New .45-70 Marlin 1895 GBL

[Slamfire]

Interesting how this action works. The bolt locks at the rear. When the lever is racked and ready to fire there's a block that slides up into a slot in the rear of the bolt to lock it closed. The block also depresses the safety feature 2 piece firing pin in line so that it will function when struck by the hammer.

The Speer Reloading Manual states their load data doesn't exceed the industry standard working pressure of 28,000 CUP for new Marlin 1895 rifles. I thought it would be interesting to calculate the estimated safe operating chamber pressure of this rifle for reference and illustrative purposes only (not for design).

Chamber pressure should be limited so that bolt thrust doesn't cause the bolt block to yield under shear force (exceed the elastic limit of the steel it's made from).

Shear yield stress SYS = 0.58 TYS (Tensile Yield Stress) [von Mises Yield Criterion]

For AISI 4140 which is typical firearm steel, TYS = 417.1 MPa = 60,495 psi ( http://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?ID=AISI_4140&show_prop=all&Page_Title=AISI%204140 )

Bolt thrust T = chamber pressure P x case head cross-sectional area A = P x A

Block shear stress t = T / block area a = T / a = PA/LW

Re-arranging, chamber pressure to induce bolt block yielding P = LWt/A

From direct measurement, L and W = 0.4"

45-70 case head diameter = 0.505"

P = (0.4)^2 x 0.58 x 60,495 / [pi x 0.25 x (0.505)^2] = 28,028 psi

ANSI PSI = -17902 + 1.51586 ANSI CUP ( https://www.shootingsoftware.com/ftp/psicuparticle2.pdf )

P = 28,028 psi = 30,335 CUP <--- industry standard for this rifle is held to about 90% of this value.

 

[Steveo830]

Nice rifle, I love mine with a Skinner rear sight and Williams firesight front under a windowed front sight hood. As others have suggested, the WWG happy trigger and bear proof ejector are nice upgrades. I would also strongly suggest a Bear Tooth Mercantile cross bolt safety delete.

 

[Slamfire]

XS Lever Scout Mount

Received the XS Lever Scout Mount and installed it with my Leupold M8 Compact 4x28mm scope. Exactly how I like to have the scope mounted on a Marlin with the eyepiece way forward of the hammer.

The scope objective just barely clears the rail using the low height Burris Zee rings. No issues with the scope being mounted that far forward because it has about 6" of eye relief. The rifle has quite a handy feel - like it should.

 

[scott_r]

Nice rifle Slamfire....Im about to pull the trigger on one myself but am bummed I missed out on that $100 rebate.

 

[Slamfire]

Thanks! My purchase qualified for the $100 rebate. Pays for the XS Lever Scout Mount.

 

[Slamfire]

Got my big loop 6 shootin' '95 lever rifle sighted in today.

The crimp I applied with the Lee Factory Crimp Die needs to be a bit heavier because the overall length of the rounds in the magazine shortened a bit under recoil.

 

[Slamfire]

Update: 500gr bullets

Hornady 45 caliber 500gr soft nose bullets provide way better penetration. Excellent results in my 458 Win. Mag. on Moose at 1600 fps impact speed. It's a heavy bone smasher and straight-through penetrator plus it transmits lots of shock. If backed off a bit to 45-70 Marlin speeds it should still perform well.

My experiences with conventional jacketed flat nose 45-70 400 and 405gr bullets in the Marlin have shown that these over-expand at close range on heavy game because of their thin-jackets which limits penetration. Being a 45 caliber the bullets really don't need to expand very much to stomp heavy game. With clear-through penetration greater wound volume results plus there's usually an exit wound using 500gr bullets (which provides a good blood trail if needed).

Hornady 500gr DGX and DGS bullets (on sale!) were used and the rounds were single-loaded for safety. The DGX bullet soft nose diameter is a bit narrow to be stacked safely in a tube magazine (and the DGS bullet nose is FMJ so these rounds should never be stacked in a tube magazine). Still need to get this sorted so my rifle will function as a repeater with 500gr bullets.

Good results at near-maximum pressure in my rifle (only!) using Reloder7 at 1500 fps MV, and group size was about 1-1/2" at 100 meters off the bench rest. I tried IMR4198 but found pressures to be considerably higher at comparable speeds.

Ballistics compared for the 500gr at 1500 fps vs. 400gr at 1800 fps: energies are nearly equal at 100 yards, and beyond that the 500gr surpasses the 400gr.

45-70 Marlin GBL & 500gr

 

[Slamfire]

Rebate cheque received

Changed out the scope to a Bushnell Legend Ultra HD 1.75-5x32mm. The lower power settings can be useful, has generous eye relief even at 5x and has the anti-fog lens coating.

 

[quarterman]

Bought the same rifle 3 days ago and some 400 grain speers haven't fired it yet. Your post is getting me excited

 

[yomomma]

Mine too sits unfired. Have some reloadingto do this week end.

 

[Slamfire]

Bought the same rifle 3 days ago and some 400 grain speers haven't fired it yet. Your post is getting me excited

Marlin done real good with the GBL model.

 

[yomomma]

Marlin done real good with the GBL model.

Lots of sharp edges left from machining though on the internals

 

[geologist]

I went with QD rings on my GS.

 

[Slamfire]

^^
Looks great.

Final iteration (I think) for my GBL. A Leupold M8 Compact 2.5x20mm, Burris Z rings and XS Lever Scout mount. Got the weight down to 8.3 lbs.

 

[mikeelliot]

Mine is in need of the XS Rail and some new sites.
Great looking levers and good info on this thread!

 

[Slamfire]

And Barnes 400gr at 1850 fps muzzle speed.

 

[scott_r]

Lots of sharp edges left from machining though on the internals

you arent kidding, mine makes a real mess of the brass. Gotta break it down and polish some of the edges off. It does feed and function 100%