I just got myself a Stoney Pt. OAL gauge and bullet comparator so I could take precise measurements of my seating depth and distance to the lands in my Ruger M77VT Mk II 22-250.
When I measured the chamber I was surprized to find that there is a lot more freebore before the rifling starts than I had expected. I found that if I were to seat the 55gr. V-Max bullets to the Max COL of 2.350", there would be a gap between the bullet and the rifling of 0.135"! In order to seat the bullets at 0.020" off the lands the COL goes up to 2.465", and I really can't seat them any farther than that because at that depth only 0.24" of the bullet is inside the case neck.
I was just wondering if this much freebore is normal for all factory rifles, or if it is a Ruger specific thing. Being that these is such a large gap for the bullet to jump at normal seating depths, I'm a little surprized that the rifle shoots as well as it does.
RE: Is excessive freebore normal for factory rifles?
Yes, it is normal to see a huge variation on freebore. I once did an experiment, and went around to gun stores to measure freebore on 300RUM's. I used the same bullets, same case I ordered from stoneypoint. It varied from 3.65" COL to 3.85" COL. I saw how fast they ream these things at the factory, and now comes clear to me. For a 22-250, I would be happy to have .24" of neck tension. The rule of "one caliber" in the neck has served me well for a long time.
I don't believe its BS. I have shown to myself so many times how seating depth does matter.
RE: Is excessive freebore normal for factory rifles?
I am not sure. I know the RUM has some freebore built in on purpose. According to reamer vendors I talked to, they said that is the spec for thier reamers. It is a safety factor and a way for the RUM to compete with the Weatherbys in speed. There is a guy on the accuratereloading forum AJ300, that had his 300RUM special built to where there was no freebore but could reach the rifleing and still fit in his magizines. He said basically, the manuals had to be thrown out when he did this due to pressures building. It also shows this on quickload software. He did show me groups that showed the gun to be a tackdriver however. And he seems to be able to find accurate loads out of most all bullets. Where I have to pick and choose bullets.
I have no problem with the RUM's having freebore in them, as long as its consistent. Problem is when I measure the differences I did, that shows very sloppy workmanship. For me to reach the rifling on my 300RUM custom, I have to load out to 3.84". Which unless you use a 200gr accubond or long bullet, you can't do and have sufficent grip.
but with my 308Win browning Medallion I can reach the rifling and still be within SAAMI specs, but it doesn't fit in my clip.
RE: Is excessive freebore normal for factory rifles?
I haven't seen too many factory rifles that have a short freebore- most seem to extend beyond what you can seat a bullet to reach.
On high velocity magnum cartridges, cutting alot of freebore makes it possible to keep pressures down and gain extra velocity. I've read rumors about basement gunsmiths in the past who blew up their rifles trying to chamber them for weatherby magnums without cutting an adequate freebore.
On factory rifles, I don't think you get any huge advantage to seating bullets at or near the lands- There are other factors that need to be considered- is the bore perfectly in line with the receiver? Is the chamber cut square to the barrel and receiver? In a factory rifle its doubtful that a throat is going to be cut perfectly square with everything else, having the bullet seated to the lands will not necessarily align it perfectly with the boare.
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RE: Is excessive freebore normal for factory rifles?
Briman, my gunsmith did that exact same thing to a 300Weatherby. When the guy shot factory loads, it locked the brass up in his gun. He could only handload for it.
RE: Is excessive freebore normal for factory rifles?
I don't know if they are all that way or not. Several of the last new Savage rifles that I have had did not have enough freebore. I would have had to have the chambers reamed deeper just to seat the bullets to the crimping ring. I traded them in instead. TYhey would chamber a factory round but not a Hornady bullet of the same weight.
Is excessive freebore normal for factory rifles?
