Author Topic: New NOE 225-39 FN (Read 3106 times))

Hobbyman2007 · « **Reply #20 on:** December 24, 2018, 02:43:37 PM »

Quote from: rsterne on December 24, 2018, 01:55:58 PM

Mike, can you post a sketch of the bullet you are seeing wobbling or spiralling, with dimensions.... and also post the twist rate.... I would like to run it through the Kolbe Twist Calculator and see what the SF is.... It is likely becoming Dynamically Unstable downrange as it slows....

Bob

Bob , I think mike is using the 1:14 TJ’s barrel and the mold is a decked down 257420 to weigh close to 50 grain . I would bet it’s pretty close to .4 “ in length as it’s bing shot from an Evanix magazine .

K.O. · « **Reply #21 on:** December 24, 2018, 03:12:37 PM »

I have been using Ace pure silicone lube spray(aerosol can)... had it for car door locks... seems to work... but want to experiment... Have any of you folks tried any of the spray silicones...

looked at the MSDS and to me it looks like every thing else will flash off leaving just the Polydimethylsiloxane... ??

Acetone 35.0 67-64-1
Hexane 23.6 110-54-3
Propane 15.0 74-98-6
2-Methylpentane 10.9 107-83-5
Poly(dimethylsiloxane) 5.0 63148-62-9
3-Methylpentane 4.0 96-14-0
2,3-Dimethylbutane 3.4 79-29-8
Cyclohexane 1.4 110-82-7
2,2-Dimethylbutane

rsterne · « **Reply #22 on:** December 24, 2018, 04:21:12 PM »

Ahhhhh, OK.... If he decked the mould to the back of the middle drive band, he would shorten the bullet to about 0.39" LOA and the weight would be about 49 gr.... Even driven right at Mach 1 (worst case for stability), it would only need a 23" twist.... In a 14" twist, at 1000 fps the SF = 4.7, about 3 times what it needs to be.... and at 900 fps the SF = 5.... That is getting into the region of spinning way too fast.... and when the bullet looses velocity (but not RPM) as it goes downrange the tendency to become Dynamically Unstable and start spiralling would be extremely high....

Bob

KnifeMaker · « **Reply #23 on:** December 24, 2018, 10:30:01 PM »

Mr. Bob, I have three bullets for the 1-14 twist TJ's bbl right now. 43.6 gr 44.6 gr. and a 51 grain. GRRRRR!!! The longest is .416 long at 51 grains.

My attempt was to get a decent amount of shots (a full mag) for the Squirrel woods. LOL! Not to mention just to fit the mags with some mod's.

Oddly enough, the Factory Rainstom barrel was a 1 in 14.2. but it was a laser with pellets. Bothe the .25 gr and the Mark II's.

Mike

rsterne · « **Reply #24 on:** December 24, 2018, 10:39:28 PM »

Dynamic Instability is one of the least understood things in ballistics.... It is so complex it cannot even be predicted with computer programs, from what I have read.... Most often, it is brought on by spinning a bullet too fast for it's length and velocity.... That is why it often appears as spiralling which gets worse the further the bullet travels downrange... because the forward velocity decays much faster than the RPM....

Bob

KnifeMaker · « **Reply #25 on:** December 24, 2018, 10:58:55 PM »

Thank you Bob. If I remember correctly, TJ's carries both 10 and 14-1, so I may very well be sol!

I'll give Mike a call after the first of the year.

Mike

rsterne · « **Reply #26 on:** December 24, 2018, 11:11:56 PM »

You may have misunderstood me.... If you want to shoot a shortened and sized 257420 you should be looking at a SLOWER twist rate.... something in the 20-23" range.... Mike at TJ's has a 22" twist in .25 cal that could be ideal, and it shoots pellets like a laser as well.... It is 0.250" groove and 0.243" lands....

Bob

KnifeMaker · « **Reply #27 on:** December 24, 2018, 11:34:44 PM »

Quote from: rsterne on December 24, 2018, 11:11:56 PM

You may have misunderstood me.... If you want to shoot a shortened and sized 257420 you should be looking at a SLOWER twist rate.... something in the 20-23" range.... Mike at TJ's has a 22" twist in .25 cal that could be ideal, and it shoots pellets like a laser as well.... It is 0.250" groove and 0.243" lands....

Bob

No Sir, I didn't misunderstand. I can't find a slow enough twist as he only offers 1-10 and 1-14. I need much slower. I know he supposedly made a few custom. I need to call him.

I not wanting to shoot shoot a .25 in the Rainstorm, but rather .257. I have quite a few molds in .257 and none in .25. I do make .25's but it is a lot of sizing to do right, and is borderline for what I am wanting to do. GRRRR!!

Mike

I don't get to shoot much beyond 199 yards, so I may just stay with what I have as it will shoot right at 1 inch at that range. But would like better.

Oop's, should have read 100 yards. About 1 1/2" with the RS.

Mike

rsterne · « **Reply #28 on:** December 24, 2018, 11:59:37 PM »

Sorry, I didn't understand that the 50 gr. was for a .257.... I thought you made that bullet because you needed a lighter bullet for a .250 cal barrel.... Is it just that you want a lighter bullet with less FPE for your .257 cal?.... I know it's more money for the metal, but how about casting the 257420 out of pure tin.... It would be just under 50 gr. and the 14" twist barrel should be perfect for it.... It would have a better BC than the greatly shortened bullet in lead.... and pure tin is about BHN 9-11.... The "Popcorn" tin I got from Rotometals was 11 when I tested it with the pencil scratch method....

Bob

Hobbyman2007 · « **Reply #29 on:** December 25, 2018, 07:02:59 AM »

Now that right there might just be the ticket Bob . Wonder is there’s a better place to source pure tin other than rotometals . It’s beyond pricey for shooting stuff.

K.O. · « **Reply #30 on:** December 25, 2018, 05:53:54 PM »

still following and visualizing the 225-39 FN making one .22'' hole at 50 yards...

Nvreloader · « **Reply #31 on:** December 25, 2018, 07:32:41 PM »

Denis

IIRI, those tubes of different creams/medical creams use to come in pure tin tubes,
this was discussed on a casting site I visited in the early 70/80's. LOL ;

But now a days, everything is plastic.

What about pewter, I see it on several sites or solder, might be worth looking, depending on your needs.
Just some random thoughts..........

Try here:
https://www.ebay.com/itm/1-Pound-TIN-metal-ROUND-ingots-99-97-pure-Bullion-Ingot-453-6-grams-lb/192232468707?hash=item2cc1f2b0e3:g:YJ0AAOSwRLZUD0yQ:rk:47:pf:0

or here,
https://www.ebay.com/sch/i.html?_from=R40&_nkw=tin+&_sacat=182920&rt=nc&LH_PrefLoc=1

Tia,
Don

K.O. · « **Reply #32 on:** December 25, 2018, 07:54:35 PM »

And also wishing all a Merry Christmas

K.O. · « **Reply #33 on:** December 25, 2018, 08:01:09 PM »

well different alloys of pewter are different... but it is basicly about 20-25 BHN iirc... way to hard...

Nvreloader · « **Reply #34 on:** December 25, 2018, 08:15:18 PM »

Kirby

Don't you use just a percentage of tin per lbs's of lead?

Depending on the hardness/filling the mold blocks out, you want?

I don't know the percentages of tin -vs- lead or the correct formulas.

Tia,
Don

KnifeMaker · « **Reply #35 on:** December 25, 2018, 08:50:08 PM »

No way I can afford to shoot tin. LOL! I shoot cast because it is so inexpensive.

I will contact Mike at TJ's after the first to see what he has to offer. I know he made a different twist for Jim Gaska. We'll see.

If nothing else, I can go with a .25 barrel and size down again. GRRRRR!!!

Mike

rsterne · « **Reply #36 on:** December 25, 2018, 11:54:55 PM »

Don, Lead/Tin alloys for the most part end up harder than pure Tin.... with the exception of those with only a very small percentage of Tin (which are very heavy compared to Tin).... It's kind of the opposite of the melting point of solders.... an alloy of tin and lead melts at a lower temperature of either pure tin or pure lead.... Alloys do NOT have linear properties.... A small amount of lead in pure tin makes it a LOT harder....

Bob

Hobbyman2007 · « **Reply #37 on:** December 26, 2018, 02:19:39 PM »

Knife , if you’re interested in getting another barrel . You might want to look at a Hatsan .25 barrel as most are same spec as LW in .254 /.248 in a 1:17.7” twist . Lots of room for engagement and can size most .257 bullets to fit . They are choked so you would probably want to remove that . I have a barrel and rifle prepped to shoot them if you need a tester .

Hobbyman2007 · « **Reply #38 on:** December 26, 2018, 04:13:12 PM »

First range report , not too bad and better than the 38 gr that I have . I’m having issues with smearing of lead on the bases and the next time out I’ll be sizing base first in three steps instead of two. Groups are averaging 1” at 50 yards . I’ll also try sizing them a tad bit smaller as there were pretty close to choke size at .220” . I’ll try them at .2195” . The pic is of three shot groups . Again I’m not the best shot to start ,these were shot from a bipod with no rear support.

KnifeMaker · « **Reply #39 on:** December 26, 2018, 11:35:02 PM »

Thanks Denis!

I have a L/W barrel here in .25 if I should decide t go that way.

My groups @ 80 yards are about like you are showing. But a bit tighter. Not that there's anything wrong with your groups what so ever. I'm just an accuracy snob. LOL!!!

My .257 T/D will print 1/4 to 1/2" or under at the same 80 yards. But that is with 80 gr bullets. (Noe RanchDog FP and HP). With the 1-14 twist TJ's bbl. and is pretty much what I am looking for. The Rainstorm is printing right at an inch on average. Man, when the bbl. starts leading, it scatters!
I'll get there!

Mike

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New NOE 225-39 FN

Author Topic: New NOE 225-39 FN (Read 3106 times))