SealT5
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Switch barrel
- Thread starter John Roland
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SealT5
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Deleted member 103481
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important words in today's craze for shouldered prefits. Everybody and their mom is wanting and getting shouldered prefits for actions that smiths have never seen, and unlike with nut systems they are just tossing them on and often not checking headspace "because it's a shouldered barrel"
it's pretty easy to send your action in the first time and have it measured
What's the issue if you're headspace is 8 thou too deep?
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In this case it wasn't so much they got the headspace wrong, they made the decision to set the headspace so that the top of the Barloc closes and didn't notice the POI issue in their testing. It wasn't until the barrels were out in customers hands that the issue became apparent. A guy over on snipers hide fixed his by running a finish reamer in an additional .007" which allowed him to tighten the barrel enough to stop the POI shift.
I considered it but I generally like the Barloc and would prefer to keep it. Based on my calculations I need to back the barrel off approximately 1/16th of a turn to match up with my go gauge which corresponds with a shim approximately .004" thick. Assuming that some additional thickness is required to ensure proper preload on the system then the .007" difference as explained above seems to be the ideal for fixing the issue.
Here's my question. Why go thru all that? Anyone that can cut a shouldered Barloc barrel can cut a straight shouldered prefit. It does not appear that the Barloc offers you more flexibility in assuming a generic tenon length. What's the point in it when you can just screw a shouldered barrel on down to...it's immovable, consistent shoulder?
If it is too long then your brass has excessive room to stretch and you run the risk of the brass failing with a case rupture. Typically a no go gauge is +.004 over the go gauge and I believe a field gauge is .006" so .008" is getting on the edge of dangerous.
In my case however it is the opposite, my headspace is approximately .004" to short which causes the Barloc clamp to bottom out on itself prior to fully transferring the load to the washers and tensioning the barrel threads. This allows the system to slide and causes a POI shift.
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Deleted member 103481
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I don't have answers for an exact amount, just that excessive headspace causes brass to stretch and can lead to case head separations. @J E Custom
My point was not that prefits have improper headspace nor that prefits are inherently bad. Simply that the action world is being flooded with actions that are "perfect" according to them, and in reality the custom shooting world does not have the preliminary testing timeline and amounts to actually compile the data without things like this happening, where shooters become data testers, and a bunch of them don't know if they actually have headspace issues, or oversized chambers etc. Tooling is wearing on the action side and the aftermarket parts side at all times, and as much as we want them to be sometimes they aren't legos.
SealT5
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Let's get back on topic. The process of cutting a barrel to spec without the action in hand has been successfully performed for decades. You can argue this all you want but please include an excuse for the thousands of barrels cut for panda actions and the countless records and matches won with these barrels. The only thing that has changed is the demand for actions with these capabilities.
I do agree that there are incompetent smiths and incompetent consumers that have no business doing what they are doing.
Joe S.
I do agree that there are incompetent smiths and incompetent consumers that have no business doing what they are doing.
Joe S.
When done correctly it might be slightly more convenient than a shouldered barrel but probably not by much. The only thing I need to change the barrel is a small wrench with a Borka 90in-lb torque limiter, I don't need to brace it between my legs and wrench on flats machined on the end of the barrel so it is someone more convenient in that regard.
The one benefit I really like it for is savage prefit barrels and shouldered carbon fiber barrels as I can change them without removing them from the stock.
J E Custom
Well-Known Member
Pre fits can be very precise, very close, barely exceptable or rejectable. They can take on many forms and be great or just plain bad. Switch barreled rifles can be very good if the person knows how to properly set each barrel up correctly. if it is something like a savage with a barrel nut there are more chances of getting it right.
I still believe that the most consistent head spacing is performed by a competent gun smith. I have re head spaced many pre chambered barrels using many different process depending on the action and barrel set up to bring the head space to very exacting dimensions for best overall performance of primer strikes, case fit and life,
and best accuracy and have always seen improvements if everything is done right.
Close is not in my vocabulary so I am not willing to use pre chambered barrels for anything, I prefer to chamber even the AR style rifles to get the best fit and function.
Just Me
J E CUSTOM
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Deleted member 103481
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I agree we should get back to OPs question.
were it me in your scenario, I would save the money of an extra bolt/bolt head and just do a 6 creed and a 308.
To be honest though I would most likely just do a 308 and be done with it
were it me in your scenario, I would save the money of an extra bolt/bolt head and just do a 6 creed and a 308.
To be honest though I would most likely just do a 308 and be done with it
25WSM
Well-Known Member
300 wsm all the way throated long to fit your mag length. I shoot the 6.5 creed in my 1000 yard light gun and the 300wsm in my heavy. My 300wsm is the most accurate rifle I own. Even beats my 6ppcs at 100 yards. I hunt with a 6.5saum. If you want easy on barrel changes have a Smith chamber all your barrels and just screw them on. Get a cheap benchrest barrel vise and a rear entry action wrench and it doesn't get any simpler. Even slightly different torque values are going to show minimal headspace differences. From hand tight to fully tight is only .002 difference well within the headspace required range. Use of a torque wrench will have you very consistent. Only my glued in benchrest actions need the barrel taken off with it still in the stock. That method requires a large barrel channel. On your sporter contours you will have to remove the stock so putting it between your legs to remove the barrel won't work anyway. The barrel nut method works well too but I just don't like the look. It does make prefits simple. Good luck with your project.
Shep
Shep
