Anybody loading 7.62x39 +P for Bolt Actions?

[Rdlningcltchdmpr]

I agree with gunsandgunsmithing.

Get a .308" barrel if you're handloading.

A 0.308" barrel will shoot 0.311" bullets with out generating excess pressure.
Ruger mini-30 was originally made with 0.308" barrels and nobody had any issues shooting surplus .310"-.311" ammo.

And go with a 13" twist because the 0.308" 125gr Nosler ballistic tip needs a 13" twist to fully stabilize at 2,000 fps at sea level, according to Berger's twist calculator.

Wrong. I am shooting sierra 125mk in a 17twist , it is longer than a ballistic tip by a lot and i am getting zero's-one's

 

[gunsandgunsmithing]

You mean r7 not r17 ?

That's a small "L". rl7 or RL7..but yes, Reloader 7

 

[dcali]

A .308" barrel is definitely the way to go, but the Mini 30 is *not* a good example of why. I doubt there has ever been a less accurate rifle. It's like they made it suck on purpose. I believe (don't quote me on this) that they used a long tapered throat to keep the .311 bullets from creating too much pressure in the .308 bores. Mine was tragically inaccurate with any and every bullet I tried. Just a dreadful rifle.

 

[Laurie]

The primary cause of this ammo's poor performance is poor static and dynamic bullet balance. This causes radial group dispersion. The faster the bullet is spun, the greater the radial dispersion of the group. So going from 1:9.45" to 1:16" should yeild a noticeable decrease in group size.

Interesting. I had a 7.62X39mm Cz527 Carbine many years ago. Despite the fast industry standard twist I was surprised to find bullets barely stable at 500 yards, and the butts crew reporting them as tumbling at 600. These were 123gn Lapua FMJs. I did notice that looked at from the base end, the lead cores had very deep conical depressions swaged in, presumably to get the bullet long enough to have a decent bearing surface length within the weight and wondered if this was the result of such a short, fat bullet giving dynamic stability issues.

 

[Zero333]

I have an unknown custom 14" barrel for a TC Contender. I have no clue what the twist is, but it is a .311 barrel in 7.62x39. This is something my grandpa picked up 30 yrs ago for silhouette shooting. I found some loads that he made, IMI brass, 1680 powder, Federal primer, and a custom rebated boattail 145 gn JSP with a long taper that looks like the Sierra 155 gn Palma bullet. I have fired 15 of these rds and they are very accurate. 1 hole at 50yds from a Ransom Rest. I have 123 gn either Rem or Win that don't come close. Are there any good 140 gn to 150 gn bullets in .311 dia. I think the 123 gn bullets are meant to be sprayed out of rifles and not meant for accuracy. My purpose for the load is to be able to knock down steel rams at 200 meters, so want something heavier than 123 gn

Sierra makes a 150 gr .311" soft point (.334 G1 BC)

Speer makes a 150 gr .311" soft point (.328 G1 BC)

Hornady makes a 150 gr .312" soft point (.361 G1 BC)

Barnes makes a 150 gr .311" TSX (.322 G1 BC)

 

[misser]

a few years back I was working up a load for a TC-E FoxRidge custom barrel .I tired may different powders and bullets . had all but given up . I then tired AA2460 and a bullet from Hornady 123 gr Z Max it was a OMG moment ,one hole kind of stuff

 

[msalm]

I put a 30 caliber pilot on a 6.5 Grendel bolt reamer and opened up a 7.62X39 chamber in one of my Howa mini's up to the n/s junction... Have only fire formed so far but hoping for 2600+ with the 125's...we'll see!

 

[MrMajestic]

I assembled a 20" PacNor sporter contour .308 15tw barreled "Salvage" 10. With Lapua cases and VV N-120 the Nosler 125's and Hornady 110 grain V-Max shot pretty decent. Any light weight hunting gun that shoots 3/4 MOA is very useful in my opinion...

 

[NZ_Fclass]

Had a play with the "x39" some while back. Factory, Chinese loads can be duplicated with Win 296 with a 125g Hornady. I suggest that CFE Black would be a better choice these days.

Anyone know why the AK47 et al use a 1-9.5 twist? seems odd - stability issue?

 

[misser]

A .308" barrel is definitely the way to go, but the Mini 30 is *not* a good example of why. I doubt there has ever been a less accurate rifle. It's like they made it suck on purpose. I believe (don't quote me on this) that they used a long tapered throat to keep the .311 bullets from creating too much pressure in the .308 bores. Mine was tragically inaccurate with any and every bullet I tried. Just a dreadful rifle.

years ago I called Ruger asking what they considered good accuracy with the mini 30 , they said 1.5 at 50 yards . which is like 3 inches at 100 .I was able to get it down to 1.5 at 100 yard

 

[MOA]

I believe the AK47 has such a fast twist to stabalize the longer steel core and toolsteel tipped subsonic armor piercing ammo that was developed to run a through a suppressor at 300ms. It was developed pretty early in the AK life span.

 

[Rdlningcltchdmpr]

Interesting. I had a 7.62X39mm Cz527 Carbine many years ago. Despite the fast industry standard twist I was surprised to find bullets barely stable at 500 yards, and the butts crew reporting them as tumbling at 600. These were 123gn Lapua FMJs. I did notice that looked at from the base end, the lead cores had very deep conical depressions swaged in, presumably to get the bullet long enough to have a decent bearing surface length within the weight and wondered if this was the result of such a short, fat bullet giving dynamic stability issues.

They were falling subsonic which destabilized them , it wasn't the rifling twist

 

[Laurie]

They were falling subsonic which destabilized them , it wasn't the rifling twist

Yes, I knew it wasn't the spin rate - if anything, they would have been theoretically heavily 'over-stabilised' in gyroscopic terms, so this was mighty puzzling at the time. Not that I was too bothered as I didn't see the cartridge in standard form as a 600 yard number and wasn't interested enough to load it with a longer range 155 SMK or suchlike.

With hindsight, I suspect the dynamic stability issue you raise about the lighter bullets was the root cause, the transition to transsonic and then subsonic speeds and accompanying turbulence destabilising the bullet. A quick look at Litz's 'form factor' numbers for equivalent flat base light thirty cal bullets suggests i7 values around 1.2 which translates to ~0.15 G7 BC. At 2,230 fps MV in the conditions of that day, that gives a calculated terminal vel of 1,060 fps at 500 and 980 at 600. (33-MOA elevation at 600 over 100 zero and 1.3-MOA lateral movement / 1 mph crosswind - not an F-Class winning combination )

Interestingly some of the surplus east European M43 around in the UK in those days produced very high MVs of well over 2,500 fps and was claimed by those who shoot a lot of 7.62X39 generally performed better than standard velocity milspec examples even at short distances.

Ironically I'm back in this ballistic ballpark again these days having built a .30BR 'plinker' on an old Paramount 4-lug Palma rifle platform with a 1:10 twist (No significance, the barrel was almost new, spare and is a Krieger so needed a home.) With 125gn flat-base Sierra MKs this is in the essentials a slightly beefed-up 7.62X39 in internal / external ballistics terms, albeit using a tight match chamber needing thin necks and employing very high-grade small primer / flash-hole brass.

 

[Rdlningcltchdmpr]

Yes, I knew it wasn't the spin rate - if anything, they would have been theoretically heavily 'over-stabilised' in gyroscopic terms, so this was mighty puzzling at the time. Not that I was too bothered as I didn't see the cartridge in standard form as a 600 yard number and wasn't interested enough to load it with a longer range 155 SMK or suchlike.

With hindsight, I suspect the dynamic stability issue you raise about the lighter bullets was the root cause, the transition to transsonic and then subsonic speeds and accompanying turbulence destabilising the bullet. A quick look at Litz's 'form factor' numbers for equivalent flat base light thirty cal bullets suggests i7 values around 1.2 which translates to ~0.15 G7 BC. At 2,230 fps MV in the conditions of that day, that gives a calculated terminal vel of 1,060 fps at 500 and 980 at 600. (33-MOA elevation at 600 over 100 zero and 1.3-MOA lateral movement / 1 mph crosswind - not an F-Class winning combination )

Interestingly some of the surplus east European M43 around in the UK in those days produced very high MVs of well over 2,500 fps and was claimed by those who shoot a lot of 7.62X39 generally performed better than standard velocity milspec examples even at short distances.

Ironically I'm back in this ballistic ballpark again these days having built a .30BR 'plinker' on an old Paramount 4-lug Palma rifle platform with a 1:10 twist (No significance, the barrel was almost new, spare and is a Krieger so needed a home.) With 125gn flat-base Sierra MKs this is in the essentials a slightly beefed-up 7.62X39 in internal / external ballistics terms, albeit using a tight match chamber needing thin necks and employing very high-grade small primer / flash-hole brass.

Yes, I knew it wasn't the spin rate - if anything, they would have been theoretically heavily 'over-stabilised' in gyroscopic terms, so this was mighty puzzling at the time. Not that I was too bothered as I didn't see the cartridge in standard form as a 600 yard number and wasn't interested enough to load it with a longer range 155 SMK or suchlike.

With hindsight, I suspect the dynamic stability issue you raise about the lighter bullets was the root cause, the transition to transsonic and then subsonic speeds and accompanying turbulence destabilising the bullet. A quick look at Litz's 'form factor' numbers for equivalent flat base light thirty cal bullets suggests i7 values around 1.2 which translates to ~0.15 G7 BC. At 2,230 fps MV in the conditions of that day, that gives a calculated terminal vel of 1,060 fps at 500 and 980 at 600. (33-MOA elevation at 600 over 100 zero and 1.3-MOA lateral movement / 1 mph crosswind - not an F-Class winning combination )

Interestingly some of the surplus east European M43 around in the UK in those days produced very high MVs of well over 2,500 fps and was claimed by those who shoot a lot of 7.62X39 generally performed better than standard velocity milspec examples even at short distances.

Ironically I'm back in this ballistic ballpark again these days having built a .30BR 'plinker' on an old Paramount 4-lug Palma rifle platform with a 1:10 twist (No significance, the barrel was almost new, spare and is a Krieger so needed a home.) With 125gn flat-base Sierra MKs this is in the essentials a slightly beefed-up 7.62X39 in internal / external ballistics terms, albeit using a tight match chamber needing thin necks and employing very high-grade small primer / flash-hole brass.

125 mk.

 

[Laurie]

Very good! I haven't got there yet with my bitzer 30BR, but it's very early days still. Is that the 30 Remington AR or something that Robert Whitley or whoever has dreamt up based on another case?

 

[dolek]

125 mk.

30 AR is not a 7.62 x 39mm ...big diffrence.

 

[Rdlningcltchdmpr]

30 AR is not a 7.62 x 39mm ...big diffrence.

10-4 , i was just saying i shoot both . they are both great. And very different.

 

[Rdlningcltchdmpr]

Very good! I haven't got there yet with my bitzer 30BR, but it's very early days still. Is that the 30 Remington AR or something that Robert Whitley or whoever has dreamt up based on another case?

30AR is a standard cartridge made by remington , originally for ar guns but no one really bought them and they are obsolete for the most part. This cartridge is great in bolt actions as it is a tiny bit bigger than a 30br and you just buy brass , load it and shoot!

 

[MGYSGT]

This barrel is a bit of an experiment. I want to see how good Russian steel case will shoot with bullet diameter grooves, optimized twist and a better throat to begin the bullet's journey. The primary cause of this ammo's poor performance is poor static and dynamic bullet balance. This causes radial group dispersion. The faster the bullet is spun, the greater the radial dispersion of the group. So going from 1:9.45" to 1:16" should yeild a noticeable decrease in group size. No bullet is perfectly balanced, so even the finest match bullets should benefit from keeping the stability factor between 1.4 and 2.0. Since their balance is so much better, the improvement will be less, But it should still be measurable.

Better take along a cleaning rod to remove those steel Socialist cases when they get stuck in a normal size chamber.

 

[MrMajestic]

Better take along a cleaning rod to remove those steel Socialist cases when they get stuck in a normal size chamber.

a little duct tape and don't leave home without it...