6.5x284 Throat Erosion

[mslman]

I bought a new CBI barrel and put it on a year and two days ago. Using 140gr Berger VLDs, it measured 2.449 (average of five projectiles) to the ogive. It has been shooting fantastic until my last trip out to the desert and it wouldn't group as normal on steel. I shot a few rounds over the chrono last week and they are up almost 70 fps from load development. I thought it might be a carbon ring, but decided to check the throat using the same 140 grainers. It now measures 2.487 at the ogive; same 5 projectile average. Just to add, it has just over 500 rounds on it and using 57.4gr of Retumbo.

I do not have the original bullets used to measure, so I am not sure it that has had any influence at all on measurement. I guess my question really is, is this .036 wear normal for this caliber? Same OAL gauge as before, so either it has eroded, the bullets are not the same measurements, or a combination of both. Thoughts?

 

[Raptor]

In the future you should keep the bullets you use to record your throat. Bullets can vary quite a bit from batch to batch and even in the same box. I shot the barrels out of several 6.5x284s but I was using H4350 and used them in comps. They were toast at about 1200rds. When my last one went it went from a .3 gun to a .8 gun in one match.

If you do have to re barrel it I would recommend that you go to a straight 284. You will never look back. I love mine and just had it set back with over 2300rds through it. They are easy to get to shoot and you will love the 7MM bullets they really fly. I am shooting the 162s in mine and have shot it out to a mile. I was amazed that it shot that far as accurately as it did with the lighter bullet.

 

[mslman]

Lesson learned on the keeping the original bullets used part. Did you see the same erosion values in yours?

 

[Joe Salt]

mslman He is also right about H-4350, And the bullets changing from lot to lot, always check with the ones you will be shooting. If you like Retumbo, you may want to try some IMR-7828 SSC I'm going to give that a try this spring if it ever gets here! And you might want to try Fed.210 or 215's

Joe Salt

 

[dkhunt14]

The bullets changing could be some of it. If the bullets are fatter they can give more velocity. If you have carbon in the throat it can pick up velocity. If the throat moved farther ahead it should not have changed velocity that much. The only way I can see that happening is if you are in the lands and now you are not. I believe it is something else causing it. A different lot of components can change things. Powder or anything new. I shot a few 6.5-284 in competition and the throat can really move in some barrels. I have seen them completely gone in less then 1000 rounds. Matt

 

[Rtheurer]

Just about every barrel I have used in the last 5 years has increased in Velocity after the 100 to 200 rounds mark. I never paid attention to it until someone brought it up about 5 years ago. Sure enough he was correct. I cant explain it and don't know what causes it but for sure it happens with the EXACT same loads and even loads that where loaded up at the exact time the barrel was brand new.
For this very reason I have moved to putting 100 rounds on a barrel before I get real serous about finding a load for Long Range. Sure I look for a good load early but always revisit it after 100 rounds are on the tube. Always.

Just put a new Krieger Barrel on the ole 6.5X284 last week. It has a wopping 97 rounds on it as of yesterday. It is really shooting well with a wild Arse guess on a powder I have not used in matches before. (H1000)

I keep my first Freebore checking bullets in an old Berger bullet box with the Lot Number and barrel info on the top. It stays with the others for rechecking erosion later on if so needed.

Because the 6.5 is a little harder on throat's, I like to soft seat bullets with this rifle. It works well as I don't have to chase the erosion as it gets longer in the tooth. Kinda like hitting the easy button if you will.

This is barrel Number 7 in 6.5X284 for me. Lots of folks have moved away from it, I have kept on, since I have a lot of stuff for it and until that is gone I will remain with it. Its still a winning combo. Hard to beat those long 6.5mm bullets. Anything over 180grains is too much for me to handle accurately for a full day or weekend of shooting. Been tempted sooo many times to shoot the 284 Winchester... maybe some day I will give it a try.

Russ T

 

[SWRichmond]

OP,

I moved the throat in my FTR gun more than 0.040" in 2400 rounds, pushing 185 Juggernauts as hard as possible. Cant imagine what the 6.5x284 does, except it is certainly much worse.