A question for all you bisley or palma match 308/7.62 shooters.
I bought a target rifle and a spare barrel from an old lad who has retired and is suffering from alsheimers, so I am not getting much sense from him when I tried to follow up on these questions.
Both barrels are stainless steel made by Maddco in OZ. Now they are not on the web and only list a phone/fax # which is why I am posting here in the hopes that some one can answer this.
The barrels are a 1 in 14" twist, and shoot the 155gr Palma match bullet very well. I rebarrelled my sons hunting 308 with the spare barrel.
I gather that maddco make this 7.62 nato barrel and also the 308 Palma barrel, and list them differently. What could/would the difference be.
Obviously the very slow twist seems to favour the 155gr bullet, is this generally the case with 308 target rifles?

Thanks,
500

The 1 in 14 twist will run into stabilizing limits at roughly 168 grain bullets. I say roughly because weight of the bullet is one factor and the other is overall length of the bullet. The 1 in 14 twist with the 155s allows you to burn a little more powder and slightly elevate velocities beyond what a 1 in 10 twist 308 would produce. A benefit when trying to reach Palma distances.

I have a Krieger 1 x 13" twist and groove diameter is .3065". You may want to slug those barrels and see if they're not that small. If they are, the one you put on your son's hunting rifle, IMO, would be all but totally unsuitable for that purpose.

The original Palma Matches had all shooters shooting the host nations service rifle and using service ammunition. The match is fired at 800, 900 and 1000 yards. Then the shooters were allowed to bring their own rifles but the cartridge was 7.62 and continued to be 7.62 M80 milspec issued by the host nation. It was know that the faster 1-10 and 1-2" twist generated high RPM. The higher the RPM the greater the effect on the imbalances in the bullet which results in less accuracy. It was quickly found that a 1-14" twist barrel of 27-30 inch length produced increased velocity with less RPM and thus greater accuracy with the M80 145-155 gr milspec M80 bullets. That is the reason for Palma barrels to be longer and have the 1-14" twists.

Given standard target rifles with 26" barrels a 1-12" twist barrel will give slightly better accuracy with M80 than a 1-10" twist barrel. However a 1-14" twist will give noticeably better accuracy than either of them.

For example; in 10 and 12" twist barrels I most often get 2 1/2-3 MOA with numerous lots of U.S M80 Ball. The 12" twist most often has slightly smaller groups than the 10" twist barrel. This is consistant through 600 yard tests and more noticeable at the longer ranges. However, my 27.5" Palma barrel with a 14" twist will shoot those same lots of M80 at 1 1/2 to 2 MOA and two lots shoot right at 1 MOA from 100 through 600+ yards.

I also have shot Fed Match with 168 MKs, my own loads with 168 MKs, M118 Special Ball with the 174 bullet and my own loads with 175 gr MKs. All still hold MOA or better through 600 yards.

Bottom line is we spin our bullets too fast in most target rifles with the 10" twist. The 12" twist is better, especially at 600 to 1000 yards. With the longer barrels and the slower twist Palma barrels the bullet is not over stabilized you also get more efficient external ballistics at longer range.

Larry Gibson

Thanks Guys.
I get .5moa with match bullets from my son's 308, and with military ball just over an inch. I have tried the local GS Custom HP 130gr hunting bullet and it shoots under an inch so I am reasonably happy. That was with the first test load, so I anticipate some improvement with a bit of load development. Getting barrels here with all the licencing and crap that goes with it is a nightmare, so sometimes one has to accept windfalls even if not possibbly 100% ideal. His 308 with factory barrel could not do better than 2" no matter what we fed it.
I cut the barrel to 24" for hunting purposes but left the target profile pretty much intact.

later,

500

Maddco is just up the road here so I'll try to ring tomorrow and ask him. He used to be quite approachable.
Also, I heard our barrel makers used to make the 7.62 barrels a little undersize to suit our Mil ammo., all sorts of warnings were put about when we started loading the 155gr sierra, but the only difference we found was better accuracy. My last was a Ferlach 1 in 12 which loved the Mil, but took some load development for the 155gr before settleing on 5/8" with peep sights.

OK Rang Maddco, and from what I can remember the main difference, going back 30 years or so, is his 7.62 barrels were made with 4 groves as his personal tests showed 6 groves would not shoot nato ammo worth a damn no matter what the bore or grove dia. was. The 7.62 barrels may have been tighter ie 307/299 due mainly to customer expectations.

Now (I guess) orders are for .308x3000, 6grove for the commercial bullets.
I gathered the twist was depending on customer demands/preferences.

Another thing that came up was that he has never had a barrel split and never expects to, due to quality controls etc.

He's not on the net because of time constraints but has phone and Fax.

Very good posts here, you guys know your Palma stuff.

I used to shoot a "little" Palma and some Any/Any.

I think it was Scott Medusha [USA] that was making some 3 groove bbls that shot really well.

I have used a couple of his 1000 yard "angled" scope mounts. His work was very good.