Where to crimp? .45 Colt-300 gr. XTP

[Rocket6R]

Hello all! I’ve got a question for you guys. I’m shooting the 300gr. Hornady XTP boolits out of my Blackhawk. There are two crimp grooves on the boolit. Does anyone know which crimp groove (top or bottom) I should be crimping at?

Thanks, Paul

[44MAG#1]

Your loading data should have the OAL listed. Refer to that for your cartridge. Most data nowadays do have it listed

[Rocket6R]

I don't have any load data to compare to for this boolit. I'm running 22gr. of H110 and a Fed 150M primer. At 23gr. I saw pressure signs (primer flat and sticky extraction) so I backed off to 22 gr. I shooting these boolits at 1248fps with an E.S. of 17 (4 5/8" barrel) at 22gr (no adverse pressure signs). When I tested at 23gr. I got 1295fps and an E.S. of 17. I currently crimp at the top crimp groove. I was wondering that if I crimped at the lower crimp goove, making my OAL longer, it might lower the pressure of the round.

Paul

[44MAG#1]

My question is where did you get your data? Why wasn't the OAL given? Always get the OAL when discussing data with others if you trust them. I have used 23.5 H110 with it seated out and have shot 24 grs.. OAL is always an important part of the ballistic equation.
I have Hornady manual somewhere and can get their OAL if you want it.

[Rocket6R]

I just measured the OAL length for both crimp grooves. Crimped at the top groove = 1.60" Crimped at the bottom groove = 1.70" Will crimping at the bottom crimp groove (gain of OAL of .10") reduce pressures? 1.600" appears to me the max OAL for the .45 Colt, however, the Blackhawk may allow me to go to 1.70". I have not loaded a round yet that reaches 1.70" in the Blackhawk to test it.

Paul

[44MAG#1]

The Blackhawk will take the length. Hornady's data was shot with the short OAL length. The longer length will reduce pressure with a given charge. Why don't you just reduce the charge at the length you are shooting now? Shoot a few and see if the accuracy will hold and if you are satisfied.

[Rocket6R]

I'm good at 22 gr. at this point. Would like to see if using the bottom crimp groove lowers pressure to a better level with 23 gr.

Thanks, Paul

[44man]

No real reason. I just seat long and work my load. You just did the same seated shorter.
If you have accuracy, pressures will be so close because you might need more powder by 1/2 gr seated long. You will wind up at the same place.

[Mohillbilly]

44man is right , crimp long to see if it fits ( it should ) then work up your load . compared to the short seated load , you should get more velocity with a slight more charge . Accuracy is more important than velocity .

[Rocket6R]

I crimped long (bottom crimp groove) on the XTP and this put my loads at 1.680". The rounds would not clear the cylinder. Too Long! I went to the top crimp, which fits the cylinder. Well, top crimp groove it is! I'm headed to the range on Sunday to try two different loads:

22.3gr. of H110 with the 300 gr XTP

9.3gr. of Unique with a 255 LSWC

This was my first post/thread to this forum and I just wanted to say thanks to both of you for your impute.

Thanks again, Paul

[44MAG#1]

I can tell you this. I have checked two of my Blackhawks and they will accept an OAL of 1.755 to the end of the cylinder.
Do you have one of the new flattop smaller frame Blackhawks. Mine are the large frame Blackhawks.

[DougGuy]

I shot that same 300gr XTP over 22gr of W296 crimped short and had no flattened primers, it was accurate and stout on recoil. I killed two deer with one shot from a 4 5/8" Vaquero using that load, and to date is the only XTP I have recovered from game. Boolit looked like it hit a brick wall, flattened all the way back to the cannelure and expanded to .672" diameter. Nice birthday present it was.. Or should I say they were..

300gr Hornady XTP as recovered from the second deer:

http://i1202.photobucket.com/albums/bb374/DougGuy/Guns/DSC01672_zps5ab117d5.jpg (http://s1202.photobucket.com/user/DougGuy/media/Guns/DSC01672_zps5ab117d5.jpg.html)

OP, what exact Blackhawk model do you have? 2 digit prefix or 3 digit prefix in the serial number?

The reason I ask this, if yours has the 3 digit prefix, the loads you are asking about are NOT SAFE in that gun! The load you are shooting is right up near the 30,000psi pressure ceiling for a large frame Ruger, and they are well beyond the maximum of 23,000psi of the medium frame New Vaquero and the New Model Flattop.

[Rocket6R]

My serial number is 48-20XXX. I assume it is the large frame Blackhawk.

Paul

[Rocket6R]

I just tried to drop my 300gr. XTP through all of my chambers and I can't drop them through the cylinders or push them out by my finger. I measured that XTP and it is right at .451". I measured the chamber throats on all of the cylinders and they measure .450" to .451". The chamber throats seem too tight. My understanding is they should be at least .001" over the boolit I'm shooting. This would seem even more of a problem shooting .452" boolits. Throat reamer?

Paul

[DougGuy]

Definitely time for a reamer. Mine is out on loan at the moment. Half thou over boolit diameter is fine, most go with .4525" throats and they work very well.

Try Cylindersmiths, all he does is .45 cylinders currently, prices are fair and turnaround time is maybe a week or two?

How long is your cylinder measured on the edge? Better yet, if you seat a case in the cylinder and measure from the back of the case to the front of the cylinder, what does it measure? Odd that you can't chamber that XTP seated long.

[Rocket6R]

The measurement from the rear of the case to the front of the cylinder measures 1.756".

Thanks, Paul

[DougGuy]

That is the same exact 1.756" I get with a loaded round in my Vaquero.

I'd just roll with it and check into getting the throats opened up to .4525"