Can any one tell me if any rifle manufacture presses in their barrels? I�m having an on going debate about this with a guy on 24-hour campfire. It came up in a discussion about Browning rifles. (Rifle forum)
I�m aware of how the BBR works by the way.
I say it is not possible. For more reasons than one.
Thanks Shawn
PS I also understand how the 710 rem. works.
I am asking about guns that have bolt lugs that do not grab the barrel or extension in any way.

bluetick Steyr "presses" in the barrels on the SSG sniper rifles, they have rear locking lugs, thus the bolt does not lock into an extention of the bbl. I think the H&K barrels are pressed in then a pin is used to hold it in place, the H&K's do not really solidly lock up at all, being a delayed roller blowback.

[ 03-17-2003, 10:52: Message edited by: N E 450 No2 ]

Does Steyr press-fit barrels, or does it "shrink-fit" them? Technically there is a difference. I don't know which they do. Am just asking, not disagreeing.

"Shrink-fit" seems like a more appropriate term. Steyr uses a proprietary process, based on thermic dilatation. BTW, I'm not sure it's possible to rebarrel without sending the rifle back to the factory.

Anschutz barrels are pressed in and then pinned.

Many of the AK47's & SKS's

What is the difference between shrink fit and press fit?

Thanks,
Lucs

Steyr barrels are threaded in just like everyone else's. The only difference is they are a very tight fit. They claimto heat the receiver and essentially shrink it onto the barrel threads. In some cases this may be true but in others the barrels are fitted just like any others. They come off easily and go on the same way. This leads me to think Steyr's proprietory process exists as much in the brochure as anywhere. Regards, Bill.

500A2--

A press fit is exactly that....depending on material and diameter it can be from .0005 (small dowel pin) to .010 in the case of a railroad wheel on the axle.

Shrink fit is a press fit made MUCH tighter and more solid by using heat to expand one part and cold to shrink the other.

Whether press or shrink, the receiver is under tension.......and I don't care for that.

The REAL odd ball was the "Red Eagle" Ruger Standard model pistols. They had no threads but did have a necking cut in the barrel shank. The receiver was made with a cooresponding lug to engage the necking cut but in two halves. The receiver halves were clamped over the barrel shank and then the two halves of the receiver were TIG welded together and then turned to size.

JBelk, thanks for the explanation. Why don't you care for tension in the receiver?

Thanks,
Lucs

500A2---

Because with age steel changes. Steel hard enough for a rifle receiver (32Rc) will eventually crack when under constant tension. The Eddystone P-17s and pre-war M-70s are a good example and they just had tight threads.

Jack you have a PM. - Dan

I believe I read the newest Remington high-powered bolt rifle has a press-fit barrel, since the bolt head locks into the rear of the barrel and not the receiver.

Alberta Canuck you are correct, the SSG were "shrink fit". They "must" be re-barreled at the factory.....However I know one fellow [experienced gunsmith] who cut the bbl off, threaded what was left in the reciever and re-barreled it. He said he did not want to do another.
Never saw a SSG that was not real accurate, never heard of one cracking a reciever. I shot about 10,000 rounds through one, the bbl started to loose accuracy and first round dependability at about 7000 rounds. Only broke one part, the cyolac magazine well/trigger guard. I really liked the way the scope mounts worked, and the 10 round magazine worked real well.

TG-1, Matt--

I've tested three cracked P-17s.

Two were very hard, mid 40s, one was 35, which is average for the Remington P-17.

All three squeeked and groaned with REALLY large thread diameter. One of the hard ones cracked *because* the barrel was removed. It was a fresh break without the microscopic gunk of the old ones.

Pre-war Model 70s are almost always 40 to 43 Rc and "feel" harder somtimes. I think the consensus of opinion is that the cracked receivers are the result of heat-treat stresses combined with stress risers associated with the pecker tracks rolled into the top.

I tested a fragmented M-70 at Rc53 !!! 1945 barrel on a '41 receiver. I think somebody ran it through the furnace again, or maybe forgot the draw stage..... it was WAY too hard.

JBelk, do you know what exactly happens to the steel over time that causes the receiver ring under tension to crack? This is something I had never thought of and am very interested in learning more about it.

Wouldn't the harder actions actually be stronger? If this is the case the harder actions should be able to handle more loads, right?

Thanks,
Lucs

[ 03-18-2003, 21:54: Message edited by: 500 A2 ]

500A2---

Steel ages just like everything else. As it ages it becomes mores stable.....cryo treatment is advanced aging of metal......Any stresses in the steel tends to gather at the weakest place....these are called "stress risers". It usually is in an area of a sharp angle or chip or scratch. Sharp inside corners are especially probematic.

The harder a steel is the less elongation it has. It's said to be "brittle". If it's too brittle it shatters instead of rebounds from stress. Hard actions are BAD!!! Soft actions are BAD!!! In between is just right.

Rc 30 to 40 is the normal range but the alloy of the steel and the process by which the receiver is made can massage the upper figure higher without a problem. Ruger Number Ones are usually 43Rc and the new Montana 99 is about the same. No problems with them, but a pre-war M-70 at 45 Rc is a hand grenade under some conditions.

Case hardened actions can be Rc60 on the surface but depends on a softer, stronger, much less brittle "core" for it's strength. They're the very best of all.

With due respect to Jack, it is called "temperature differential" method. The parts are machined to have and interference fit and the female part is heated and the male part is frozen or, more correctly, cooled and the parts and then slipped together. With a press fit it is the same except not heat or cooling is used, only pressed together. A fule of thumb here is .001" interference difference per 1" of material. By the way, pressing railroad wheels is quite a task. We used a 120 ton press with a pressure guage and printout to put them together. Sometimes .010" was too much, other times, just right. The pressure curve on the graph had to be just so.

JKobe--

"temperature differential"!!??

Yall Yankees make things so HARD!! In the South there are five kinds of machine shop fits--

1) Loose. It rattles.

2) Tight. It don't rattle.

3) Slurp. Tight and smooth.

4) Hammer. Sometimes called the BMFH fit.

5) Shrunk. Heat the outside part with a rosebud and hose the other one with the CO2 fire extinquisher and THEN hammer it tegether.....

"temperature differential" My foot !!!

[ 03-19-2003, 05:22: Message edited by: JBelk ]

"YANKEES"??? You've been living in Idaho so long they think you must be a Republican. Maybe a Republican with a southern accent. Just kidding Jack, sure don't take much to get your attention.

Matt---

Maybe someday.........

Jim Brockman brought over a new M-70 action Monday for surface grinding. The outside of the action, and the scope mount holes, were .017 out of alignment with the axis of the bore and bolt. Oddly the barrel threads were pointed in the right direction but the outside of the receiver was at an angle. It looked like a bent-frame car coming down the road.

Sometimes I wonder what those folks smoke on the breaks.

I would imagine that Phillip Morris didn't roll it for them.

We had the custom shop put together a barreled action for us a few weeks ago, and the chamber had a scar running in it about .025-.030" deep. I was planning on using the barrel for a tent stake anyway, but jeeez!

When the lawyers and the beancounters quit running the gun industry, maybe we'll see some quality products.