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Re: 6x45 Contender Rifle

Posted: Tue Jun 23, 2015 9:56 am
by mtngun
Update: after giving the Bellm bolt spring a workout in the 357 barrel, it was noticeably stronger than the Wolff spring so I put a Bellm spring in the 6x45 barrel, too. Eventually all my TC barrels will have Bellm bolt springs.

Re: 6x45 Contender Rifle

Posted: Sat Jun 27, 2015 6:01 pm
by mtngun
Today we tested a new plain base bullet. Why plain base? Just because I don't have much experience with plain base bullets in rifles, so I see it as a learning experience. I like to try different things and see what works and what doesn't.

Since my 357 barrel is shooting plain base decently at 2000 fps, I assumed plain base would work in this barrel at 2000 fps, too, so I loaded accordingly. Unless otherwise stated, all of today's loads used oven treated WW, sized 0.246" and nose-sized, Rooster HVR lube, CCI #41 primers, and 0.010" jump to the rifling.

20 gr. IMR 4350:
-- 1813 fps
-- 1.55% velocity standard deviation
-- 8 shots in 2.85" at 100 yards (the other two cartridges were duds)
-- no visible fouling

22 gr. IMR 4350:
-- 2066 fps
-- 2.09% velocity standard deviation
-- 9 shots in 20", the other 2 missed the target :o
-- no visible fouling

21.1 gr. WW 760:
-- 2184 fps
-- 2.73% velocity standard deviation
-- only 2 shots even hit the target :lol: :lol: :lol:
-- no visible fouling, and no lead on a tight fitting patch.

One group at 1813 fps, the other shots at 2100 fps are a wild pattern, with some completely missing the target.

Conclusions and Lessons Learned:
-- what the heck ? :lol:
-- why does my 357 barrel shoot plain base decently at 2000 fps but the 6x45 barrel, which is a better quality barrel, can't keep plain base on the target at 2000 fps?
-- there was no fouling to be seen, so if they didn't fail due to fouling, then how did they fail ?
-- I don't know the answers, but I'd like to find out because whatever is messing with these plain base loads is probably messing with my gas check loads, too.

Things to Try Next Time
-- keep velocities below 1800 fps
-- possibly use a faster burning powder because the standard deviation was awful with 4350 and 760.

Re: 6x45 Contender Rifle

Posted: Sun Oct 11, 2015 6:17 pm
by mtngun
Water tank experiment with plain base bullet.

The only thing I could see wrong was some erosion at the corner of the base of the bullet. Maybe it got a little too hot and began to melt or gas cut?

Things to try with plain base next time:
-- water tank experiment with even higher velocity to magnify whatever is going wrong
-- soft check
-- coating to keep the base from melting

Of course I could simply use gas checks, but I'm curious to learn how fast plain base can be driven and how they fail.

Re: 6x45 Contender Rifle

Posted: Wed Nov 04, 2015 7:31 pm
by mtngun
Bases painted with epoxy spray paint. These are plain base, not gas check.

I started out with the same charge that couldn't even hit the target backer last time:
-- 22 gr. IMR4350
-- CCI #41 primer
-- 2.300" COL (right at jam)
-- WW oven treated, ~ 25 BHN
-- sized 0.245" x 0.2385"
-- HVR lube
-- 1927 fps but the chrono was uncooperative and only measured 3 shots. Last time this load clocked 2066 fps.

OK, so at least the painted bases hit the target. That's a definite improvement compared to missing the target. :lol:

Then I upped the powder charge to 24 gr. IMR4350. Fortunately the chrono decided to cooperate and the load averaged 2185 fps, 2.04% standard deviation. 4 shots were in a decent group but there was one bad flyer. :( Still, there's no doubt that the painted bases performed better than unpainted bases.
I had intended to shoot more groups comparing painted bases vs. unpainted, but gave up because of the chrono problems and I was running out of daylight anyway. I'll try to get the chrono working better and then repeat the comparison test to make sure it wasn't a fluke.

Re: 6x45 Contender Rifle

Posted: Thu Nov 12, 2015 8:29 pm
by mtngun
The winter storms subsided long enough to let me do a little shooting today. Temperature outside was in the low 20's (F) but a small electric heater kept the shooting shack 50 - 60 degrees. Not as warm as I would like, but tolerable. 8-)

Today's goal was to continue testing plain base bullets with coatings. Why plain base bullets? Because if I can figure out how to make plain base bullets work at high velocity then gas check bullets should be a piece of cake, right? 8-)

We used the same basic 24 gr. IMR4350 load for all of today's tests, only the coating changed. I chose the 24 grain load because it seems to push the plain base bullets fast enough to be right on the ragged edge of failing. No sane person would choose a load that is right on the ragged edge of failing but such a load is ideal for a crazy experimenter because it is sensitive to small improvements or un-improvements. :lol:

I made new fixtures to hold the bullets base-up while I spray painted them. Most people stand bullets on their bases to coat them, naturally I do the opposite and stand them on their nose. :lol: The idea is that the base needs protection more than the nose.

I also tried shake-and-dry Minwax polycrylic. I had tried polycrylic previously full strength, but it was too thick and too slow to dry, so this time I thinned the polycrylic with 5 parts alcohol to 1 part polycrylic. Even so it was still a bit thicker than ideal so if I do it again I'll thin it even more, perhaps 7:1.
To avoid problems with coating being damaged by oven heat treating, I heat treated the bullets first, then coated them and let them air dry for several days. I applied 3 very thin coats. Most of the coatings added a total of 0.001" - 0.0015" diameter but the Rustoleum enamal added 0.003" - 0.004". I don't think it is good for it to be that thick. :? I resized the bullets 0.245" after the coating dried. Sometimes the Rustoleum would rub off a little during re-sizing. None of the other coatings rubbed off.

Continued .....

Re: 6x45 Contender Rifle

Posted: Thu Nov 12, 2015 8:43 pm
by mtngun
Unless otherwise stated, all of today's loads were:
-- 24 gr. IMR 4350
-- CCI #41 primer
-- oven treated ~ 25 BHN
-- HVR lube in addition to any coating
-- re-sized 0.245" after coating
-- nose sized slightly
-- seated right at the jam point

Because I used several different batches of bullets that had been sized at different times, the amount of nose-sizing varied. In the future I'll try to standardize on a common nose-size setting.
-- Hi-Tek bullet 0.2405" on front band, jam at 2.288" COL
-- Rustoleum 0.2415" on the front band, jam at 2.259" COL
-- uncoated 0.2400" on the front band, jam at 2.275" COL
-- epoxy bases 0.2385" on the front band, jam at 2.300" COL
-- polycrylic 0.242" on the front band, jam at 2.252" COL

Here is the first target.
-- to my astonishment the uncoated bullet shot a decent group. :o
-- the polycrylic coating performed best though not enough shots were fired to "prove" a significant difference.
-- Hi-Tek & HVR did surprisingly well despite the Hi-Tek bullets being softer (~ 15 BHN)
-- I could not detect any leading with any of the bullets, not even the uncoated bullet. No visible leading, no specs of lead on a tight fitting patch.

Continued .....

Re: 6x45 Contender Rifle

Posted: Thu Nov 12, 2015 9:13 pm
by mtngun
Next up the red Rustoleum enamel. As mentioned previously, the Rustoleum came out too thick, and then it partially rubbed off while re-sizing. I did not expect the Rustoleum to perform well and indeed it did not.

It couldn't even keep all its shots on the target backer. I gave up after 10 shots because obviously it was a lost cause.

The puzzling thing is that when I tested uncoated plain base bullets back in June, they wouldn't even stay on the target above 2000 fps. So how come they shot one decent group earlier today ??? :?: I dunno, so I retested the uncoated bullets to see if it was repeatable. No, they shot wild. What the heck is going on? :roll:

I was starting to wonder if the scope had gone haywire, so for a sanity check I shot a string of 46 grain gas check bullets left over from a previous experiment. The 46 grainers had shot 2.5" - 4.4" groups previously so I was confident they should at least hit the target if the scope was good. :mrgreen: Loaded over the same 24 gr. 4350 charge that I used for everything else today.

Not a great group but at least it's a group so it appears the scope is OK. It's a Weaver T36 by the way, a decent scope.

Continued ....

Re: 6x45 Contender Rifle

Posted: Thu Nov 12, 2015 9:42 pm
by mtngun
I forgot to mention that I made some progress with the chronograph problems I was having last time. I found one broken LED in the lights. Problem was that the LED's are wired in series so the one broken LED killed the entire series. I patched across the broken LED to restore the series and it seems to work, today the chrono recorded every single shot, yea ! 8-)

Today's Velocity Stats
-- uncoated good group 2147 fps, 1.38% standard deviation
-- uncoated wild group, 2184 fps, 2.16% standard deviation
-- epoxy bases & HVR, 2171 fps, 1.23% standard deviation
-- polycrylic & HVR, 2153 fps, 1.48% standard deviation
-- Hi-Tek & HVR, 2111 fps, 1.95% standard deviation
-- Rustoleum & HVR, 2145 fps, 2.05% standard deviation

Obervations, Questions, and Lessons Learned:
-- I have no clue why the uncoated plain base shot one good group but other times can't stay on the target. :|
-- Rustoleum enamel is a no-go.
-- Hi-Tek showed some potential
-- polycrylic showed some potential

Things to Try Next Time:
-- try to standardize the nose-sizing for a 0.242" front band.
-- I have a couple more coatings to try yet
-- test Hi-Tek with no lube
-- test Hi-Tek with linotype and/or Lyman #2, since it is not possible to heat treat Hi-Tek bullets
-- test polycrylic with 45 BHN reclaimed shot
-- test polycrylic with no lube
-- keep retesting uncoated plain base with the hope that I can figure out why it is so inconsistent?

Re: 6x45 Contender Rifle

Posted: Sat Nov 21, 2015 7:03 pm
by mtngun
More Coating Tests. Once again I'm sticking with the same load even though it is not an optimized load, because I'm trying to test the coatings, not the load. ;)

All of today's loads used:
-- plain base or bevel base spitzer
-- 62 grains in wheelweight or 58 grains in lino
-- 24 gr. IMR 4350
-- CCI #41 primer
-- seated right at the jam point
-- sized 0.246" after coating
-- nose sized so that front band was 0.242" on plain base or 0.2415" on bevel base (same setting on nose die).
-- 10 shot groups at 100 yards, but some groups had only 9 shots because there were several dud primers today.

First up, VHT rattle can epoxy plus HVR lube on the plain base bullet. You have to admit it's pretty. :lol: This wheelweight bullet was oven treated at 475F before coating.

-- 2149 fps
-- 1.50% velocity standard deviation
-- mean radius = 0.81"

Next, a lino plain base, hi-tek coating, plus HVR lube.
-- 2185 fps
-- 1.70% velocity standard deviation
-- mean radius = 1.00"

Next, a lino bevel base, hi-tek coating, without lube.
-- 2181 fps
-- 1.27% velocity standard deviation
-- mean radius = 1.07"

Next, air-cooled wheelweight plain base, hi-tek coating, plus HVR lube
-- 2101 fps
-- 1.63% velocity standard deviation
-- mean radius = 0.95"

Today's target. No bragging size groups, but no wild groups, either. The accuracy differences between coatings were too small to be considered significant.

Observations, Conclusions, and Questions:
-- VHT rattle can epoxy seems to be a satisfactory coating, at least at this velocity.
-- Hi-Tek seems to be a satisfactory coating, at least at this velocity.
-- Hi-Tek seems to shoot equally well with or without lube
-- when both are coated with Hi-Tek, air-cooled WW seemed to be just as accurate as lino (at this velocity). I was surprised. :o
-- none of today's loads leaded the barrel. No leading visible to the naked eye, and no lead specs on a tight fitting patch.
-- the only bad thing about the coated air-cooled bullets was that velocity was 48 fps slower. :(
-- in general, most of the coatings improve accuracy at this velocity compared to an uncoated bullet. Bear in mind that the uncoated bullet sometimes struggled to stay on the target with this powder charge.

Things to Try Next Time:
-- there's a couple more coatings I want to try
-- continue comparing lube vs. no lube with various coatings
-- continue comparing air-cooled vs. heat treated with various coatings
-- more water tank autopsies when the weather permits
-- once I settle on a pet coating combo, I'll try ramping up the velocity.

Re: 6x45 Contender Rifle

Posted: Sun Nov 22, 2015 5:56 pm
by mtngun
Testing another coating, with the usual bullet and load. 3 very light coats of rattle can polyurethane. The 3 combined coats added about 0.001" to the diameter.

-- 62 gr. flat base @25 BHN
-- 24 gr. IMR4350
-- CCI #41 primer
-- sized 0.246" x 0.2415"
-- seated right at the jam point
-- lubed with HVR

I fired one fouling shot, then 21 shots on paper. As often seems to happen with coated bullets, the first group from a clean barrel was not so great, but it seemed to shoot better after it was well seasoned.

-- mean radius = 0.83"
-- 2081 fps
-- 1.65% velocity standard deviation
-- no leading

Conclusions, Observations, and Questions:
-- accuracy was about the same as the other decent coatings
-- velocity was nearly 100 fps lower than other coatings. That may simply be due to temperature because IMR4350 is temperature sensitive and it was a little cooler in the shooting shack today.
-- I imagine that rather than using rattle can urethane, you could probably get equal results by shake & dry with highly thinned liquid urethane. It would cheaper in the long run, and no special fixture would be required.

Things To Try Next Time
-- I don't have any more coatings that I want to try at the moment,
-- I'm not going to powder coat at this time because I haven't been happy with shake & bake powder coat, and I'm not currently set up with a powder coat gun. Maybe someday. :)
-- retest polycrylic without lube.
-- retest polycrylic with air-cooled WW rather than heat treated WW.

The reason I want to do more tests with polycrylic is because I'm leaning toward making it my standard coating. It's cheap, easy, and I like the invisible look. But it remains to be seen if it will shoot as well as Hi-Tek without lube and without hardening.