How big over bore dia. is too big?

[RU shooter]

heres my issue,I got my Ishy 2A 308 the only molds I have are .311-.313 Soooo not wanting to wait for Midway to send me my sizer I loaded some up anyways the barrel slugs @ .3075x.299 but the chamber is verrrry ample in this rifle and they all chambered fine .Accuracy was OK but not great 2-3" @50yds .

Could the boolits being too big cause a loss of accuracy? I only tried two different loads with each boolit(3 different types) and still need to experiment some, But it sure aint like my M39! Can the boolit be Too big even if it chambers fine?

[missionary5155]

Good morning Have you slugged the bore at the chanber to know what the chamber diameter is ? That is the real key... Tapered bores have been around many years... the bore decreases in diameter going to the bore ... and these barrels turn out great accuracy. I have shot oversized cast bullets on the +2-5 thousands in all sorts of rifles and would not be conserned enough not to take them out and bust some 4 leeged critter.

[45 2.1]

They are oversize when it won't chamber easily regardless of groove dimension. Use the biggest boolit that will fit a fired case neck.

[dubber123]

I have shot .006" over in my 50-70 Contender (huge chamber), and they turned in some of my best groups. I believe the oversized bullet held the cartridge straighter in the chamber. I would shoot as big as will readily chamber.

[trk]

I'm working on a tapered bullet Saeco 771 - .376 at the top and .383 at the bottom. I could only find .375 H&I dies, so I've modified the Lee push-through dies - one at .376 and one at .378", I'll do another at .380". This is to test the question of whether or how much over bore affects accuracy. If I load the bullet as-cast the neck of the case has to be pushed a bit to get it to chamber (so I HAVE to size some what). The groove diameter is about .375 and the throat is at least .376". So the question is, how much bigger? Stay tuned.

[Char-Gar]

Don't know if we will ever know what "to big" is. The rounds get to big to chamber before we hit that point.

[Bullshop]

trk
If you are testing solely for accuracy potencial why not just eliminate the case neck as a variable. Tapered boolits are usualy designed for breach seating. If you breach seat you wont get any interfearance from tight case neck sizing the boolit down and changing its diameter that would kind of interfear with what your testing for.
I have a 38/55 with about a .378" groove. The most accurate boolit I have found for it is a taperd design very close to the dimentions of your mold.
Mine is a multi groove much like the lee TL. My rifle does its very best shooting with 30/1 alloy and the base of this boolit run far enough into a .380" diameter die to apply lube to the bottom two grooves.
The same boolit and load made into fixed ammo wont come close to the accuracy of the breach seated load. This set up won us top honors in a Waksupi postal match two winters ago with 10 shots at 100 yards into a fairly small cluster that were all touching as I recall. This has been a very finiky rifle to get to shoot well and I have earlier on held a hack saw to its barrel thretening its life but was each time convinced by BS Mom to try one more time before taking such action, God bless her!
Anyway sumthin for ya to think about.
BIC/BS

[trk]

Bullshop -
I'm working on two rifles, Ruger #1 in .375 H&H and #3 in .375 Win (setup as a Scheutzen rifle with a breech seater).

It is likely that I'll end up making two different moulds for this project. But in the process I'm taking every opportunity to learn details of what works and what doesn't. I've seen folks do well under an inch at 100 yards with cast. My objective here is to do so on a regular basis.

So here I have an opportunity to try several different shank sizes and to see first hand whether (if) there is any significant difference.

Chamber casts are next on my agenda.

[Larry Gibson]

heres my issue,I got my Ishy 2A 308 the only molds I have are .311-.313 Soooo not wanting to wait for Midway to send me my sizer I loaded some up anyways the barrel slugs @ .3075x.299 but the chamber is verrrry ample in this rifle and they all chambered fine .Accuracy was OK but not great 2-3" @50yds .

Could the boolits being too big cause a loss of accuracy? I only tried two different loads with each boolit(3 different types) and still need to experiment some, But it sure aint like my M39! Can the boolit be Too big even if it chambers fine?

Since the bullets chambered they should shoot fairly well. As mentioned if the fit in a fired case then they are ok. As to the accuracy you got we need to know how well the rifle shoots with good jacketed bullets and what load you were using. If the rifle is only capable of 2-3" groups at 50 yards then cast bullets won't improve on that regardless of the fit. Second, if the load wasn't good then the fit wouldn't matter either.

Larry Gibson

[RU shooter]

Since the bullets chambered they should shoot fairly well. As mentioned if the fit in a fired case then they are ok. As to the accuracy you got we need to know how well the rifle shoots with good jacketed bullets and what load you were using. If the rifle is only capable of 2-3" groups at 50 yards then cast bullets won't improve on that regardless of the fit. Second, if the load wasn't good then the fit wouldn't matter either.

Larry Gibson
I shot 8 jword 150 gr hornady w/3031 into a nice round 1.5 at the same distance .My cast loads were 16.0gr. 2400 w/ Lee 155,160,185 second load was same boolits and 12 gr of unique. I just slugged the chamber end of said barrel and got .308x.301. I guess I'll start playing around with different loads till I find a sweet spot.And judging by all of your replys I have nothing to worry about about being 4 or 5 thou. over bore dia.

[Phil]

I recently measured the throats and groove diameters of two 6.5mm rifles.

The first one was an Italian M91. The groove diameter was .2695". The throat diameter was .275", pretty bad I thought.

Second rifle was a Japanese Type I, and the groove diameter was .268". The throat diameter was .285!!!!!!!!!!!!!! I had to measure that one three times to make sure I was seeing what I thought I was seeing.

Both rifles would be good candidates for breech seating, it would be fun to see what cast bullets of those throat diameters looked like after being blown through .268"/.269" barrels.

I made a pretty neat cam type breech seater for a Ruger single shot, will have to see if I have any pix of it. If I do, I'll post them here.

Cheers,

Phil

[BAGTIC]

When the bullet is so big that you can't get the round to chamber it is too big.

Undersized bullets are much more a problem than 'oversized' ones.

[charger 1]

I always go for filling the neck up as close as possible. I would have to say that for me the 30 cal was not a place to send a new caster/shooter of cast. In those tiny cals cast can more often than not be very finiky. You just dont have the surface area. Everybody says the world of cast starts at 35 cal. .I wouldnt go below 40. I can honestly say that if I hadnt started with the 45/70 I probably wouldnt have stayed with it. Myself and a buddy have been fooling with cast in his 308 for over a year. In that time between the two of us we've probably gotten a dozen 40+ cals to shoot worm holes, and we still play trying to get that 08 to consistantly shoot under 4" at hundred without fliers. Just not acceptable. Its headed back to a copper diet

[joeb33050]

I always go for filling the neck up as close as possible. I would have to say that for me the 30 cal was not a place to send a new caster/shooter of cast. In those tiny cals cast can more often than not be very finiky. You just dont have the surface area. Everybody says the world of cast starts at 35 cal. .I wouldnt go below 40. I can honestly say that if I hadnt started with the 45/70 I probably wouldnt have stayed with it. Myself and a buddy have been fooling with cast in his 308 for over a year. In that time between the two of us we've probably gotten a dozen 40+ cals to shoot worm holes, and we still play trying to get that 08 to consistantly shoot under 4" at hundred without fliers. Just not acceptable. Its headed back to a copper diet

I don't understand this, it is the reverse of my experience. 30 caliber guns are and were common, frequently with good sights (03 or 03/a3 vs. Mauser) and decent barrels. The brass is easy to find or make and cheap. I believe that any reasonable-condition 30/06 or 308 will shoot iron sight 100 yard 5 shot 5 group averages of 2 1/2" or under with a variety of loads and bullets. 311299/314299 or 31141 or 311291 or 308403 with appropriate loads of Unique or SR4759 or IMR4227 have worked with new casters/reloaders for the past 47 years, and I have never seen a case where a gun that was right wouldn't shoot cast accurately. I believe that with a modern new 308 with any decent 3-9 cheap scope that one could develop loads grouping under 2" (as above) in 2 hours cold at the range-I'll bet that I could. Larger calibers will shoot, but the recoil goes up, and we don't see accuracy go up with it. There's a reason that the CBA and ASSRA guys use 30-32 calibers. Accuracy with cast, in my experience, starts with 30 and ends with 32 caliber. My 45-70's have shot and do shoot, and I have a .6" 5 shot 100 yard 45-70 group, but a good 30 beats a good 45 any day.
joe brennan

[joeb33050]

heres my issue,I got my Ishy 2A 308 the only molds I have are .311-.313 Soooo not wanting to wait for Midway to send me my sizer I loaded some up anyways the barrel slugs @ .3075x.299 but the chamber is verrrry ample in this rifle and they all chambered fine .Accuracy was OK but not great 2-3" @50yds .

Could the boolits being too big cause a loss of accuracy? I only tried two different loads with each boolit(3 different types) and still need to experiment some, But it sure aint like my M39! Can the boolit be Too big even if it chambers fine?

As several folks have said, if the cast bullet goes in the case mouth and the ctg.chambers, it is not too big. You may/will find that the max OAL goes up as you size bullets down-and this may increase accuracy. You may also find that a thicker case neck gives you a less-sizing chamber-filling case that helps on the accuracy. 308 cases made from (mil) 30/06 cases will have thicker case necks. Also, these can be made as step-necked cases that eliminate all resizing.
I don't know what an Ishy 2a is, but I do know that older shooters operate with an enormous handicap with issue iron military non-peep sights. I've glued or soldered copper washers to front and rear sights to get apertures on both, and it has helped-but I need close-to-eye aperture rear and aperture front sights not to be kidding myself. A scope, the cheapest, solves this problem. If you're under 40, disregard this sight business.
joe brennan

[Phil]

I've also gotten great accuracy with 35 caliber rifles. But I've probably fired more 30/31 caliber bullets than anything else and gotten very satisfactory accuracy. In some cases well sub moa. But the most important thing is to just have fun. When you turn your hobby into work, its time to find another hobby.

My two favorite cast bullet cartridges are the 30 Krag and 8.15x46R. Never really been a fan of the 308 Win for some reason or another, but I enjoy shooting cast from a number of 30-06's and 303's. Then there is the 8x57, 7x57, 7x7 Japanese, 7.65 Argentine, oh well, you see how it goes.

Cheers all,

Phil

[charger 1]

I don't understand this, it is the reverse of my experience. 30 caliber guns are and were common, frequently with good sights (03 or 03/a3 vs. Mauser) and decent barrels. The brass is easy to find or make and cheap. I believe that any reasonable-condition 30/06 or 308 will shoot iron sight 100 yard 5 shot 5 group averages of 2 1/2" or under with a variety of loads and bullets. 311299/314299 or 31141 or 311291 or 308403 with appropriate loads of Unique or SR4759 or IMR4227 have worked with new casters/reloaders for the past 47 years, and I have never seen a case where a gun that was right wouldn't shoot cast accurately. I believe that with a modern new 308 with any decent 3-9 cheap scope that one could develop loads grouping under 2" (as above) in 2 hours cold at the range-I'll bet that I could. Larger calibers will shoot, but the recoil goes up, and we don't see accuracy go up with it. There's a reason that the CBA and ASSRA guys use 30-32 calibers. Accuracy with cast, in my experience, starts with 30 and ends with 32 caliber. My 45-70's have shot and do shoot, and I have a .6" 5 shot 100 yard 45-70 group, but a good 30 beats a good 45 any day.
joe brennan



If you wanta teach me how to .6moa or - a 30 cal I'll send money and kisses

[45 2.1]

Accuracy with cast, in my experience, starts with 30 and ends with 32 caliber. My 45-70's have shot and do shoot, and I have a .6" 5 shot 100 yard 45-70 group, but a good 30 beats a good 45 any day. joe brennan


So goes opinion. Not a fact actually.

[charger 1]

Well like I said I came here knowing 0. Now I might know 1%. And of that I've learned I would truly love to know how to accurize 30 cals to the consistancy of 40+ cals

[PPpastordon]

Oversize boolits? How 'bout oversize bullets?
Though I cannot remember all the details, I am certain it was in P.O. Ackley's Handbook for Shooters and Reloaders that I read about shooting quite oversize bullets during testing action strength. I do not have these books anymore - they fell apart years ago (too much use?) and I couldn't find other copies. However, it seems that the bullets were unbelievably larger than the bore
IIRC, and if anyone has the books, look under the section on the testing of the Japanese Arisaka action.
BTW; I have been known to fire .458-.459 cast boolits in my Ruger .45 Colt with no problems. The barrel slugs .451, and the chamber mouths are .454. Makes a nice sizing system!

[Phil]

There was an article in the American Rifleman back in the fifties about a gunsmith who was asked to check a rifle for some guys who thought it recoiled excessively. Turns out it was a T38 (6.5mm) Arisaka that someone had rechambered to 30-06. The only way I can think of to do this would be to turn the pilot down until it would enter the bore, or just cut it off. That was the only change to the rifle, just the chamber recut to 30-06. The gunsmith sent it to the NRA who tied it to a tire and fired it with no damage to the rifle at all. Extraction was normal as I recall. They had great fun and fired it a number of times with the same result. The Good Lord truly looks out for drunks and darned fools, eh?

Thats the story as I recall it, close enough for government work at any rate.

Cheers,

Phil

[joeb33050]

Well like I said I came here knowing 0. Now I might know 1%. And of that I've learned I would truly love to know how to accurize 30 cals to the consistancy of 40+ cals

I don't understand this, are you joking? For bench rest accuracy, for some reason/s or other, 30 - 32 calibers, CBA - ASSRA, shoot best. What am I missing? Would you like to see the match results?
Does the bullet designer think that there's any question that 30 caliber CBA bolt guns outshoot 45? That 32 caliber SS guns outshoot 38s or 45s? Even the BPCR guys seem to be lowering the caliber and recoil, they're in the 38 caliber area now. Is that an opinion, o bullet designer?
??
joe brennan

[charger 1]

I don't understand this, are you joking? For bench rest accuracy, for some reason/s or other, 30 - 32 calibers, CBA - ASSRA, shoot best. What am I missing? Would you like to see the match results?
Does the bullet designer think that there's any question that 30 caliber CBA bolt guns outshoot 45? That 32 caliber SS guns outshoot 38s or 45s? Even the BPCR guys seem to be lowering the caliber and recoil, they're in the 38 caliber area now. Is that an opinion, o bullet designer?
??
joe brennan

I could understand the high 30's, just cant get the low 30's to work for me. If you can give me a 30/06 recipe I'd truly appreciate it

[Char-Gar]

Charger .... 30 cal rifles are very easy to obtain accuracy with cast bullets. Rifles vary but you can get all the accuracy the particular rifles has to give. Right now I have:

3 rifles in 30-06
3 rifles in .308
4 rifles in 30-40
4 rifles in 30-30

Every one of them will deliver 2 MOA or better with cast bullets. Several will deliver 1 MOA on demand. All of this is done with no great tricks or special hidden secret mojo. Here is how.

1) First of all the start with barrels free of copper metal fouling

2) Have a bullet that fits the barrel. I have found 311291, 311284, 311467 and RCBS 165 Sil all to be sure fire performers is the fit is right.

3) Cast the bullets from ww, or No. 2

4) Size you bullets .311 if they will fit your rifle. If not then .310. I have not found a rifle that would not accept .310 bullets. I do have a couple of Krags with big bore that require .312.

5) Use any decent lube

6) In the 30-30 size cases use 14-16/2400, in the .306/30-40 size cases use 15 -17/2400, in the 30-06 use 16-18/2400. Others have good luke with 4227 and 4759 in the same dosage.

7) Have a steady hold, draw a fine bead, hold your breath and squeeze the trigger.

There is not much more to it than than. I am not going to get into which caliber is more accurate than another or where accuracy with cast bullets starts and end, because I really don't know. But, I do know cast bullet accuracy in 30 cal rifles is pretty easy to come by.

Good luck and good shooting!!!

[joeb33050]

I could understand the high 30's, just cant get the low 30's to work for me. If you can give me a 30/06 recipe I'd truly appreciate it
I don't use 2400, no particular reason. For 30/06 ~200 grain 311299/314299 or ~170 grain 31141 and ~17/SR4759 or IMR4227 and a large pistol primer. Also, while failing to become a competent offhand shooter with 30/06 I shot thousands of 10-12 Unique with any 160-210 grain bullet. Most all guns would shoot 10 shot 200 yard targets ~4" with irons, smaller with scope. Most guns, although I had an 03 that would NOT shoot cast, and the barrel looked perfect.
joe brennan

[45 2.1]

Does the bullet designer think that there's any question that 30 caliber CBA bolt guns outshoot 45? That 32 caliber SS guns outshoot 38s or 45s? Even the BPCR guys seem to be lowering the caliber and recoil, they're in the 38 caliber area now. Is that an opinion, o bullet designer? joe brennan

No its not opinion. If you put the same effort into the bigger calibers, you would discover that there is no practical difference in accuracy. To date, i've not seen that done by others. And yes, i've seen better accuracy out of my 45s than what i've seen on the line at cast bullet matches with the expensive CBA bolt guns. If you put up a proper 45 along the lines of the Miller-Dehaus action and did the same thing, you should see the same accuracy. I don't think of your 5 shot 0.6" group as anything special either.

[leftiye]

Considering the millions of man years that have been put into shooting cast in .30 caliber in the last century, I'd say it's to be expected that they (finally) figured out how to get them to shoot well.

However, precision is on the side of larger (proportionally). The same defect that throws a .30 in the barrow pit hardly affects a .45. Normal machining accuracy in a .45 cal will outdo the best you can do in a .22.

All other factors don't favor one more than the other (except being proportionally more accurate in the larger still). The only factor that is obvious is recoil. People learn to manage it. Or, put the guns in a "vise" and rule it out. Theory favors the larger. Look at the .50 BMGs.

[felix]

How you handle recoil is most important with the larger bores because the longer barrel time. How you handle the ambient conditions becomes most important with the shorter barrel time offered by the smaller calibers. It seems to me that the velocity, in a 24 inch heavy varmit BR barrel off of a car roof (13+ pound gun), should exceed 2200 to just begin helping in the recoil department, making it less mandatory over that of sighting. ... felix

[joeb33050]

No its not opinion. If you put the same effort into the bigger calibers, you would discover that there is no practical difference in accuracy. To date, i've not seen that done by others. And yes, i've seen better accuracy out of my 45s than what i've seen on the line at cast bullet matches with the expensive CBA bolt guns. If you put up a proper 45 along the lines of the Miller-Dehaus action and did the same thing, you should see the same accuracy. I don't think of your 5 shot 0.6" group as anything special either.

leftiye "Considering the millions of man years that have been put into shooting cast in .30 caliber in the last century, I'd say it's to be expected that they (finally) figured out how to get them to shoot well.

However, precision is on the side of larger (proportionally). The same defect that throws a .30 in the barrow pit hardly affects a .45. Normal machining accuracy in a .45 cal will outdo the best you can do in a .22.

All other factors don't favor one more than the other (except being proportionally more accurate in the larger still). The only factor that is obvious is recoil. People learn to manage it. Or, put the guns in a "vise" and rule it out. Theory favors the larger. Look at the .50 BMG"

Both muzzle loading and early breech loading rifles went through an evolution from larger to smaller caliber in the 1800s. Breech loaders going from 45 to 38 to 32 to 28-with Pope's side trip to 25, then to 22 rimfire.
This with target guns, not hunting guns.
I've owned centerfire rifles from 45 to 22 caliber, and found that 45/70, 40/50 SS and 38/55 had substantial recoil that negatively affected my ability to shoot them from the bench. Offhand is different, I can shoot 45/70/450 all day offhand with no problem, and from prone, but bench is bothersome.
The bench shooters sometimes/frequently have/had guns that weigh upwards of 15 pounds, some ML and even CF guns going into the 30# and above area.
I always assumed that the reduction in caliber was a search for the right combination of accuracy and recoil S.T. ACTUAL accuracy = what a shooter can do from the bench, was maximized.
Also assumed that the SS 32 caliber vs CBA 30 caliber business was a matter of tradition.
Here, above, we have two suggestions that accuracy increases as caliber increases. I'd like to know more, and to see any data supporting this.
Maybe benchrest accuracy improvements lie in heavier barrel bigger caliber rifles.

(BTW, my "notebook" .6" 45/70 group measures .693" for 5 at 100 yards, dated 9/6/92, and is the smallest 45/70 group I've ever shot. )
joe brennan

[45 2.1]

Here, above, we have two suggestions that accuracy increases as caliber increases. Not really I'd like to know more, and to see any data supporting this. You want an article out of this. A lot of us don't shoot benchrest matches anymore. I have no interest in them either, now.
Maybe benchrest accuracy improvements lie in heavier barrel bigger caliber rifles. No, the problem is in the methodology used. Everything that is necessary to do this has been in my past posts on this and previous incarnations of this board. Some folks who have read this have went back and read everything i've written about it, then contacted me. I don't do public classes.

(BTW, my "notebook" .6" 45/70 group measures .693" for 5 at 100 yards, dated 9/6/92, and is the smallest 45/70 group I've ever shot. ) My smallest group is not measureable. The 4570 will shoot right with the big boys and make them hump to catch up if you know how.
joe brennan

[joeb33050]

Here, above, we have two suggestions that accuracy increases as caliber increases. Not really I'd like to know more, and to see any data supporting this. You want an article out of this. A lot of us don't shoot benchrest matches anymore. I have no interest in them either, now.
Maybe benchrest accuracy improvements lie in heavier barrel bigger caliber rifles. No, the problem is in the methodology used. Everything that is necessary to do this has been in my past posts on this and previous incarnations of this board. Some folks who have read this have went back and read everything i've written about it, then contacted me. I don't do public classes.

(BTW, my "notebook" .6" 45/70 group measures .693" for 5 at 100 yards, dated 9/6/92, and is the smallest 45/70 group I've ever shot. ) My smallest group is not measureable. The 4570 will shoot right with the big boys and make them hump to catch up if you know how.
joe brennan

Sorry to bother you. I guess I misunderstood what this forum business is all about.
joe brennan

[45 2.1]

Sorry to bother you. I guess I misunderstood what this forum business is all about. joe brennan

Your answer is a good example of why that doesn't happen. I've told all of this in the forums and you all still haven't got it. One on one with specific questions and answers does though. Something that doesn't happen publically because most assume they know whats goin on from a little talk. If you really want to find out, then you have to do it my way, not yours!