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Vihtavuori 3N38 or N105 for 155 XTP in 10mm

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3N38 is denser and faster burning than N105 so you get more powder in the same case volume as well as higher velocity with 3N38. N105 burns slower than 3N38 so you will reach a maximum amount of powder burned before the bullet leaves the barrel sooner.


When cooking up crazy velocity hand loaded ammo its best to consult the SAAMI spec's for maximum pressures and velocities. You can fit a crap ton of powder in a 10mm case which dramatically increases the chance of a KABOOOOOM if you use too much or the wrong burn rate powder. Its all fun and games until you blow up your favorite blaster.

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That's not a lot of barrel length to burn a lot of slow powders.  I think you'll be blasting a lot of it out the front unburned.  Perhaps that's why VV only lists loads with N340, N350 and 3N37 for that bullet.

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It does seem a bit slow for that short of barrel but I was hoping some one has had experience with the two and compared them in a Tanfog 4.5 gun.


I have a 7 inch 1911 and a  Stock III with the Poly rifled 4.75 inch barrel.  My chrono is showing a consistent higher velocity between the 4.5 and the 4.75 and over 100 ft/sec faster on the 7 inch barrel.  All with the same assortment of ammo (both factory and reloads)


the current off the web data below is confusing as it has N105 for the 155 but not 3N38, and 3N38 for the 165.  I suspect its like some one on here said, testing is expensive and they can not test all combinations.  I do not have 3N38 in the chart below but I did look, the 3N38 is a bit faster but has less PHE.  this suggests that it might work better for the 155 versus the 165.  the caveat is the barrel length, the VV data is for a 5.5 Barrel.  The  3N38 has lower heat then Blue dot with about the same Burn rate suggests the 3N38 might be a good compromise.


Blue dot, BE-86 and AA#7 are all  doing ok, but I am not getting velocities that match the published data, and Fed 150 primers are getting flat even then.  The same load (even used the same piece of brass and same lot of bullets (Horn Jacket 155, old stock not XTP) and CCI 300 are not flat........but we all know the Fed 150 are softer.

Primers as a indicator for pressure in handguns is always iffy due to the lower pressures involved, even in 10mm.

With the above caveat in mind I did work the loads with BE-86 higher until the CCI 300 got as flat as the Fed 150, velocity still did not match the published data (it was higher).  Published data is for 5 inch barrel for the none VV powders, but my 4.75 is close enough to 5 inches I would expect the velocity to be better. 


But I seldom get "LOADING BOOK" velocity from my reloads........ I am risk adverse and seldom have the same exact components the reloading books are published with. 

AND......powder is not the same lot to lot.


The 4.5 gun is a Witness Steel owned by a friend, he wants the 155 XTP for CC..........this will not be a load he shoots a lot of, but I still want a load that is not stressing the gun.  I have chrono data for both Buffalo bore and Underwood  in his gun and my STOCK III (assorted bullets), the velocities are lower then what those two companies publish (not surprised given the short barrel).  The 4.75 barel was a bit faster then the 4.5,  I wonder if its barrel length or the Poly Rifling, if any one has real data or info, please pass that along.


He is willing to buy ammo, but that makes my Dillon feel marginalized. 😀







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Up dated the data.      If any one has data for BE-86 I please pass it on.  I called Alliant and that was a waste of time.


3N38 based on rate and energy looks ideal given both #7 and blue dot were not "quite" right.  I found comments on another forum that claims for shorter barrels, the ideal is a bit faster burn rate with a lower energy content.  If the assertion is true, 3N38 should be idea for the 155


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Another thing to consider is that every bullet has an optimal RPM/Velocity that will produce the best accuracy. Pushing a bullet way faster or slower than that optimal RPM/Velocity will result in poor accuracy. Basically put, just because you can cram a bunch of powder in a case to create a maximum velocity doesn't mean that is also the optimal velocity for that bullet. If the bullet doesn't go where you intend it to go, then who cares if it has a few hundred more FPS?


This also leads to another topic that is probably far more important for the desired intention of this ammo you are making. What is the marksmanship skill of the person you are making the ammo for? Most importantly can they actually hit what they are shooting at under pressure with any level of consistent accuracy? If the answer is no, then making super optimized self defense ammo isn't going to make any difference when the proverbial s#!t hits the fan.

Edited by CHA-LEE
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