18” twist barrels

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JonnyV
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18” twist barrels

Post by JonnyV »

So I’m curious as to what the consensus is on which bullet weight to run in an 18” barrel. 1350 fps seems to be a bit of a sweet spot on velocity, so let’s assume we’re working in that general range. The rifle will be used at longer ranges, say out to 1200 or so for target and gong shooting.

Thanks!
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Re: 18” twist barrels

Post by Clarence »

You might want to include the caliber...

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JonnyV
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Re: 18” twist barrels

Post by JonnyV »

45 caliber rifles for now, running Swiss powder 1.5F. Over primer wad, CCI LR primer, Emmert's Improved lube....the mold I have currently is the 545 gr BACO money mold with first two bands reduced. 20-1 alloy from John Walters...
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bpcr shooter
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Re: 18” twist barrels

Post by bpcr shooter »

bullet weight has nothing to do with twist. It is length that you should concern yourself with, and for a 45 with a 18 twist a 1.40-1.44" bullet will work. I would shoot for 1.41 myself, and it would be PP so that I could get more powder in for 1200yds.


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Re: 18” twist barrels

Post by TexasMac »

bpcr shooter wrote: Wed Nov 17, 2021 8:28 pm bullet weight has nothing to do with twist. It is length that you should concern yourself with, and for a 45 with a 18 twist a 1.40-1.44" bullet will work. I would shoot for 1.41 myself, and it would be PP so that I could get more powder in for 1200yds.
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Matt,

I'm not yet a PP shooter & was wondering why it allows addition powder over a greaser of the same length & nose profile?

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martinibelgian
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Re: 18” twist barrels

Post by martinibelgian »

Wayne,

That's only the case with a bore-dia. PP bullet: After all, most of the bullet sits in the barrel, not in the case, contrary to a (groove dia.) GG (or PP) bullet. So 80+grs of powder. So not necessarily a GG/PP issue. I alos shoot groove-dia. PP, which has the same powder capacity limitations (or is that advantages?) as the typical GG bullet.
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Re: 18” twist barrels

Post by bpcr shooter »

martinibelgian wrote: Thu Nov 18, 2021 1:06 am Wayne,

That's only the case with a bore-dia. PP bullet: After all, most of the bullet sits in the barrel, not in the case, contrary to a (groove dia.) GG (or PP) bullet. So 80+grs of powder. So not necessarily a GG/PP issue. I alos shoot groove-dia. PP, which has the same powder capacity limitations (or is that advantages?) as the typical GG bullet.
Or with a short seated DDPP bullet (.100). I would only want this "more powder" for 1200yds its not needed for 1k. It helps keep your face on the stock or you can get/make a bigger cheek piece



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Re: 18” twist barrels

Post by JonnyV »

No more than 1.44”….I was wondering what the relationship between weight and length was. I know that the Greenhill formula gives an approximate number, but I’ve heard where it didn’t work out in certain situations as well. Thanks!
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Re: 18” twist barrels

Post by TexasMac »

martinibelgian wrote: Thu Nov 18, 2021 1:06 am Wayne,
That's only the case with a bore-dia. PP bullet: After all, most of the bullet sits in the barrel, not in the case, contrary to a (groove dia.) GG (or PP) bullet. So 80+grs of powder. So not necessarily a GG/PP issue. I alos shoot groove-dia. PP, which has the same powder capacity limitations (or is that advantages?) as the typical GG bullet.
Thanks for the clarification which makes sense when comparing PP to GG in many situations, but GG's with the 1st 2 or 3 driving bands reduced offer similar powder capacities.

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Re: 18” twist barrels

Post by Coltsmoke »

You can use a 1.460, wouldn't want one any longer. A lot of shooters used the PJ money bullet and did great with it at 1.460.
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ian45662
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Re: 18” twist barrels

Post by ian45662 »

TexasMac wrote: Thu Nov 18, 2021 8:37 am
martinibelgian wrote: Thu Nov 18, 2021 1:06 am Wayne,
That's only the case with a bore-dia. PP bullet: After all, most of the bullet sits in the barrel, not in the case, contrary to a (groove dia.) GG (or PP) bullet. So 80+grs of powder. So not necessarily a GG/PP issue. I alos shoot groove-dia. PP, which has the same powder capacity limitations (or is that advantages?) as the typical GG bullet.
Thanks for the clarification which makes sense when comparing PP to GG in many situations, but GG's with the 1st 2 or 3 driving bands reduced offer similar powder capacities.

Wayne
Just to give you an idea…. The top of my polly wad is .1” below the mouth of my cases. After sizing the mouth of the case I slip fit the bore diameter projectile into the case. I can use 81-85 grains of powder or more if I wanted with the 45-70 case
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Re: 18” twist barrels

Post by bobw »

Can you actually get 1350 fps out of a 545 grain greaser in a 45-70 with any barrel length or twist using 1.5fg or 2 for 3fg.? Just asking. Bobw
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Re: 18” twist barrels

Post by jackrabbit »

I believe Farringer is doing so. If not, he is darn close
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Re: 18” twist barrels

Post by Aviator »

Well, my 45/70 with a 540 gr bullet is ~1320 fps with 74 gr of 2F Swiss, with Starline brass.
With Winchester brass, I have been up to 1400 fps with 2F Swiss, but it doesn't shoot as well as my 1320 fps load.
I have a little over .330 inch of bullet in the case.
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Re: 18” twist barrels

Post by desert deuce »

Unfortunately I feel the need to comment at this point, because, Aviator is too humble to mention a salient point or two. Moreover, it could/should help Johnny V get off on the correct foot should he choose to do so.

While it is true that Aviator has been shooting BPCR and BPTR for a relatively short period of time he quite astutely picked up on what he individually needed to do to be successful in that short period of time. Hard to over emphasize how important that individual effort is to success. Which, by the way, (and this is an accusation) is an indication of above average intelligence in my opinion which in this particular case has not proven to be a handicap.

The example of his intelligent approach: He started out with one Shiloh in 45-70 with a 16" twist barrel somewhat by chance and spent serious range time learning to correct any problems with the rifle and determine by examining targets as to what works best for him and that rifle according to the target. As far as I know he is still shooting that same rifle both Scoped and with Irons and Grease Groove Money Bullets from BACO. Sort of a becoming one with the rifle through the target as the intermediary. And yes, he expends a considerable amount of range time, powder and primers doing so. V-Bull refers to it as trigger time.

Finally, he takes the information and results he acquired at home to matches and further increases his overall acumen of what he needs to do to be successful in the field of competition by competing with some of the best contemporary shooters around these days.

To distill this down. While it is true that he did listen to the available information (he absorbs information like a sponge and dissects it like a neurosurgeon) he then went to his home range and worked out what works best for him and his rifle according to the target. He then takes that information to matches and further improves his performance at competition through match experience, still with the same rifle.

I took Johnny V down the long road because he mentioned shooting at 1,000 and 1,200 yards, but it even holds true for lesser distances.
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