30 Sherman Magnum 20” Build

[backwoodsshooter]

After carrying around long barreled heavy rifles for years I wanted something that hit hard and was more packable for mountain hunts. I've always been a big fan of the versatility of .30 cals. After years of shooting game with cartridges from .17cal-.338 I favor bigger calibers even for deer sized game. Just less margin for error at the cost of more recoil. With this build I wanted to try for a do it all rifle, medium weight with the larger cartridge, and something that gets preference every time I go hunting with the exception of varmints. All I've done so far is a pressure test with 215 bergers, ADG brass from Rich, N570, and shot some factory PRC ammo. I will be posting results over time as I test multiple powders and bullet combinations. Imr 8133, H1000, Ramshot LRT, 230 Berger, 220 Berger, and something from the Hammer line. I will post rifle weight when I get a chance to put it on the scale. As always a big shout out to Rich for his help and all his efforts to create innovative cartridges.

Rifle Specs
Rem 700
Ti FPA
20" Proof CF
Stock is from an original Proof Tac II rifle
Murphy Ti base 20MOA
NXS 5-22x56 for now
Seekins Rings
Badger knob
Jewel trigger
Hawkins BM
Terminator T3/Suppressor


Pressure Test done with a single piece of brass
55*
COAL 3.722 +.005"
N570
ADG brass
Fed215M
215 berger
NT .001

84 2881 2 Firings on brass
85 2917 3X
86 2946 4X, fired case could easily be chambered again
87 2983 5X, clicker, primer was still round
88 2988 6X, Bolt lift, flattened primer, no ej mark not even a faint one. Hot load though!

These are case web measurements just above the extractor cut measured after the case was sized on each firing.

virgin unfired .529"
83gr 1X .5315"
84gr 2X .532" 2881fps
85gr 3X .532" 2917
86gr 4X .532" 2946
87gr 5X .532" 2983
88gr 6X .5325" 2986

Velocity is right where I expected it with the proof. I hope to find my load around 85-86gr with the 215 bergers.

Velocity Data was measured with a Magneto Speed. I recorded one shot from factory 300PRC ammo with the 212gr ELD-X at 2626fps.

I will continue to update this thread as I test and gather data. Rifle has 21 shots through it as of now.

View attachment 256464View attachment 256465View attachment 256466

not gonna lie, that is a sexy rifle.

 

[CA48]

Phorwath, I don't think I ever started getting compressed charges even at 88gr. The 215s seated at 3.722" are seated pretty far out there. I'm sure I was getting very close and il double check for you in a few days when I get back. If remember correctly powder was still just below the neck with 88gr. I made a drop tube probably around 16" and that made a big difference.

I have 565 but I've tested it in a lot of 300PRCs and 6.5 PRCs and it gets almost identical velocitys within a .5gr of h-1000 in the 78-79gr charges (milder loads).

If I had some 560 I would try it but I believe it's to fast, closer burn rate to h4831/h4350 I believe.

I'm hoping N568 will give Identical velocitys as 570 but with more ideal case fill in the SAUM sized cartridges.

My guess is RL26 will be within 30-50fps short of 570 at equal pressures.

 

[elkaholic]

Phorwath, I don't think I ever started getting compressed charges even at 88gr. The 215s seated at 3.722" are seated pretty far out there. I'm sure I was getting very close and il double check for you in a few days when I get back. If remember correctly powder was still just below the neck with 88gr. I made a drop tube probably around 16" and that made a big difference.

I have 565 but I've tested it in a lot of 300PRCs and 6.5 PRCs and it gets almost identical velocitys within a .5gr of h-1000 in the 78-79gr charges (milder loads).

If I had some 560 I would try it but I believe it's to fast, closer burn rate to h4831/h4350 I believe.

I'm hoping N568 will give Identical velocitys as 570 but with more ideal case fill in the SAUM sized cartridges.

My guess is RL26 will be within 30-50fps short of 570 at equal pressures.

I think youre probably right on all counts.
568 should be a good one in several of my chamberings.

 

[CA48]

Phorwath, 88gr is compressed. I'm thinking Il end up in the 85gr range though 2900Fps+. 85 looks to be in the 97-100% range with powder level settling right around the shoulder/body junction.

Barrel has 125rounds through it now and brass is formed. Should be around a week or so before I start load development. Right now the barrel has very minimal fouling. Cleans up easily with a brush and a few patches.

 

[CA48]

Went out today and did another pressure test with n570. When I started the barrel had 125rds through it.

75*
CBTO 3.956" +.005"
215 Berger
N570
Fed215M
NT .001"
ADG brass

83.7 2880
84 2870
84.3 2880
84.6 2893
84.9 2895
85.2 2942
85.5 2963
85.8 2949

When conditions are better Il shoot the ladder at 700-800 yards. Never saw any pressure signs with 1x brass.

I loaded up a single case with 85.5gr and shot it 8 times. By the end the base measured .532.5" after sizing. It could have gone for more firing but I was tired of messing with it at this point. The first firing was with 83gr jammed to form it. By the 3rd firing I was getting clickers and 1 or 2 of those later firings had faint ej marks. With 85.5 I could shake the case and hear powder moving. Load density is ~95%. I would call 85.5 max working pressure for this stainless Rem 700 receiver.

 

[highdrum]

I loaded up a single case with 85.5gr and shot it 8 times. By the end the base measured .532.5" after sizing. It could have gone for more firing but I was tired of messing with it at this point. The first firing was with 83gr jammed to form it. By the 3rd firing I was getting clickers and 1 or 2 of those later firings had faint ej marks. With 85.5 I could shake the case and hear powder moving. Load density is ~95%. I would call 85.5 max working pressure for this stainless Rem 700 receiver.

So if I'm reading this correctly, after 3-4 firings you had clickers for the last 4-5 firings? And ejector marks started showing around 6th firing? Just trying to get my head around this. That's some pretty great velocity from that short a barrel.

 

[elkaholic]

Went out today and did another pressure test with n570. When I started the barrel had 125rds through it.

75*
CBTO 3.956" +.005"
215 Berger
N570
Fed215M
NT .001"
ADG brass

83.7 2880
84 2870
84.3 2880
84.6 2893
84.9 2895
85.2 2942
85.5 2963
85.8 2949

When conditions are better Il shoot the ladder at 700-800 yards. Never saw any pressure signs with 1x brass.

I loaded up a single case with 85.5gr and shot it 8 times. By the end the base measured .532.5" after sizing. It could have gone for more firing but I was tired of messing with it at this point. The first firing was with 83gr jammed to form it. By the 3rd firing I was getting clickers and 1 or 2 of those later firings had faint ej marks. With 85.5 I could shake the case and hear powder moving. Load density is ~95%. I would call 85.5 max working pressure for this stainless Rem 700 receiver.

When did you buy the dies?

 

[CA48]

So if I'm reading this correctly, after 3-4 firings you had clickers for the last 4-5 firings? And ejector marks started showing around 6th firing? Just trying to get my head around this. That's some pretty great velocity from that short a barrel.

I'm going to test it again. Not a good run as I forgot to trim that piece of brass. So it was causing some issues.

Rich, I think I bought dies this last Oct or Nov.

 

[slikmrc]

What barrel twist and groove are you running? Glad to see I'm not the only one still using the Bob Hagel style of measuring cases for pressure.

 

[snox801]

Looking forward to you trying the 214 hammer.
I have a 26" proof on mine and am gonna be launching the 214 or 199's out of mine.

 

[Elk Hunter 338]

So if I'm reading this correctly, after 3-4 firings you had clickers for the last 4-5 firings? And ejector marks started showing around 6th firing? Just trying to get my head around this. That's some pretty great velocity from that short a barrel.

 

[elkaholic]

I'm going to test it again. Not a good run as I forgot to trim that piece of brass. So it was causing some issues.

Rich, I think I bought dies this last Oct or Nov.

those dies we're borderline sizing enough so clickers were more likely. I had Hornady tighten them up another .0005" and they are perfect

 

[CA48]

So if I'm reading this correctly, after 3-4 firings you had clickers for the last 4-5 firings? And ejector marks started showing around 6th firing? Just trying to get my head around this. That's some pretty great velocity from that short a barrel.

Running an 8 Twist.

I ran one case again, for 10 firings this time, but it could have gone more.
I didn't explain it very well last time but I was seeing increasing pressure with the same charge due to the piece of brass growing as I never trimmed it throughout out the process last time.

This time this I cleaned the barrel. Shot 1 factory Hornady round through it to help foul the barrel. I then grabbed a piece of adg that had been formed with a mild load and started. So 10 firings total counting the mild FF load. 1 at 83gr of N570 then 9 with 85.5gr.
No Pressure signs until the 4th firing then I started to get clickers and very faint ej marks that you really had to look for and could only find in the sunlight. With each shot I was lining up a letter on the case head with the ejector so I knew where to look. After the 6th firing I started pushing the shoulder back more. Then shots 7-10 the clickers went away but I was still getting the very faint ej shadows that you really had to look for in the sun to see.

As far as me pushing the shoulders back more and the clickers going away. Part of my thinking is when I took my initial shoulder measurements for my bump it was on a once fired case that was not fully formed yet in addition to the Hornady comparator which is not going to be perfect or in the exact right spot on the shoulder for a precise measurement. But the clickers did indeed go away once I started pushing shoulders back .001" more. I know this shouldn't have much to do with the base of the case not getting sized enough which is where clickers usually come from if I understand correctly, just relaying what I experienced.
After the case had been fired 10x i sized it again and measured the base with Mitutoyo calipers. It measured .5326"

The 10X fired case

The 9 velocity readings in order with 85.5gr of 570 at +.005" with the 215s after the barrel had been fouled with one shot. After looking at these readings it looks like I would have had a much lower ES if I had put a few more shots through the barrel before I started taking readings. It seemed to stabilize after the 3rd shot from clean bore.

1 Hornady factory
2 2966
3 2922
4 2956
5 2951
6 2946
7 2958
8 2956
9 2948
10 2955

 

[CA48]

those dies we're borderline sizing enough so clickers were more likely. I had Hornady tighten them up another .0005" and they are perfect

Good to know. So I'm good for a trade in right