.309 vs .310

[AJC1]

Is there a downside to going a thousandths larger on a cast range plinking bullet. I have a mold coming for my 308 and I've shot a pile of .310 commercial cast gas checked bullets. I'm trying to decide between a 309 vs a 310 lee sizer. This is a plain base bullet and will be loaded with 4227 and 4198.

 

[bluejay75]

Get the .310. .311 if the barrel is well worn.

 

[Thomasss]

No offense, but you are going a hundredth larger. You may have answered your own question. How did the .310s shoot? Were they accurate? Did you have much leading in your gun? That's your answer! Now most people don't need gas checks for plinking loads is you stay under 1,100 fps. The only other items you need to consider is whether you plan to powder coat your own bullets and what lead mix are you planning to cast.

 

[AJC1]

Get the .310. .311 if the barrel is well worn.

Lee Sizers seem to be 309 and 311. I would have to order the noe to size 310 but was considering going that route. I've wanted their sizer but have not seen it in stock for ages.

 

[Bazoo]

The only way to know for sure is to test both. But in general, the larger sizes are better all the way around. It is less likely to lead and more likely to be accurate.

It’s thousandths of an inch btw.

 

[AJC1]

No offense, but you are going a hundredth larger. You may have answered your own question. How did the .310s shoot? Were they accurate? Did you have much leading in your gun? That's your answer! Now most people don't need gas checks for plinking loads is you stay under 1,100 fps. The only other items you need to consider is whether you plan to powder coat your own bullets and what lead mix are you planning to cast.

Everything is different between what I have used and what I will have. 150gr vs 165gr plain base vs gas checked and powder coated vs traditionally lubed. I was shooting in the 1900 to 2000 fps range and intend to stay in the same zone. I'm under the impression that less than 2200 fps makes things significantly easier to get dialed in and figure out. First rifle mold so I'm asking questions.

 

[fxvr5]

No offense, but you are going a hundredth larger.

It's a thousandth not a hundredth.

 

[mdi]

The difference in bullet to barrel engagement is .0005". As far as pressures, probably no noticable difference, but the particular gun may perform a bit different accurately, and of course slug your barres a few times.Two thoughts; go with 311" and try that diameter. Get a .309" sizer and polish it out to .310", an easy 30 minute job.

I haven't experienced a velocity threshold for finding a good load for a cast rifle bullet, but I've only cast for two bolt guns and one Garand. My Garand loads were running about 2,300 +/- 100 fps or so. I was not getting good accuracy with any, and at the time had a couple new guns to play with so I stopped the work ups. I guess there may be a difference dialing in a 1,000 fps load over a 2,000+ fps load but what's the theory behind that?

 

[Barbaroja]

Have you slugged your barrel?
I shoot cast in my savage 340 30-30. It .measures at .309 so I size my Bullets with the .311 Lee sizer. Works for me

 

[Charlie98]

I used to just get .309" cast bullets and they worked well enough... until I got my Savage 99 in .30-30. There, I had to go to a .310" bullet. Luckly, my other Savage 99... in .308... doesn't care which bullet I use, so now I just get .310"s. It really depends on your rifle...

 

[AJC1]

I used to just get .309" cast bullets and they worked well enough... until I got my Savage 99 in .30-30. There, I had to go to a .310" bullet. Luckly, my other Savage 99... in .308... doesn't care which bullet I use, so now I just get .310"s. It really depends on your rifle...

Maybe the best way forward at this point is to cast up a few and see how big they drop. If I'm getting less than 310 then uniform them at 309. If I get at least 310 then PC and uniform at 311. I dont coat heavy and dont intend to try and coat heavy enough to control diameter. I love casting so many details to figure out.

 

[AJC1]

The difference in bullet to barrel engagement is .0005". As far as pressures, probably no noticable difference, but the particular gun may perform a bit different accurately, and of course slug your barres a few times.Two thoughts; go with 311" and try that diameter. Get a .309" sizer and polish it out to .310", an easy 30 minute job.

I haven't experienced a velocity threshold for finding a good load for a cast rifle bullet, but I've only cast for two bolt guns and one Garand. My Garand loads were running about 2,300 +/- 100 fps or so. I was not getting good accuracy with any, and at the time had a couple new guns to play with so I stopped the work ups. I guess there may be a difference dialing in a 1,000 fps load over a 2,000+ fps load but what's the theory behind that?

I think there are a couple of important factors that I understand the academics but the theory to practice is forthcoming. The first is skidding. I believe this is controlled by hardness and diameter. The second is leading due to things like flame cutting. I havent experienced this in pistol and I'm not planning on being at full rifle velocity or pressure. This I also believe is a hardness and diameter issue. Let the games begin.

 

[243winxb]

Buy the Lee .309" sizer and size a few.
The finished diameter is dependent on the alloy used. The harder alloys produce the larger diameter.
Same for molds. Lees molds are regulated with lead & tin. 95%/5% Adding ww with antimony, makes bigger, harder bullets.

Its easy to enlarge the sizer a thousandth, if needed.

 

[Bazoo]

PC is more forgiving all the way around it seems. That said, I run my 31141 @.310 and lubed with GC for my 30-30. I enjoy traditional lube. If I had a bullet say, .3096.... I’d lube it and run through the .310 sizer. It wouldn’t size it any and that’s fine.

When you measure your bullets you should measure around them and use the smallest measurement. So if the smallest measurement is .309 and it’s .311 on another side, you don’t have a .311 bullet, rather, you have a .309 bullet.

 

[FROGO207]

As long as the finished round will chamber without pinching the necks I personally have not experienced any problems with oversized bullets. I am also of the opinion of the bigger the better especially with lead bullets. It works well with .311, .312 bullets in 7.62 X 39 in my Mini 30's .308 barrel for one.

 

[dartor]

I cast, coat and size mine to 0.309". I haven't slugged the barrel. You should get great results with IMR 4227. I"m currently working up a load for a 150gn Lee bullet. I have half a dozen powders that will work for the 308/150gn combination. I started with IMR 4227 and my best group is 0.790", 5 rounds at 100 yards. Please keep us up to date with your endeavor.

 

[AJC1]

I cast, coat and size mine to 0.309". I haven't slugged the barrel. You should get great results with IMR 4227. I"m currently working up a load for a 150gn Lee bullet. I have half a dozen powders that will work for the 308/150gn combination. I started with IMR 4227 and my best group is 0.790", 5 rounds at 100 yards. Please keep us up to date with your endeavor.

With a 150 my best loads were around 23 grains 4227. Hope that helps.

 

[Charlie98]

I was shooting in the 1900 to 2000 fps range and intend to stay in the same zone. I'm under the impression that less than 2200 fps makes things significantly easier to get dialed in and figure out.

The first cast rifle bullets I loaded over 2000fps was for my .348WCF... a 200grn Montana Bullet FN/GC bullet over IMR3031. I had it tooling along around 2300fps. I lucked out... it was the perfect bullet for my rifle, sized at .349"... although I would have gone to .350" if they would have had them available.

The .308's were a different story, however. In my Savage 99 .308, a generic 173grn .309" commercial cast (LaserCast...) worked well enough, loaded to 1800fps. Again, I lucked out... if not the perfect bullet, at least an adequate bullet. Moving past 2000fps in the 99, I had to go to the Montana 173grn GC bullet to get the triumvirate of velocity, accuracy, and no leading... I don't know if that was due to bullet material, the gas check, bullet cast quality... or any combination.

When I got my Savage 99 in .30-30... things strayed a little. The same .309" LaserCast bullet produced horrible accuracy. Switching to the Montana, I was surprised to find they did, too, even with velocity ranges of 1400-1800fps. A quick order to Montana for the same bullet, but in .310", proved to be the correct combination... for that rifle.

Once you get your mold, and start dropping bullets worthy of loading... I would start with a target velocity of 1600-1700fps... easy enough with IMR4227. Work your way up to the velocity you want to achieve... looking for signs of deteriorating accuracy, and/or things like barrel leading. I'm more likely to say you will start seeing issues at 2000fps, rather than 2200fps... just my experience. Don't discount powders like IMR4198 or even IMR3031, but their starting velocities will be higher, normally.

 

[EMC45]

I load cast bullets as fat as possible while still being able to chamber. I have .309, .310, .311 and .314 sizers. I use accordingly for specific rifles.

 

[AJC1]

I load cast bullets as fat as possible while still being able to chamber. I have .309, .310, .311 and .314 sizers. I use accordingly for specific rifles.

I'm sure when I get to project arisaka I'll be in that .313 .314 range.

 

[GooseGestapo]

I’ve used a .311” for EVERYTHING until I got a Enfield No.4Mk I. It prefers a .314”, as does the Izvesk Mosin-Nagant.

The Marlin/Glenfield .30/30 w/micro groove NEEDS a .311” so that’s why I started with it. I also use the .311” for .32acp.

I started with a .308” sizer in 1975, but quickly found an unsized .311” bullet shot better in ALL applications. LIGHTLY sizing though uniformly sizes all bullets ROUND so is worth the trouble.

My Ruger Single-7 INSISTS on a .314” cast bullet, but the Taurus Mod-71 in .32 H&R is happy with a .311, but TACK DRIVES with a .313” NOE wadcutter sized in a .314” sizer...

 

[Ru4real]

.309 vs .310

0.001 difference. My work is done here.

 

[AJC1]

.309 vs .310

0.001 difference. My work is done here.

Your so basic.

 

[Ru4real]

Your so basic.

Nah. I’ve been drinking.

 

[Alaskamike]

If it were me, I'd get some samples from a commercial caster, like maybe 10 each, both .309" and .310". Then try them both with your preferred load in your rifle, and see which performs better.

That said, I have both .309" and .310" RCBS sizers, and .310" consistently performs better in all 5 of my .30-06 rifles. Doesn't mean that'll be the case in yours, so the cheapest way you can actually test would be what I would recommend.