Sr 4759

[bullshot]

Gents
Have a new toy HiWall (modern manufacture) in 40-70 sbn 2.1, which is the 45-70 case necked to 40 cal. Been using SR 4759(best results)(22-26gr) along with others and a RCBS 300 CSA boolit weighing 312 gr with my alloy (Boolits weighed) and 50-50 lube. Bore is .408 groove, tried boolits sized .409 and .410. Rifle will shoot 5-6 rounds in one big hole at one hundred yards out of ten and the rest may take the group out to 3-4 in. I have read conflicting reports as to 4759 being position sensitive. I'm thinking this is what is happening. Tried to be consistent as to the loading but I have to load without tipping the rifle up so the best I can do is most of the powder at the boolit base. No crono. I would like to try toilet tissue to hold the powder on top of the primer. Never used fillers. Any ideas or suggestions appreciated.

[canyon-ghost]

I've never has SR 4759 give me that kind of trouble.

[Shiloh]

Used it in .30-06, my sons .30-30, and a .30-40 Krag. No issues at all

Shiloh

[Calamity Jake]

Gents
Have a new toy HiWall (modern manufacture) in 40-70 sbn 2.1, which is the 45-70 case necked to 40 cal. Been using SR 4759(best results)(22-26gr) along with others and a RCBS 300 CSA boolit weighing 312 gr with my alloy (Boolits weighed) and 50-50 lube. Bore is .408 groove, tried boolits sized .409 and .410. Rifle will shoot 5-6 rounds in one big hole at one hundred yards out of ten and the rest may take the group out to 3-4 in. I have read conflicting reports as to 4759 being position sensitive. I'm thinking this is what is happening. Tried to be consistent as to the loading but I have to load without tipping the rifle up so the best I can do is most of the powder at the boolit base. No crono. I would like to try toilet tissue to hold the powder on top of the primer. Never used fillers. Any ideas or suggestions appreciated.

Sounds like bore fouling or lube purging to me, try dry patching it a couple of times during the 10 round string.

[bullshot]

Calamity
I know bore fouling but not the terminology lube purging. Just to be a little more clear on my end. The group does not degrade as the string continues, it is random. For instance three tight, three random, two back in the first three and two more wherever. Try a different powder charge at the same session and do a similar pattern.

[rockrat]

Had some flyers in my 375 H&H, so tried mag primers. Solved that.

[Guesser]

I have had really good success with SR4759 in 45-70, never noticed any of the position sensitivity you mention.

[JeffinNZ]

How is your neck tension?

[runfiverun]

neck tension is a good lead.

you could try less lube on the boolits first and see if it goes away..
if the dispersion were vertical i'd say use a filler.
if it's random left right up down i'd look at the lube or the neck tension.

i'd not use toilet paper as a filler i'd use dacron.

i would also look at how the lube is coming off the boolit, if it's coming off in chunks on the way to the target that will cause random flyers also.
stiffening it to stay in the grooves all the way to impact or softening it to come off all at once at the muzzle.

[bullshot]

JeffinNZ
Runfiverun
I neck size then use a Lyman M die to expand the neck to .408 and .412 at the mouth and no crimp. Not vertical dispersion, its random.

[DLCTEX]

Try a crimp first, then if boolits are good quality and sorted to weight, look to lube.

[cbrick]

I'll thow my voice into the "never had such issues with 4759" and I use it by the 8 pounder.

Agree with the neck tension theory, could be mixed lot brass or brass of different numbers of firings etc, either will give variation in neck tension and bullet movement before the powder is fully ignited. Try a crimp as was suggested by DLCTEX and see if it doesn't at least improve.

It's doubtful that it's the powder, only slightly more likely it's the lube if your using a quality lube.

Rick

[stubshaft]

What weight variance do you cull at?

[bullshot]

CBRICK-- All new brass, all Rem, flash holes uniformed, first firing after fire forming.

[bullshot]

Stubshaft-- 1/2 grain spread.

[Gtek]

Sounds like your close, first I would first confirm Boolits weight and size. Shoot three, push, shoot three to ten and see what happens. Lube?, under 2k Javelina/NRA formula just about covers most our world. I used to do a lot of drag racing and the old guard taught me a rule to live by. " You change more than one thing chasing it, how do you know". Welcome to the madness! Gtek

[curator]

Using 18 grains of SR4759 and the same boolit in my .40-65 Win-Martini. I have no problems like you discribe but did at higher velocities. I had tried wax-gas-check, fillers, and fiber wad but found the lower velocity load solved all problems. I also lube only two of the three lube grooves and shoot air cooled wheel weight alloy at 12 BHN sized to .411. Boolits seated out to kiss the rifling origin when seated.

[runfiverun]

did they do this on the fireforming too?
if so i am gonna say the brass is a bit too soft,i'd try another round on a few if it improves you need to work harden the necks a little bit.
i have had groups open after annealing brass and have had to run them through the neck sizer a couple of times to get things back.
the clue/change here is the new brass.

[bullshot]

Runfiverun--When I fire formed the brass I only loaded five rounds of each powder charge. I used different powders 4198 5744 and 4759. The best was the 4759, so I loaded ten of the loads that looked to have potential all with 4759. Seeing your post I went and looked at the fire forming targets and yes they did show some of the same erratic groups. Being only five round groups it wasn't as obvious. Some of the groups were four tight and one out. Easy to blame other conditions like the guy shooting. On the next trip I will just load the same again an see what happens and then try all the suggestions one at a time. I appreciate all the help from everyone.

[44man]

Runfiverun--When I fire formed the brass I only loaded five rounds of each powder charge. I used different powders 4198 5744 and 4759. The best was the 4759, so I loaded ten of the loads that looked to have potential all with 4759. Seeing your post I went and looked at the fire forming targets and yes they did show some of the same erratic groups. Being only five round groups it wasn't as obvious. Some of the groups were four tight and one out. Easy to blame other conditions like the guy shooting. On the next trip I will just load the same again an see what happens and then try all the suggestions one at a time. I appreciate all the help from everyone.

You have received a bunch of good info. 4759 is not touchy unless it is downloaded too much. It can fail to ignite even with Dacron.
I shoot it in my revolver and I use Dacron but have found little difference if I leave it out.
I use a LP mag primer in the revolver and even in my BPCR with BP.
Accuracy went down with rifle primers.
Brass, new brass can be a problem with neck tension all over the place.
I don't know your alloy but soft lead gives me fliers from the 45-70 revolver, three in one hole and two out. Soft needs a GC for me. I use water dropped WW metal mostly.
It sounds like you are shooting good and just need to solve fliers.
Brass, lube, primers and alloy.
Darn, sounds like starting from scratch, not much left. The bad thing is that changing one thing at a time might not get results.