lee 160-312tl/2600+fps part 2

[Forrest r]

At the same time I tested the pc'd bullets I also made up the same loads to test the traditionally lubed lee 160-312 bullets. Because of the tl design there isn't a lot of lbt lube that goes into the tl grooves. So I did 1 thin coat of 45/45/10 on them also.
https://i.imgur.com/dzDCFfV.jpg

What I found about this bullet/lube combo I never expected. I always thought of bullet lube as a gasket, today sure proved it. I tested the traditional lubed bullets with the same loads I used for the pc'd bullets. 10-shot groups @ 100yds.
https://i.imgur.com/y5CttId.jpg?1

The brass was range pick-ups/mixed nato, the bullets were not sorted for defects. Cast them and picked out any obvious flaws, no sorting. The H335 powder isn't the greatest for cast bullets. And the primers were I have no idea how old magnum large rifle primers. A pillow stuffing filler was used with all loads, lightly packed to the bottom of the neck of the case. The traditional lubed 34gr/35gr 10-shot groups were 2 1/2" outside to outside. The 36gr loads went south and the 37gr loads were all over the place.

The rifle I used was an old puma rifle I just re-barreled and bedded. This was the 1st outing with it. I did test the bbl before I bedded it the other day. It's a 30" bbl and it usually takes 1 round for every inch of bbl to season a clean bbl. This is what the muzzle looked like after 14 shots with traditionally lubed bullets.
https://i.imgur.com/bydam1r.jpg

The bbl is slick, real slick with a taper at the muzzle. Shot fouling shots and 40 pc'd test loads 1st. Then more fouling shots and 40 traditional test loads. There was no leading in the bbl, it cleaned up with 2 wet patches, a couple of passes with a nylon brush and a couple dry patches.

What was surprising to me was that the lube failed but there was no leading. Both bullets had gc's installed the same way from the same batch of al (home made). There just wasn't enough lube to seal the bbl but there was enough to keep it from leading.

Results from 10-shot strings pc'd bullet and traditional lubed bullet both sized to .311" cast from the same casting session/same pot of ally/same batch (1 20# pot). All bullets got gc's installed at the same time from the same batch of home made al gc's. The pc'd bullets got pc's and then sized in a lee push thru sizer. The traditional lubed bullets got sized in a lyman 450 sizer (lbt blue) and a coat of 45/45/10 applied.

34gr of H335
pc'd bullet 2489fps lubed bullet 2464fps
sd 25.3fps sd 15.7fps
es 75fps es 50fps

35gr of H335
pc'd bullet 2550fps lubed bullet 2536fps
sd 15.1fps sd 11.7fps
es 49fps es 34fps

36gr of H335
pc'd bullet 2610fps lubed bullet 2574fps
sd 15.6fps sd 21.4fps
es 47fps es 55fps

37gr of H335
pc'd bullet 2679fps lubed bullet 2617fps
sd 11fps sd 16.6fps
es 29fps es 58fps

As you can see as the powder/pressure/load went up the traditionally lubed bullets failed. The 37gr load couldn't hold 10 shots on the paper. The was also a loss in velocity and the sd/es climbed. While the best group of the day was with the pc'd bullet/37gr combo, it did 2 1/4" outside to outside. While 2" groups are not that great I'm sure they could get tightened up a little tweaking and some actual bullet culling.

I plan on giving the bullets a 2nd/thick coat of the 45/45/10 and re-testing the 36gr and 37 gr loads.

These bullets had a gc on them, there was no leading in the bbl. But the lube failed because there just wasn't enough of it there to seal the bbl with the higher pressure loads. Figured I'd keep using H335 for awhile, faster learning curve.

Just some interesting results for the 1st time out with the new bbl.

[runfiverun]

if gas can cut a solid it can surely cut through a piece of soft wax.
all a tumble lube does is act as a barrier between the lead and the steel.

you actually made a good choice in boolit design, the regular lube groove design of that one is horribly balanced and has a poorly placed COG.

[Oklahoma Rebel]

I might have missed it, but what alloy? and you said that boolit is better than the 155, with the 1 bigger groove? now say I was shootin a 375ruger-416ruger with 1-14 twist, at a max of 2200fps, would the one groove , then crimp groove design be ok?i am looking at accurate's #41-350L and #41-400L. with proper sizing and a medium/ slow powder ( rel 15 , 4064) would those designs be decent for 150-200 yard max shooting, with 75-100 on hogs and deer being average? also I was looking at a#38-290S TC design increased in diameter and length to fit the 416's. whats your opinion on those boolit designs. thanks for listening! original poster, amazing results for the first powder tryouts!!! especially considering your speeds...... you may be tempting me to sneak over to the dark side... powder coating! thanks again-Travis

[Forrest r]

It's a 4 to 1 alloy/ 4parts range scrap 1 part mono-type that is water dropped.

Any time you have large deep cuts in a bullet ie: lube grooves/wiper grooves/crimp grooves. It weakens the bullet where it counts the most, at the beginning of the shot. The nose of the bullet is in the lands moving rotating (torque) while the back of the bullet is in the case/ball throat/freebore being pushed forward as it swells/seals/grabs everything it comes in contact with. The end result is the back of the bullet is expanded/holding pushed strait while the front of the bullet is being twisted like wringing water out of a towel. Up the pressure & it up's the torque.

There was a group of people who did a study and designed a bullet for hv high power rifles, the xcb bullet. The lee 312-160tl reminds me of that xcb bullet that neo makes the mold for.

I couldn't answer you about your bullet selections and velocities are always well, a question. 2200fps out of a 16" bbl takes a lot different load then a 2200fps load in a 30" bbl. Sounds like you need to start a thread on alloy vs bullet design vs pressure/torque. You alway's do well with the threads you start.

Not much help, sorry

[runfiverun]

the single groove in this case is a poor design it is not a design fault being exploited.

the long sided designs like the T/L design suffer from alloy flow and trailing edge failures.
even Harry Pope knew this in 1905.
he later designed a 200 yard scheutzen bullet with a tapered shape [loverign] and the bottom drive band was back tapered to allow the displaced alloy to not extend past the base of the bullet.
this design was copied and altered slightly to have a stop ring at the base which done the same thing as the reverse taper of Popes design.
Lyman of course altered the critical feature when copying it.

you can go pretty far with easy.
but when you want to go all the way to the end of the rabbit hole you have to look a lot closer at what is really happening and not jump to the first thing you see that is different.

[Oklahoma Rebel]

well, its ok, I designed a 2 groove using the 38-290C (truncated cone, single lube groove) to have to .08 lube grooves, plus the part in front of the GC. the bottom 2 drive bands are .1 and the top one is .12