PRB in a 1:32” Twist

[Walkingeagle]

So I have a surplus Lyman GPH barrel in .54 cal and have been reading some online, as well as what little I can find on here, about the viability of effectively shooting a .530prb with .018 ticking patch. I know these barrels also have shallow rifling along with the faster twist and likely should not be very accurate with high charges. What I gather is quite mixed in results, ranging from very accurate to not at all.
Any on here have actual experience? I know I will try and find out for myself, just wondering if its a waste of time. I would likely run 70-80 grains 3f Goex as my test.
Walk

 

[azmntman]

I once played with a buddy's unmentionable 1-32. It shot a pattern not a group. I have read others here say use LIGHT charge and do OK. I would start at 45 gr and go up until accuracy goes too far for your acceptability. Not the greatest hunting charge but it should decapitate a bunny or squirrel

 

[Grimord]

It is unlikely that you will get a prb to shoot good groups in a rifle with a 1:32 twist with shallow rifling at the powder charges you would like for hunting purposes. My best, with a 1:28 shallow groove rifle, was 2" at 40 Yards with 40 grains of 3f. Beyond that charge the groups went to just barely getting on paper. Consider looking for a Great Plains barrel that comes with a 1:60 twist. They can sometimes be found on flea bay.

 

[azmntman]

Might also try 1f or 2f powder??

 

[Frontier's]

60gr 2fg, .018 patch and a .490 shoot great in my brothers CVA Mountain Stalker with 1:32 twist. You never know unless you try.

 

[BrownBear]

So I have a surplus Lyman GPH barrel in .54 cal and have been reading some online, as well as what little I can find on here, about the viability of effectively shooting a .530prb with .018 ticking patch. I know these barrels also have shallow rifling along with the faster twist and likely should not be very accurate with high charges. What I gather is quite mixed in results, ranging from very accurate to not at all.
Any on here have actual experience? I know I will try and find out for myself, just wondering if its a waste of time. I would likely run 70-80 grains 3f Goex as my test.
Walk

My 54 GPH barrel absolutely love 30-40 grains of 3f and ticking with a .530 ball, but accuracy starts going south at 60 grains. Increasing ball diameter to .535 and continuing with ticking increased loading effort considerably while letting me go up to 80 grains of 3f with good accuracy. It doesn't seem to like 2f with any charge from 30 to 80 grains, however.

 

[Walkingeagle]

Thanks for all the info guys. I am hoping to run some tests next week and will report on findings.
Unfortunately this is yet an unfired barrel so I expect serious testing wont result until I’ve shot quite a few prb’s down her to clean things up anyhow.
Walk

 

[hanshi]

Fast twist isn't all that bad; but when pared with shallow rifling it can be a disaster. You may find good accuracy with small game powder charges. But only experimentation will tell you if deer loads are possible.

 

[BrownBear]

Fast twist...with shallow rifling it can be a disaster.

The magic words, hence the requirement for really tight patch/ball combos in all my experience and experiments. If you can start the combo without a mallet it probably isn't tight enough in a shallow fast twist for charges approaching "deer" loads.

 

[Okie Hog]

i've had very good results firing patched round balls in muzzleloaders having 1:32 twist. One rifle shoots great with powder loads to 70 grains. A tight patch that requires a golf ball on the ramrod
is used.

My attempts to work up patched round ball hunting loads for rifles having 1:28 or faster twist rates
were unsuccessful.

 

[yonderin]

Fast twist for PRB is bad mojo is a rule of thumb.

Thumbs can be broken.

 

[Walkingeagle]

So I have not made it out with the aforementioned .54 gph yet, but I did a very rough test with a .50 gph I also own one day this week. It really was an afterthought at the end of a couple hours shooting at random targets with a friend and our flinters. We pinned a target to a board at 15 yds as I just wanted to see if there was a chance at accuracy. I was shooting .490 rb, .018 pillow tick wet lubed with moose milk and 50gr ffg Goex. Things appeared to group well as this shooting was not off a bench and very close range. Hopefully to further test near the end of next month from a bench, and further distances.
Worst case, would the higher charges not be similar to simply shooting a smoothbore in regards to groupings?
Walk

 

[Grenadier1758]

Listen to hanshi and BrownBear. Accuracy is not just about twist. Accuracy is a combination of several factors. Two factors are twist and the related depth of rifling. Deep rifling and a tight patch, ball and lube will have better accuracy over a wider powder charge distribution than a rifle with the same conditions but shallow rifling.

The early Jaeger rifles would have one full turn in their 28" barrel. The grooves were deep. Accuracy with patched round ball was good over the environments that they hunted small deer or chamois.

 

[Walkingeagle]

Again, being shallow rifled with the 1:32” twist, would the worst case scenario not match the accuracy of a smoothbore?
Walk

 

[8 BORE]

It would be more accurate in a smooth bore

 

[Grenadier1758]

8 Bore should have explained his reply a bit better. The smooth bore has consistent conditions in the bore so the flight of the ball is consistent, but without the stabilizing effects of spin.

A ball and patch in a shallow rifled barrel may have the patch partially grab the rifling or skip over the rifling. With such differences, the flight of the ball may be more unstable than a ball fired from a smoothbore.

Walking Eagle, did you record the data on the days when accuracy was excellent? Do you have data from the range sessions when accuracy was poor? What changed? Wind, sun, cloud cover, temperature or whatever may have had an impact.

 

[Walkingeagle]

8 Bore should have explained his reply a bit better. The smooth bore has consistent conditions in the bore so the flight of the ball is consistent, but without the stabilizing effects of spin.

A ball and patch in a shallow rifled barrel may have the patch partially grab the rifling or skip over the rifling. With such differences, the flight of the ball may be more unstable than a ball fired from a smoothbore.

Walking Eagle, did you record the data on the days when accuracy was excellent? Do you have data from the range sessions when accuracy was poor? What changed? Wind, sun, cloud cover, temperature or whatever may have had an impact.

Have not yet done any serious testing. Hoping to next month sometime.
Walk

 

[8 BORE]

8 Bore should have explained his reply a bit better. The smooth bore has consistent conditions in the bore so the flight of the ball is consistent, but without the stabilizing effects of spin.

A ball and patch in a shallow rifled barrel may have the patch partially grab the rifling or skip over the rifling. With such differences, the flight of the ball may be more unstable than a ball fired from a smoothbore.

Walking Eagle, did you record the data on the days when accuracy was excellent? Do you have data from the range sessions when accuracy was poor? What changed? Wind, sun, cloud cover, temperature or whatever may have had an impact.

I try to stay from long replys.Dont have the time

I just give "THE BOTTOM LINE"
You all can do the explaining.
And you did an excellent job.

 

[Walkingeagle]

Update...
I took the GPH .50 caplock barrel out yesterday and played with .490 Hornady RB, .015” moose milk pillow tick patches, 60 gr. Goex ffg powder and CCI #11 caps. To be honest I thought it shot absolutely wonderful, with great groups. I took it on a trail walk and almost ran the course of gongs ranging from 20-110 yards. Only missed (just wide) one hanging vertical bar of 1” width, a hanging wine bottle cork and a 1/4” dowel, both at around 15 yards. I suspect these were all my fault and no fault of the accuracy of the load. I had been shooting 5 hours at this point, and fatigue was setting in.
I am actually quite happy with the results and will push things further next time out to find the limits.
Walk

 

[Sparkitoff]

Definitely have to experiment. I have a 1:24" barrel and was told no way PRB would work. It happens to have deep cut rifling. It shoots one big hole groups at 50-yards with tight patch and ball. That's with 80 grains FFFg Triple 7. I've never tried accuracy further because PRB was not my intention for this rifle. I was pleasantly surprised. You just have to try a few things and see for yourself.