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A common .44 bullet, the hornady XTP 300 grain hollow point has two crimp grooves.  The listed hodgdon max load is 19 grains of h110/w-296.  With the bullet seated at the upper groove I can still hear the rattle of powder in the case, no compression, although it is cose to seating atop the powder.  This load is listed around 38500 CUP.  Now, seating the bullet on the lower crimp effectively legnthens the case.  Does this really allow you to throw an extra couple of grains in and not blow pressures of the chart?  How do you work these up, by reading primers?  I assume many of you have worked up loads for Marshall's dual crimp bullets.  
 

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Matt,

Unfortunately the only answer I can give is from the Speer manual. They offer loading data for their 44 mag 300 using the dual crip groove. The loads for rifles use the front cannelure and revolver loads the front. A side note in the manual states that these loads were tested at 40,000 CUP. None of the other bullets are given pressure ratings. In the rifle they list a load of 20.5 grains of H110 as max and 22.5 as max for the revolver.

Now the good part. Using the LBT dual crimp groove bullet you get an extra bonus. Using the standard crimp groove, your still placing less bullet into the case than a jacketed bullet. Add to that the fact that lead bullets produce less resistance in the bore and pressures are dropping already from the data provided using jacketed bullets. To the best of my knowledge Lyman has the only manual that lists pressure using a wide range of lead bullets. Seating further out to the second crimp groove and you can add more powder and still keep the pressure down.

Reading pressure when looking at primers alone can be misleading. When primers flatten or are pierced we've already gone way past the safe zone. Then there are some loads that just aren't safe and won't show any sign through the primers. They may look right but danger lurks within. Starting low and working your way up slowly, measuring the case head expansion in addition to keeping an eye on the primers is the safest bet.

Hope this helps a bit
 

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Hi Matt,
I wish I had one of those Hornady 300 grainers to look at.  I just opened up my Horanady reloading manual and they call for a 1.600 overall length for the cartridge with this bullet.  The max load listed is based on this length.  I think that will be with the lower canelure or the one that puts more of the bullet out of the case.  

I think (you should confirm this) the upper canelure is for loading the bullet in 444 Marlin's.   You are probably not looking at a dual canelure for performance sake but so one bullet can be used in 44's and 444's.  Check with your calipers but the 1.600 cartridge length is probably as good as you are going to do in 44mag.  

As far as reading pressure by primers goes, I have never been able to do it in handguns running normal magnum pressures.  In my experience, if you are showing primer flattening or cratering, you are already way way over pressure.   The problem is there are so many variables to what pressure signs show up first and what they mean, you could go nuts trying to figure it out.  With jacketed bullets I'd stick with the reloading manuals recommendations.  This is also to be specific to bullet, brass, primer and firearm.  The other issue is that what may seem over pressure in one gun will appear quite normal in another.  I recommend you get some reloading manuals and read up on all the signs of being over pressure.  Others on this forum know more than I do and may have some better advice.  

Your 300 gr Hornady bullet is very good as jacketed bullets go. Because of its hard jacket and size, work up loads slowly.  Big pressure spikes can come quite suddenly with this combination.  Hope this helps.

God bless.................  Bill M
 
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