Reloading .260

[Dranmelex]

All,

I have had a couple custom rifles that I have bought used, but finally had my new left hand custom built in 260 Remington. I specified to the builder that I was going to shoot 140gr Amax's through it and took delivery a month or so ago. The question I have is pertaining to freebore and OAL. I have found that (and it may be fault for not specifying) there appears to be hardly any freebore in this rifle. When developing some initial loads for fireforming, I noticed that the base to ogive length is 2.132" measured with hornady OAL gauge and zeroing for the comparator. This yields an OAL of 2.752" to the lands. I'm afraid that I have too much bullet in the neck as the taper for the shoulder into the nose of the bullet is very close to the case mouth. Granted the rifle liked the 140 amax with 41.0 gr h4350 seated at 2.735" and achieved a .246" center-to-center 3 shot group. But I don't know if I'll be able to achieve the higher velocities to get out to longer ranges without exceeding pressures from seating shallower.

The builder says he will throat it for no cost, but I'm sure that will tie the rifle up for another month or so. Any guidance/feedback would be appreciated.

Thanks,
Dan

 

[CJ6]

I take it you're feeding from a SA mag? Using the 140 class in a magezing is a comprimise

 

[ShootDots]

All,

I have had a couple custom rifles that I have bought used, but finally had my new left hand custom built in 260 Remington. I specified to the builder that I was going to shoot 140gr Amax's through it and took delivery a month or so ago. The question I have is pertaining to freebore and OAL. I have found that (and it may be fault for not specifying) there appears to be hardly any freebore in this rifle. When developing some initial loads for fireforming, I noticed that the base to ogive length is 2.132" measured with hornady OAL gauge and zeroing for the comparator. This yields an OAL of 2.752" to the lands. I'm afraid that I have too much bullet in the neck as the taper for the shoulder into the nose of the bullet is very close to the case mouth. Granted the rifle liked the 140 amax with 41.0 gr h4350 seated at 2.735" and achieved a .246" center-to-center 3 shot group. But I don't know if I'll be able to achieve the higher velocities to get out to longer ranges without exceeding pressures from seating shallower.

The builder says he will throat it for no cost, but I'm sure that will tie the rifle up for another month or so. Any guidance/feedback would be appreciated.

Thanks,
Dan

If it is a single load action, tell him you want a freebore of .165 to .170. That will be puuuurrrrrrrffffect for the 140 class bullets..

 

[ballison]

I have a 260 and had a reamer made to shoot the Berger 140 hybrid. Dave Kiff @ PTG recommended a .110" freebore. However, the Berger 140 hybrid and the 140 Amax are different animals. The nose length on the hybrid is a lot longer than the Amax, so the hybrid requires a shorter freebore to not exceed mag length. If you have a good smith, seat a 140 Amax with the length you want it and give it to him. He should be able to get the freebore from that.

If you're not mag feeding, then you can do any length you want.

 

[Dos XX]

140 Amax is very long for a .260 at short action mag length, even a 2.950 OAL mag.

 

[Dranmelex]

So, I originally thought about just keeping it and shooting the Berger 130 AR hybrids as they were designed for a shorter OAL. Does anyone else shoot these in .260? And if so, how does it stack up to the base to ogive length of 2.165" that I have with an OAL of 2.762" to the lands?

 

[ballison]

Funny you should ask, because I switched to the 130AR in my 260. My BTO measured with a Hornady gauge is 2.295" to the lands, and COAL is 2.885". This is with a freebore of .110". With H4350, I'm getting 2960fps with no pressure signs. Ballistics are just as good, if not better, than the 140 hybrid at 2800-2850fps.

 

[dkhunt14]

It only takes a little time to throat it out. I would try the shorter Berger and see where they are in the case. You can hold a bullet alongside a case with a seated bullet and see where the pressure ring of your seated bullet is. I would not want the pressure ring past the sized part of the case. Matt

 

[chalkeye]

With H4350, I'm getting 2960fps with no pressure signs. Ballistics are just as good, if not better, than the 140 hybrid at 2800-2850fps.

2960fps with a 140gr AMAX?? That is screaming!! How much H4350 are you tipping in?

 

[ShootDots]

It only takes a little time to throat it out. I would try the shorter Berger and see where they are in the case. You can hold a bullet alongside a case with a seated bullet and see where the pressure ring of your seated bullet is. I would not want the pressure ring past the sized part of the case. Matt

^^^^^^This why you want a freebore of at least .160 for the 140 class bullets. If you are going to use the 140 Hybrid, 140 VLD or the 139 Scenar, you will want it right at .170....

 

[dkhunt14]

2960fps with a 140gr AMAX?? That is screaming!! How much H4350 are you tipping in?

You need to read his post again. He is shooting 130's. matt

 

[ballison]

^^^^^^This why you want a freebore of at least .160 for the 140 class bullets. If you are going to use the 140 Hybrid, 140 VLD or the 139 Scenar, you will want it right at .170....

OP, are you mag feeding or single feeding? I shoot PRS with a 260 where mag feeding is a must, and IMHO, a .170 freebore will put you too long with the 140's if you want to get close to the lands. If you are shooting F-Class or bench and single feeding is OK, then you are fine with a longer freebore.

The 139 Scenars, 140 Amax, and 130AR's have a much shorter nose, and mag feeding is not as much of an issue.

 

[Dranmelex]

I am mag feeding, so max length would be constrained to about 2.875-2.890 or so. However, even with the 130 Berger AR Hybrids, I would be seating at 2.750". I'm not sure what I'm looking for as far as a pressure ring goes.

 

[ballison]

Regardless of what bullet you choose, if you currently have NO freebore, I would definitely have your smith add some. How much? Depends on what bullet you want to shoot. IMHO, the 130AR can't be beat in a 260. If you want to seat one and measure it so you can give it to your smith, PM me your address and I'll stick a few in the mail for you.

 

[Dranmelex]

I am assuming that I have no freebore due to the short measurements I am seeing. I don't actually know how to verify with complete certainty.

I have a few of the 130 AR Hybrids I am messing with. I believe I will send a seated one to the smith as you suggested, but I'm unsure of what OAL I want to run. Is there any benefit one way or another for a mag fed rifle as far as chasing lands once the throat starts to erode?

 

[ballison]

First, choose the bullet you want to shoot. Second, figure out the max COAL that will reliably feed from your mags. Third, seat your bullet to that max COAL and see how it looks (where is the boat tail with respect to the case neck). If you have enough room, I would go an extra 30-50 thou to allow for throat erosion.

 

[jcampbellsmith]

I've shot 140 A-Max in this rifle - http://www.thestalkingdirectory.co....leries/p2948-remington-700-sa-in-260-rem.html it has a Wyatt's Outdoors Extended Magazine Box which measures 3.1 inches. Regardless of what bullet you choose to shoot, I suggest having a look at fitting this longer magazine.

Have fun.

JCS

 

[jimbires]

I'm reading this thread to get ideas ,as I'm working with a short action , factory length box , 260 right now . yesterday I ordered a wyatts extended box from midwayusa . I ordered the MBE-5 . it's 3.070 outside length and 2.995 inside length . I didn't see any short action boxes that are longer .

http://www.wyattsoutdoor.com/index.php/cPath/1

 

[ballison]

I'm reading this thread to get ideas ,as I'm working with a short action , factory length box , 260 right now . yesterday I ordered a wyatts extended box from midwayusa . I ordered the MBE-5 . it's 3.070 outside length and 2.995 inside length . I didn't see any short action boxes that are longer .

http://www.wyattsoutdoor.com/index.php/cPath/1

Make sure your action and chassis/stock will accept a COAL that is that long too. I just had a 6x47 built, and had the smith spin up a 308 practice barrel for it. When I started loading for the 308, I realized that the bottom port of the action limits me to a 2.88" COAL, even though my mags will take anything up to 2.95".

 

[jimbires]

Make sure your action and chassis/stock will accept a COAL that is that long too. I just had a 6x47 built, and had the smith spin up a 308 practice barrel for it. When I started loading for the 308, I realized that the bottom port of the action limits me to a 2.88" COAL, even though my mags will take anything up to 2.95".

good tip , thank you . Jim