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Post by boolitdesigner on Jan 17, 2017 22:14:58 GMT -5
Thanks Fermin! I'm looking forward to more when you get around to it. I have a 25-20 single shot rifle that needs a workout sometime this spring.
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Post by 38 WCF on May 24, 2017 18:47:27 GMT -5
Even so, there is still no way to flare the case mouth for cast. I made an expander plug, similar to the RCBS pistol neck expander dies for the 25-20. It works quite well for cast. Any pistol neck expander die and plug can probably serve as materials for one. I am using a Lyman 25 M die with excellent results on my 257 JR.
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Post by cherokeetracker on May 28, 2017 16:10:31 GMT -5
Even so, there is still no way to flare the case mouth for cast. I made an expander plug, similar to the RCBS pistol neck expander dies for the 25-20. It works quite well for cast. Any pistol neck expander die and plug can probably serve as materials for one. I am using a Lyman 25 M die with excellent results on my 257 JR.
Yep I used to use a 357 die and just bump the 30-30 cases. Many years before the so called "cowboy dies" came along,,,, As my Daddy always said : Where there's a will, There's usually an in-law.
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Post by 2 Dogs on Oct 20, 2017 11:13:32 GMT -5
Good Grief already! I have had this test ammunition loaded for MONTHS! I finally got a chance to get out and shoot it. Just to bring you back up to speed, the 257 Jackrabbit while displaying very good accuracy has also displayed pretty wild velocity swings. I am quite sure this can only be attributed to powder position sensitivity as I have even gone through the trouble to have a custom crimp die built to eliminate bullet crimp as a suspect cause.
Now, in the meanwhile, my buddy Rodd O, who is also a forum member here also had a .257 Jackrabbit built. The difference between his and mine is he used the factory cylinder (rechambered) and mine is a longer heavier oversized custom unit. As I have said before, if you decide to go the route I did, just build a 25-20! Rod has worked with quite a few powders and has been plagued with case set back at relative lower velocity compared to my unit. I made a few suggestions to Rod to address the case set back. He called me after and reported that the case set back he "should" have experienced (he loaded a load that he expected to set back but made absolutely sure the case was free of any lube) did not happen. What did happen however, was his velocity went DOWN! That was unexpected to say the least.
A couple days later I also shot my 257 JR with Lil Gun and the Miha 55 grain GCHP. I have been working up in 1/2 grain increments to see if I could find what "maximum" for my little sixgun would be. Here is what I saw:
12.5 Lil Gun 1528/1495/1568/1546/1508
13.0 Lil Gun 1472/1534/1541/1498/1552
13.5 Lil Gun 1581/1507/1500/1508/1509
Again, at 12 grains of Lil Gun, I was seeing 1587 to 1765 for a spread of 178 fps! This was far more stable, but the speed went down instead of up!
So, with the Jackrabbit, we might have reached the point where we have enough powder in the case where powder positioning is no longer a factor. This is way different that what Huey has seen in his 250 GNR where everything has worked wonderfully for him. I mean the guy has tried everything but dried Yak poop with fantastic results. My plan from here is to continue to work up to see where I land as to maximum. None of the above loads showed the slightest hint of any pressure in MY gun. YOURS might be different.
I also spoke to Lee, the option to grind and "improved" reamer still exists for us. So lets see where the standard JR takes us for now. Sorry this has taken so long. Lots of unforeseen circumstances have interfered with my shooting not the least to mention the dang hurricane.Thanks for staying with me.
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Post by Encore64 on Oct 20, 2017 11:37:43 GMT -5
Good stuff Fermin. But, keep in mind, the reciprocal is also true. Another gun in 250 GNR may give different results than mine.
I've thought about this a lot. Probably too much. A few things that may prove different.
1) The 250 GNR is straight tapered with a sharp shoulder. Sort of a tiny little Ackley Improved.
2) The case of the 32 Mag is very thick and strong. Lee has correctly pointed out several times that neck tension is beneficial to proper ignition and powder burn. I also resized loaded ammo for uniform/max neck tension.
3) J.D. Jones told me years ago that seating the base of the bullet to the bottom of the neck stabilized ballistics in pistol length barrels. We were discussing TCs, but could matter here.
4) The straight walls of the 250 GNR helps reduce setback before pressure becomes high enough for uniform pressures.
In the end, just thoughts. I have no way to prove or disprove any of this.
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Post by blacktailslayer on Oct 20, 2017 14:37:59 GMT -5
This is good info, thanks for the update. Stay the path!!!!
Don D.
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Post by 2 Dogs on Oct 20, 2017 20:29:13 GMT -5
I have to hurry. I am almost out of time. Hunting season is getting closer and closer. With it comes the Holidays and all the associated cheer and what not. I went out and shot the .257 Jackrabbit again today. I took my reloading press, powder measure and chronograph. My intention was to see if I found case set back (maximum powder charge) or if I ran out of case capacity first using Lil Gun. As fate would have it, I went all the way past compressed powder charges to where when I seated a cast slug on the Lil Gun, the compressed charge was pushing the cast bullet back out of the case. Maximum speed achieved was 1625 fps BUT it did climb in a linear manner with only one round of the several I fired showing a slower speed than the others. There were no spikes however. There were also no signs of excessive pressure. Primers were fine and cases extracted normally. I will weigh and edit in that powder charge here in a while.
This is interesting. This tells me Lil Gun with a 55 grain bullet is too slow for the .257 Jackrabbit. This indicates I need a "faster" powder. I went back and reviewed my notes with H110 and saw that I quit H110 at 9.5 grains on 12-28-2015 and went to Lil Gun. At that time, I was running a 60 grain Jacketed bullet. So what I think now is that VOLUME is a factor. So, I am going to start again with H110 at 10.0 grains and work up in 1/2 grain increments and when I reach the point where velocity DROPS, that might be an indicator I have the volume right. Then the question will be at what point or powder charge will I get case set back? And if I drop the charge 1/2 grain from that point, how fast will my 55 grain MIHA GCHP be going?
Now, I got a couple PMs from Bob K.... He think I need to change powders. After today, I can see he is correct. (really, does the guy have like a crystal ball or some such?) His input is always golden. Thanks Bob. Anybody else got 2 cents worth?
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Post by cherokeetracker on Oct 21, 2017 7:32:19 GMT -5
Yes my 2 cents worth is this! 12.5 grs should do you just about right. At 13.0 grs you are going to be at 100% case capacity but you will be over pressured for that setup. I would start about 11.0 grains. You and I know that Alan used 9.5 grains and the target looked good. So this is also where I would be paying close attention. I go to leave and I did not get a chance to run numbers, but N105 is the slowest of the Pistol powders from Vihtavouri. If H110 did not or does not work, then that would be my next try. Take 2 billfolds to LGS when you want to buy some. 2 cents 3 cents nosense who counts among friends.
Charles
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Post by 2 Dogs on Oct 21, 2017 21:41:30 GMT -5
Thanks Charles.
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Post by dougader on Oct 21, 2017 22:03:18 GMT -5
N110?
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Post by 2 Dogs on Oct 22, 2017 9:00:19 GMT -5
That would be a hard powder to find in S. Texas....
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Post by cherokeetracker on Oct 22, 2017 10:00:21 GMT -5
N110 Forget about it.... No, It is not a good powder for this application. Maxed out or even with a compressed load, velocity is not there. Fermin : I did get a chance to run some info with the 55gr GT bullets this morning. Actually you can squeeze more, than the 12.5 grs like I previously thought. You might be able to go to 13.5 While 14.0 grs is going to give you the 100% fill,,, the pressure is going up to where were I would not be comfortable with. Food for thought. While the 25-20 is rated for 39160 PSI I would not really want to go that high with the jackrabbit. Charles
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Post by Encore64 on Oct 22, 2017 10:02:51 GMT -5
2400 might be worth trying. Especially with light bullets.
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Post by dougader on Oct 22, 2017 10:13:16 GMT -5
I can't remember if you've tried Longshot yet. If the VV powders are hard to come by, then Longshot is close to N105 on Hornady's burning rate chart.
AA9?
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Post by cherokeetracker on Oct 22, 2017 10:20:50 GMT -5
Huey , With the 55 gr GT and using 2400,,, start at 8.0 grs and I would probably not go past 11.0 grs
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