H&R Topper 22 Hornet converted to .223 Remington

[vacek]

In 1985 I purchased a used Topper in 22 Hornet with serial number AY456533,  case hardened frame.  I was planning on using it in Australia as a friend and I were planning on metal detecting for gold in the Outback and wanted a nice takedown rifle.  Anyway, I had the barrel rechambered to .223.  Knowing what I know now, I would have never done that as a rimmed cartridge sure seems to work more consistently than a non-rimmed.  Regardless, although this rifle has been shot off and an for the past 25 years it probably has less than 250 rounds through it. 
 
My basic question is... Max 22 hornet pressure is around 25,000 CUP and the .223 is around 50,000 CUP and the 5.56 NATO 60,000 CUP.  The rim (contact surface) of the Hornet is 0.350 inches diamter with an area of .0962 sq. inches, while the .223 is .378 in diameter with an area of .1122 inches.  This is not a large gain in overall area to distribute the extra pressure from a .223. 
 
About a month ago, I shot a surplus 5.56 and felt a gas leak and when ejected noted the primer was pierced.  While this rifle has had other 5.56 shot through it, obviously that won't happen again. 
 
So here is my question to Tim.  I never reload at the Max, but what is the opinion of Tim and team if I should continue to load and shoot the rifle?
 
Thanks,
Vacek
 

[vacek]

Yes, I have read the FAQs

[quickdtoo]

The 223 is unsafe on that platform, the cast iron frame was never meant for high pressure rounds, IMO it's a disaster waiting to happen, sorry, but that's the way I see it. The underlug is also brazed or soldered on, certainly not the best for use with a 55kpsi round, so I wouldn't even use the barrel on a stronger frame. 

Tim

http://www.leverguns.com/articles/saami_pressures.htm

http://www.gboreloaded.com/forums/index.php/topic,121724.msg1098413838.html#msg1098413838

EDIT TO ADD: If your Topper is a model 158, it was also available in 30-30 Win which has a SAAMI MAP of 42kpsi and a .422" case head which produces a ball park estimated 5874lbs breech thrust, the 223 Rem's .376" case head and pressure at 55kpsi produces 6107lbs breech force, so it's not a lot more intense even at the higher pressure, but that certainly reduces the safety margin for overpressure situations that may cause a catastrophic failure of the weaker cast iron frame and questionable strength of the underlug attachment. The 223 Rem was available from Remington in 1964, plenty of time for H&R Inc to offer their firearms in that chambering by 1982(AY) which they never did. Breech force of the 22 Hornet is ~2671lbs from the .278" case head at ~44kpsi to keep it an apples to apples comparison.

[Catshooter45]

 
I would have to agree with Tim.  And when a rifle fails it isn't like a handgun.  Handguns are often no more than embarassing, but that rifle is tucked up to your cheek.
 
Could you re-chamber into a 219 Zipper?  That's just a necked down 30-30 and is .223, I beleive.
 
 
Cat

[vacek]

I am still somewhat confused here.  I know that this frame was used on 30-30's back in the day and the SAAMI is 42000.  I am loading the .223 at 218 Bee velocity so don't really see an issue if I keep my loads light.

[JMcDonald]

If you handload, I'd just keep loading it relatively mild like you're doing and you'll be fine. I mean, with some powders you can load, for example, a 45gr bullet to barely over 30k PSI and still be a few hundred FPS faster than the Hornet.
I did a whole bunch of research on the hornet at one point when I was really looking into buying one. I then realized that the Hornet is only worth it if you handload. Then I realized you can get a .223 and load it with starting loads or even specifically-reduced loads, and still have much more performance and practically infinite case life.

[ratdog]

lighter loads are probably ok . but what might happen if some one else sticks hotter load in it. mcdonald is right about the hornet i went to the 222 cal then to the 223 cal there are a few people on here that are down loading for squirrel hunting.

[cwlongshot]

IMHO its not the safest alteration one could do.
For safety sake, I see two options for you. First, make a tomato stake outta it or second (JMcDonalds idea and a good one) rechamber to one of the older 30-30/22 calibers. Something that required handloading would negate the worries of too hot a factory load finding its way into the chamber.
 
I have read that it was done years and hundreds of rounds ago. But look at it like its russian roulette... Sooner or later it could blow. When it does, it might not be pretty...

[otterbob]

Vacek,

I am not here to argue with the “experts” on the forum, but here are a few interesting numbers.

As posted above 40,000 psi calibers are being “considered” safe by many members.
Yet they also throw in breech force as a variable that must be considered.

Using the formula posted here on the forum for breech force and rounding off , these are the numbers I get.

Your 22 Hornet = 2999
Your 223 = 6075
Some of the other calibers and gauges that appear on an SB1 and or pre SB1 frame :
30-30 = 5875
44 Mag = 5902
45-70 (28,000) = 5608
12ga 3 inch = 5999
12ga 3 ½ inch (SB1)= 7304
*** 45-70 (40,000) = 10,100

As you can see the 12ga 3 ½ inch breech force far exceeds your 223 on the same frame, it is only my opinion that if the barrel can handle the chamber pressure then the action should not have a problem with the “breech force”.

As for the interesting “*** 45-70 (40,000) = 10,100” see the article in the link below
http://www.realguns.com/Commentary/comar52.htm
Please note that the article is concerning lever guns but lists heavy bolt actions and single shots as having stronger actions.

Run the numbers for yourself and make your own decision


Otter Bob

[keith44]

good advice, but since SAAMI is the group that sets the standards for firearms and ammunition, and ANSI is a consumer safety group they are often issuing conflicting statements.  Much like those mentioned in the article you linked to.  Since H&R/NEF set the proof testing to lever gun levels (during Marlin's ownership of the company) and since it is really hard to damage a Marlin (or Handi Rifle for that matter) any experienced handloader will stay within published data ranges for the bulk of the shooting.  A few loads that are at the "proof load" level will be painful, but if the gun is in good condition will not harm it.  Now a constant use of such loads will cause damage, and risk of injury or death.

[av-doctor]

Did they make the toppers in 12ga 3in ,all the ones i recall were 2.75, was the 44 offered on a topper frame? and i believe that 45/70 was only to be used at trapdoor lvls.
   I only note this so the OP does not get confused with all the numbers being thrown out here.
 
Personally i wouldn't shoot it as is. even downloading can become dangerous as pressures can spike at ignition more than a full power load. I feel the risk is not worth the reward.

[otterbob]

  Yes ,  The topper was in 12ga 3 inch.

 
Yes , The Shikari introduced in 1972 was built on the topper action and offered in 45-70 and 44 Mag.

 
My Shikari 45-70 (1978) was NOT marked "trapdoor loads only" and was regularly loaded with lever gun data from that time period.

 
Most barrel steel produced is formulated and heat treated for 100,000 psi plus, 25 - 32 rockwell. What H&R has done in the past and present is a secret, that is why all we can do is compare what has been done and what is being done on what frame in order to make an educated judgment.

 
As you can see from the numbers posted, Vacek is at the max of what has been done in the past and below what is being done in the present. Vacek is the only one that can make the judgment call. If it were my gun and considering as Vacek said about not pushing the max with hand loads, I would be enjoying it. BUT that said, that is my opinion made for myself and NOT Vacek.

 

 
Otter Bob

[av-doctor]

What time (estimate) did they start seperating 45/70 into different power lvls? 
    I agree its his choice but what if that gun ends up in the hands of another?
     is it 100% safe? maybe, we will never know.
   will it be good for another 1000,10000,100000? nobody can guess.
   Like i said if it were me i wouldn't use it as is. there is a potential danger and once identified i wouldn't tempt fate.

[vacek]

Thanks to all for the feedback,
 
The gunsmith who converted the 22 Hornet to .223 back in 1985 is still around and is considered one of the top gunsmiths in my area.  I am also going to visit with him and get his opinion as well.  I do like the ideal of a rechamber to a lower pressure load.  I have also considered an 22 hornet insert made by MCA Sports/Ace Bullet Co.