Lets settle it once and for all...
03-29-2010, 07:11 PM
#11
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
Sharp Shooter
Does that apply @ 100 yards?
Both my 54cal and my 58cal are 1-48" twist and they love roundballs even with heavy powder charges.
03-30-2010, 06:36 AM
#13
Giant Nontypical
Join Date: Nov 2005
Posts: 6,585
A 1-48 is a versatile twist, it will do all kinds of projectiles, I have shot PRB sabot and conical with good enough accuracy for hunting. Of course any thing that is made to be versatile is not going to be the very best in all situations. It is good enough to be what most people like the best. Part of the difference is if you us some of the old methods for determining how much powder you want, to me using the guns my grandfather or I made a charge of 130 gr was not unusual in commercially made guns you should go by what the manufacturer puts in the manual as the material is not always of the very best quality, and the parts are not hand fitted and have "tolerances".
Also people that have not made there own from scratch and proof tested them have a different scale of what a heavy or light charge is, ton me a charge under 90 gr is a light charge and a charge over 120 is a heavy charge. The point of max efficiency changes with different powders and with the different bullet weights, very few of us a looking for the most efficient powder load, the load of max efficiency is never the highest velocity but is the point at which you get the most feet per second per grain of powder. Due to age how long we have been in the sport and past experience we tend to use different terms while meaning the same thing. I have noticed my self and mike do this every once in a while. Lee
Also people that have not made there own from scratch and proof tested them have a different scale of what a heavy or light charge is, ton me a charge under 90 gr is a light charge and a charge over 120 is a heavy charge. The point of max efficiency changes with different powders and with the different bullet weights, very few of us a looking for the most efficient powder load, the load of max efficiency is never the highest velocity but is the point at which you get the most feet per second per grain of powder. Due to age how long we have been in the sport and past experience we tend to use different terms while meaning the same thing. I have noticed my self and mike do this every once in a while. Lee
03-30-2010, 07:51 AM
#14
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
What I would like to know going back to the original question and adding this... which twist rate will provide you the best hunting accuracy @100 yards or beyond?
50/75 yards is not a problem at all with a 1/48. But for myself, shooting a 1/48 going to 100 yards really opens the pattern up, especially when shot with what i would call a hunting load charge 80/90 grains in a 50 cal.
Another question... What size of group might an average shooter expect using open sights @ 100 yards with a PRB?
50/75 yards is not a problem at all with a 1/48. But for myself, shooting a 1/48 going to 100 yards really opens the pattern up, especially when shot with what i would call a hunting load charge 80/90 grains in a 50 cal.
Another question... What size of group might an average shooter expect using open sights @ 100 yards with a PRB?
Last edited by sabotloader; 03-30-2010 at 08:46 AM.
03-30-2010, 09:54 AM
#15
Giant Nontypical
Join Date: Nov 2004
Posts: 5,425
Sabotloader...I assume you are talking about deer calibers...As I mentioned in my first post, if a fellow wants a round ball barrel he is best served with deep cut rifling (.015-.018 deep) vs button rifling (.006 deep)...This will better grip the patch...
I could look up the rifling twist on Getz's or Rice's website but as I remember these are standard twists for round ball barrels...
.40 caliber...1-48
.45 and .50 caliber 1-66
.54 caliber 1-72
I know my little .40 shoots good with from 25-70grs of Goex FFF and the .54 does well with from 50-120grs of FFF...That's a pretty wide spread and I vary the charge for game being persued...I believe this is one of the big differences between factory and custom round ball barrels...The factory rifles I have shot had a "sweet" spot where they shot a certain powder charge well...In other words, custom barrels aren't as picky as powder charges and ball/patch combinations...
I could look up the rifling twist on Getz's or Rice's website but as I remember these are standard twists for round ball barrels...
.40 caliber...1-48
.45 and .50 caliber 1-66
.54 caliber 1-72
I know my little .40 shoots good with from 25-70grs of Goex FFF and the .54 does well with from 50-120grs of FFF...That's a pretty wide spread and I vary the charge for game being persued...I believe this is one of the big differences between factory and custom round ball barrels...The factory rifles I have shot had a "sweet" spot where they shot a certain powder charge well...In other words, custom barrels aren't as picky as powder charges and ball/patch combinations...
03-30-2010, 12:23 PM
#16
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
nchawkeye
OK so let me ask the re-pharse the question again....
What I would like to know going back to the original question and adding this... which twist rate will provide you the best deer hunting accuracy @100 yards or beyond? Adding another stipulation - using the shallow grooved bore of the time.
50/75 yards is not a problem at all with a 1/48. But for myself, shooting a 1/48 going to 100 yards really opens the pattern up, especially when shot with what i would call a hunting load charge 80/90 grains in a 50 cal.
Another question... What size of group might an average shooter expect using open sights @ 100 yards with a PRB?
I understand the deeper grooves are probably superior to todays shallow grooves, but in a production gun available today I think we are limited to shallow grooves...
OK so let me ask the re-pharse the question again....
What I would like to know going back to the original question and adding this... which twist rate will provide you the best deer hunting accuracy @100 yards or beyond? Adding another stipulation - using the shallow grooved bore of the time.
50/75 yards is not a problem at all with a 1/48. But for myself, shooting a 1/48 going to 100 yards really opens the pattern up, especially when shot with what i would call a hunting load charge 80/90 grains in a 50 cal.
Another question... What size of group might an average shooter expect using open sights @ 100 yards with a PRB?
I understand the deeper grooves are probably superior to todays shallow grooves, but in a production gun available today I think we are limited to shallow grooves...
03-30-2010, 01:11 PM
#17
Spike
Thread Starter
Join Date: Mar 2010
Location: Pennsylvania
Posts: 19
I assume that my firestorm has a shallow-grooved barrel, and I forgot to mention its a .50 cal. All of that to say, sabotloader and I probably have similar set-ups, and I'd love to hear answers to his two questions...
03-30-2010, 08:51 PM
#18
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
Got this answer back on another forum....
I prefer a slow twist deep grove rifling for prb , I have a tc hawkins in 54 cal , wiff the factory barrel ( 1-48 twist ) it does not have deep grove rifleing , it shoots a concal bullet good but for prb I get 2 to 3 inch groups at 50 yards , so I replaced the barrel wiff a green mountain barrel 1-72 inch twist deep groove rifleing and all I can say wow , it shoots a one hole group at 50 yards and at a 100 yards I can get 2 to 3 inch groups or better. I use 90 grains of ffg , last fall I shot a doe wiff it using prb, she was 100 yards from me and I drop her using one shot in the head , for me I like a slow twist barrel , others mite not but it works for me and very pleased wiff the groups I can get. Dats my 2 cents
I prefer a slow twist deep grove rifling for prb , I have a tc hawkins in 54 cal , wiff the factory barrel ( 1-48 twist ) it does not have deep grove rifleing , it shoots a concal bullet good but for prb I get 2 to 3 inch groups at 50 yards , so I replaced the barrel wiff a green mountain barrel 1-72 inch twist deep groove rifleing and all I can say wow , it shoots a one hole group at 50 yards and at a 100 yards I can get 2 to 3 inch groups or better. I use 90 grains of ffg , last fall I shot a doe wiff it using prb, she was 100 yards from me and I drop her using one shot in the head , for me I like a slow twist barrel , others mite not but it works for me and very pleased wiff the groups I can get. Dats my 2 cents
It has a 1:48 twist.
03-31-2010, 09:24 AM
#20
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
A couple of more repies that i have gotten...
To me it still looks like the slower twist would be the a more consistently accurate barrel. And while using the 1/48 you may need to reduce the charge to gain long distance accuracy. I feel very comfortable with a 1/48 out to 75, even shooting an animal @ 100 - although, i know I could do it but I could never actually feel good shooting that far with a PRB - not enough experiance + plus my accuracy concerns.
The Lyman GPR is by far the best RB rifle I have ever owned. The 1 in 66 twist with a .010" riflings really hits the spot. At 70 -75 grains FFG off a bench you can shoot 2" groups all day if you swab the barrel often.
The twist rate on any rifle is to spin the bullet and stabilize it during flight. The length of the bullet and the velocity of the bullet are the deciding factors for twist. If you shoot a bullet that is 2-3 times the bore diameter in length, then you need a faster rate of spin 1 in 28 - 1 in 36. You can compensate for an improper twist rate to bullet length by varying the velocity. That is why every rifle/load combination has a sweet spot.
The rifling depth is to imprint the cloth patch. seal the bore and make sure you get all the spin your supposed to out of your bore.
If you have to err on twist rate it is better to err fast. A 1-48 twist rate will do an exceptable job with a RB. as long as you don't try to push it too fast. Try 70 - 75 grains with your 50. This load will shoot completely through a mule deer at 75 yards. I know.
The twist rate on any rifle is to spin the bullet and stabilize it during flight. The length of the bullet and the velocity of the bullet are the deciding factors for twist. If you shoot a bullet that is 2-3 times the bore diameter in length, then you need a faster rate of spin 1 in 28 - 1 in 36. You can compensate for an improper twist rate to bullet length by varying the velocity. That is why every rifle/load combination has a sweet spot.
The rifling depth is to imprint the cloth patch. seal the bore and make sure you get all the spin your supposed to out of your bore.
If you have to err on twist rate it is better to err fast. A 1-48 twist rate will do an exceptable job with a RB. as long as you don't try to push it too fast. Try 70 - 75 grains with your 50. This load will shoot completely through a mule deer at 75 yards. I know.
To stabalize a round ball or any projectile for that matter you need to get enough revolutions per second. To do this you can do a faster twist with a slower speed or a slower twist with a faster speed. If you are going to be shooting at distances of 100 yards and beyond I recomend you go with a slow twist with faster speed for flatter trajectory. If you are going to be shooting a maxi-ball type projectile a 1-48 will work fine at 100 yards with the correct powder charge.