I THINK I Can Make This

[gitano]

A 1:10 twist will theoretically stabilize a 100-grain lead bullet doing 950 f/s. With a little room to spare. And, by the way, I have some 50-grain FMJ bullets left over from the .25 ACP project, but they are only point two five ONE inches  in diameter.


Paul

[Jamie.270]

Hitting the broadside of that barn at any significant range is always tricky when you're flirting with trans-sonic velocities.  

Passing through that barrier is disruptive to any object's flight path, but from everything I've read, is exacerbated as the mass of the projectile is reduced.
Many air gunners have learned this the hard way.


I think if it were me, I'd try for even less muzzle velocity, (950?fps) unless the goal is just to consistently hit targets on the porch/deck.

[gitano]

I too have read quite a bit about the issues associated with bullets crossing the 'sound barrier', but I THINK that's a problem more for the benchrest crowd that are looking for microscopic precision at LONG ranges where small fluctuations in the bullet's path lead to unacceptable, to them, variance in the bullet's point of impact. I base that opinion on personal experience with .22 RF performance.

Part of the challenge is slowing the bullet down. At 1050, I'm already looking at charges in the 1 to 2 GRAIN, range. When you get down there, small changes make big differences, AND it's difficult to get the necessary precision in the charge weight.  Its MUCH easier to go up in MV than it is to go down. 1050 is on the ragged edge of what I think I can achieve in terms of consistent charge weight precision. 1250 f/s is "acceptable" because it is still typical .22 RF performance, but not particularly "quiet".

I have to frequently remind myself of my goal: To BUILD this rifle's action, (which happens to be integral with the barrel). I'm getting to the point of considering purchasing a .22 RF BBL. But then I'd be back at what to do with the .257 bbl?


Paul

[gitano]

Re "ranges of interest": I would want this thing to be a MOSTLY 50 yd and less cartridge, but have the energy and trajectory to make a 100 yd shot if I so chose. Kind of .22 WMR performance as a function of bullet diameter and weight, not velocity.

Paul

[gitano]

As is often the case when I get tired of speculating about this or that, I just go 'verify'. So, instead of continuing to guess what .257 bullets I have in hand, I decided to inventory exactly what I have.

At first I was a little surprised at the total count as well as the variety, but then I remembered that my youngest had done a "research project" in about the 8th grade in which she looked at bullet penetration based on weight, type, and impact velocity. Also, "you" may recall that I tried - in vain - to get the various .25s I have/had to shoot "slower". Lo and behold, I found a box of the 60-grainers that are "out of stock" on the planet! I also found a box of the gas-checked, cast 72-grainers. So I don't have make any more of those until I find out they actually work. Furthermore, I have three varieties of 60-grainers in "30" caliber, and I am most certainly not above squeezing bullets into the size I want! I might very well squeeze some of those .30 caliber bullets through some 7mm, 6.5mm, and .257 sizing dies.

I'm still considering buying a .251 barrel liner (at $6/inch ), IF I can get it in a "fast" - at least 1:12 - twist rate. That's a BIG 'if'. I would put it in one of my milsurp 8mm take-off barrels and use the .25 ACP case.


Paul

[gitano]

Correct that - $7.89 per inch! :angry:

17-incher costs ONE HUNDRED THIRTY-FOUR DOLLARS AND THIRTEEN CENTS! !@#$%^&*

And the twist rate is 1:14. I'll have to see if that 'works'.

Paul

PS - It appears that 1:16 twist rate will stabilize the 60-grainer. Therefore, the 1:14 should work.

Paul

[gitano]

Or... I could just give in and run the MV up to between 1500 and 2000, and have a reloadable .25 caliber "22 Mag". That's easy to do and keep max pressure below 25000 PSI. But it certainly wouldn't be quiet.


Paul

[gitano]

Just got a promo for .22 RF ammo, and was looking at Norma Match ("Elite Match Grade Long Rifle"). Published MV is 1082 f/s. I THINK if flirting with the sound barrier affected precision in RFs, "they" would stay away from it in "match" ammo.

Paul

[Jamie.270]

Just got a promo for .22 RF ammo, and was looking at Norma Match ("Elite Match Grade Long Rifle"). Published MV is 1082 f/s. I THINK if flirting with the sound barrier affected precision in RFs, "they" would stay away from it in "match" ammo.

 Paul

Could be I s'pose.
But, .22 rimfire matches are (for the most part) at 25 and 50 yds. At those ranges I doubt the trans sonic barrier would even be factor.
And even then, all the "match" ammo I've seen for the .22RF has been 40 gr (or more), which is a relatively long bullet for the .22.


Honestly, I THINK consistent velocity will likely be a bigger stumbling block than the sonic barrier, when it comes to developing acceptable precision, at shorter ranges anyway.



And if all else fails, there's always PCP airguns!

[gitano]

I had a substantial response, but because I do a lot of these on my phone, it went "into the ether". :angry:

I was cleaning my fort and found some 32 Smith and Wesson Long cases. Hmm... I wonder what one of these would look like necked down to .25? The answer is: Pretty much the same as the necked-up TCM case does. The TCM cases are easier to get. Not that that matters much, as I probably have a lifetime's supply (300) in hand.

I also discovered a bullet-maker called "Bear Creek Bullets". They make swaged, solid lead, coated, bullets for mostly obsolete cartridges. They make one 90-grain bullet in .258 caliber. That's heavier than I want, but at least they have them, and a significant number of people really like their bullets, so I'll probably get some. Everyone claims zero leading after thousands if shots. We'll see.

I think I have a pretty clear picture of the internal ballistics of the thing I want. Looks like it's time to start 'making chips'.

Paul

PS - For $.02, I'd put this whole thing on an AR.

Paul

[Jamie.270]

Well, I for one, am waiting with baited breath (so to speak) for the results of this endeavor.
So let the chips fly!

[gitano]

I have been distracted by another project. One everyone here will be keenly interested in, but I don't want to reveal the details now. When it gets 'locked in', I'll post what it's about here. I promise it will be interesting.

That said, I've got some machining I have to do for some repair work for the next few days. As soon as I can get started on this project, I'll post here.

Paul

[gitano]

The original barrel on the Stevens Model 15 is chambered for the 32 Long Colt, so I went looking for ammo. (Fat chance, right!) What I found was a guy that makes"reloadable" .32 LC cases. Sorta. What he makes is a brass sleeve into which you load a .22 RF BLANK or nail gun cartridge and a .311-.312 bullet,:mad: in the mouth. The 'blank' is offset so that the centerfire firing pin hits the rim of the blank, and that propels the bullet. Interesting solution. If I remember correctly, the cases are $3.50 each. That's not terrible, and I think probably fairly 'doable'. Here's an interesting note: OF COURSE you can't mail ammo unless you use UPS AND pay a HAZMAT fee. However, no such constraints on blanks! I just bought 100 rounds off of Amazon. I can make my own 'sleeves', but at $3.50 each, i might have to buy a few of them.

This doesn't negate the. 25 caliber project, but it does mean I might be shooting the Favorite sooner than later. I also just bought a .22 RF barrel for it, but I have to get a .22 ejector for it. The 32 Long Colt ejector doesn't work.

Paul

[gitano]

Hmm... I have a 1:9 twist, .223 caliber barrel liner 'left over' from when I made the 10/22 from the 80% receiver. (The barrel liner maker would not sell just 1 liner.) That liner fits almost perfectly in 8mm Mauser milsurp take-off bbls.

Consider this:
1) I put that liner in one of the MANY 8mm milsurp take-off bbls I have;
2) Chamber it for either the .22 TCM or the 5.7x28;
3) Stick that bbl on one of the two RB actions I have that are waiting for bbls;
4) Use Pyrodex RS BLACK POWDER substitute behind a Lyman gas-checked 53-grain cast bullet, for which I have the mold;
5) And get 1050 f/s muzzle velocity with that .22 caliber cast bullet without having to wildcat the TCM or 5.7x28 case up to .25 caliber. (In other words, not have to buy a custom reamer.) Furthermore, while staying well within the pressure specs of the RB, I could get a jacketed bullet up to .22 RF magnum velocities - (2k-ish).

Hmm...

Paul

[Jamie.270]

That oughta work.
If'n you don't care if it smokes a little.