What I think is happening with my 8mm Mauser?

[xsquidgator]

I *think* I know what's going on, but would like to ask for advice and hopefully confirm that I'm on the right track here...

I was given what I think is a Russian capture K98 a few years ago (from Mitchell's Mausers, I know I know) and I slugged the bore at 0.325-0.326" - that's the max diameter of the slug in one or two places after it comes out. That's with a 1" micrometer, not calipers, so I'm pretty confident in that number.

I have tried handloading some cast boolits (water quenched, wheelweight type alloy, IIRC I can get it up to about a BHN 13 or so) using the Lee 170 grain mould (C324-175-1R) that I ran through Lee's .323" sizing die. Sized boolits come out about 0.323" to 0.324". Accuracy has been very poor, even at 25 yards they don't group they pattern.

My mould has been dropping the boolits at about 0.325 to 0.326" max diameter. If you were me, would you feel comfortable trying some unsized of these boolits? Of course I'd check the dia of all boolits before loading, just to make sure nothing over 0.326" gets through. I think it ought to be ok, and I was able to slug the barrel again with one of these unsized boolits, although it took some tapping to get it through. However, loading up some rounds with unsized bullets is a new one to me and I'm just a little nervous about doing this, even though I think it should be ok.

What do you think? Is it safe to load up 0.326" cast boolits in this rifle?


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A little extra info, maybe or maybe not relevant to the discussion above...
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I also tried some Hornady 0.323" 150gr jacketed soft points in this rifle, with disappointing results. I hand-trickled all the powder charges between 40.0 and 46.0 grains of BL-C(2), all the same to within 0.1 grains, and still the standard deviations on my bullet speeds were way high, like 100 fps out of five rounds fired. The bullet speeds were disappointingly low, too. For instance, with 46.0 grains of BL-C(2) under the 150JSP, they should be running about 2600 fps. Instead, I measured 2330 fps +/- 100 fps. Accuracy isn't ,but I haven't tried shooting a group with these.

Would you take this as a clear sign of undersized bullets? I mic'd the Hornady bullets and they are all right at 0.323", and all are within 0.3 grains in weight of each other. In retrospect it seems like an obvious undersized bullet issue.

[bobk]

Looks like an opportunity to try the .329 that LEE makes, if they cast close to that. Probably want to check for loaded neck dia., versus the size of the chamber neck. The other option may be to bump up the boolits you have, assuming the nose doesn't get too big to chamber.
Bob K

[jack19512]

I was given what I think is a Russian capture K98 a few years ago (from Mitchell's Mausers, I know I know) and I slugged the bore at 0.325-0.326






I haven't been casting that long myself but wouldn't you want the cast bullet at least .001 over bore diameter?

[xsquidgator]

I haven't been casting that long myself but wouldn't you want the cast bullet at least .001 over bore diameter?

I've heard that, but don't remember where. I'm just a little nervous about putting a tighter-fitting bullet into the bore, although I think it would be the thing to do here. When I mean nervous, I'm imagining pulling the trigger the first time on these and kaboom!

[mooman76]

The bullet is suppose to be tight. Not way oversized but tight. The gas pressure is going down the sides of you undesized bullets and erroding the lead bullet before it leaves the barrel and thus not stablizing becuase it it not griping the groves of the barrel. Try shooting unsized and if it doesn't improve enough go to a bigger bullet.
I have a Spanish mauser like that that can't group on a pie plate at 25y. Unfortunately I can't go to a bigger bullet because they don't make a mould that size.

[Freightman]

I have a KAR 230g LEE mould that works fine for the aplication you are talking about, it cast 328 +- .001 mostley + the problem I have is the nose is far to big. So I size it to .308 the nose, and eather size the base at .326 or just put a GC on and use it as cast. If you size them and they are too small for your bore wrap them with teflon tape serves as paper patching and lube also will make them as big as you need with more rounds of tape. The 175 LEE mould works great with the tape and you will be amazed at the cleanness of your bore.

[35remington]

You need to worry more about neck clearance and room to release the slug. Load some and check chambering to make sure they do not fit too tightly. My guess is they probably won't be. If that is the case, bang away.

How are you going to seat the gaschecks? There needs to be some kind of plan for that.

[xsquidgator]

I haven't been using gaschecks. I have been loading up some of the rounds with cream of wheat filler and using those, or at least, shooting those last to clean out any leading. Accuracy with cream of wheat rounds has been poor (unclear if c.o.w. makes it worse) but the c.o.w. definitely cleans out leading like a charm.

[runfiverun]

the unsized ones may be too small still.
measure the inside of a fired neck to see how much room you have to work with.
you also want to watch the re-sizing if your necks measure 321 after sizing it is gonna be pretty hard to get a 325 boolit in them.
and if you do you may size them down some.
just a few things for you to think on.

[GrizzLeeBear]

Might help everyone if you let us know what your load is. Its hard to help figure out what the problem is with only half the information.

Try putting an unsized boolit in a fired unsized case by hand. If it will slip in, even with a little effort, your chamber is big enough to allow the unsized boolits. If you do some research, MANY cast shooters prefer to shoot unsized boolits whenever they can. Sizing boolits is most of the time neccessary only to get the boolit to chamber and fit the bore. If your unsized boolits fit the bore as they drop from the mold count your blessings and shoot them that way. As long as they will chamber, the occasional fat one ( .001 or .002 bigger) will be no problem.

Whats the bore look like? How is the crown? How is the bedding in the rifle? Is the handguard contacting the barrel? Etc.
Since you are also having trouble with jacketed bullets, there may be issues with the rifle, not the bullets. Even .323 jacketed bullets in a .326 bore should shoot fairly well IF the rifle is in otherwise good condition. Jacketed bullets are much more forgiving of bore diameter. The .326 bore measurement makes me suspect that the barrel may be pretty worn. Not that worn barrels can't shoot well, but it may indicate that there are other issues with the barrel. Like bad pitting, or crown.

[mike in co]

if the numbers are right and it is a 325/326 bore....the next thing you need to do is to get a 326 sizer and quite using the 323....dont use it anywhere near that rifle....... the 326 may only seat the checks(when you use them)......or shoot as cast.

and
then tells what loads are you using...... 4227 in the teens to low 20's.

mike in co

[Bret4207]

By all means try the as cast boolits. Just run 13.0 gr Red Dot and see if you have any grouping. I'd also suggest either the Midsouth/Lee 8mm Karibiner or the Lee .329 mould. Don't be afraid of boolits .001-.003 oversize.

[dromia]

I'd want a good throat and groove fit, 2 thou over groove is recommended, commensurate with your throat dimensions in relation to your boolit shape and seating depth.

From your slug dimensions I would want boolits 0.327" 0.328" for that rifle.

Sounds to me as though your boolits are undersized.

As to safety then I'd want to work up the load from minimum data.

Remember that comparing jacketed and lead loads is like comparing apples and oranges, look to lead data.

[Junior1942]

My Turk 98 8x57 shoots circa 4' groups at 30 yards using any of several cast bullets at over 1400 fps. That's 4' and not 4". Slow 'em down to 1300 fps or so, and they dang near go in one hole. IMHO, it's an RPM problem.

I swaged down several different brands of .323" jacketed bullets to fit a .3155" bore Mosin-Nagant, and the easiest to swage down was the Remington 185 gr. It will probably also be the easiest to swage up to fit your bore.

[siamese4570]

Just had some brain flatulence. What if the barrel has an odd number of rifling? Say 5 grooves instead of six. When you measure across the bullet, you'd really be measuring from the top (or outside) of the groove on one side to the bottom (or inside) of the groove on the other side. It would give you an undersized measurement. This was covered in the Beartooth Cast boolit manual. Just a thought.

Saw your article about the cast 30-30 boolits. Good stuff! I'm waiting for my Ranch Dog mould to get here. Come on post office!

Siamese 4570

[xsquidgator]

Had to think about this. I'm going to try the 0.326" boolits first. Interesting point about maybe having an rpm issue too, I'll plan to work up from a low load (using fillers).

[xsquidgator]

My Turk 98 8x57 shoots circa 4' groups at 30 yards using any of several cast bullets at over 1400 fps. That's 4' and not 4". Slow 'em down to 1300 fps or so, and they dang near go in one hole. IMHO, it's an RPM problem.

I swaged down several different brands of .323" jacketed bullets to fit a .3155" bore Mosin-Nagant, and the easiest to swage down was the Remington 185 gr. It will probably also be the easiest to swage up to fit your bore.

Junior-thanks for the tip! In hindsight it's obvious and simple.

I finally got around to trying what you said this weekend and had MUCH better luck with my 8mm Mauser and my 7.62x39 in my SKS. With the SKS even up to 1400-1500 fps the accuracy was much much better. I had to blindly experiment with reduced loads to find what would produce these speeds but now that I've done it once I think I can just crank out some 1400 fps plinkers that will be good and accurate. With my 2200 fps lead boolits that I was using before I think all I was accomplishing was turning my SKS into a semi-auto musket!

[9.3X62AL]

X-Squid........

I have a G98/40 Mtn Carbine in 8 x 57, and although its bore was a little casual it has done fine work with the Lee 175 gas-checked and sized at .325". Lyman offers a sizing die at that spec as a regular stock item, BTW.

Most 8 x 57 service rifles have a 4 turns/meter twist rate, about 1-9.75". This is a little fast for ideal cast boolit work, and when you add that fast twist rate to an undersized boolit lacking a gas check........I'm thinking "Lead Mine In 5 Shots Or Less" for your bore. I think you would yield benefits from attaching a gas check to your Lee boolits, and sizing at least .325". There is a little "stop" gizzy for the Lyman sizer that allows you to attach and crimp a gas check onto a boolit shank without running the boolit sidewalls into the die, if you wish to leave the boolit itself unsized. Lyman calls it a "gas check seater".

[rusty marlin]

I've heard that, but don't remember where. I'm just a little nervous about putting a tighter-fitting bullet into the bore, although I think it would be the thing to do here. When I mean nervous, I'm imagining pulling the trigger the first time on these and kaboom!

trust me you want lead bullets that are .001-.002 oversize.

Let me give you a neat example of what one can get away with.
This was a controlled test, first conducted in a proof box, then latter on the range. I do not recomend repeating this test with out proper guarding against ruptured cases.
.22LR in a .17HMR chamber. It works, makes interesting spegetti looking bullets, shoots into 1.5-2" at 50 yards with only the occasional ruptured case.

[Fleataxi]

X-squid: What OAL are you using, and how much leade do you have?

If you've got more than a couple of tenths leade, and your under the max OAL, try seating the further out by a couple of hundredths.

This may or may not solve your problem, but I've read sometimes really bad accuracy issues were related to bullet seating depth, and either excessive leade, or not enough.

Fleataxi

[xsquidgator]

Hmm, I couldn't tell you what the leade is on my K98, and I don't have the slightest idea what the twist is on this thing either.

My little science experiment this weekend with reduced loads did happen to be with unsized cast boolits, although my hunch is that this had less to do with the results than slowing them down with reduced loads. I don't think I can seat the bullets much further out than I am. I'm using the Lee 170 grain 2-cavity mould, and actually there's precious little bullet for the case neck to hold on to at the 2.875" OAL I settled on. I picked that length b/c that seems to get one lube groove down into the case neck, which means that there are two ridges of lead being held in place. If I seat the bullet further out, they seem to get cocked to one side and are barely being held in place.

I'm going to make a few more boxes of what seems to be a good plinking load, that is 2.875" OAL, 20-22 grains of BL-C(2) with Lee 170 grain cast bullet, which seems to run at 1350 to 1480 fps in my K98. Unlike my previous attempts with much higher bullet speeds, these seemed to group pretty well and I'm going to see what I can do with them.

I'm really looking forward to making a bunch of lead plinkers for my SKS also, now that I seem to have something that ought to be accurate enough to hit soda cans at 25-50 yards.

[Fleataxi]

X-squid: leade is the distance between the chambered bullet and the start of the rifling. If you're reloading for accuracy, you should know what the leade for your rounds is. There are ways to measure it, I just can't remember how right now.

Fleataxi