Short Freebore Questions

[Crews]

I'm hoping I can get some advice here from those way more knowledgeable than me on something. I'm most definitely not a reloader, so please bear with me through these silly questions:

I have a 6.5 Creedmoor custom, it has a short (.125) freebore. Apparently it has some advantages for reloading VLD type bullets that I won't be able to realize. I took it to a local well respected precision rifle smith to re-throat so i could shoot factory Hornady 140's. He checked it out and told me I'd be fine with it, the bullets might be jamming a tiny bit but nothing to worry about as long as there aren't any warning signs during use. I have been shooting factory Hornady ELD-M 140's ever since, with zero issues. Acceptable/repeatable ES and SD over 300 rounds.

Last week, I went to the range and had some issues getting the bolt to close on a chambered round. It closed, but took a lot of extra force. On top of that, the ES and SD numbers were way higher than what I normally see, with the average MV being 30fps faster than historical. Ammo from another box didn't indicate repeatable results, it chambered just fine.

1. Is it possible that I'm just right on the edge of being too long and I got a lot that exceeded the tolerance? Are the symptoms I noted indicative of this?

2. I'd really like to keep on shooting heavier grain projectiles, when i do the math on wind and downrange energy I'm still better off with the 140's at 2540 fps MV than I am with the lighter bullets (16.5" barrel.) Is there a 140ish grain bullet that would be more forgiving of my short freebore? Obviously I'm limited to factory ammo, and Hornady is hard to beat for $22/box. Would Prime with 130's be a better choice?

3. Would it be wiser to just get a smith to bump the throat out and be done with it?

 

[spife7980]

1. Is it possible that I'm just right on the edge of being too long and I got a lot that exceeded the tolerance? Are the symptoms I noted indicative of this?

Yes, it could be that the bullets are longer, ejecting a chambered but unfired round should show marks from where you are pushing the bullet into the lands. They may not be as pronounced as this pic but coloring a bullet in sharpie will smudge and show up easily.

2. I'd really like to keep on shooting heavier grain projectiles, when i do the math on wind and downrange energy I'm still better off with the 140's at 2540 fps MV than I am with the lighter bullets (16.5" barrel.) Is there a 140ish grain bullet that would be more forgiving of my short freebore? Obviously I'm limited to factory ammo, and Hornady is hard to beat for $22/box. Would Prime with 130's be a better choice?

Cant really speak to this but I wold expect that a secant bullet like a berger vld would deal with the shorter freebore better. A lighter bullet could as well but that really just depends on the bullets form and where its seated in the case. A light bullet seated way out in the neck could touch the lands before a heavy bullet seated way in the case. The pic doesnt exactly show that but it does show how different bullets can have different geometries.

3. Would it be wiser to just get a smith to bump the throat out and be done with it?

Maybe, but it really depends on what youre doing with it. You could both potentially make it perfect for the elds or you could potentially make it so that your rifle doesnt like anything at that throat length. I am inclined to side with your local smith and run with it as is since all but one box has been fine for you.

 

[918v]

Your gunsmith believes that chasing lands is the way to go, except you just proved him wrong without knowing anything about reloading. Congratulations!

I’m a fan of bullet jump and the resulting benefits, i.e. happier longer lasting brass, easy bolt operation, ammo flexibility, etc.

 

[krw]

I had a 260 reamer ground so I could use Lapua brass and have .003” nexk clearance, and load 123 SMK’s at 2.800” oal and have .010” bullet jump. Pressure has always been issue with both 260’s made with this reamer. I backed off to 2930fps and load oal to 2.780”. This helped a lot. Try seating you bullets .020-.040” deeper. Will be same as lengthnin your freebore

 

[Crews]

Do the 130 BTHP bullets that Prime loads have a secant ogive? How do they compare to the 130 hybrids that are in the FGMM loadings as far as seating depth and my issues? I’ve tried the FGMM before, and always get unacceptable velocity deviation as compared to the Hornady stuff. Wondering if it’s a seating depth issue, or just a consistency problem.