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I bought a number 4 long branch last year in auction. It was a bit of a punt especially as the rifling looked weak, but it was a bargain so she (Sheila) came home with me.

Anyhow, it's conditioned for deer and range work and I took it along to the range for a play. Long story short PPU 174grns were shocking.... Argggg I've bought a lemon. However I put a couple of Sierra 150 grain pro hunter (home loads) though it and wow! It was transformed. Any ideas why??
Ps I haven't taken it out on a stalk yet as I haven't put the pro hunters through a chrono.

Lampuki wrote:I bought a number 4 long branch last year in auction. It was a bit of a punt especially as the rifling looked weak, but it was a bargain so she (Sheila) came home with me.

Anyhow, it's conditioned for deer and range work and I took it along to the range for a play. Long story short PPU 174grns were shocking.... Argggg I've bought a lemon. However I put a couple of Sierra 150 grain pro hunter (home loads) though it and wow! It was transformed. Any ideas why??
Ps I haven't taken it out on a stalk yet as I haven't put the pro hunters through a chrono.

I can say that neither my Mosins or SVD, all .311", like 174gr bullets but love 150gr bullets especially 150gr PPU SPBT's.

That said were the 174gr PPU's factory ammo?, if so that could explain why your 150gr home loads are more accurate, especially if you've worked them up for that particular rifle.

I have moved you post to the correct forum.

The gunsmithing forum is not the place to discuss handloading. I appreciate the thread you posted in is wandering off topic somewhat but this is taking even further it is a handloading question NOT a gunsmithing question.

Familiarise your self with the forums and post appropriately. Further mis-posts will be removed.

Pro hunters are flat based bullets, you say worn rifling, so a flat based bullet will obturate and set up in the rifling better than a boat tail which the PPU's are.

I shoot Pro-Hunter in my 1920s No1Mk3 BSA and they perform very well out to to 100 yards. Using the rifle as a woodland stalker with open sights I have no plans to shoot even that far.

Put a mic or even a decent set of calipers on the two bullet models - you may find the Sierras are larger diameter. As Dromia says, FBs will often shoot better too in barrels with a bit (lot?) of wear.

Third post telling off! Sorry.

Laurie wrote:Put a mic or even a decent set of calipers on the two bullet models - you may find the Sierras are larger diameter. As Dromia says, FBs will often shoot better too in barrels with a bit (lot?) of wear.

My SVD has no discernible wear and a fairly low round count but is still more consistently accurate with flat base bullets or bullets with a very short boat tail.

I put it down to flat base bullets having better concentricity than a boat tail, it's easier to produce a good flat base than it is a boat tail.The Finns cracked it with a rebated boat tail on the Lapua D166 bullet.

Plus they stabilise over a shorter distance than boat tails

snayperskaya wrote:The Finns cracked it with a rebated boat tail on the Lapua D166 bullet.

There are various claims for the RBT form that appear to stand up. One is that they continue to perform well in well worn barrels. Sadly, it's a type that has largely gone out of favour in recent years. AFAIK, there are only two significant producers these days: Lapua with only a few very elderly relatively high-drag FMJRBT designs, and David Tubb the top US competition rifleman. David's latest DTAC 6mm long-range bullets are RBTs whilst earlier generations were conventional boat-tails. I was hoping to acquire and test some this year, but fat hope of that now!

Bryan Litz / Applied Ballistics llc almost certainly produces the best mix of theoretical and practical knowledge and testing of the bullets civilian shooters use. Bryan has written and published two books in recent years on top of his well known 'Applied Ballistics for Long Range Shooting' series and bullet testing books under the titles of Modern Advancements in Long Range Shooting (two volumes now written), incorporating variou theoretical and practical tests in the form of essays on all sorts of ballistics and handloading topics. In a Vol II piece the long-range stability of the 185gn 0.308" Berger LRBT 'Juggernaut' is examined in depth in one of the book's sections. Bryan says the small rounded radius between the bottom of the boattail section and the bullet's base impairs stability. To test this, a number of bullets had a sliver milled off the base giving a sharp tail to base junction and stability at over 1,000 yard distances improved noticeably. As he points out, it's too difficult / expensive for bullet manufacturers to incorporate this feature in production bullets, but it show just how important the tail/base form, both in design and manufacturing consistency.

https://store.appliedballisticsllc.com