Jacketed bullet to bore fit?

[mdi]

A theoretical question for the jacketed bullet fellers. What is the optimum jacketed bullet to bore fit? Bore Diameter? Groove diameter? Groove diameter + .001"? Any other suggestions?

Question relates to a surplus rifle with odd diameter bore (.303 British with a .318" groove diameter). A new to me shooter, I have shot .310" factory ammo and so-so results plus a bunch of copper fouling. I have some cast coming and if they work I'll pick up a mold and cast my own. But I also want to reload with some jacketed bullets and looking for the optimum size...

[DukeInFlorida]

When casting, it's almost always groove diameter plus .001". Do a slug of the barrel, and whatever diameter is the biggest, add .001" to that. That's your optimum bullet diameter. For jacketed bullets, the groove diameter would be optimum, unless that size just isn't available. Then, you're often better off with a larger cast bullet, and size it down to where you need to be.

For cast bullet sizing, I would direct you to Glenn Fryxell's free book, available here on Cast Boolits:
http://www.lasc.us/Fryxell_Book_Contents.htm

BIG area on this subject, and it explains WHY...........

[docone31]

My SMLE, takes a .312 jacketed bullet. I paper patch to .314 with the cast bullets.
Excellent results.

[Cane_man]

i think the bench rest fellas like to have a 'pressure ring' at the base of the bullet that is approximately 0.0004 over diameter...

[mdi]

Thanks fellers, but I'm asking about jacketed bullets. My Lee-Enfield's bore measures .318" My cast bullets for this gun will run .320". I was curious as to the optimum jacketed bullet diameter to bore (groove diameter) fit. I've been casting and shooting lead bullets for my guns for 17 years and have been able to get decent accuracy and little leading by properly fitting the bullet to the barrel (most of my guns like .002"+). I have not reloaded jacketed bullets for an odd bore size, and just wanted the optimum bullet to barrel fit for jacketed bullets. That's why I came to the Swaging Forum, folks here deal with jacketed bullets...

[uscra112]

Jacketed bullets should be groove diameter, period. Although there are many people who shoot 7.62x39 bullets that mike .312 through a .308 groove, it's never going to do accuracy any good, and it will raise pressures. (d'oh)

I have a 1912 German single-shot 6 lb. "stalking rifle" that's chambered 8mmx57R, and it has the .318"-groove rifling that was still common for civilian rifles back then. So I've studied on the subject a bit. There are sources for .318" jacketed bullets. Try Huntingtons, for one. It is also possible to size down bullets meant for the .32 Special, which run .321". As with shooting oversize jacketed bullets, it doesn't do accuracy any good, but it ain't horrible either. No, I haven't done it personally, just quoting the old authorities.

BTW the old soldier who sold me that singleshot handed me a box of milsurp rimless ammo with the .323 bullet. There were three empty slots. He'd personally brought the rifle home from WW2, and had fired the three rounds himself, then put the gun away because it kicked like H*** H***, he said. At just 6 lbs., I'll just bet it did! But I reckon the rifle is safe, if it stood that. Someday I mean to work up cast loads for it, but it won't be soon. Too many other projects!

[Prospector Howard]

If it was me, I'd get a push through bullet sizer made up or make it myself at .3175, just under bore groove diameter, (I'm the careful type). Or you could get a lee .314 push through lube & size kit (that's the closest size they make), and lap it out with sandpaper to .3175. Then get some Remington 8mm 185 grain jacketed CL softpoints and size them down from .323 to .3175. They shouldn't be too hard to get through the sizing die if you put a light coat of 50/50, lanolin/castor oil swaging lube on them. That would probably be the most economical way to go, instead of buying overpriced odd size jacketed bullets. uscra112 is right about oversized jacketed bullets raising pressures, so starting a little small is a good idea to me.

[BT Sniper]

This does bring up an interesting subject. What size bullet is safe in a given barrel groove diameter, what size bullet will give the best accuracy for the same given groove diameter.

I think there maybe some liability issues in the possible answers and probably why all the big name bullet manufactures replace their dies when they get too big. I plan to test some theories but when it comes to shooting oversized bullets one must take carful care in their load development.

Heck you could look at it from another angle and look into why some well know barrel manufactures have been know to make tight barrels, by about a half thousandth.

I'm sure there are a lot of theories that could be tested or may already have been. Safest answer is bullet of same size +/- .0005 as your groove diameter. If your "groove" diameter is .3180 I personally would feel safe shooting jacketed bullets that measured at their widest point .3175-.3185

BT

[mdi]

Thanks fellers. This is about what I was thinking, and hoping shooting smaller might be OK. But now the search for a .318" bullet begins. Mebbe the idea of a .314" Lee sizer die opened up to .318" will be my best bet.

[BT Sniper]

Lee sizer opened up to .318 then probably have to size down 8mm bullets. For best results a one step swage die (bump die) to take 30 cal up to .318 would give you the best results.

BT

[mdi]

My "machinist self" tells me it would be easier to make a .323" jacketed bullet .005" smaller than trying to make a .308" jacketed bullet .010" larger...

[BT Sniper]

Swaging up is pretty easy compared to sizing down, but making a 318 sizing die is certainly easier then making a 318 point form die :)

[Prospector Howard]

mdi, I may have given you some bad advice on the Rem 185 core-lokt bullets. They used to be the best buy for 8mm bullets, but I noticed the price is as much or more than other brands now, twice as much as I paid the last time I bought some. Anyway, uscra112 had a good idea about the bullets made for the 32 Win Special. They are .321, so a little less sizing. You might not like the shape though, they are generally a flat nose for lever action rifles. Also, there is another reason I'd start out a little small on the sizing die at .3175. If you get a Lee die and lap it, those dies are made to size lead bullets. If you're putting harder copper jacket bullets through it, the die might tend to wear a little over time. Good luck.

[mdi]

This project is starting to get pretty involved. I can purchase a die and rework it, but can't afford a dedicated swaging set-up for just one size bullet and one old gun that has an odd sized and dark bore. Casting is another story as a mold and sizing die is workable, but I just wanted to shoot some jacketed bullets in my .303...

Sometimes I'll get involved in a project and before I know it, I've gotten in up to my chin. Like cast lead bullets for my 629 in the early '80s. I bought some bullets but didn't really like them, then I bought a mold (first), then a bottom pour pot, researched lead and collected a half ton, then I studied lubes and sizing, and now I have 14 molds for 4 different calibers and 5 sizing dies mebbe 20 lbs. of assorted lubes, a couple thousand gas checks and a whole bench full of associated tools and equipment. All I wanted was an accurate 240 gr. LSWC to shoot in my .44 Magnum...

[Prospector Howard]

You shouldn't have to get a "dedicated swaging set up" for this. As long as you have a decent reloading press like a Rock Chucker or Lee Classic Cast. I size down .311 123 gr fmj's that I got bulk cheap years ago to .308 on my Lee Classic cast press all the time when I want to shoot them in my .308 and 30-06. They go through the lee sizing die pretty easy with a light coat of swaging lube on them.

[mdi]

You shouldn't have to get a "dedicated swaging set up" for this. As long as you have a decent reloading press like a Rock Chucker or Lee Classic Cast. I size down .311 123 gr fmj's that I got bulk cheap years ago to .308 on my Lee Classic cast press all the time when I want to shoot them in my .308 and 30-06. They go through the lee sizing die pretty easy with a light coat of swaging lube on them.

OK, you talked me into it! (that was easy!). My heavy duty C-H single stage press should be heavy enough. Hmm, first the die...

[wonderwolf]

I'm looking at this info thinking about how hard jacketed bullets (as well as data) are to find for the 40-65, I have read so much on variations in groove diameter (up to .410" and as little as .405" in others in some rifles reported on the internet....so take it with some salt) that I finally got around to slugging my 40-65 to find it is .399 lands and .407 groove. So that means I can swage bullets using my .410" (41 mag) die set and make a push through sizer (13/32 reamed=.4062") that would bring them down to .406,7 or 8.

In all my books (and I have a lot of books) jacketed bullet fit is hardly touched on, especially when it comes to rifles....older rifles they have more data on because of the variations and the need to tailor the fit but most of those were cast BPCR guns......

Curious how the die turned out mdi since its been almost a year since the last reply to this thread.

[bullet maker 57]

You can try Buffalo Arms for the bullet diameter you are looking for.

[Forrest r]

Before you go to all the trouble of making/swaging bullets you might consider just buying a couple 100 jacketed bullets (your're going to have to buy jacketed bullets to swage down anyway) to see if the bores any good.

Do a search on 8mm 8x57 j-bore bullets. The old mauser j-bores were .318.

http://www.midwayusa.com/product/530261/woodleigh-bullets-8x57mm-mauser-318-diameter-200-grain-bonded-weldcore-round-nose-soft-point-box-of-50

If the bbl/throat is wore/pitted too bad & you don't get the accuracy you're looking for out of those jacketed bullets you might be better of using cast bullets from molds that drop .311 & paper patching them.

[44magLeo]

Wouldn't it be easier to replace the barrel with one of a more appropriate bore size?
Leo

[MIBULLETS]

US commercial 8mm Mauser ammo is loaded down quite a bit because of rifles out there with .318 barrels. Your barrel will swage down an oversized bullet, but you need to load them carefully. Probably a good time to have a chronograph to monitor your loads. The 32 caliber .321 suggested would probably work fine.