Help - Resizing Lapua 308 Win Palma (small primer) brass to 260 Rem for 260 AI

[Romulus]

I've read a lot of information and more opinions on resizing 308 Win to 260 Rem.

• If anyone has experience resizing for this situation, and better yet, with said brass I'd love to hear your experiences and/or measurements. I don't want some too-thick-necked brass but I like the idea of running small rifle primers on my 260 AI that I'm putting together in the next 3 weeks.
  
• Also, if anyone has general info on small rifle primers results on performance in 260 or 260 AI feel free to rant on that as well.
  

If I do indeed need to do inside turning, is the Forster equipments the best way?

 

[ShootDots]

Howdy Romulus! I did EXACTLY that! However, with a minor twist... My friend uses the "Palma Brass" necked down in his 7mm-08.. When I built my .260 A.I. he sent me 100pieces. I necked them down to .264, then fireformed the brass.. It worked ALMOST perfectly.. One of our dies (I do not know which one) sized the neck just a hair further down. That resulted in an "almost doughnut".. It was just enough of interference to cause the groups to be horrible on those pieces of brass. The others worked fine and grouped VERY well indeed!! If it were me, and I was going to use the Palma Brass again, I would do something "out of the norm".... I would first use a mandrel to "iron out" the necks, then get a GOOD outside chamfer on the neck, lube up both the inside and outside of the necks and run them into a REGULAR .260 F/L die.. Then go fireform and use your A.I. die from there on out.. I know it seems a bit much to go from 308 to 264 BUT I have seen it done with no problems at all>>IF the aforementioned steps are adhered to. I also found out that in MY particular rifle, the 142's charged with H4831SC and a CCI BR-4 primer produced extremely nice groups and very low e.s.'s.. I set the 142's 5K OFF the lands and that is where I stopped>>>Doing a ladder test for seating depth would not have made the groups any better>>they were excellent! Now one point: if you decide to go from 308 all the way down to 264 in one step, use a REGULAR .260 F/L die as the shoulder will need all the support it can get or you MAY ( I am not sure) you MAY collapse a neck>>>with the REGULAR .260 Die, you will not! AND one more suggestion>>>the brass after necking down / fireforming will need annealing right after your fireform job.. Then you will be in business!!

Oh I forgot!! Unless you have used a reamer designed for the Palma Brass, you will need to turn your necks down to 12K thickness>>>>If not you will have a VERY bad time trying to tune your rifle.. AND If you do turn your necks down, you will see a slight build up of brass right at the junction of the neck and shoulder>>>set your neck turner to turn that right off>>>save yourself a headache later..

 

[dooley]

I am also using .308 Palma brass in my .260, I had an engineer do this for me, he could not do this in one stage he had to go through a 7.08 first, on making a dummy round the neck size was 0.298 thou, so I had to neck turn off 000.2 thou, this made a 0.296 assembled round, as I have a o.298 thou neck size in chamber I intend to neck turn off another couple of thou after the first firing, I found that the lenght of the case was 2008 thou before the first firing and grew 5-6 thou after firing, it might be the right lenght after the 4th reload, I have used CCI 450 primers and CCI small rifle primers and found very little difference in velocity and accuracy, I found that the ES was slightly smaller with the ordinary small rifle primers which suprised me, question is was it all worth it?
dooley

 

[ShootDots]

Hey Dooley... if you plan on "experimenting" as in running up pressures with H4350 or N160 or N560 etc.. you will need the Palma Brass as the small primer pocket is considerably "thicker / stronger" in the web area. It is difficult to run up pressures with H4831 as it is at the slowest end of the usable spectrum>>>BUT it is also incredibly great powder for the .260A.I. using heavy bullets.. Just something to consider..

 

[Romulus]

What velocities were you guys attaining with 139-142s? I'll have a 28" bbl.

 

[ShaneG.]

I bought a Redding form trim die to run my 308 brass into. It left the neck just oversized enough a bullet would slip in. I then ran it into my 260AI sizer. I ran some into my 260AI sizer before using the trim die and it worked but just went smoother using the trim die.

http://www.midwayusa.com/product/781383/redding-trim-die-260-remington

Using 140 amaxes I was getting 2900 with a 28" Criterion. Using MR2000

 

[ShootDots]

I am getting 2870f.p.s. with a 26" barrel.. I am using 48.5grs. of H4831SC and a BR-4 Primer with 142SMK's set 5K off the lands..

 

[Erik Cortina]

You need two dies.
You will need a Redding 260 AI Type S F/L sizing die and use 2 bushings to step it down to about .277" or so. Then use a 260 F/L sizing die (the one that uses no bushing) to get it down to 6.5mm. (This die will size the entire neck unlike the bushing die)

At this point it would be good to anneal it again to minimize chance of split necks.
Now run your expanding mandrel in the necks and neck turn for proper clearance.

After first firing, go back to your 260 AI Type S die and resize with proper bushing.

CCI 450 primers is what I would recommend.

 

[GabbyJs]

I tried using the Remington .308 small primer pocket brass necked down to 7-08 about 20 years ago. I used almost every primer available at the time, and would get hangfires. Is there anyone finding similar results with the Lapua brass?

 

[dooley]

Hi shoot dots, thanks for the imfo, at present I'm using Rel 17 + 139gr Scenars, with a 1-8.5 twist 26 inch barrel I'm getting 2900fps, however ES's are not brilliant with this powder I think I will try H4831 and settle for less velocity and better ES's, this is a standard 260 not a AI, in my last 260 1-8 twist barrel I used to use H4350 and used to get ES's in single figures.
What lenght did you find your 308 palma cases were when you necked them down to 260 ? Best Regards, dooley

 

[ShootDots]

Hey Dooley>>>>they were, on the average, 8K shorter... Fireforming and blowing the shoulder out "pulled" the neck down a smidgen..

 

[BradY]

Im using the palma cases as well in a 260 30 degree improved. One thing I have found is that H4381 wasnt very good. I have a feeling it may be a bit too slow for that small primer to ignite consistently. Often it would shoot well, then out of the blue I would get slower shots then back up to normal speed and then back and forth. There was no pattern to it. 47.5gr shot well aside from the slower ones, so I went looking to 48.5gr to get some velocity and up the pressure more to try and get a better burn. All that did was make me have to use a drop tube. Aside from that velocities were similar and the low speed shots kept coming. Dumped that idea and went back to H4350 and run 43.2gr with hybrids jammed 15 thou for 2835fps and a 10fps ES. I can load up to 45gr H4350 and shoot the higher node but havent done enough work up that high yet to find a load as good as this.

Yes you will have to neck turn your cases. I have sized successfully from 308 to 260 with brand new cases only and lots of lube. Fired ones you will need (and I prefer to do it anyway) with a 7mm-08 FL die and then a 260 FL die. I run a 292 bushing for a 293 loaded round and a 298 neck chamber. Those who think 2 thou neck clearance is fine is kidding themselves in this chamber. Try 4 or 5 thou and notice the total lack of vertical spread at 1000yds. 2 thou I had troubles but another skim with the tuner and it works real well.

 

[prwhite]

I'll also agree that H4831 & H4831SC are too slow to use with the small primers, with velocities way below what might be expected. (150-200fps) H4350 gives excellent results, but I've found the small primer gives 20-25 fps slower speeds, and only a few points less ES for an equilavent charge weight between the large and small primers. I've shot the small primer loads down around 40 deg/F with no sign of any hangfires. YMMV.

 

[michaeljp]

I resized some palma brass last night in 1 step to 260 rem by slowly lowering the Redding F/L die a couple of thou at a time. I ended up with a bulge at the neck/shoulder junction. I then neck turned the bulge and turned into the shoulder a bit aswell. But i ended up with a very small step in the shoulder. Is this normal or did i turn to deep?

 

[ShootDots]

Michael, if you read my first reply, you would have the answer for your question... Let's hope it will blow out when the shoulder blows to 40deg.. I set my neck turner to go very slightly past the shoulder / neck junction>>>then turned off the excess brass BEFORE it MAY go "inside" and become a "doughnut" as it were...

 

[michaeljp]

Thanks Shootdots.
So what i did is ok. My rifle is a factory Tikka super varmint 260. In your first post you said to turn the 308 case necks to 12 thou. Ive turned my necks just enough to clean the high spots and it measures about 0.1500- 0.1450. If i turn them down to 0.1200 will i not have to much neck/ throat/ chamber clearance? My 260 loaded rounds measure 0.295 and the new palma brass loaded measure 0.295 thats with both brass turned to the 1500-1450k.

 

[ShootDots]

Go back and turn them down to 12K.. It will work just fine... ALSO when you turn them down this time, CUT that build up of brass off at the Neck / Shoulder junction.. You will be pleased at the results of your brass.. I think there is some REAL validity to the ideas postulated by the 2 other Forum members that H4831 may in fact be a tad slow for the small primer pocket. Additionally, going towards a MAX charge will also necessitate a very compressed load. That, coupled with the "slowness" of H4831 and small primers may induce erratic ignition. Try some H4350 first..

 

[michaeljp]

Go back and turn them down to 12K.. It will work just fine... ALSO when you turn them down this time, CUT that build up of brass off at the Neck / Shoulder junction.. You will be pleased at the results of your brass.. I think there is some REAL validity to the ideas postulated by the 2 other Forum members that H4831 may in fact be a tad slow for the small primer pocket. Additionally, going towards a MAX charge will also necessitate a very compressed load. That, coupled with the "slowness" of H4831 and small primers may induce erratic ignition. Try some H4350 first..

Thanks mate,
I'll give it a go as you described. And yes, im using the equivalent to H4350 which is ADI AR2209. I loaded some up the other day and tested them using 140gn berger hybrid target. My best group was .250". 0.02" jump, 3 shot group with 37.5gn of AR2209 at 100yards. I also use the free recoil method of firing and squeeze the trigger and trigger guard together. I did try some H4831 or ADI AR2213sc the best i got with it was 0.381 and 0.371 that was with 260 lapua brass. These were the first trial loads in this rifle, so i have a fair bit more experimenting to do with other projectiles aswell.

Thanks for your advice.

 

[ShootDots]

That is quite alright... That is what this forum is for! Everyone helping everyone, if we can!! Good Luck and Good Shooting!!

 

[BradY]

Thanks mate,
I'll give it a go as you described. And yes, im using the equivalent to H4350 which is ADI AR2209. I loaded some up the other day and tested them using 140gn berger hybrid target. My best group was .250". 0.02" jump, 3 shot group with 37.5gn of AR2209 at 100yards. I also use the free recoil method of firing and squeeze the trigger and trigger guard together. I did try some H4831 or ADI AR2213sc the best i got with it was 0.381 and 0.371 that was with 260 lapua brass. These were the first trial loads in this rifle, so i have a fair bit more experimenting to do with other projectiles aswell.

Thanks for your advice.

Hey mate I think from memory about 42gr 2209 is a pretty common accuracy load with the 260 so your 37.5 is pretty low. I would juice it up a little. Also I found the hybrid liked 5-15 thou jump with a bit more neck tension like 2-3 thou or a jam with 1 thou. The jam 15 thou and 43.2gr 2209 with the small primer cases in my 260 improved just placed me 2nd in the WA Queens prize after dropping 6 points at 300yds due to a scope issue. The load and gun was working beautifully.