7x30 waters cast bullet extending into neck? good/bad?

sabbathman
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7x30 waters cast bullet extending into neck? good/bad?

Post by sabbathman »

I'm reloading for 7x30 waters and using the lee 130 grain GC in a 14" contender barrel. I've got the bullet out as far as it will go while still being able to lock the barrel up. The GC and one driving band extend past the neck into the shoulder area. I've read countless articles on this and there seems to be a 50/50 split.

Specifically, anyone out there shooting a 7x30 waters with cast have any experience with this?

Ball powder better or worse?


thanks
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by high standard 40 »

So if I understand you correctly, the gascheck and one drive band are below the neck and into the powder space? Does that put the crimp groove below the case mouth? Do you have a micrometer? If so, give us the diameter of the nose section of the bullet. If it is greater in diameter than .277", your solution would be to size the nose of the bullet to that size so that the nose section of the bullet can be seated into the rifling. I don't load cast in my 7X30 yet, but I do in my 7TCU and my 7BR. I size the nose on my bullets to .277"and seat them out as far as my chamber throat will allow. This usually leaves the grease groove exposed but accuracy is far better when sized and seated as I described. I had the Lee 7mm 130 mold at one time but on my particular mold, the resulting bullets has a nose diameter of about .274"-.275" and accuracy was far less than acceptable.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by sabbathman »

hey i'll have some digital calipers tomorrow morning, i'll check then and get back with ya. that's what i get for buying a cheap cast bullet mold. rcbs here we come.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by high standard 40 »

Try this. Take one of your cast bullets and slip it nose first into the muzzle of your 7X30. It should be a slip fit. If it is a loose fit and you can wobble it, good luck getting decent accuracy. If it won't slip inside the muzzle up to the first drive band without forcing it, then you will have to size the noses of your bullets.
Sadly, even some of the higher priced name brand molds can be off spec for your needs. I use the RCBS 7mm 145 Sil mold and the nose on bullets from it come out of the mold at .279" which is preferable to me. I can size the nose down to what I need but if the nose comes out too small there is little you can do. At one time I had 6 different Lee molds for rifle calibers. Every one of them dropped bullets with noses too small for my guns. I have never tried the Lyman 7mm 160 but I have heard others say that their mold dropped bullets with a .277" nose. Sometimes, even that is not the right size. I have a Stainless Lilja barreled 7BR and the bore on it is .2765" not .277" as on all my other 7mms. I made a custom sizing bushing for it. Even my RCBS mold had to be modified to be "perfect" for my XP100 7TCU. The chamber on it has a throat that is .2865" and my mold dropped bullets slightly under that. I had Eric at "Hollow Point Molds" true up and enlarge the drive bands on that mold. Casting, loading, and shooting cast bullets is really not all that difficult. Carrying it to the ultimate level requires just a bit more effort. I don't want to just shoot a 40X40 with cast. I want to be able to also hit all of the shootoff targets.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by 260 Striker »

I have shot some cast loads where the base of the bullet was below the neck and didn't have any accuracy issues or gas checks coming off, at least that I could tell. I was not using ball powders and prefer to use AA5744 or SR4759 which I think are more suitable for cast loads. Not saying there aren't other powders for CB but these two have always given me great accuracy with my cast loads. I have not tried my 7X30 Waters barrel yet with cast but would use the 145 and/or 168 RCBS moulds with SR4759 to start with. I may have to play with that this year just to see what it would do. I have many Lee moulds but never tried their 7mm mould so can't comment on the nose size of bullets from that mould.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by sabbathman »

here's what i've got so far...

high standard:
i've got two guns i'm trying to get the lee bullet to work with; 7x30 waters contender and 7br xp100. i got the calipers and have measured ten bullets that i had pulled from my bucket of sized bullets. three of them measuered .285 in front of the crimp groove out to the curve leading to the nose. This diameter would not fit either muzzle end of either barrel to the first drive band. bullets measuring .276/.277 would fit up to the driving band of the muzzle end of the contender barrel with some force. these same bullets were a a slip fit into the xp. it appears the xp is slightly larger than the barrel of the contender. i then took and measured the driving bands after sizing, most were .285 with a few.284 and .2835 thrown in the mix. my plan is to make a chamber cast later this afternoon for the contender barrel. i would imagine now that fitting the bullet to the muzzle end of the barrel would increase accuracy? it seems to make sense or am i thinking wrong? so as far as the 7x30 goes, i need to custom fit the bullet so i can seat that bullet into the rifling up to the first drive band? am i thinking right?


260 striker:
to date i have tried h335 and aa2460. the 2460 on both guns have been the preferred powder, but neither has been really acceptable so far. i see now the wisdom of having a digital caliper. perhaps my issues are more from the various size of bullet noses i have. i also noticed that the powders you are using are considered slower burning than the powders i am using. i was under the impression (perhaps falsely) that i wanted to burn the slower powders for these cartridges. the books i've been using don't have any recipes for the powders you use. i do have some RL-7 and imr 4198 that are listed as somewhere between what i've been using and what you are using. Do you think it worth while to use those powders?

thanks for helping me both of you, i am learning a lot form you.

lyle
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by high standard 40 »

sabbathman wrote:here's what i've got so far...

high standard:
i've got two guns i'm trying to get the lee bullet to work with; 7x30 waters contender and 7br xp100. i got the calipers and have measured ten bullets that i had pulled from my bucket of sized bullets. three of them measuered .285 in front of the crimp groove out to the curve leading to the nose. This diameter would not fit either muzzle end of either barrel to the first drive band. bullets measuring .276/.277 would fit up to the driving band of the muzzle end of the contender barrel with some force. these same bullets were a a slip fit into the xp. it appears the xp is slightly larger than the barrel of the contender. i then took and measured the driving bands after sizing, most were .285 with a few.284 and .2835 thrown in the mix. my plan is to make a chamber cast later this afternoon for the contender barrel. i would imagine now that fitting the bullet to the muzzle end of the barrel would increase accuracy? it seems to make sense or am i thinking wrong? so as far as the 7x30 goes, i need to custom fit the bullet so i can seat that bullet into the rifling up to the first drive band? am i thinking right?
If you had 3 bullets that measured .285" on the nose section I suspect that on those bullets you did not have the mold completely closed when you filled the cavities. I'd consider those rejects.

What do the drive bands measure on your bullets before you size them? After a chamber cast you may discover that a sized diameter of .284" or .284" may be too small. Measure some before sizing to see if you have enough as-cast diameter to go to a larger sizing die if needed.

What method of sizing are you using? If it is a lubrisizer, invest in a .277" die and run all of your bullets nose first into this die, after the bullet body has be sized and lubed, but size only the nose to .277". This will assure uniformity of the bullet noses.

Cast bullets perform best when the bullet is aligned perfectly with the bore once the cartridge is chambered. If the bullet is not aligned it will be deformed as it enters the rifling and accuracy will suffer. To help achieve this preferred alignment I do several things:

1. I neck size the cases once they are fireformed and size only half of the neck. The unsized portion of the neck will help center the case in the chamber, thus helping align the bullet to the bore.
2. I size the body of the bullet so that it is a slip fit in the chamber throat,, which helps with alignment and eliminates the possibility of the burning powder gases from damaging the bearing surfaces of the bullet.
3. I size the bullet nose to be a slip fit inside the rifling to help with alignment.
4. I seat the bullet out as far as I can within the limits of the bullet design and the particular chamber throat.
5. During case prep, I use a Lyman M die with a custom sizer plug so that I never have more than .0015-.002" bullet pull. This is to prevent sizing down my "perfect" bullet by seating it in a case neck that is too small in diameter.

In regards to powder selection, I use the same type powders and at the same charge levels as I do with jacketed bullets. If the cast bullet is of sufficient hardness (about 18 BH) and is fitted properly to the chamber and bore, there is no reason to use anything else. I know a lot of people use and swear by SR4759 but one good reason not to start there is that this powder is being discontinued and will become hard to find, if not impossible.

Lastly, a digital caliper is a handy item and I do have and use one. They are however not a replacement for a good micrometer.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by sabbathman »

high standard 40:

thanks for the response, i will get back with you a bit later today with the as cast measurements. i appreciate your time.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by 260 Striker »

+1 what High Standard 40 said. Also true about starting to use SR4759. While it is a great powder it has been discontinued so use whatever powder gives you good accuracy and will still be available. AA5744 has not been discontinued but might as well be since it is very hard to find these days. I always use the .277 H&I to nose size the RCBS 145 and 168 bullets since the parting line just needs smoothing out. Bullets then fit my 7mm barrels. I used to shoot cast in a 7BR and the RCBS moulds always gave great accuracy after sizing the noses. I never got too scientific about chamber casts and just sized driving bands to .285 and must have just been lucky to get good accuracy. Also shot those same bullets out of a 7INT XP I had with great success. Most of my bullets had a hardness of 12-15 on the LBT hardness tester. Never had any leading and was using LBT Blue lube. HS40 has some great advice that will guide you to some good loads.
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Re: 7x30 waters cast bullet extending into neck? good/bad?

Post by sabbathman »

well ok...i cast some bullets from straight wheel weights and measured the driving bands. .284 to .2845 for 90% of the bullets. Here's what i discovered. after seating the gas check, i noticed that the measurement of the driving bands increases from .284 to .2845/2850 . apparently i am probably putting waaaay to much pressure seating the check. the nose before i seat a check or size is .275/.2755/.276 as it comes from the mold. after i seat a check the nose gets larger. it appears i'm squishing the bullet in my sizing press as i seat the gas check. this i assume is probably not the correct way to enlarge the diameter of a cast bullet.

Anyways, after seating gas checks/resizing, i cannot slip fit about 90% of the bullets into the muzzle end of either barrel, where as right from the mold, i can. So, it appears i need to rethink the way i seat GC's. I can only assume, this is having a direct affect on accuracy.

I then took one of the bullets that was dropped from the mold and that would slip fit into the muzzle end of the contender and made a dummy round. The outcome of the dummy round was a 1/4 inch gain in OAL, which means i no longer have the problem with the base of the bullet extending past the neck and into the shoulder area. it would seem at least, that my initial problem seems to be rectified.

Let me know what ya think please.
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