when is a cast bullet to big

[soonerfan66]

I have another post titled Trapdoor carbine bullet about finding the right diameter bullet mold for it and I have a mold from Accurate ordered . This question is about when is it just to big for safety , over pressure or leading issues . Went down to buy some more black powder today and got talking with some guys . I talked about the types of ways to increase size I have tried but was getting some that dropped WAY over size and putting them back in to melt . One said the statement I have heard and read before about "if it seats in the case and chambers fire away" no worries . What are your alls thoughts on this . When does leading and over pressure star happening with a larger bullet ?

[Rich/WIS]

Size is relative to bore diameter and hardness. Most here size several thousandths over bore diameter. Pressure is not an issue but this is mostly in more modern designs than the trapdoor. Over size and hard bullets will increase pressure when sized by the barrel, how much I don't know, but suspect it isn't much. Curious if anyone has tested this and what the results show. If you are already sizing bullets after casting then you should not be loading bullets way over size.

[fredj338]

I don't think you can really nail down when pressures get out of control or leading happens. Variable like type of rifling, bore smoothness, peak pressure & alloy will play into it. I have found no issues going 0.002" over bore dia with magnum handgun pressures. YMMV.
I have tested my 9mm loads at 0.357" & 0.356". Vel are very close, telling me pressure isn't being raised much if any.

[rking22]

I am of the camp you referenced, if it allows a couple thou for case neck to release in the chamber it is good to go. That does not apply to the extreme of 300BO in a 223, just cause it fits don’t make it ok! Use common sense. That said I use a .459 Lyman Gould hp in my Browning low wall 45 Colt. The chamber is HUGE, I dropped a .462 as cast bullet into a fired case, it rattled! Plenty case neck clearance, load is ok in lever guns, the same gun was also chambered in 260 Rem.

[Rcmaveric]

Quickloads lets me go a certain percentage over groove before it throws a warning flag about not being able to reliably calculate pressures. Shooting from the hip and memory i think its about 3%.

When it comes to things that spike pressures. Seating a bullet jammed into the lands will spike pressures more dramatically than an oversized bullet. I personally size to my throat on all my guns. Just leave .001 to .002 for the case neck to release. The bullet will get sized one way or another, might as well let the gun and powers that be do it for you.

I wouldnt be concerned about an over sized bullet unless it was made of something like hard copper or brass.

Sent from my SM-G950U using Tapatalk

[centershot]

I have another post titled Trapdoor carbine bullet about finding the right diameter bullet mold for it and I have a mold from Accurate ordered . This question is about when is it just to big for safety , over pressure or leading issues . Went down to buy some more black powder today and got talking with some guys . I talked about the types of ways to increase size I have tried but was getting some that dropped WAY over size and putting them back in to melt . One said the statement I have heard and read before about "if it seats in the case and chambers fire away" no worries . What are your alls thoughts on this . When does leading and over pressure star happening with a larger bullet ?

That is true. If it enters the chamber without binding it should be safe to fire. Case in point: I have a Marlin 1894 carbine chambered in .357 Magnum, It's bore mikes 0.3556" in diameter. I routinely fire the Lee 158 RNFP in it, unsized, at a diameter of .360". That's .004" oversize, and it shoots great! No pressure signs at all. Soooooo............I won't say this will work so splendidly for everyone, or ANYone, but it worked for me!

[soonerfan66]

I don't plan on going over a few thou once barrel has been slugged but the main question was after is the part about if it seats and chambers go with it and if anyone has gone that route and what was results and how much over was it . I am a very basic reloader , going by the book or proven loads and don't test ammo like some people do for research . Most of you guys probably go a lot deeper into reloading and was just courious about it . And yes commen sense goes along way , just cause it fits or it is ok to do it don't mean go do it . Example my nephew got some Ghost peppers once and asked me to try one . I could , its ok to , it would fit but its not going to happen .

[rking22]

"Example my nephew got some Ghost peppers once and asked me to try one . I could , its ok to , it would fit but its not going to happen"
Exactly, made me laugh too , wise man :coffee:

[Outpost75]

Release clearance determines max. safe bullet diameter.

If cartridges chamber without effort the bullet is not too big.

[mto7464]

I've gone up to .359 in 9mm. (loaded as cast) They shot well. Better then undersized for sure. No leading good groups. Velocity was a little higher but I only shoot very mild charges so no where near max.

[soonerfan66]

Thanks a lot guys you answered my question , this is a great forum .

[beshears]

Ackley ran a 35 cal reamer in a 30 cal barrel and had no problems with jacketed bullets .050 over size.

[leadhead]

I really don't think you'll get leading with an over sized bullet.
It's when the bullet is under size, is when leading happens.
Denny

[reddog81]

It’s relatively easy to size a bullet down .005 in a normal press. I’d assume the pressures involved with firing a gun will accomplish sizing an oversized lead bullet in the .003 to .006 range with ease. Any bullet larger than that and still chambers probably means the gun has some questionable tolerances.

[FLINTNFIRE]

I had a brother in law shoot a 308 out of a 264 win mag bullet made it half way down barrel before case that could not seal chamber let gas out the back , I am of the opinion that if it chambers and the case is the correct caliber you should have no issues , case expands seals chamber cast bullet softer then jacketed will size itself the little bit it has to as for leading if it is bigger then bore you should be good your mileage may vary and it is your call size them if you want to your bore and throat.

[vtech26]

I've got some of those Russian slug molds for my 12 Guage...they are pretty big!

Sent from my SM-G965U using Tapatalk

[wmitty]

Since you didn’t say specifically that you are interested in shooting cast boolits in the Springfield I am going to assume this is your intent and go from there. The three groove rifling is tough to measure, so go with the as cast diameter from your mould using a soft alloy. As far as size (diameter) and hardness raising pressures and how far one can go, it would seem accuracy would deteriorate to the point of uselessness or non-expansion in the case of a hunting boolit before damaging the rifle might occur; even with a weaker action rifle like the trapdoor. I tried the Lyman 457124 in dad’s ‘84 Springfield and very quickly learned the meaning of the term “keyhole”. I hope you have better luck and obturation than I.

[richhodg66]

Ackley ran a 35 cal reamer in a 30 cal barrel and had no problems with jacketed bullets .050 over size.

I read this somewhere as well. I have also heard reference of someone shooting a .308 round through a Model 700 in .270, apparently the cartridge length allowed it to headspace well enough on the bullet ogive to fire. The rifle suffered a broken extractor I was told but no other damage.

Lead alloy bullets are a lot more elastic than jacketed ones, I doubt that being oversized but still able to chamber is going to cause a safety problem in an otherwise safe load.

[GhostHawk]

I have run unsized .314 90 gr cast bullets through a .30-30. Only thing that tipped me off was it barked louder than I expected.

Sized to .3115 or .312 and it was back quiet again.

2-3 thousandths over is what I aim for. Have done as little as same/same ie .312 .312 and got horrendus leading. 1 thou over is bare minimum IMO.
But YMMV.

[mdi]

Just a couple thoughts; If I remember correctly, I read in "Cast Bullets for Beginner and Expert" by Brennan, that some Schutzen shooters breach seated their bullets that were .006"+ over groove diameter. I saw very interesting article in an older magazine and a video about a 17/22 lr. rimfire rifle. The rifle was chambered for 22 Lr but the barrel was 17 caliber, over .030" difference in bullet diameter. Lots of testing, bullet swaged fine, no over pressure problems.

K.I.S.S.; Slug bbl, buy a Lee sizing kit .002" over groove diameter. This in an excellent place to start, and for me more often than not works very well...

Just thinkin'. For me, if it chambers, it fires...

[Larry Gibson]

Release clearance determines max. safe bullet diameter.

If cartridges chamber without effort the bullet is not too big.

Concur. I have measured pressures in several different cartridges with various size cast bullets including the 45-70 with TD level loads. The 45-70 test was with the Lee 405 gr HB bullet at .459, .4615, .463 and .464. The test barrel has a groove diameter of .458. All bullets were from the same casting with the same lube and the same load.

Understand the "oversize" bullet is swaged down in the first bearing length of barrel travel when the pressure is still relatively low and on the "rise" to peak pressure. There can be a slight variation in the "rise" to peak pressure but the average peak pressure of the varied sized bullets remained consistent within test to test variation of peak pressure......bottom line there was not concern about higher pressure. There was a difference in accuracy though. The results were basically the same as with the same type test conducted with several 30 caliber cartridges with .308 groove diameter barrels. Those tests used the same cast bullet sized .308, .309, .310, .311, .312 and .314. Pressure based solely on the size of the cast bullet was not meaningfully effected. Again, as with the 45-70 test, accuracy was effected. I found in both tests that bullet larger than .003 over groove diameter lost accuracy. I did not experience any leading in either test.

Caveat; the above applies to cast bullets specifically. Jacketed bullets are a whole other game and pressures can rise significantly with oversize bullets having harder steel jackets, harder cores and particularly steel jackets with steel penetrators in the cores. Even copper jacketed bullets of the same weight but with longer bearing surfaces can raise pressures of a given load.

[rking22]

Larry Gibson, thank you for posting actual pressure tested results. I have always been comfortable that neck clearance is all that’s needed(for pressure safety) but having verified measurements and a size range is very valuable to our understanding.