300 Sherman Shortmag (SS)

[Tidesloe]

The 180 was the original freebore. He now has a 110 as another option. If you're running an xm action you will have plenty of room. With the 215 Berger seated properly with only the boat tail below the neck/shoulder junction is 2.952". I believe with my first 300ss with the 180 freebore the 215 Berger was around 3.030". I'll have to check my notes later. With my new 300ss I have a custom throat that's is about 140. I'm also using cci 250 primers in this one.

Here is the new oneView attachment 401551View attachment 401552

That is a wild looking rig there. I like that!! Do you happen to know at the shortened reamer with 215 seated to the optimal spot in the neck where that puts the ogive from the lands? Pretty sure I could figure that out as Berger does post their dimensional details. I'm not opposed to the .110, but if I'm not limited by mag length more room to play will benefit me and .180 is certainly not too much. Is your .140 fb specific to your bullet choice?

 

[Idaho Trecker]

I'd definitely do the 180 with your setup. I wasn't limited on my first one being built on a tikka "long" action. My new one is limited by the mag length at 2.980. If I had the ability I would do the 180. I had the 110 reamer then had a smith use a unithroater to get where I wanted it being pretty specific to the 205 berger/208eldm.

 

[Tidesloe]

I'd definitely do the 180 with your setup. I wasn't limited on my first one being built on a tikka "long" action. My new one is limited by the mag length at 2.980. If I had the ability I would do the 180. I had the 110 reamer then had a smith use a unithroater to get where I wanted it being pretty specific to the 205 berger/208eldm.

Thanks! I just got bullet dimensions from Bergers website and if my calculations are correct, seated to the lands I'd still have plenty in the neck and a little wiggle room within where I normally end up running my seating.

 

[elkaholic]

So, it sounds like with an XM action .180 is my best option. Anybody out there have that reamer, with the reamer ground down to the new chamber dimension specs? I believe that would be my best option.

Those reamers aren't out for a while.

 

[Tidesloe]

Those reamers aren't out for a while.

Ok, I'll keep an eye out on availability on it.

 

[Tidesloe]

I'd definitely do the 180 with your setup. I wasn't limited on my first one being built on a tikka "long" action. My new one is limited by the mag length at 2.980. If I had the ability I would do the 180. I had the 110 reamer then had a smith use a unithroater to get where I wanted it being pretty specific to the 205 berger/

 

[Ray Gross]

Back home and able to look at my book again. I also revisited the 180 Berger elite hunter a while ago to see how fast I could stoke that up since the bc is higher than the other bergers up to and including the 190 grain vld for a hunting bullet.

300 SS
ADG brass
Fed 210 GM
Cartridge BTO 2.197" COAL 2.920"
36 degree F 27.1

RL 26
68 grains basically max capacity (with drop tube) pressure good
3110, 3102, 3106 .4" group

Hybrid 100V
over estimated again on starting load to much pressure
64 and 64.5 grains 3166 and 3206 fps
probably run good pressure around 3110 fps

N560
Maxed out capacity and pressure was starting to show.
67.5, 68, 68.5 3020, 3072, 3095

RL 16
pressure getting high at max charge, would not run this load
61.5, 62, 62.5 3098, 3122, 3155
this would run comfortable at 3100 fps.

Not to shabby for a 180 grain bullet and low 60's for powder charges with most of the powders that suit this size.

I am wondering if you had any load data for the Berger 180 Elite Hunter and RL17.

I've read through this thread and see that you were using RL17 with some heavier bullets, but didn't see any references to the 180 gr bullets. (maybe I missed it??)

If not, is there a reason that you didn't think that RL17 & 180's would work?

I found some Reloader 17 for sale, but if it is not a good combo, I'll pass.

 

[Idaho Trecker]

Rl 17 is great for speed but not so great for temp stability so I don't use it. I've had the same 8 pound jug for 10+ years and barely touched it. If you hunt in a relatively narrow temp band or adjust for temp it will produce great speed and is usually pretty accurate.

 

[Ray Gross]

Thanks

Rl 17 is great for speed but not so great for temp stability so I don't use it. I've had the same 8 pound jug for 10+ years and barely touched it. If you hunt in a relatively narrow temp band or adjust for temp it will produce great speed and is usually pretty accurate.

Thanks, I didn't know about the temp stability.

 

[Tidesloe]

I'm about to have my 300 SS chambered as soon as I get the guy chambering it a dummy sent in. I'm trying to get worked out exactly where I want the lands to be. I'm not limited by length, as it's gonna be an XM action, and I will be shooting 215 hybrids. After necking up 2 pieces of brass I realized I'd pushed the neck back a little bit. Nothing fireforming won't cure. What should the min and max case length be on it for future reference? Another question I've got is how many fireforming loads " should" it typically take to fully fireform ADG brass, and how much should I expect my brass to grow until fully fireformed? I went with a mechanical ejector on this build an fully fireforming might potentially be a little more critical to dependable ignition.

 

[elkaholic]

I'm about to have my 300 SS chambered as soon as I get the guy chambering it a dummy sent in. I'm trying to get worked out exactly where I want the lands to be. I'm not limited by length, as it's gonna be an XM action, and I will be shooting 215 hybrids. After necking up 2 pieces of brass I realized I'd pushed the neck back a little bit. Nothing fireforming won't cure. What should the min and max case length be on it for future reference? Another question I've got is how many fireforming loads " should" it typically take to fully fireform ADG brass, and how much should I expect my brass to grow until fully fireformed? I went with a mechanical ejector on this build an fully fireforming might potentially be a little more critical to dependable ignition.

Since you aren't limited by magazine length, the original 180 FB reamer worked pretty well with a 215 Hybrid loaded at around 3.030". For short action builds that are magazine fed, I recommend the .110 FB reamer.
If you have the new /B reamer, fire forming is no different that any new pierce of brass. If you have the original chambering, I would start with a low end saum load. Once its been fired a couple times and trimmed to length, stretching is quite minimal with the low body taper and 40 degree shouldered case.

 

[cjl2010]

Since you aren't limited by magazine length, the original 180 FB reamer worked pretty well with a 215 Hybrid loaded at around 3.030". For short action builds that are magazine fed, I recommend the .110 FB reamer.
If you have the new /B reamer, fire forming is no different that any new pierce of brass. If you have the original chambering, I would start with a low end saum load. Once its been fired a couple times and trimmed to length, stretching is quite minimal with the low body taper and 40 degree shouldered case.

Is the new /B reamer .110 FB?

 

[elkaholic]

Is the new /B reamer .110 FB?

Yes you can add FB with a throater if need be.

 

[Tidesloe]

I will be beginning initial testing with my 300 SS this coming weekend. I've got the .180 freebore and intend to shoot Berger 212's. However I'm hunting Elk in the timber in Oct, so I think I'm gonna give some 182 gr Hammer Hunter Tipped a try for this hunt. I sure might loose a little case capacity with this bullet but it really doesn't matter with this load and mostly close range shots. Of the powders I have on hand, I'm thinking I'll do pressure tests starting at 53 gr of H4350, H100V, and N550. Is this a reasonable start?
As far as burn rates go, does the longer bearing surface and harder material in copper bullets affect the go to burn rates in powder selection? I will get back to Bergers after this hunt in Oct, but I've never tested copper bullets and unsure of the theory behind a change to copper bullets. Thanks for any advice or direction you guys might have to give.