Throat erosion

[tony]

My 22/250 ack semi custom has not been shooting so good of late, groups have been getting inconsistant, have always used the same load etc etc so had a little think and checked to make sure all was secure with rifle, all ok. The total round count so far from this rifle is around 450 and the seating depth of my loads have not changed at all so I thought ahh, best check for throat erosion and sure enough when I checked this using my OAL gauge I found that the throat has receded 0.050 thou, question, is this pretty much what you would expect to see after 450 rounds.

Your feedback gentlemen would be appreciated.

Tony.

[oaken]

You could try lengthening your oal. It worked on my 223, I had the same after about 600 rounds

Also, are you annealing your brass, you may be getting some variable neck tension.

How are you cleaning your barrel? Might be time for an exceptionally rigorous clean?

Hope its not a pre-quarry excuse :-P

Rup

[Lee]

Tony,

 

This is very typical and varies from cartridge to cartridge. With one of my 6.5x284 fclass rifles the throat would wear .010" every 100 rounds.

 

you just need to keep checking the throat but also make sure you clean the rifle well so your not measuring the copper and carbon fouling on the the throat.

 

Our 5R cutrifled barrels show reduced throat wear which is interesting.

 

Lee

[onehole]

50 thou in 450 rounds !!!!!OMG Tony,,,,,how you doin anyway? OK I hope.

 

Lee,,, on my behalf you very kindly provided Dasherman with a 5R cut 308 a good while back ,,,,round count is something like 1300 and I have lost only 7 thou!! from new,,,,amazing,,,only run mild load 44/140 which probably helps.

 

Some more comparisons,,,,,my 12T 6br,,,450 rounds 3 thou gone,,,,,,,my 8T 6brn,,,9 thou gone after 900 rounds,,,,,,both cut kreiger barrels 31.5/135 75vmax and 29.5/140 105 Amax,,,,,,,,,,pacnor barrelled 5 groove 9T 223 about 900 rounds and 7 thou gone and run with 52 Amax and 23.5/130 vit.

 

Think I will stick to these calibres,,,,have considered barrel burners but dont miss much with these,,,,,regds Onehole.

[tony]

Thanks for your feedback gents, I tend to keep things pretty much up to scratch with all my rifles on the cleaning side, having said that I will give it a good going over and do a recheck. You could be correct Rup, on the pre quarry excuse, not long to go so got to get it right.

 

I am pretty good thanks Onehole how you doing yourself, hope all is OK with you mate.

 

10 thou loss after 100 rounds, thats interesting Lee, Is it one of your 5R barrels, as mine is too.

 

Thanks again Gents,

 

Tony.

[Lee]

hi onehole, fantastic mate, hope she keeps tight for you

 

Tony, no the 10 thou loss after 100 rounds was a normal 6 groove cut rifle barrel in 6.5-284 , my 7mm wsm is 5R and that's never shifted apart from the first breaking in period when the chamber is fresh and with sharp corners, about 20-50 rounds or so it settles in and the throat has stayed put even after 800 rounds.