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Author Topic: ELR PCP for Precision Rifle Training  (Read 1018 times))

Offline bear air

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Re: ELR PCP for Precision Rifle Training
« Reply #20 on: March 24, 2021, 07:27:25 PM »
That's how I got involved in shooting airguns. I started with a bunch of inexpensive Walmart break barrels. I was hooked!!!!!!
  • Sioux City IA, USA
Benjamin Armada Bottle Carbine 30 cal UTG 10x44, Benjamin Armada 25 cal Kuiu Vias vinyl wrap 20'' MMHF barrel UTG 4x16x44, Benjamin Marauder 22 cal x2 1-24'' MMHF barrel 500cc bottle gun Bushnell Nitro 2.5x10x44 FFP, 1-20''LW barrel Bushnell 4x12x40 Engage, Benjamin Marauder 17 cal 20''LW barrel Bushnell Engage 4x12x40, Benjamin Fortitude 22 cal 20'' LW barrel Boyds at one thumbhole stock Discovery 3x12x44 FFP, Beeman Quiet TEK 22 & 177 cal Beeman Silver Kodiak x2 22 cal & 177cal Psalm 107:14  He brought them out of darkness and the deepest gloom and broke away their chains

Offline precisionaction

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Re: ELR PCP for Precision Rifle Training
« Reply #21 on: March 26, 2021, 06:31:46 PM »
In my last post I mentioned some concerns about twist rates, stabilization, and projectile weight. In my quest to become more knowledgeable on the subject to better understand the nature of the concerns I ran across this well written article by our very own @rsterne published in hard air magazine. So, I thought I would share.

https://hardairmagazine.com/ham-columns/pellet-twist-rate-and-stability/

Thanks Bob!
I am the dude, playing the dude, disguised as another dude. -- Favorite Quote from Tropic Thunder.

Offline rsterne

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Re: ELR PCP for Precision Rifle Training
« Reply #22 on: March 26, 2021, 08:20:19 PM »
Glad you enjoyed it.... Here is an index to all my articles on H.A.M....

https://hardairmagazine.com/ham-columns/the-definitive-index-to-bob-sternes-ham-technical-articles/

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline shifty06

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Re: ELR PCP for Precision Rifle Training
« Reply #23 on: March 27, 2021, 02:20:38 PM »
Not familiar with the term "ELR".... or "PRS competition", for that matter.... As far as "weight downrange" having a better BC, that will apply to some extent if you keep the caliber constant.... but BC is really connected to the Sectional Density, which allows you to compare calibers.... A 120 gr. slug in .35 cal will have the same SD as a slug half that weight in .25 cal.... with the BC then being a matter of the Form Factor (shape).... A 60 gr. slug in .25 cal will be more slender than a 120 gr. in .35, so the .25 cal would likely be less affected by the wind than the .35....

Pellets have a much poorer BC than slugs, so if you are really interested in the best performance in a crosswind, with a moderately powered PCP, I would look to a slug shooting .22 or .25 cal.... My favourite long range PCP is a .257 of about 140 FPE, shooting a 70 gr. slug at 950 fps.... The Lyman 257420, or one of its variants, is a great 200 yd. slug in a 14" twist.... This is not to say that you can't do as well, or even better, with a really powerful .30 or .35 cal.... but since FPE and air use is proportional to bullet weight (at a given velocity), and the FF advantage actually lies with smaller calibers.... I'd just as soon avoid the extra recoil and air requirements just to break even on performance....

Bob

Good answer, It makes sense of course. I don't know why I didn't think of this. It is the same with powder rifles, a 6mm round is more slender and posses a better BC than a 7mm or 6.5mm.

ELR = Extreme Long Range
PRS = Precision Rifle Series

6mm do not have better BCís especially against 7mm they have some of the best B.Cís per given weight. It has to with diameter vs length to get the length in perspective for a bigger round it compared to diameter it get very very long and no more practicable. Because as bullet gets longer your eating into case capacity.

6mm are the choice in PRS comepition bc of recoil. Less recoil easier to spot impacts an make follow up shots. Now when you get out west you will see more 6.5ís as caliber
of choice. Wind velocity has a lot to do with it. Where I live 3-10 is normal over 10 is what we call a windy day.
 Shoot the heatstroke in Nebraska 8-20 is normal for them an have had wind in the upper 20ís lower 30ís. Play with a JBC calculator or your kestrel with wind speeds in 20-30mph an watch the 6.5ís take the advantage.

But bc is diameter/length factors among a lot of other factors. Brian Litz has a very good book on it.
  • USA, IL, Adams Co
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FX Impact .35 converted to .22

Offline rsterne

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Re: ELR PCP for Precision Rifle Training
« Reply #24 on: March 27, 2021, 06:52:19 PM »
PB's enjoy the ability to use slugs with a much higher Sectional Density than what we can use in airguns, because of the much lower pressures we run.... SD is still the primary factor in determining the BC.... I do agree that smaller calibers have a big advantage in reduced recoil, also in report and air usage in airguns.... While .257 cal is still the preferred caliber for long-range airgunning, lack of barrels of the proper twist rate, and a wider selection of bullets, is the prime factor in holding back 6mm and .224 cal use in airguns.... Our Subsonic ballistics are significantly different than when you are playing in the 2000-3000 fps arena....  :o

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline shifty06

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Re: ELR PCP for Precision Rifle Training
« Reply #25 on: March 28, 2021, 05:03:00 PM »
MY comments were concerning PB's SD is mainly used to determine terminal ballistics in PB. Not so much in determining BC. but it is a factor. Just trying to point out the length to diameter ration is more important. 7mm or .284 offers the best length/diameter ration for high BC bullets. Look at 30cal. they have higher SD, an weight. which contribute to higher BC's. but lower BC's than 7mm. grain for grain 7mm is the sweet spot. IN PB. Airgun's don't know much about at this point. But I am interested in swaging some at some point. 
  • USA, IL, Adams Co
Benjamin Disco. Since 2012
Benjamin Akela Arrived DOA
FX Impact .35 converted to .22