Buffalo 45-70 Velocity

[WFN]

I am interested in purchasing an H&R Buffalo Classic 45-70 with 32" barrel. It has been proven that longer barrels are more effective with increasing FPS on higher velocity cartridges (Lyman tests).

What would be the increase in FPS from a 45-70 Marlin 22" barrel to a Buffalo Classic 32" barrel for these cartridges?

Remington 300 gr 1810 FPS (advertised velocity)
Remington 405 gr 1330 FPS
Buffalo Bore 300 gr 2350 FPS (claimed FPS for lever)
Buffalo Bore 405 gr 2000 FPS

What is the length of barrel that would actually cause a decrease in FPS from expended powder burn and bullet drag?

[quickdtoo]

Welcome! I've made some comparisons between the 22" Handi and the 32" BC, I think a lot depends on the powder and bullet combination, an H4198/300gr Nosler PP load in the 22" barrel does 2425fps, same load in the 32" BC does 2450fps. On the other hand, an H322/350gr Hornady RN load does 2027fps in the 32" barrel, ½gr more does 1850fps in the 22" barrel. Using IMR4198 and the 350gr Speer, 1932fps in the 22", 2082fps in the 32" with ½gr more powder, 3 shot averages. The 350gr Hornady load was very accurate at 100yds, btw.  You'll find a lot more info on H&R firearms up in the H&R Centerfire rifle forum. 

Tim

[WFN]

Thanks Tim. From your results, it sounds like the difference between a 22" and 32" barrel can range somewhere from minimal to around 200 FPS, depending on the load. Good data!

[kevinsmith5]

Tim can backstop me here, but it seems to me my loads with slower powders show the greater difference between my tested loads and book predictions.

[quickdtoo]

I dunno, haven't made enough comparisons to know, and with my current range opportunities, doubt I will for a long time. But the slower powders used with bigger bullets seems to me would give you a bit of performance increase in the extra 10" of barrel.

Tim

[Graybeard]

I've shot the full line of Buffalo Bore ammo over a chrono thru a Browning High Wall BPCR some time back and in all cases the velocity worked out just barely over the factory stated level as I recall. That review is posted somewhere on here I'm sure. Here it is tho I see I didn't list my chrono numbers in it as I was thinking I did. http://www.graybeardoutdoors.com/product_test/review-18.shtml

Still my best recollection is none gave less than stated velocity thru the 32" barrel of my BPCR and all gave a tiny bit more it seems. With a round like the .45-70 and such max performance loads as BB makes you're not gaining a lot from the longer barrels due to the expansion ratio of the round.