What is the purpose of this plastic "shroud"?

Does anyone know how the T3 prevents gas from reaching the shooters face in the event of a case rupture?

The Tikka bolt shroud serves no purpose other then to cover the bolt cocking piece. Gas would be diverted thru the magazine well in the case of a failure.

Good answer!

hanks! I was concerned about getting my face blown off. On a canadian site there was some mention of bolt shrouds hitting shooters in the face when a primer was pierced. I was starting to get concerned. I handload but don't push my loads hard.

Its a super strong design ...the cocking piece assembly is held in place by the bolt handle which runs in a dovetail across it. The tolerances are very tight

oo ooo ooooo...Can I say it? The bolt shroud shrouds the bolt!


Sorry,,,I'm in a goofy mood today...

And of course the shroud itself is metal. It's just covered with 'plastic'. At least that's how it is on my A7.

The T3 shroud sitting on my desk is pure unadulterated "Plastico" it has a slight crack on the tab that sits next to the cocking piece

Hmmmm, must be another minor difference between the T3 and A7.

I think the A7 has metal feed lips on its magazine .They(sako) seems to like the plastic reinforced with steel thingie.

another reason to buy a remington,ruger or kimber

Must be a pattern. My friend put his new T3 (.270Win.)in his gun cradle to put on the bases/rings and a black plastic piece fell onto the cradle. This happened when he opened the bolt.
He looked and looked and finally saw the triangular piece of plastic missing from the forward, bottom left side of the bolt shroud.

The dealer took it back and my friend is thinking of spending mucho coin for a Kimber Montana.

I should add the dealer was very surprised as he has sold several hundred of Tikka's over the past few years and has seen the problem now twice.

That's wishful thinking. If all the gases came through the firing pin hole, they would vent out the holes in the bottom of the bolt into the magazine. However it doesn't all come through the firing pin hole, they will also vent on either side of the locking lugs. On the right side they will come out though the locking lug raceway on that side. On the left side some will vent out the hole on that side of the action, but because the gas from a pierced primer or blown case head is pretty intense, and since it will follow the laws of physics, and not want to make a nice clean 90 degree turn to vent out the hole, some will continue in its original rearward direction of travel back through the left hand side raceway. Because the bolt is completely enclosed on that side by the receiver it can't vent anywhere but at the very end where it meets the plastic bolt shroud. If it is cracked, well guess what, you're getting it in the face. Here are links describing this exact situation:

https://www.snipercentral.com/forums...7092367dcc0351

http://www.canadiangunnutz.com/forum...ud#post1523241

http://www.canadiangunnutz.com/forum/showthread.php?t=399356

There may even be some on this board.


Mauser type actions have a space on the side of the left receiver wall, whether it is the stripper clip cut out, or the small space like on the top left rear of the Ruger 77 receiver wall that will let some gas escape. They all have a nice solid steel flange on the shroud to defelect the gases that do reach the end of the left side raceway away from the shooters face. Another thing to keep in mind is that the shroud on the T-3 fits inside the receiver, making the gap for the gas to escape even smaller. In the event of gases coming down the left side, this means they are further compressed before they can escape (like putting your thumb over the end of a garden hose).


It seems all the Tikka guys are in denial about this, and want to keeping asking the same question until someone says "Yes don't worry that plastic piece that is prone to breaking off, and has actually hit shooters in the eye, it will be fine on your rifle, so don't worry about it."

If you check at the very end of the linked thread, you'll find a company in Australia that manufactures alloy shrouds, that should offer better protection.

Hinterland Shooting Supplies Pty Ltd
Richard Garwood / Fiona Parker
Phone / Fax: (07) 5455 6925
Mobile: 042 787 6817
Email: [email protected]
PO Box 807, Tewantin, Queensland, 4565, Australia.
ABN: 60 115 465 588


And here are the pics they sent me of their shroud:

http://s225.photobucket.com/albums/dd93/Richardoz1971/shroud/

I didn't even realize my shroud was cracked until I wen to the range and noticed the shroud had a lot of extra movement in it when I worked the bolt. When I notified Beretta they told me they were out of stock on Shrouds . That means either they break quite often or never break and they don't feel the need to stock them. I don't own the rifle anymore but it was the top 2 of most accurate rifles I have ever owned and there has been a lot of them.

Too bad the Aussies didn't keep the original shape of the shroud. I like the look of the T3 shroud and how small it is.

If gas were to escape at 50K plus pressure I doubt that a piece of plastic cracked or uncracked would keep the bolt shroud from flying off and I doubt seriously that a manufacturer would allow that design to be produced if that would be the outcome.

I think he has to have that shape in order to CNC it if I am not mistaken. That design would save on cracked shrouds that is for sure. AT 40 bucks delivered they are no bargain.

Perhaps we've hit on one of the virtues of the plastic part then. It's compact. In fact I cannot think of a smaller bolt shroud of any brand metal or plastic. Maybe a cast alloy part would be a good compromise here. Formed like plastic but less likely to crack.

If you check the links, you'll see this is exactly whats happening. I've found three cases with just a quick check on the internet. It's not even that it only happens with handloads, in one case it was a S&B factory load. Design flaws happen, why do you think they have product recalls. Even Tikka makes mistakes (any one remember the stainless steel barrel problem they had), so why does everyone find it so hard to accept. The piece of plastic doesn't just keep the bolt shroud on, it is the bolt shroud. Some guys say it's only cosmetic, and when it breaks off they'll keep using the rifle without it, which means the little protection it did offer is gone. Remember that that hot gas and metal particles will be travelling at high speed directly towrds your open eye, and tell me if you still feel it's such a great design.

Let me repeat this very clearly. The Plastic shroud on the back of the Tikka bolt serves no purpose but that of covering the cocking piece and rear of the firing pin. If you had one you would see very clearly what I am talking about. The Shroud on every other rifle I am familiar with has the firing pin as an integral part of it and sometimes has a safety that is attached to it...Weatherby Mark V and Model 70 are prime examples. It is not a traditional shroud. The tolerances on the rear flange of the tikka firing pin assembly have no more tolerance then what is found in your run of the mill high power rifle at that point in fact it probably has less and nevermind it is held in place by the bolt handle in a precisely milled dovetail. I have owned exactly 1 Tikka rifle and do not own it any longer for my own personal reasons but safety or lack of was not one of them.

I talked to a well respected gunsmith in my area yesterday and also talked to beretta rep. They basically agree with you OEH

If you take the plastic bolt shroud off, and look at the rear of the bolt, you will be able to see down the locking lug raceways on both the left and right side, all the way to the front where the locking lugs engage. The shroud blocks this raceway when the bolt is closed, performing the same function as the shroud on the Winchester 70, Weatherby Mark V, Remington 700, Browning A-Bolt and X-Bolt, Ruger 77, and Mauser 98, and countless others. If you did not read it on my other thread I'll repeat it here. The shroud is there to prevent hot gases traveling down the raceways from striking the shooter in the face. The shroud provides a 90 degree block to those gases, and deflects them at a right angle from the shooters face. This has nothing to do with the firing pin or striker assembly and how it is held in place, or any other function that bolt shrouds may perform on this or any other rifle. In the above rifles it may serve a second function, such as being the end of the striker assembly like the Remington, or being the end of the striker assembly and the location of the safety mechanism like the Winchester or Mauser. But in all cases, including the Tikka, it is also there to block those raceways.

On the Savage 110 series, one of the best designed rifles as far as handling rearward gas flow, there is a large ring of steel, ahead of the bolt handle that acts as a shroud, by blocking the rear of the raceways. The Savage also incorporates a set of baffles behind the locking lugs, that block the raceways directly behind the locking lugs. On controlled round feeding actions, the right raceway is blocked by the extractor, and on the Winchester there is a steel baffle on the left side, opposite the extractor, that is held by a ring around the bolt body blocking the left raceway.

The Tikka does not utilise any baffle system to block the raceways.

Think of it this way, if you were to hook a high pressure water hose to the muzzle, and give it a blast of water down the barrel, where would the water come out. Some may exit throught the firing pin hole at the front of the bolt. Gases going through the bolt body will exit through the vent hole located at the bottom of the bolt (now facing the left hand side of the rifle, in line with the vent hole located at the front left wall of the receiver. Some will also travel the length of the bolt bady, where it will exit thru a relief cut in the bolt handle. On the right side some would come out through the raceway that the locking lug passes thru before it comes into battery. On the left side some will go through the vent hole, and some will continue to move rearward where it will hit the front surface of the shroud. Therefore the shroud is not cosmetic, it is there as a safety feature.

here's another example of a T3 Bolt shroud failing from a ruptured case:

http://www.varminthunters.com/forum/showthread.php?p=107289

and here's the correct link to theone on snipercentral:

https://www.snipercentral.com/forums/viewtopic.php?p=269763&sid=dc7496cfa65346a46b499bb700c6a40b