Need your opinions! Puma M92 .454Casull bore diameter issue.

[Incitatus]

Hello everyone. I have a Puma M92 stainless lever gun in .454 Casull which has a poor accuracy problem. I got the gun maybe more than 10-15 years ago when I was a newbie and didn't knew much about firearms. The accuracy when it was new was great, I remember shooting 2" groups at 100 yards with factory copper jacketed ammo. Then one day somebody gave me two boxes of reloads with cast lead bullets which were loaded very hot. After shooting 25-30 rounds I realized the bullets caked the barrel with lead really, really badly. Thinking back, I assume the bullets didn't had gas checks. Once I got home I started cleaning the barrel with the 45 brush and Hoppe's, but it was just.. hopeless. I put chore boy around the brass brush, lead kept coming off but it was like never ending, couldn't get all of it out. Somebody told me about lead cloth, I got one, cut it in small patches, ran 15-20 of them through the barrel, then more brush with chore boy, then another 15 patches of lead cloth and I finally managed to see the barrel free of lead. I think I scrubbed that barrel a total 4-5 hours put together.
Couple of years later I started reloading and I cast my own .452 diameter bullets with gas checks for plinking. Accuracy wasn't such a big issue and I didn't paid much attention since I like to shoot steel gongs at 50-75 yards and the rifle with my cast boolits reloads was OK for that. But last month I got drawn for a premium area deer hunt (I live in California so that's a big deal for us) and I decided to start reloading using 250 grain, .451 Barnes copper solids for this upcoming hunt (we cannot hunt with lead bullets in my stupid socialist State). So I tried different loads starting with Win 296 and H110 from low to high, and the accuracy was bad on every try, like 2-3 inches groups at 50 yards bad. I started thinking maybe I ruined the barrel years ago when I scrubbed the hell out of it so I took the rifle to a gunsmith to look inside with a borescope and slug the barrel. Today I went and picked up the rifle. The gunsmith told me the rifling is good, there is no damage or noticeable wear, and that the measured bore diameter is .4555
First thing that hame though my mind: isn't that a little too wide for a .451 Barnes bullet riding through the barrel? I'm thinking that may be the cause of poor accuracy. The regular copper jacketed bullets are .452 could that make a difference in accuracy? I looked for slighter larger diameter copper solid bullets online, the closest are the .4580 diameter used in 45-70 caliber. Would it be wise to try a few considering the diameter of my rifle barrel measured by the gunsmith is .4555 (the .458 bullet is only .0025 larger than the diameter of the barrel)?
What do you guys think? How can I fix this problem and increase the accuracy with solid copper bullets for this hunting season? Should I try the .458 or do you think that may cause over pressure and blow up the barrel?

[Hickory]

I'd try light 458 bullets in your gun. No more than 300 gr.
If there is anyway to reduce the size of those bullets just 0.001" 0.002 would be better you would be in the ball park for sure.

[Bubba w/a 45/70]

You can buy custom sizer dies from many sources, and it all depends upon which style you use.....

Like Hickory said, try some light .458 boolits and see what happens.

With enough grease/lube even copper bullets will resize down the amount you need. If not load them up on the lighter side, as pressures will be higher than normal from the resizing taking place when you shoot the larger bullet.

[Incitatus]

Hornady has some .458 diameter 250 grain flex tip lead-free bullets available that look pretty good.
I though about buying a box and shaving .002 of the diameter, but unfortunately I don't have a lathe. Any ideas how can I do that in a different way ?

[cwlongshot]

I have re sized many cup n core bullets thru a LEE bullet sizer. Just a wee bit if imperial sizing wax and run them thru!!

BUT a solid copper bullet might be too hard... plus there is nothing perfectly correct as far as diameter. IINM they offer a 457....

But as you may know solid copper bullets need differnet recipes than cup n core. Esp something like this! In the recent years companies have worked hard to find ways to make loading them with cup n core recipies safe. IMHO them running them .001 small is part n parcel to that end.

Good luck on your quest!!

BTW. Thats a gun I have looked for for many years.

CW

[pietro]

Hornady has some .458 diameter 250 grain flex tip lead-free bullets available that look pretty good.

I though about buying a box and shaving .002 of the diameter, but unfortunately I don't have a lathe.

Any ideas how can I do that in a different way ?

FWIW, AFAIK the .45 Colt, .454 Casull both have bores that use .458" boolits.

IMO, your accuracy issue is caused by using boolits that are under bore size, and more viable for a .45ACP than a .45 Colt/.454 Casull.

A smaller diameter pure lead (softer) boolit can be used in the larger bore, but only if the powder charge is sufficient to bump up the boolit diameter when it's fired.

.

[cwlongshot]

I have seen large bores before. But the 45 Colt and 454 made today are designed for .452 dia and will generally NOT chamber a 458 dia bullet. I have one that dosent even like my preferred 454 dia bullet! The throat is too small, even on the largest bores I have seen or read about.

The “old” 45 Colt was 454 then it and the 454/460 are 452. Sammi drawings are 452 bullet. I realize the OP had his measured larger. But I will be suprised if he can chamber a case loaded with a 458 bullet.

CW

Load one and try and chamber it! The case dia is

[Thumbcocker]

IIRC the RCBS Scoville boolits cast 457 or so.

[missionary5155]

Good morning
As you have to shoot those non-lead slugs I would be seeing if .454 is available. Cast a couple .454 lead and make a couple dummies and see if they will chamber. If so order the .454 copper things. If they are a snug fit you can thin the neck area of the brass.

You wrote the .452's shot OK or seemed to... so if that is all that is available use them. Jacketed are very forgiving but will still "leak" some pressure down along the slug. But a corn cruncher will never know the difference.
Mike in Peru

[nhithaca]

Or investigate using a paper patch on the copper 0.452" slugs. Never tried it, but it may solve the problem cheaply.
I'm guessing that the cup and core bullets are being bumped up in diameter when shot with a stiff load while the copper bullets don't "swell up" the same way.

And lastly, research custom turned bullets in 0.454-5" diameter. Have seen ads for them in Handloader and other mags plus the interweb.

[Incitatus]

Well, I tried paper patching a solid Barnes .451 bullet which came to .455 with the paper and it doesn't chamber.
What now?

[grayscale]

You might try casting Bismuth bullets, Rotometals has pre alloyed BiSn for just that. Some guns like them and others hate them and there's only one way to find out.
Be sure to print out a copy of the rotometals non-toxic certification letter and a receipt if you do take bismuth boolits into the field. You may still have trouble if Mr. Ranger
is feeling stroppy, but with documentation the onus will be on him/them to prove your rounds are lead.
Its worth a shot (sic) Grayscale

[Ramjet-SS]

Slug the bore yourself then measure just to make sure and see with your own eyes. My other suggestion is try a few other non-lead bullets you might rly Lehigh defense extreme defenders or other mfg. I would not shoot .458 bullets the pressure could be a real issue especially with monolithic bullets.

[Texas by God]

Will PC stick to Barnes bullets? If so, it might help meet diameter needs.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[cwlongshot]

PC will stick to Most anything sans maybe Teflon...