30-06 Throat with LFN

[levernut]

Veral,
After trying many things to get my Ruger 77 30-06 to shoot bullets from my LBT mold, I am going to have the throat reamed with a short freebore followed by a 1 1/2 degree taper.  The freebore needs to accept a .313 diameter bullet in order to fill the chamber in the neck area.  With a freebore of maybe .314 diameter, will a jacketed bullet shoot accurately?  Groove diamter is .3085.
Thanks in advance for your reply.

[Veral]

  Jacketed bullets are very forgiving, and especially long ones.  I have an elderly 30-06 enfield with the throat worn to .316 at the origin, and so long that no normal jacketed bullet can be seated to touch the rifing.  Yet it is very accurate.  The last time I took an animal with it I used a 165 gr boattail to fold an elk at about 500 yards. (That was the last boattail bullet I will ever use on game.)  I'm telling about it because it was about as bad a bullet as one can get for such a huge throat, but it hit the elk behind the foreleg 'exactly' where I was holding for. (Exactly on big game at this range, means in a 6 inch circle when I'm talking.)
  If you find accuracy inferior with jacketed, seat your bullets a bit farther than normally recommended off the lands, then crimp your rounds with the Lee factory crimp die.  If the bullet isn't long enough so the crimp can be well away from the ends of the bearing surface, don't use the crimp.  If it lands somewhere in the middle, leaving at least 3/16 inch of bearing surface undeformed, the crimp will help center the bullet base.  The crimp should be just deep enough that the remaining crimp on a fired case will offer some resistence to a jacketed bullet when inserted with the fingers.  In other words, the crimp becomes a centering collet for the bullet.

  Never use the pistol lee factory crimp dies for any lead bullet.  They are an entirely different animal than the dies for rifle cartridges.  My recommendations are ONLY for the rifle type.

[levernut]

Veral,
I had my Ruger re-throated with a .310 dia x .200 long freebore followed with a 1 degree throat.  I sized my .310-170-LFN-GC bullets to .3095 and seated them to touch the rifling.  Bullet hardness was 13 for the first group and 23 for the second group.  I used a mild load of H414 (same as W760) and shot them at 100 yards with a 8x scope.  Velocity was not chronographed but was probably around 2500 fps.  I also shot a group with BHN 13 bullets using 2400 powder at 2000 fps.  Group sizes with the H414 powder was 15.00 to 16.00 inches (yes, the decimal is in the right place).  Group size with the 2400 powder was 5.00 inches.
This rifle has been fire lapped and is very smooth and restriction free.  Before having the freebore, the rifle grouped 6.00-9.00 inches at 100 yards.  I was hoping for a tack driver but haven't found the magic formula yet.  Any suggestions?

[Veral]

  From what you are telling me, your rifle should print that bullet into an inch with any mild load, and probably far tighter, like a quarter inch.

  So I'm stumped at this point.  Send me a half dozen sized and lubed bullets like you did your shooting with.  Don't sort out just the finest, make sure it is a lot like you shot.  I'll inspect and let you know what I can learn.

[levernut]

Veral,
As you requested, I sent some sized and lubed bullets on Sept 16.  I also sent some 44 mag bullets since I am having similar problems with my Marlin.  I'm looking forward to your findings.
In the meantime, I shot the 30-06 with jacketed bullets just to see the effect of the new throat.  Before re-throating, this load patterened three shots 1.50 inches c-c at 100 yds.  After throating, the same load grouped .63 c-c at 100 yds.  I hope we can get the cast bullets to do the same!

[Veral]

  I received your sample bullets and order for a mold, and have shipped the mold along with brief answers, but have saved the details for this forum.
  With visual inspection your bullet samples were of excellent quality and workmanship.  So I chucked them in a lathe and run a dial indicator against the edge where your Lyman sizer stop plugs made contact with, and made their impression on the gas checks.  It is visable by a fine relitively sharp line right at the edges of the checks when viewed straight at the bottom.  Out of square varied from nothing up to .0025 which was the runout of the stop plugs which I believe you use to size the two diameters of bullets which you sent.  The variation was caused by the amount of pressure you applied at the bottom of the stroke when you sized.  Those which barely hit bottom, were marked least and squarest.  Those with a very legable imprint were out to match the plugs.  Such is normal for all casters who aren't alert of this concern.

  Of the 8 stop plugs which you sent for me to machine, one was flat, and I suppose from RCBS, one was cupped and had a tiny flat around the edge, which is what I recommend, and is how I machined all of them.  I didn't bother checking for squareness on the flat plug or the one which appeared to have been machined per my recommendations.  I just machined them all so I knew they were right, and returned them with your mold.
 
  So the importance of perfectly square bases on cast bullets is understood, consider what would happen if these bullet samples which you sent were shot from a gun with a similarly out of square muzzle.  Some of the bullets would exit with the effect of perfectly square bases, some with an out of squareness of .005, and you'd seed the results clearly on target.  A perfectly squared muzzle, which is rare, would show the least problems on target, while one that was more out of square would be slightly worse than if it's out of square matched the maximum out of square of ones bullets.

  To use the remachined stop plugs properly, apply enough pressure at the bottom of your sizer stroke to get a ring at least 80% of the way around your bullet bases.  Whether GC or PB bullets.  These perfectly square bullet bases, if not knocked out of square from something wrong in the guns throating or excessive loads will be imune to an out of square muzzle.

  The bullets you sent were of higher quality than I expected to get.  Out of squareness is often as much as .015 thousandths, so my answer previously may not be as precisely right as I hoped for.

  The ball is now in your court!  Bounce it back by posting the results you get. 

[levernut]

Veral,
I used the stop plugs to size some more bullets for the 30-06 with the special cast bullet throat.  With enough of H-414 to shoot at about 2400 or 2500 fps, groups were just good enough to get one or two shots out of four on a 32 inch x 32 inch board at 100 yards.  Then I shot four loads with Universal powder at about 1500 fps and the group was 3.00 c-c at 100 yds.  Something is bad wrong here but I don't know what it is, but I'm about ready to give it up to jacketed bullets.    What about your glue on patch mold?  Is this a fix all?

[levernut]

Veral,
An update.  Previously, I checked restrictions in the bore by using some homeade lead slugs.  These pushed through smoothly so I thought everything was OK.  Then after reading some details about your push through slugs, I purchased some and received them yesterday.  After cleaning the bore, I ran two different slugs through it.  There was still some copper fouling on the lands but no visible lead or powder residue.  It was very jerky all the way and the slug got stuck at the muzzle.  It was stuck enough that I had to thump the handle of the cleaning rod in order to get it out.  The muzzle was re-crowned when I had the throat modified so maybe this caused the restriction.  When I used my homeade slugs to check the bore, I pushed from muzzle to breech which would have hidden any muzzle restriction and made the slug undersized, which in turn let the slug push through easily.  The bore feels super smooth when I clean it and it looks great, but the slug tells differently.  It looks like I've got some lapping to do.

[Veral]

  You have just learned why I developed my push through slugs!
  You will be done lapping when one goes smoothly from breech to muzzle.  No jerks or loose spots, just steady light pressure after the first bump to engrave the rifling at the throat.
  Keep us posted!

[levernut]

Veral,
OK, I shot 25 lap loads through the barrel then checked it with one of your push through slugs.  It was smooth but I shot 25 more to make sure.  Then I broke in the barrel and shot for groups.  With H-4895 powder I got 6 inch groups at 75 yards.  The load probably shot around 2400 fps.  The groove diameter opened up to .309 after the lapping so I shot .310 bullets at BHN 12.  I also shot some loads with H414 (W760) and couldn't keep all the shots on the 32 x 32 inch board, just like before I lapped the bore.  Remember, this throat has the free bore like you recommended so it should shoot really well.  I'm getting beat at this game.  I'm ready to trade my mold for a Glue On Patch mold.  Do you recommend this?  If not, then what do you recommend?

[Veral]

  Have you tried it with harder alloy.  20 bhn, which is water dropped WW alloy, one day or more after casting.
  In my experiance with 30-06 and soft (12 BHN) bullets, 2400 fps is obtainable if everything is perfect about the throat, bullet etc. but by using the slowest powders.  Even incresing hardness to 16 bhn will make a dramatic difference in the amount of pressure that can be put behind the bullet, yet that hardness will expand well on game, if that is one of your concerns.

  At this point I'm sceptic about glue on patch with this rifle for two reasons.  !. I've recently had some poor customer feedback when a large throated rifle was used. 2. If you can't make the bullet you have shoot, and it should drive tacks at some speed, then just trying a glue on patch bullet in a gun that has proven itself to have a problem, would be a wild guess.  I have a strong aversion to guessing while buying molds, and an even stronger dislike for selling molds on a guess!

  Cast bullets are a mechanical thing and the answers are all scientifically precise.  We need to find your real problem here first.  You have really jumped through a bunch of hoops with this rifle, done everything I have suggested,  and have prooven it accurate with jacketed.  Also the sample cast bullets you sent for me to inspect were of excellent quality, and should shoot very well.

  Have you made a throat slug since having the gun rethroated?  If not, I believe a throat slug, laid alongside your cast loads, and perhaps with some precise measuring, will show a distinct problem that can be fixed.  Definately the fastest way for you and me to work this thing out is for you to email me direct, rather than posting your questions, because I try to answer emails every night, though I sometimes skip a day.  But the forum, I often don't look at for more than a week.  Once we find the solution we can jump back on the forum and inform everyone of the findings.

  You see, what really bugs me is the fact that I've never seen a rifle that I couldn't have shooting cast into tight groups if I had it in my hands for a while.  Normally the first bullet mold I make, and first loads will not shoot over 1 1/2 inchs at 100 yards, and often go into a half inch.  Therefore, I'm convinced we are missing some critical thing here in our correspondence, and I'd like to get a choke hold on it quick like.  So don't give up yet.  Hit me by email, and let me know about a throat slug.  We'll go from there fast as possible.  Don't waste any more of your time, primers and powder experimenting, except to try good hard bullets with the powders you named above, or the slowest power suited to the 06 behind your soft slugs.  If you try the slower powder, start with a charge that predicts maybe 2200 fps, and several higher till you find the velocity where accuracy goes south.

[jk3006]

Levernut,

You said you have a .310 throat now, right?  Are those .310 bullets a snug enough fit, or is there some room still to size them bigger?  .001 can make a big difference.

Also, try some slow burning powder like 4350 (like about 48-50 grains of it) with some polyester dacron (about 1 grain) to take up that lost powder space.  My gun didn't like 4895 in my testing.  Try at least 3 different primers if you haven't already.  I've found that can halve group sizes.  Make sure that the bullet is seated to just touching the lands.  And, of course, get those bullets harder (around 20-25 bhn, like Veral mentioned).  I shoot a 200 grain (actual weight) LBT spitzer in my '06 at around 2400 fps.  Groups are usually pretty good.    

[Veral]

  I don't recommend dacron fillered loads unless enough is used to fill the case up to the bullet, as they are known to frequently ring barrels.  The air space between filler and bullet causes the problem.  Use a filler that fills the case to the bullet.  Best I've used is plastic shot buffer, but cornmeal or cream of wheat both work great, just harder to get the right amount in.  With granulated buffer the case can be filled to the brim and compressed with the bullet.