.22 hornet/martini cadet.

[ironjaw]

i am trying to build this gun but really need help. set the barrel in last summer. chambered it. but the primers flow back into breech hole. send it off to a fella in Raton,n.m. no change. took it to a shop in havasu and they replaced firingpin. still does the flow back.
i have read and been told to bush the breech block and reduce the dia. of the f.pin. ????
this should have been done last winter. the wood is waiting to be put to work.
anyone that can help would be appreciated. this was to be my last made gun. just need to get it right.

[reed1911]

How large is the FP and FP hole now? What pressure are you running your loads to?

[Ballistics in Scotland]

Well first, have you used falling-block rifles before, or got to compare your primers with some fired in other Martinis? The shearing action of the block can make the primer look bad to someone who has used only bolt actions or automatics, when in fact nothing is really wrong.

I have always thought that for a cartridge of moderate pressure, which the Hornet is, fit of the firing-pin in its hole and shape of the tip are more important than its diameter. But unless Raton and Havasu have both come up short, these have been adequately dealt with.

Does the firing-pin strike seem unusually light or quiet? Martinis, large and small, are the only firearms in which I have ever found a broken coilspring. It might be that this, and perhaps even removal of one of the bits, has reduced the resistance of the firing-pin to being forced back by the primer.

I've replaced a Cadet spring with a square-wire spring (made for separating injection moulding dies and bought from www.mcmaster.com though there are plenty of other sources). As well as increasing spring tension, these increase the inertia of moving metal which primer extrusion has to push into reverse. If you grind the end of the spring to length on a fairly blunt sanding disc or wheel, with vigorous pressure, the heat will anneal and heat red just enough of the spring to produce a flat closed end. This will reduce friction on the block tunnel and pin, by keeping the thrust on the spring straight.

[Chill Wills]

but the primers flow back into breech hole. send it off to a fella in Raton,n.m. no change. took it to a shop in havasu and they replaced firingpin. still does the flow back.
i have read and been told to bush the breech block and reduce the dia. of the f.pin. ????
this should have been done last winter. the wood is waiting to be put to work.

You did not say what work the Raton Gunsmith did or was intended to do. Raton is full of gunsmiths. Care to say who? I know some of them. Some of them are very good and really, this problem is Gunsmmith 101. As in not hard for someone to fix.

Regardless of low pressure or high pressure cartridges a good fit and well made block and pin should not give you trouble. (not saying anything about weather a cartridge and action are a good match)

You sound like you have the ability to check and measure a few things.

As you likely know -Headspace and firing pin protrusion work together.

I agree a smaller diameter can't hurt, BUT, Regardless of pin diameter, a close fit and correct length pin make a difference. I have seen gunsmiths turn out overly long pins and it makes me wonder. This could be part of the problem - or not.

With tight lockup, as in minimum headspace, pin protrusion as short as 0.055" even on an old, large firing pin should give you reliable primer strike and if the breach face around the pin is not cratered out or the hole is loose, the rifle should show normal fired primers. The nose of the pin should be ground to a good round hemisphere. Check the protrusion. 0.060" - 0.065" is not uncommon. 0.080" and up is getting crazy and I have seen much worse.

[ironjaw]

will try to get accurate measurements of pin and hole. had to let this thing rest for a day or so.
when the breach is closed on a round it will leave some marks on case head.i cerrocast chamber measures correct dims.
will post more soon.

[ironjaw]

gentlemen, have finally found a bit that fits the breech hole. in measures .092 , tight. the new f.pin measures .091. would seem to be tight enough. protrusion is .061. the orginal spring is still used. should i buy /make new one that is stronger ? will make trigger pull awful.
hope you are still out there reading this post.
i have some experiance with s.s rifles. competed in b.p. cart matches.for some time. but it was a rolling block action that i built.
await some more advice.

[Chill Wills]

If the rifle fires reliably I am not sure a new main spring is needed. The pin hole diameter is the large size, as in correct for early rifles. The pin protrusion is good in my opinion. Just the fit of the pin remains to be measured. Or, I missed that in your reply.

So what did the other two gunsmiths do to the rifle?

If the pin fits the hole in the BB and the protrusion is good and the rifle fires......

If there is not a crisp edge in the BB and the firingpin hole, primer brass may come back into that area, a crater, but most times it is not a large amount nor a large problem.

Got a picture?

[ironjaw]

the raton smith shortened the pin and fired primed cases. but when i fired loaded rnds had problems. the az smith tried a new f.pin. same results. there is no cratering of the breech block hole.
i loaded new cases with little gun ,10.5 grns, with 55 gn, 224 bullets, hornaday says this load is 28000 cup. +-
am thinking primers soft ? need milder spring?

[ironjaw]

will take photos and try
try posting

[Travelor]

Try going to a harder primer. My experience is that the Remington 7 1/2 primer cup is harder than others.

The softest primers I have used are the Wolf Small Rifle primers but the Wolf Small Rifle Magnum primers being much better.

[Reg]

Your firing pin is your problem. Your dia. is way too big and protrusion way too long.
Ideally you want a diameter of .062 - .065 and closely fitting the hole and a protrusion of .050 minimum with a .060 maximum. .055 is ideal. The tip must be hemispherical and highly polished.
There are several different ways to bush the face of the breech block. I would refer you to books by Frank deHaas or any other good gunsmithing book. Also it is recommended you have the gas escape hole in the top of the breechblock-- just in case.

[Ballistics in Scotland]

gentlemen, have finally found a bit that fits the breech hole. in measures .092 , tight. the new f.pin measures .091. would seem to be tight enough. protrusion is .061. the orginal spring is still used. should i buy /make new one that is stronger ? will make trigger pull awful.
hope you are still out there reading this post.
i have some experiance with s.s rifles. competed in b.p. cart matches.for some time. but it was a rolling block action that i built.
await some more advice.

If I am right in thinking this means a .091 hole working in a .092 hole, and if the edges of the hole aren't depressed, it is large, but sounds fine for the Hornet. Something else worth considering would be a collar around the firing-pin to increase spring pressure by preloading it. A plastic collar would probably do to find out whether that makes any difference.

[Huffmanite]

Elderly gent in nearby town, that's a retired machinist who has done gunsmithing on the side for a darn long time was quite experienced in working with Martini cadet actions. LOL, when I first showed him my Francotte Martini cadet action, it took me a number of minutes to convince him I wasn't interested in selling it to him, ending this discussion by saying, LOL, NO! I'm not selling you the action, just build me a x#$$# hornet rifle for me with it. He did and it turned out very nice.

Anyway, as I recall, one of the things he almost always did with a cadet action was bush the face of the block, which he did to mine.

[shortfal]

i am trying to build this gun but really need help. set the barrel in last summer. chambered it. but the primers flow back into breech hole. send it off to a fella in Raton,n.m. no change. took it to a shop in havasu and they replaced firingpin. still does the flow back.
i have read and been told to bush the breech block and reduce the dia. of the f.pin. ????
this should have been done last winter. the wood is waiting to be put to work.
anyone that can help would be appreciated. this was to be my last made gun. just need to get it right.

I bought a Martini Cadet in 218 Bee. Firing pin was way too big. I bored out the breechface and bushed it then bored a normal sized FP hole in it. Then machined the FP to match.
Pete in St. Louis

[Sur-shot]

What shortfall said is exactly right. You need to drill out the bolt face in two steps leaving enough material to act as a stop for the firing pin at the rear, unless ou want to thread the bushing, put in a bushing with a shoulder, large diameter out. Reduce the size of the firing pin leaving a square shoulder and drill a hole through the bushing to match with play. If done correctly the bushing will not take any outward pressure at all and black Locktite will hold it in place forever. I have built several of these for 357 Super Mag and 225 WM conversions. You buy a set of coil spring banks and cut them to correct length for the high pressure round's firing pin spring. You might need to cut a couple of lengths to get the function just right. My Avatar is my 357 Super Mag or if you prefer, the Max.
Ed

[ironjaw]

thanks for all the great advice. will bush the breech block and use .062 pin. have a copy of Dehass's book. will post results in a few months.

[ironjaw]

back to all of you who helped. the new smallpin and bushed breech block works fine. ejects and fires fine. used decap pin and piece of power saw blade for bushing. drilled blade and fitted to altered face. soft soldered all parts.