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Discussion Starter #1
Can anyone give me an idea of what would be a max charge of universal clays in a Ruger Bisley 45 Colt with a 250 grain RNFP sized at 0.453" with 0.4525" throats? I shot some mid-kansas cast bullets yesterday with 10.0 grains of univ. clays. Accuracy from sandbags with 2x scope averaged 1.7" at 25 yards. I had some fliers though (5 shot group average was 1.3") and wonder if a bit more powder might eliminate fliers. I shot one group at 50 yards and it was 5.25", bigger than expected based on 25 yard group sizes. I vaguely remember Marshall saying why that might happen but do not remember his answer (was it stability?). With throats at 0.4525" should I try bullets sized to 0.453"? Thanks to all who reply, Brian C.
 

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Brian,,

Your load will be turning about 1000 fps if I'm not mistaken, and it might well be that 1.7" 25yd groups are all you're going to get from that bullet.  Generally with a .45-250g bullet, 10.0g Universal Clays is an accurate load.

Can't say for sure, just a hunch.  It's kind of like giving a haircut over the phone!  I don't know if the bullets are PB, BB, or GC, how hard they are and what the ogive and bearing band configurations are like.   Mid-Kansas makes machine cast bullets, and there are included air-voids in many of those bullets that will introduce uncontrollable variables that you might not easily overcome.   One of the reasons for our strictly hand-cast operation... consistentcy!

Probably not the answer you were looking for Brian.  

Have a safe and Blessed New Year!

Marshall
 

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Discussion Starter #3
Thanks for the reply Marshall. Do you think I could go to 10.5 or 11.0 grains (I plan to try 9.0 and 9.5 grains also) but started with 10.0 based on your earlier recommendation when I was working with the Oregon Trails Laser Cast bullets. These Mid-Kansas bullets are shooting better for me than the Laser-cast bullets were. I am looking forward to trying your 285gc that I have on order but thought I would try the Mid-Kansas bullets in the meantime. Happy New Year. P.S. We had a great time of sharing how God has been faithful this morning at the church I attend, Brian Carlson.
 

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Brian,

I suspect that your loads will open up more with the 10.5g and 11.0g loads of Universal Clays and your .45-250g Bullet rather than close them up!  Perhaps the lighter loads will shoot better, but only testing will show for sure.

Let us know what you find!

God Bless,

Marshall
 

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Discussion Starter #5
Marshall or anyone, I did try 9.0, 9.5 and 10.5 grains of Universal Clays along with 6.0, 6.3, 6.5 and 7.0 grains of Tite-group with the Mid-Kansas 0.452" 250pb rnfp. 10.0 of univ clays was still most accurate overall with this bullet. I just tried the slip fit of these bullets and your 0.452" 340gc through the cylinder throats of my Ruger Bisley 45 Colt. The mid-kansas bullets seem to require about the same effort to get them through the throats as your bullets do. I also just measured some of the mid-kansas and Beartooth bullets with my 0.0001" micrometer. Both bullets averaged about 0.4523". Perhaps the bullet lube in the grooves caused the micrometer to read the few ten-thousandths over.  I was told by the gunsmith who opened up the throats that they should be 0.4525". Apparently the bullets are pretty well matched to the throats but I have no idea what the bore and groove diameters are. I bought this revolver new this last spring. Do you know what dimensions Ruger is using for their 45 Colt barrels? As stated before your 340gc bullets are shooting very well in this gun sized at 0.452" so presumably the problem of inaccuracy with the lighter weight bullets is not due to their diameter. My hunch is that either, as you said, maybe they have air inclusions and so are off balance or I am not getting them to obturate properly at these low velocities (low pressures). Also I understand that shorter bearing surface bullets are not generally as accurate as longer bullets since the longer bullets can span the gap between the throat and forcing cone. When I ordered the Mid-Kansas bullets I asked about trying their "Cowboy" bullet which has a BHN of 11 as apposed to their regular bullet of BHN 16 thinking that at the low velocities I was wanting to work with I might not get full obturation but they still suggested the BHN 16 bullet. Do you think a softer bullet would work better? The Mid-Kansas website indicates that for a cast bullet to properly obturate it needs a pressure of 1422*BHN so if BHN is 16 then pressure to obturate is 1422*16=22750 p.s.i. and if BHN is 11 then psi needed would be 15640 psi. Your bullets at BHN 21 would need 29860 psi. Does this sound right to you? I have no idea what kind of pressure I am likely generating with 10.0 grains of Universal Clays or 6.5 grains of Titegroup behind the 250 grain rnfp, do you? How does one convert from psi to cup? My understanding is that with the Ruger the maximum recommended pressure is 30000 CUP. From the Hodgdon manual it looks like psi is about 15% higher than CUP so 30000 CUP=34500psi. Does that sound about right? So if I wanted 22750 psi to properly obturate a BHN 16 bullet I would need 19780 CUP.  So in looking at the Hodgdon manuals load data there are two sections. The low pressure section's loads are for a maximum pressure of 16000 cup and the high pressure section's loads minimums are at 23000 cup and at higher velocities than i want. I want to achieve an accurate load with a 250 grain rnfp at about 700-900 fps. What powders and charges would do this while giving me adequate pressure to properly obturate a BHN 16 bullet? Or should I give up on these BHN 16 bullets and try the BHN 11 bullets? I do not know how much higher I can go over Hodgdon's loads in their low pressure section or how much lower I can go from the data in their high pressure section. What a dilemma. Help please! Thanks for listening to my ramblings, Brian.
 

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Brian,

I've said before that as you mentioned in your last post, bullets with a longer bearing surface will generally be more accuracy prone than those with shorter bearing surfaces.

Also, machine cast bullets are very prone to have air inclusions in the bullet, making them unbalanced to a degree, thus hampering fine accuracy.  This is not always the case, but can and does happen.

Now, about the BHN and PSI obturation issue.  Yes the figures you have quoted are right as rain.  And, with bullets that don't properly fit cylinder throats because they aren't sized properly and obturation is necessary for the bullet to seal off powder gasses and prevent blowby and gas-cutting, this can be a real issue.  However, it sounds as though your bullets are well mated to your cyinder throats, and obturation isn't an issue here!

We can all get caught running down blind rabbit trails, and spend lots of energy and time going nowhere.   I suspect that in your case Brian, with your custom fit throats on the Ruger Bisley, that obturation for accuracy is one of those rabbit trails!  The bullet fits from the sounds of things therefore there shouldn't be any gas cutting or blowby.  Obturation shouldn't be an issue.

I shoot volumes of our BHN 21 bullets at 700-900 fps with perfect accuracy, and I know that they don't obturate with the loads I'm using!  Keep in mind all RNFP profiles aren't created equal, and some don't have a strong front driving band.   This difference in designs can make a huge difference in accuracy potential.  If you will note the bullets we carry all have very strong front driving bands.  There is a reason that we don't make and sell some of the more common bullet designs... they aren't all created equal!

You might try different powders, or perhaps a different crimp.  Both can make big differences as can primer selection when it comes to accuracy in these relatively low pressure, low velocity loads.  But to chase after different hardness bullets, when what you have fit the cylinder throats so well, I beleive is one of the proverbial rabbit trails.

Yes, I know there are varying schools of thought, and one isn't the definitive answer over the other... I'm just sharing my experiences, such as they are and my very biased opinion.

Don't know whether it helps or not, but have a great day!

God Bless,

Marshall
 

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Discussion Starter #7
Thanks Marshall. I will chill on the obturation issue. You mentioned that maybe I should try a different crimp level. I am using the same crimp that I use with your 340gc and 21.0 H110. I use the Redding profile crimp die as you had recommended. Do you think I should back off on the crimp for these lighter loads? I would love to try some of your lighter bullets. I am using the WLP primer by the way. Brian.
 

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Brian,

If you're into playing with variables in your light loads, try moderating that crimp!

A couple of things come to mind here.  First, you are using the Redding profile crimp die which puts a firm and solid grip on the bullet, but perhaps too firm in this case.

It could be that with the Mid-Kansas bullets you are using in BHN16, that the severity of the Redding profile crimp die might be crushing the bullet undersize!  It is possible!

If you're curious, use an inertia bullet puller, and use your micrometer on the pulled bullet... it might indeed now be undersize!

With our BHN 21 bullets that won't be an issue, but with softer bullets I've seen it happen.   I'm not saying that it has, but I'm still trying to give that proverbial "haircut over the phone"!

Sometimes just a change in crimp itself can change the behavior of a load.   Try using just a light roll crimp.   It will be enough to hold the bullet with these light loads you are using, and see what happens.

I'm running out of ideas for you, but please let us all know what you find with the crimp situation.

These bullets that are giving problems... have you weighed them for weight consistantcy?  It might be revealing to do so.

See what happens!

Blessings to you my friend!

Marshall
 
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