Hmm, 375 Ruger, 1917 action / busted scope mount screws

[Float Pilot]

I added a steel recoil lug from an old Vz-24 to the laminated Boyds stock on my Remington made 1917 Enfield actioned 375 Ruger project because the recoil was denting the laminated wood.

So off to the range I went today with some fairly snappy loads to see how they would group.

This is a fairly light rifle for this cartridge and as a result you do know when you have touched off a round...

I only fired 15 rounds today before the screws that hold the one piece mount to the action sheared right off. The front two sheared and the rear screw was still intact when I pulled off the mount. SEE PHOTO:
So now I have to drill and tap the little buggers and try something much bigger.

All used virgin Hornady brass, and federal 215 magnum match primer. All had a COL of 3.340 inch with no crimp. The barrel is a 22.5 inch long Shaw barrel with 4 grooves.

300gr Accubond with 79.0gr H-4350 = 2,810 fps and a big group at 100 yards.
270gr Speer SPBT with 80.0gr H-4350 = 2,860 fps and a 3/4 inch group.
260gr Accubond with 81.0gr H-4350 = 2,918 fps and a 1.75 inch group.

 

[Gtscotty]

That 300 gr load looks pretty brutal... You must have a fast barrel, it looks like the 300 gr load is running 150 fps faster than Hogdon's max for that H-4350, while using a 1.7 gr smaller charge. Is there any chance your powder scale might be off?

 

[Float Pilot]

Yes I am obtaining more velocity and more pressure. The brass made this look like a near-max load.

My scale is a RCBS flowmaster digital. And I double weigh all my experimental loads with another RCBS balance beam scale.

My chronograph was 12 feet out as well.

SO... I must have a tighter (It is a Shaw) barrel than they used for their tests,
Also I have some free bore in mine. While the max OAL is supposed to be 3.340in I loaded a few to 3.395 and the bullet ojive was nowhere near the rifling. Those loads were too long for my 1917 magazine box.

I think Ruger is using a shallow 6 groove rifling for their 375 Rugers and this barrel has deep 4 groove rifling. I need to double check my twist rate as well.

This rifle is fairly light for a dangerous game rifle. I filled the fore-arm with micro-spheres mixed with epoxy. Then I used bedding compound over that.
So it has a noticeable muzzle climb when fired from the standing position.

The 260 grain Accubonds and 270gr Speer Boat-Tails shot a LOT higher than the 300 grain slugs. Almost a foot higher at 100 yards.

Here are individual shot velocity readings in shot order. Temp was 38 degrees, light rain

260gr accubond: 2,940fps (oil in barrel) 2,918 2,899 2,871, 2,860

300gr accubond: 2,836 (cold barrel again) 2,814 2,809 2,809 and 2,795

270gr Speer BT: 2,886 (cold barrel again) 2,855 2,853 ( screws sheared off ) First Two bullets in one big hole the third about 1/2 inch away when the screws sheared off. Last rounds were fired standing with no scope or sights for function checking the magazine feed rails.

 

[Vern Humphrey]

I suspect your screws were made in China, their steel is quite soft.

The answer is to re-tap the holes to the next size screw and get good, hard, American-made screws.

 

[GooseGestapo]

The 260 and 270gr loads aren't that much off from what I've seen with my Ruger M77mkII Hawkeye "African" w/23"bbl.

However, that load with the 300gr Accubond bullet is about 2-3gr higher than the data I've seen given for it. It does have a bonded lead core, but the base of the .375 "plastic tip" Noslers is somewhat heavier than most cup and core bullets and evidently is running your pressures up somewhat.

Shouldn't be too big a chore to redrill and tap for an 8/40 screw.
With only 3 6/40's and shooting it from a "sled", you're really putting some force on those screws...
When shot from the shoulder, you are "softening" the blow to the mounts/scope.
My .375 has the factory style "Ruger" integral bases and "Ruger" rings. Haven't had any issues.
I have however, seen the same thing happen with my Leupold 1-piece bases and an Interarms MkX in .30/06.... If it'll happen with an '06 fired from the shoulder (220gr Norma factory loads), I have no doubt that it'll happen with the .375.

fwiw my '06 weighed over 9lbs w/scope but didn't have a recoil pad. After cutting the stock and fitting a Pachmayer pad (this was in the '70's), it quit shearing screws...

p.s. My Ruger too has a bit of freebore. However, I get superlative accuracy with the bullets seated to fit the magazine. The Hornady's actually shoot better seated to the cannulures and lightly crimped.

 

[Float Pilot]

I could not find any data for the 300 gr accubond, so I used info for the 300 grain round nose and backed off from max by 1.7 grains. Obviously I should have backed off even further. Although the brass extracted very easily. I had flat primers with a slight crater lip, but no case head swelling and no other signs. Other than kicking pretty fair. The rifle weight 7.9 pounds empty.

According to my ballistics calculator all my loads should be going right at 2,200 fps or more at 300 yards.

FROM HODGDON:

300 GR. HDY RN Hodgdon H4350 .375" 3.280"
75.9grains=2510fps 48,300 PSI
80.7 grains =2660 fps 59,600 PSI

 

[GooseGestapo]

Check the latest Nosler book. I believe I saw ~76-77gr. I only remember that I thought it remarkable at the moment.
I use 82.0gr of IMR4350 with the 270gr Hornady RN (I stumbled onto several boxes of "pre-interloks" for CHEAP...
I use 83.0gr as top load with a 250gr Sierra BtSpt, but prefer a "lighter than factory" load with 75.0gr of RL15. Ditto the 235gr Speer, and 77.0gr with the Hornady 225gr PtSpt as that was the minimum load that gave suitable accuracy.

My efforts with the .375 were in a different direction than typical...
But then again, I don't have Brown bears in my backyard like you do.

However, I did have a ~220lb Black bear run across AL Hwy 148 in front of me this morning at about 11am, about 3mi East of Co.Rd 7 and 3.5mi east of FR-600 (on the south end of the Talladega National Forrest in Clay, County near the Talladega line. I've seen them recently in W. Georgia too. But, I was incredulous that this one was moving in broad-daylight! At first, I thought it was a LARGE black dog, but it was on all fours at the edge of a pine-thicket and only entered the woods as I slowed down to look at it.

 

[Float Pilot]

I just had this action hanging in my shop for the longest time and figured I needed to make a complete rifle out of it...
Now that I have it,,, well almost since I need to fix the scope mount base,,,, I do not know what I will do with it...
I guess I could haul it around while taking photo clients out in the tall grass. But I already have all sorts of other rifles and shotguns for that...

 

[jgiehl]

Maybe put a touch of blue locktite on the screws too.
That way you can still get them out but take up any movement also.
That high of a load may have worked something a tad loose.
Just a quick thought.

 

[jim in Anchorage]

FP- Is your 1917 a dropbox or stright floor trigger guard? Boyds lists them only for drop box and I wonder how hard it would be to shape it for my stright box.

 

[CraigC]

Are the screws 6-48's? Perhaps some American made, high grade 8-40's are in order.

 

[Float Pilot]

The action was drilled and tapped by the prior owner. He used the standard old style screws which are obviously not up to the stress. I had them lock-tighted but I guess that was not enough. The recoil was even loosening the tow side windage screws on the base of the rear scope ring. I had them as tight as I could turn them and they spun loose every two shots.

I left the action with the fat belly because the 375 Ruger is a FAT CASE and I was hoping to get 4 rounds in the magazine. Right now I can get 3 in there and almost the fourth round.
Shaw opened up the rails when the barreled and chambered it... But it does not feed all that great so something is still not right. As we speak it has a stock 1903 magazine follower inside. It works a little better than follower that was in there when I bought the action. I an starting to wonder if a P-14 follower might work better.?

375 Ruger brass next to a 308 round and a 45-70

 

[jim in Anchorage]

Does not feed great in what way?

 

[Float Pilot]

Sometimes a couple rounds will pop right out of the magazine. Almost like they opened it too much...

 

[Float Pilot]

I am measured the broken screws. They are 0.132.5 to 0.135.5 of an inch or about 3.45 mm in diameter, I think that makes them a number 6 screw. Although the broken ones in front are 0.132.5 and the one in back is slightly larger. Plus somebody buggered up one of the screw holes in the front receiver ring at some time in the past. .

The screw holes and threads are buggered now.. So bigger screws are in the near future. I inherited a few odd things when I obtained the action.

The scope was a touch on the large side ,,,but unfortunately it was the only scope that had rings on it that was not doing anything that particular day. It is a 30mm tubed Boone and Crockett model 4.5 x14 Leupold.

This rifle would be more than happy with a 1.5 x5 Leupold, although the accuracy with the 270gr BTs and the velocity suggest it could easily be a 300 yard gun... Assuming I can keep a scope on it....

Since the eye-ball doctor told me to stop shooting heavy recoiling rifles, I have no idea what I will do with this gal once she is all done...

It is interesting that the 1917 action has such a small recoil lug on the bottom of the action and no third lug on the bolt.

 

[jim in Anchorage]

Did that stock come with those cross bolts? Looks like if I modified it for my straight trigger guard the guard would be in the rear bolt.Yes the 1917 has a small recoil lug. My 35-300 Win didn't split the stock, it shattered it.

 

[Float Pilot]

I think they might make you one with a flat bottom if you call and talk to them. They have a few options. Their cross bolts are pretty small, more like a threaded rod. Installed a recoil lug out of a 1930s vintage Vz24 stock.

 

[Float Pilot]

I filled in a major void in the fore-arm with epoxy mixed with micro spheres. The I went over that with regular bedding compound. Between that and the addition of the steel recoil lug it worked out well as far as being solid and yet light weight. The rifle only weighs 7.9 pounds empty, which is fairly light for a heavy recoiling rifle.