 2023

Hi all,

I was able to make a decent slug by drilling an 11/32" (0.344") hole in a piece of wood, melting one of my old 58 cal Minie balls, filling the hole up with the Pb and cutting the resulting slug into two so that I could get duplicate measurements. The whole operation went off without a hitch in about an hour. Here are the results:

Slug #1: Grooves 0.329 and 0.330; Lands 0.313 and 0.316.

Slug #2: Grooves 0.330 and 0.331; Lands 0.313 and 0.314

 

In addition, I checked the bore with two drill bits that would ride on the lands, a 5/16" (0.3125") drill bit slid easily into the muzzle, whereas a 21/64" (0.3281") bit did not.

 

In addition, I measured the dimensions of my current bullets (Lyman 323378):

As cast: nose of bullet just in front of the first band 0.319-0.320", bands 0.326-0.327"

As sized: nose of bullet just in front of the first band 0.319-0.320", bands 0.323"

 

I'm thinking now that I might get decent accuracy with my current bullets if I reduced the charge and sized to 0.327". I'll probably start off with 12 - 13 gr of Unique and see what happens. If that doesn't work, I'll have to look for a mould that makes a 0.330" bullet (or slightly larger).

 

Once again, thanks for all your help,

 

Mike

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Duane Mellenbruch posted this 08 June 2023

Odd number of grooves or even number of grooves?

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cohenmj660 posted this 08 June 2023

Even; 4 grooves and 4 lands.

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Eutectic posted this 08 June 2023

Cohenm,

There are two major differences between jacketed and cast:

First the hardness of jackets is many times harder than the hardest lead alloy.

Second the melting point of jacket material is much higher then any lead alloy.

When black powder was king, lead and lead alloy bullets worked fine.
If you load smokeless powders to black powder pressures and velocities this still holds. 

Steve

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John Alexander posted this 08 June 2023

Shooting cast bullets from 0.002 to maybe much more under groove diameter is a pretty iffy proposition and may lead to record amounts of lead stuck in your bore.

If I were going to try it, I would cast the bullet of as soft an alloy as I could find such as 30 or 40 to 1, or pure lead, and use a small charge of very fast burning powder. Maybe 7-8 grains of Bullseye or equivalent.  And hope that the fast pressure rise would upset the bullet to groove diameter before too much hot gas got past the bullet and ruined my day. 

This bullet sounds like a candidate for paper patching or polymer coating to increase the dimeter to groove diameter or a bit more.

On the other hand if you are going to try it with #2 alloy and unique be sure and report your results we mayl all learn something. Conventional wisdom such as I suggested above is often wrong.

John

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cohenmj660 posted this 08 June 2023

Hi Steve - yes, the thing that I was not accounting for (when I observed that I obtained decent groups with 0.323" jacketed bullets but not with cast ones) is the potential for melting of the lead bullets. 

 

Hi John - I think I see where you're going with the suggestion to use a small charge of a rapidly burning powder. Since the 244 gr RN bullet is quite long, a sharp smack from rapidly burning powder may help the base of the bullet obdurate into the grooves better than a gentle push from a slow burning powder. As I don't have any Bullseye, I might try 700-X instead of Unique, since its burn rate is very close to Bullseye. My recollection is that there's a danger of either getting the bullet stuck in the bore or bulging the barrel if too little powder is used. Is that true, and if so, how does one know where to start?

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John Alexander posted this 09 June 2023

Mike,

700X should do.  I don't think 8 grains is likely to get a bullet stuck.  WHAT DO OTHERS ON THIS THREAD THINK?

Getting a bullet stuck in itself will not bulge the barrel.  Shooting another bullet with one stuck in the bore may. So peer thru the bore after the first shot if you don't see it on target. If a bullet is stuck drive it back out with a steel rod after you make sure the rod doesn't have sharp edges at the bullet end and is smooth and grit free.  A rod slightly under bore size is cheap at Home Depot.

I didn't say I was sure this would work -- only that it is what I would try If I had to use an undersized bullet.

I still think your best bet is a mold that will produce bullets the right diameter. The Lee mold suggested by longhunter would get you much closer to your groove diameter and could be easily beagled  to produce bullets slightly over groove diameter -- and it is cheap. 

John

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Ken Campbell Iowa posted this 09 June 2023

besides sticking bullets in your barrel ... another reason to not go too slow .. is

that you need to spin the bullet fast enough to properly stabilize it ...  as it gets too slow the bullet starts to make bigger groups, and then even slower will start to show elongated bullet holes.

**********************

especially with longish bullets ... I am guessing that with your current bullet you need at least 1300 fps to keep it in a safe velocity range.  Unique is good in that range ... guessing 7 or 10 grains to start ...   a side benefit is that at these lower velocities you can do well without gas checks on the bullet.

******************

***************

also, just in case you wake up in the middle of the night and wonder how the heck a bullet bigger than the groove diameter of your barrel could possibly be better ....   gotta be distorted, right ?? ... you are correct ...   

however it is a compromise in trying to get the bullet a straight launch from your chamber ...specifically the throat ....  the better the bullet fits the throat, the fewer screwy and mysterious problems you see on the target ...  most throats are bigger than the groove diameter ... in an effort to chamber easily in hunting or military use ... mostly the better end of the compromise is to have the bullet fit snug in the throat even though it will have to be squeezed down when it gets into the main barrel ...  even 0.003 or so diameter difference ...  >>>>  the squeeze-down ... and distortion ! ... is still better than a groove sized bullet bouncing around and launching sideways from the throat.   .................. it could be that metal jacketed bullet resist or unbend themselves, but non-plastic lead bullets once bent in the throat just remain bent and unbalanced all the way to the target.

and military or worn throats can be a bunch bigger than the groove diameter ... we need more tests to find out just how much diameter difference there could be before the compromise turns around.   

... and yes, a throat diameter near the groove diameter is a great thing for accuracy ... but not available in commercial rifles. ... and needs precise ammunition to avoid jams.

just some thoughts, please keep us informed of your adventures ...

ken

oh, 70 years ago when I started casting, I had a list of 40 things to worry about for cast bullets ... now I have a short list of 3 or 4 things ...  covers 99 per cent of the way to reliable 2 moa groups.  couple of those things I mention above ... I can't remember the other things ...  oh wait ... LUCK !

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cohenmj660 posted this 09 June 2023

Thanks again guys. I hear the feedback loud and clear regarding trying to cast bullets at, or slightly above, groove diameter (0.329-0.330" in my case). In addition, shorter bullets, e.g., in the 170-180 gr range for an 8 mm RN bullet, naturally stabilize easier at lower speeds. I will start looking for a mould that fits those requirements. The challenge I see now is finding a lube/sizer die for that diameter bullet. I have an RCBS Lube-a-Matic, currently set up with a 0.323" die. This sizer takes Lyman dies as well. I've been poking around on the internet and, so far, I can't find a sizer die in the range of 0.329". I realize that I could probably use the bullets as cast if I'm careful with the as cast dimensions, but then, how do I lube them properly? I realize that there are all sorts of methods for lubing in a pan or by powder coating, but from my experience, the best way to lube the bullets and swage the gas check is using a lube/sizing press.

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Duane Mellenbruch posted this 09 June 2023

You will probably find that applying a soft wax lube by hand, rubbing the lube into the grooves a bit messy and seem slow.  But it gives you a chance to inspect the bullets and as you wipe and massage them, tell them that they are well cared for and will fly straight and true.  While it may not work, it will give you something to think about if you get bored.  If your bullet lube requires a heater, hand lube might be a problem.

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