Hello, new here question about buying boolits fir 450 BM bolt action

[M-Tecs]

If it's truly that large you can used .458 cast bullets if the front of the case still has clearance.

[M-Tecs]

Update just got back from the gunsmith and he used a 45 cal soft ball pushed from the muzzle . according to his measurements my bore is 455. He said up at the top it was a bit tighter amd opened up towards the chamber.

What did he use to measure the slug?

[Rollins]

He had a round ball of lead he said made for slugging bores and used a set of fancy looking calipers from what I could see.

I dunno if he wrote it down wrong or what. I am going to get a second opinion. I have a buddy who is a machinist and have him measure rhe slug.He is used to measuring things down to the ten thousands.

I have the slug and measured it, I have digital calipers so maybe a micrometer will be different but I got .4505, .4510 and .4508.

Using the guide for slugging the bore which is how I did my mosin before. I measured from one raised ridge to the one on the other side, and got those numbers.

I dont know if i am doing something wrong, or if the gunsmith wrote it down wrong or what.

Maybe he meant 45055, and just missed the zero wrote 455?

[M-Tecs]

The reason I asked is the Ruger 450 BM uses a five groove barrel.
https://ruger.com/products/americanR...ets/16950.html

You normally can not use a standard mic or caliper to measure five grove bullets. Sometimes the land and groove lines up so you can get very close. The V-anvil micrometer is the best normal way but it is an expensive and specialized tool https://www.amazon.com/Mitutoyo-V-An.../dp/B007PSS7IW

If you machinist friend has access to a CMM, a 108 Degree 5 Flutes V-Anvil Micrometer or an Optical Comparator that would be preferred.

Next is a 108 degree V-block with a standard mic and some math.

"A way to simulate one is to make a small V-block of the appropriate included angle (108° for five grooves), calibrate it with an accurate diameter pin, and then measure the bullet and V-block with an ordinary micrometer. Then do the math given below.

The math goes like this:
Let a = the included angle of the V-block,
t = the thickness of the V-block from the bottom of the V to the bottom,
h = the measured height of the bullet and V-block,
and d = the diameter of the bullet.

Then d = 2(h - t)/(1 + 1/sin (a/2) )

An example:
For a 5 groove bullet, the included angle (a) is 108°, assume the V-block "thickness" (t) is .250" and the measured total height (h) is .5854", then
d = 2(.5854 - .250)/ (1 + 1/sin (108/2))
d = 2(.5854 - .250)/ (1 + 1/sin 54)
d = 2(.5854 - .250)/ (1 + 1/.80901)
d = 2(.5854 - .250)/ (1 + 1.23607)
d = 2(.5854 - .250)/ (2.23607)
d = 2(.3354)/(2.23607)
d = .6708/2.23607
d = .300

The easiest way to determine the V-block thickness (t) is to measure a known cylinder and then calculate it from

t = h - (d/2) (1+1/sin(a/2) ) "

After that I have read that wrapping the slug with .003" skim will somewhat work but I have never tried it sinced I have both a 108 degree V-Anvil mic and a 108 degree V-block. I am retired now so I don't have access to a CMM or an Optical Comparator.

Please post the second opinion numbers when you get them. Hope you didn't have to pay the gunsmith much.

Bore taper with large are the chamber and smaller at the muzzle is a good thing. Seems to be common with hammer-forged barrels. I don't know if it's a process function, nececcary to remove the mandrel or an actual design feature. Colt pushed it being time for the Pythons and Blackstar barrels used a chemical process to do it.

Reverse taper is less of a good thing but it is a fact of life when you recontour heavy barrel blanks to lighter contour.

[Rollins]

Wow that is a lot of math... Yeah that might be his problem that he used the wrong thing to measure. Whats weird though is that I measured according to the guides on how to do it, and seem to have exactly what the barrel should be.

Now I am not sure if I will go to another place to get it measured as they might do the same thing. This place charged 20 bucks to do it. I thought for 20 bucks they would do a bit more . I thought about juat pounding a lead ball down the barrel but was just a bit nervous in case it got stuck or I damaged the crown or rifling somehow.

From what people are telling me here, if it was as off spec as the shop says it would not shoot well at all. When I bought it a while back and shot with it, the gun shot well at leaat at 100 yds

[dverna]

Wow that is a lot of math... Yeah that might be his problem that he used the wrong thing to measure. Whats weird though is that I measured according to the guides on how to do it, and seem to have exactly what the barrel should be.

Now I am not sure if I will go to another place to get it measured as they might do the same thing. This place charged 20 bucks to do it. I thought for 20 bucks they would do a bit more . I thought about juat pounding a lead ball down the barrel but was just a bit nervous in case it got stuck or I damaged the crown or rifling somehow.

From what people are telling me here, if it was as off spec as the shop says it would not shoot well at all. When I bought it a while back and shot with it, the gun shot well at leaat at 100 yds

Actually, the math is the easy part. Making a 108* V-block will be the challenge.

Like I said earlier....if jacketed bullets work, why mess around with all this effort to get a hunting bullet? You have already wasted $20 and gas to get to the gun shop. If you have someone else slug the barrel, you are already at $50 and have not made one bullet.

https://www.midwayusa.com/product/1018229522?pid=693974

Under $125 for 200 bullets....should last many years of deer hunting.

[dondiego]

Why don't you just shoot it with some cast boolits first? You can measure all you want. Shooting is what will tell the tale.

[Rollins]

Thanks for all the help guys. After learning that 5R barrel ruger needs to be measured differently I seached the forum and they had a guide. Basically you use a thin strip of metal you measure thickness of, and then wrap it tightly around the slug where the grooves and rifling marks are and then measure. Then subtract the thickness of the metal.

I wrapped my slug with a thin metal I cut from a soda can as per the guide and took about 15 or so measurements , re wraping the slug each time and re zeroing the calipers

I got between .455 and .456 . subtract the metal band which I also measures many times at .0055 or .0060 I get the barrel at .450-.451 so that sounds right.

Yea I wasted 20 bucks but I was hoping to find the exact bore size to get either the best jacketed or cast boolits for it and also I wanted to be safe. All the guides to reloading here it seems say to slug the bore.

I think i will get some jacked bullets reloaded first to get good accuracy hopfully. Then try cast, it seems a nice guy named george will stop in sometime with a few for me to try and we can go from there. There is something attractive being able to cast your own cheap boolits or buying them for a few cents to get the cost of shooting down low.

[M-Tecs]

More cost effective factory options here https://ammoseek.com/ammo/450-bushmaster

[Tripplebeards]

If you check some of my posts from 2017’ I loaded up some lee 300 grain flat nose cast to try in my 16.5” barreled 450 BM Ruger American. The best I did was 1.1” at 100 yards. It was a load of 35.5 grains of H110 that averaged 2075 FPS on my chrony. I had a few other loads that shot 1.25” to 1.6”. The biggest issue was it turned my gun into a single shot because the big wide metplate would catch and jam. I ran my loads all the way up to 460 S&W max loads without any chamber pressure signs but the rest of the rifle rattled apart from the heavy loads.

Imo what was causing everything to vibrate loose was the factory weaver style rail. I found the rear mounting screw loose. I wrecked one optic and had optic number two slide a good 1/4” even after I installed rosin in the scope rings before I diagnosed the loose rail mounting screw. I acraglass bedded the updated Ruger picatinny rail, blue loctited the mounting screws, and sprayed 3M 77 super adhesive inside the scope rings and let dry before reassembling. That loose rear picatinny rail mounting screw is a very common occurrence from what I was told from Randy’s gun shop in Michigan who was the one who originally came up with the Ruger special run. I’d tell you if you haven’t done it yet to remove your scope rail and either bed it or bathe the bottom of it in blue loctite and reinstall it.

I bought a group buy 275grain 450 bushmaster hollow point mold last year here but haven’t cast any or shot my gun after I glued everything down. I’d be very shocked if anything comes loose again. The 275 grain mold I bought looks exactly like the current 315 grain group buy.


When I slugged my gun I measured two slugs I ran through it. One measured .450” and the other .451”. I powder coat and gas check my boolits in a lee sized to .452”. No leading issues what so ever all the way up to 40 grains of H110 with the lee 300. I’m sure the new mold I bought will bring sub MOA groups with the correct load combo and feed properly. The key with this rifle (which I found out the hard way) is to find a tapered boolit that feeds.

I probably casted up a couple thousand of those 300 grain flat nose boolits,PC’d, and GD’d them and now they are collecting dust. I would assume their too heavy to shoot in my new vaquero?

I bought a box of the hornady 250 grain red tipped j words to try. I loaded up a few but never shot them yet. Taper crimp only, If you roll crimp them and then tapper per hornady recommendation they won’t feed in the American.





CW longshot had his shooting submoa with non GC boolits.

To be honest after my 450 BM Ruger American rattled apart and I literally glued it all back together I picked up my Ruger 77/44 and started load testing for it and never picked my BM back up after I found out with the replaced under warranty factory magazine it wouldn’t feed the big lees anymore. It’s been collecting dust ever since. I might have to cast up some HP’s and load test it...or at least get it sighted in with the J words I loaded for it to try.

If you check the photos on my home page I have the gun, boolits, and group results. I tested it back in 17’ when it first came out. I was pretty much flying blind as I couldn’t find anyone else posting anything for the rifle on the internet shooting cast or reloading for it for that matter. Jeff from gunblast had an article saying he loaded up Barnes to basically 460 S&W loads without pressure signs so I gave it a try with cast. The action can handle it but the test of the gun could not.

[Tripplebeards]

I found my posts for you...

http://castboolits.gunloads.com/show...)group-results

http://castboolits.gunloads.com/show...-and-Lee-310-s

And the bedding of the scope rail...

http://castboolits.gunloads.com/show...ster-need-help!

[Rollins]

Thanks tripple beards. I will check on the scope base screws tomorrow. Maybe a layer of contact cement and red locktite to make sure it wont move.

The speer bullets are on back order for now.
I see a few speer deep curl bullets for 45 long colt. They are 452 diameter 250 grain hp bullets. I know the 45 cal bullets supposedly wont hold , but wouldn't 45 cal bullets be ok If They arw like 250-300 grains? What makes the hornady ones like the xtp mag different? They look about the same weight, and diameter .
Is there something I am missing that tells me if a bullet would work with the 450 bm ?

[Tripplebeards]

Did you slug your barrel yet? Pretty easy to do. I used a bunch fishing split shot. I piled them in a spent casing, put a propane torch to it for a couple of seconds, let cool, and tapped out with my bullet puller. I then used a cleaning rod to tap it through and measure it. You can also just cast a pure boolit if you had a mold and tap it through. Measure the outside after its through. Don’t know about pistol bullets but I would assume the longer the boolits the better it will stabilize imo. Polishing up the bolt sure makes the American cycle quiet and smooth vs sounding like wearing parachute or corduroy pants with your legs rubbing. Lol. I polished up my trigger and cut a coil or so off the spring. It brakes at a crisp 18 oz. and I can still screw in the adjustment screw to add pull weight to it.

[Rollins]

Tripple beards I paid a shop to slug the bore and he said it was .455 which everyone here thinks is way out of whack.

From what some experts on here tell me is that ruger uses a 5 groove barrel for this gun and you need special equipment or do it certain way to get the true size.

So I took the slug he gave ne after pushing it though ny barrel and I followed the directions posted on annother thread on how to do it.

I am getting ny bore about 451. Which seems to make more sense as when i did shoot it with the box ammo I was getting pretty good groups at least for me at around 100yds.

I see a place called everglade ammo and they sell some 45 ACP 250 gr hollowpoint jacket bullets and some people have good succes with them, they cost abiut 16 cents if you buy in bulk. I think I'm gonna try some for plinking and if they are accurate small critters like coyotes.

[Tripplebeards]

.451 is what mine slugged at as well. Who ever slugged it didn’t give you an accurate measurement. Hope they didn’t charge you to much for about 2 seconds work with the wrong answer.

.452 cast boolits will work fine for you in you gun. I’m shooting .452 in mine PC’d and GC’d. Some guys here like a little larger diameter boolit but if you use a lee sizing die like I do they don't offer a .453 unless you pay a lot more for Lee’s custom shop to make you one. I don’t trust myself to polish The inside of my die perfectly even with sandpaper. I would probably have an out of round .453 or larger sizer that would make my cast boolits wobble down it’s flight path. Keep it simple and try done .452” sized boolits. I’m sure they will shoot tight with the correct load. You can see some of the groups I’ve gotton with .001 over. No leading as well. I’ve put a good couple hundred cast through my gun so far. I’m still green with cast. I’ve only been at it for two years now so there are WAY more Knowledgeable casters here. The Ruger 450 bushmaster was my first go at it. I still haven’t found the right bullet yet as I only tried the lee 300 grain FN but I figured out how to make it group with “whiskey barrel” shaped boolits. I always weigh all mine within one grain variance and color coat them per weight with various colors of PC. Ive tried them the even closer in matched weight but notice no difference in accuracy. I also had a tighter (not much, 1.1” VS 1.25”) group with air cooled clip on wheel weights VS water dropped with my 35.5 grains of H110 load. Im going to try 50/50 w/pewter added for my HP group buy mold, PC and GC, and retest one of these days.