Case fillers for bottleneck cartridges

[flyboy]

I will be loading my 257 Roberts  with 100 gr. gas check cast bullets over Unique or 2400, which will come nowhere near filling  the case. 

I've read that grits, corn meal, cream of wheat, plastic shot buffer, or dacron batting have all been used with good results, and to me, it would seem a good thing to keep the small charge of powder from rattling around on the case, which can do nothing good to the powder.

Now: does filler work well in bottleneck cartridges?  Which is "best", and what are the pitfalls/dangers of using them?  Should one use the recommended starting cast bullet load from a manual, and add filler?

Thank you.

[Veral]

  I've written severl times on this forum about using case fillers, and recommend them highly for rifle loads, but they also improve revolver loads if the case isn't completely full of powder so there is room for the filler.

  Best filler by far is granulated shot buffer, but cream of wheat and corn meal work well, and I have used sawdust with good results, but it must be hardwood, not pine or other pitchy wood.  If usng anything but shot buffer, be sure it is well warmed to dry off all moisture.

  I definately recommend AGANST use of dacron fillers, as they can cause severe barrel ringing.

  Always use enough filler to get compression, so powder and filler don't get mixed.  Also, best results will normally be obtained if the case is at least 2/3 full of powder.  Too much filler seems to loosen the groups a bit, to a lot.

[crash87]

Veral, You talk some in "the book" about fillers. "1600 fps is about the upper velocity limit for most plainbase bullet designs." "To get results with odd diameter guns for which checks aren't available, fillers help get velocities up dramatically." What I'm looking for is a plain base LCFN for my 35 Whelen (1895 Win) at 250gr, and a 225 LFN for my 348 Win.  Can I get by without using checks and still hit my target velocity. That would be, not to exceed jacketed velocity with the given weights. I'm also assuming the "1600fps" you wrote about is handgun bullets as I'm looking for 2400 and 2200fps respectively. You can also rest assured the bores will be lapped and as smooth as LBT's lapping method will allow. Which after just getting done with a .416 Rigby & a .45 colt clone with "alot"  of thread crush, I can say, is as perfect as I can get them. I have checks and am willing to use them, and at one time was of the opinion it was the "only" way to get performance. After shooting, with perfectly lapped barrels, plain based bullets, I've come to change my opinion.somewhat. Understand though, the plain base bullets were for revolver cartridges used in rifles, ie .45 Colt, 44 mag and a BPCR at target velocities, which by the way put a 1 1/2 yearold Bison in my freezer, quite handily I might add. Hence my concerns (questions) for pb "rifle" bullets at much higher velocities with fillers, (which would be plastic shot buffer). Thanks CRASH87

[Veral]

  You said that you have gas checks, so I presume you also already have bullet molds?  If so, try the bullets you have without the checks and see what happens.  You'll find it a very affordable experiment!

  Best results will probably be obtained if you select a powder that leaves about 1/4 inch of space between top of powder and bullet base. Fill the ctg neck to the top with buffer and compress it down with the bullet.  This will give enough buffer to produce optimum bore cleaning action yet not so much that it acts like a long crumbly bullet base when it exits the muzzle, which hurts accuracy.

[crash87]

Veral, No I don't have the molds yet. Throat slugs need to be made and then an order for the molds.  The reasoning for the inquiry on fillers and pb bullets is to find out what mold to order, checked or plain base? If the pb bullets with filler can approach my intended velocities that is what I'd go with. If I need to play it safe and know, then I'll order the bullets with gas checks. One last thing, I assume the .348 uses 35 cal checks? Thanks again, Veral.   CRASH87
                                                                                                   

[Veral]

  I can no way say with any certainty that you'll get your expected velocity with filler only behind plain base, so by all means order the molds for gas check, but tell me when you order and I'll set the check shanks a little short, and lube grooves special for use without checks.  I have more faith in the unchecked bullets getting the speed you want with filler, than in plain base.  Filler jambs the check shank tight with plastic, real tight when chamber pressure gets up to 40,000 psi plus.  I expect it's as hard as copper at about peak pressure!

  Hornady makes 348 gc's but their maximum range is barely .350 and many 348's need that or a little more.  If you gun slugs over .350 go with 35 cal checks.  They work great.

  I'll give you an option of one cavity gc one cavity pb at no charge if you want to do some playing and testing.  If I set one up that way, the pb will have more lube room, as I'll change the lube grooves for that cavity.  You have to promise to let all the readers know what results are though!   There are quite a few cast shooters who right now are wishing they could get along without gas checks.  The only way to get a solid answer to this question is to test two identical bullets side by side, with one pb one gc.

[crash87]

And I, also, am one of those shooters wondering if we can get by in some instances without using checks and where better place to ask the question. This would be a perfect opportunity to find out such things. As always, from you, more information I had no idea existed. I would never have thought an unchecked bullet could have the potential for more velocity than a plain base. By the way, your book, to me is the definitive answer to the cast shooting world. Back a few years now, about 30, all I was able to aquire besides a magazine article or two was the Lyman handbook. In my readings I tried to get my qustions answered and on one page I would, then on another it would contradict what I had just read! All I use it now for is a starting point for load data and not to much even for that. As always, thanks Veral.                CRASH87

[Veral]

  Thank you for the nice compliment on my book etc.

  I don't believe I mentioned the fact that when shooting bullets cut for gas checks with out gas checks, they perform a bit better if the check shank is full of lube than if left dry.  This if not using case fillers.