Thread: The lightening project

Originally Posted by Stocky

I wouldn't. Doing an analysis on hoop stress shows most rifles have a factor of safety well into 5x. A contender barrel is only 20.5mm and has 2 tig welds and 2 scope mount holes right over the chamber areas. Even looking at ar15 or ar10 barrel extensions gives an idea how much "extra" is in most actions. With careful consideration it can be done. Even with huge overpressure loads failures usually occur via barrel splitting vs actions failure. I usually use a kimber as a safe minimum dimensions and they are significantly smaller than a tikka.

The one thing we haven’t got in NZ , is a proof house to actually properly test some of those experiments. I had my experience with contenders, notably a 45/70 in a pistol with high pressure loads , where the barrel would break in during the shot and expell the hot shell into your forehead. Yes, the system did not fail but showed its limit on how fare it could go.
There is a reason why you won’t see one chambered in anything past a low pressure 45/70 or 444 marlin .
As soon as you go down to 223 type cases, you reduce the pressure area and the gun can handle more , no doubt about it.
Another thing to take into account, is the material, it seems that chrome moly is better at handling high pressure than stainless ( with the two properly heat treated of course), so maybe more chances for a stainless tikka receiver to fail where a chrome moly one would have made it ( specially in sub zero temperature where the stainless get more brittle . How do I know? I used to personally know the barrel maker for accuracy international. He explained to me why he expressly recommended not to use stainless barrel for Arctic warfare weapons. When two of his barrels fails in those conditions there was a quick change of direction. )
But hey, if the gunsmith and the user are confident in the product , and nothing wrong happens…. Then all is good. Maybe I am worrying too much.

Originally Posted by Friwi

The one thing we haven’t got in NZ , is a proof house to actually properly test some of those experiments. I had my experience with contenders, notably a 45/70 in a pistol with high pressure loads , where the barrel would break in during the shot and expell the hot shell into your forehead. Yes, the system did not fail but showed its limit on how fare it could go.
There is a reason why you won’t see one chambered in anything past a low pressure 45/70 or 444 marlin .
As soon as you go down to 223 type cases, you reduce the pressure area and the gun can handle more , no doubt about it.
Another thing to take into account, is the material, it seems that chrome moly is better at handling high pressure than stainless ( with the two properly heat treated of course), so maybe more chances for a stainless tikka receiver to fail where a chrome moly one would have made it ( specially in sub zero temperature where the stainless get more brittle . How do I know? I used to personally know the barrel maker for accuracy international. He explained to me why he expressly recommended not to use stainless barrel for Arctic warfare weapons. When two of his barrels fails in those conditions there was a quick change of direction. )
But hey, if the gunsmith and the user are confident in the product , and nothing wrong happens…. Then all is good. Maybe I am worrying too much.

yeh worrying to much the contender opening issue is well known and occurs its the locking lug section and has more to do with the locking mechanism than the material strength. Id be more worried about welds on chromoly done in a factory than I would stainless being weaker (depends on the stainless as 17-4 for example is often stronger at the common heat treats used for rifle actions. No issue being cautious but there's enough in terms of actions in smaller diameters than would suggest theres not going to be issues.

Weakening of load bearing parts/section should not be done without proper assessment of a competent person.

End of story.

Originally Posted by Friwi

The one thing we haven’t got in NZ , is a proof house to actually properly test some of those experiments. I had my experience with contenders, notably a 45/70 in a pistol with high pressure loads , where the barrel would break in during the shot and expell the hot shell into your forehead. Yes, the system did not fail but showed its limit on how fare it could go.
There is a reason why you won’t see one chambered in anything past a low pressure 45/70 or 444 marlin .
As soon as you go down to 223 type cases, you reduce the pressure area and the gun can handle more , no doubt about it.
Another thing to take into account, is the material, it seems that chrome moly is better at handling high pressure than stainless ( with the two properly heat treated of course), so maybe more chances for a stainless tikka receiver to fail where a chrome moly one would have made it ( specially in sub zero temperature where the stainless get more brittle . How do I know? I used to personally know the barrel maker for accuracy international. He explained to me why he expressly recommended not to use stainless barrel for Arctic warfare weapons. When two of his barrels fails in those conditions there was a quick change of direction. )
But hey, if the gunsmith and the user are confident in the product , and nothing wrong happens…. Then all is good. Maybe I am worrying too much.

Would not lament the lack of a proof house, the UK one might as well be an employment scheme for old farts who do sweet f-all.

Makes a rebarrel job more expensive as the barrel choppers and threaders (I refuse to use the term 'gunsmith' unless they can make one from scratch) insist on sending a rifle for proof when its not required for a re-barrel, only sale of new arms.

I've bought two rifles 'in proof' which failed headspace, one too tight, another too loose...

Would be better off without it

Originally Posted by Stocky

Attachment 249381
Attachment 249382

Similarly slabbed a Howa Mini and skeletonised, also gave the bolt shroud a serious trim and slooted bolt handle. Have modeled a Tikka and a few other actions for the CNC but haven't actually got one hahaha

PM me about how much weight you got off there mate. I'm about to model up my mini and model in some cuts. Will flute the bolt too. Have already threaded the bolt.

Originally Posted by STC

Weakening of load bearing parts/section should not be done without proper assessment of a competent person.

End of story.

Agreed. They are there purely for a look to carry on the 'lines'. They offer no measurable weight reduction. I'll likley scrap them, purely because of controversy. Easy to delete of a cnc program.
Interms of weakening the action, sure it's removed material, 0.5mm to be precise. Is the action now unsafe, No

Originally Posted by Stocky

I wouldn't. Doing an analysis on hoop stress shows most rifles have a factor of safety well into 5x. A contender barrel is only 20.5mm and has 2 tig welds and 2 scope mount holes right over the chamber areas. Even looking at ar15 or ar10 barrel extensions gives an idea how much "extra" is in most actions. With careful consideration it can be done. Even with huge overpressure loads failures usually occur via barrel splitting vs actions failure. I usually use a kimber as a safe minimum dimensions and they are significantly smaller than a tikka.

The German proof house stopped accepting for proof Mauser actions with the transverse dovetail cut (for a scope base) through the receiver ring. Nothing to do with Tikkas but an example of a long "accepted" practise ultimately being found not to be a good idea. It's not known if this decision resulted from testing or from the gathering of information on failures, both functions of a proof house.

There are many variables in the engineering of rifles but given you have a potential grenade right in front of your face pushing the limits isn't usually a good idea. I for one am always deeply mistrusting of "engineering assumptions", incorrect assumptions lie at the root of most cock-ups.

That's not to say anything about Robs project, it's likey fine and dandy.

Originally Posted by Tentman

..... I for one am always deeply mistrusting of "engineering assumptions", incorrect assumptions lie at the root of most cock-ups....

It's not uncommon for engineering assumptions to generate a lot of work for testing labs. Helps to keep me employed.
Less keen on assumptions to contain an explosion in front of my face though.

Originally Posted by STC

Weakening of load bearing parts/section should not be done without proper assessment of a competent person.

End of story.

What determines a competent person? The people responsible for many more important things can become "competent" by barely skimming by or being around for a long time never furthering there learning. Technology and analytical technology has greatly increased but many refuse to learn. Absolutely an assessment should be made but if we refused to go past what the current practice we stop learning.

Originally Posted by robhughes-games

Agreed. They are there purely for a look to carry on the 'lines'. They offer no measurable weight reduction. I'll likley scrap them, purely because of controversy. Easy to delete of a cnc program.
Interms of weakening the action, sure it's removed material, 0.5mm to be precise. Is the action now unsafe, No

Agreed that it is unlikely to weaken the receiver enough to cause any issues, especially if it is a "lighter" calibre, since all tikka actions are essentially the same, which means they must have designed it to withstand the worst case. I would personally would still want to calculate the stresses in there. Then again since the 0.5 mm there save hardly any weight why bother, totally agreed!

Originally Posted by Stocky

What determines a competent person? The people responsible for many more important things can become "competent" by barely skimming by or being around for a long time never furthering there learning. Technology and analytical technology has greatly increased but many refuse to learn. Absolutely an assessment should be made but if we refused to go past what the current practice we stop learning.

In this particular instance I would say someone with a qualification in mechanical engineering and who is competent in the assessment of the strength of a machined metal part.

Originally Posted by STC

Agreed that it is unlikely to weaken the receiver enough to cause any issues, especially if it is a "lighter" calibre, since all tikka actions are essentially the same, which means they must have designed it to withstand the worst case. I would personally would still want to calculate the stresses in there. Then again since the 0.5 mm there save hardly any weight why bother, totally agreed!



In this particular instance I would say someone with a qualification in mechanical engineering and who is competent in the assessment of the strength of a machined metal part.

Having an Engineering Degree (not mechanical) I'd be hesitant of putting little to any salt in a "qualification" most learning occurs after the "qualification" and many people I've dealt with that i would say are competent have no official qualifications. I guess I have a problem with made up qualifications determining competency. You can pass a degree with a 50% average. Qualifications nowadays are there own product and industry.

Short of an actual proof house a destructive test could be done on something like this or anyone with CAD skills can do an FEA making assumptions for worst case and allowing an appropriate FOS.

I recall my older brother telling us off some MSC instructors who wanted a blown up rifle for demonstration purposes..
a suitable old and worn SMLE was found..barrel plugged with dirt,tied to tree string applied to trigger and bang she went,barrel cleared.
replugged with dirt firmly,bang same result....
metal bolt stuck down barrel,,bang...no more bolt!!!
the old gal just kept blowing out obstructions till they threaded bolt into muzzle...
SOMETIMES a loose n rattly action isnt such a bad thing after all.
at end of day this is just a souless tikka LMFAO....
I have bit of string and access to tree out in paddock if it needs destruction tested.

Originally Posted by Stocky

Having an Engineering Degree (not mechanical) I'd be hesitant of putting little to any salt in a "qualification" most learning occurs after the "qualification" and many people I've dealt with that i would say are competent have no official qualifications. I guess I have a problem with made up qualifications determining competency. You can pass a degree with a 50% average. Qualifications nowadays are there own product and industry.

Short of an actual proof house a destructive test could be done on something like this or anyone with CAD skills can do an FEA making assumptions for worst case and allowing an appropriate FOS.

Sorry not going to discuss semantics because somebody does not believe in qualifications.

Bolt done for one action. Second coming off the mill shortly. Next one is a faster twist.
Bolt flute took off 21grams and action cuts was 80. Titanium handle next for another 38. Then it can sit in the safe for the next 4 years.hahah

Very nice work!