22-250 throat length

[limige]

I have an old 22-250. When I checked the distance to the rifling I found saami length is about. 180 off the rifling. Is my throat toast already? I don't think there's more than 500 rounds threw it.

[acemisser]

Not be overly educated about such things,I thought the sammi spec's were for
making sure the loaded round would fir into the magazine of the rifle...Which
therefore would really not matter what length you measured if you were to be
shooting it single rounds at a time..

[Apache]

Depends on how it shoots. I've actually seen a rifle with what appeared to be nearly no rifling for the first 1 1/2" after the chamber neck ended and it still shot less than an inch at 100yrds.

[bigedp51]

How did you come up with "180"

http://www.saami.org/pubresources/cc_drawings/Rifle/22-250%20Remington.pdf

[limige]

ok heres the whole story. that was the first rifle i reloaded for. no chrono, no OAL gauge.

i just loaded to the standard SAAMI length and did my load workup. i had a load that looked pretty good so i loaded 10 up and hit an indoor 200 yrd range and shot it off the lead sled. the 10 rounds ate a 1" circle up in the paper. i went home and loaded all i had, 70 rounds.

then i bought a 243 and started working on that, was having issues getting it to group well and started working on feeling out the rifling by blueing the bullet up and keep trying it in the gun till the rifling marks disappeared.

i started to take that the 22-250 to shoot in between shot strings with my 243 and noticed 1 3/4-2" groups was the best i could get. played with it some and checked out the rifling on that gun, then compared that to the SAAMI cartridge and the difference was like .180.



so. i know 22-250 is a hot round and will toast a barrel quicker. since i had never checked the rifling from the start i don't know if it changed or if that was the standard reamed length for that round. my mag will not accept much over SAAMI length. i'm wondering if i should have the chamber recut and shorten the barrel up just enough to bring the rifling in closer so i'm not shooting so far off. thats the best idea i had why the groups doubled in size.

even at 100 yrds, i used to cloverleaf at 100 now i'm 3/4-1" groups.



the load was 33 gr of imr 4895 with a 55 gr nosler ballistic tip varmint round.



i'm real curious what standard barrel life is for that cartridge and what the standard throat length is.

[Tnslim]

As unbelievable as it sounds I have just over 4000 rds down my VLP 22-250 and the last time out it shot consistently 1/2" and under. I've never over heated the barrel plus I don't load the hottest it will take. The throat is probably halfway down the barrel now but I hesitate to swap out for a new barrel while it's still shooting this good.

[limige]

so did i load too hot or did the factory cut that much throat in the barrel to begin with?

what bothers me is if i want to shoot .01-.02 off the lands i won't have enough bullet in the case for proper seating. to seat the lands the bullet will only contact the case for .150 instead of the .224 i should have.

couple that with my magazine, my mag won't allow for much more than .03 adjustment. i would feel much better if i could get it .02 off the lands

so if that was the factory cut i did have a load working at that depth but i've having problems getting it to shoot again.

now the rifle is a remington 788. i'm not sure if its worth rebarreling. the lug setup on that bolt isn't the greatest design. the front locking lugs used today are much better. so my decision is, use it as is, or get it trimmed and recut or just plain sell it and buy another gun.

any thoughts?

[cookjp]

I dont know if this is a standard but I have 2 Remington 700's one in 270 and one in 7mm-08 and both of them have such long throats that if I try to load to the lands the bullet is nearly out of the case. I have found that both of them like a bit of bullet jump so it works out. I would try a few different seating depths and see if you dont get the accuracy that you are looking for.

[GaryB]

It seems that Savage has always had a little faster twist rate in their barrels than most other manufacturers to allow for the use of longer(heavier) bullets. Is it possible this is what you are seeing? You did not mention what weight bullets you are shooting.

[bigedp51]

limige

The SAAMI cartridge drawings are "guidelines" and do not have to be followed by firearms manufactures, just look at the longer throats on Weatherby rifles.

Your Remington 788 has rear locking lugs and I read in the past that the throats were longer on these rifles to reduce bolt thrust and thus bolt compression on firing. This helps prevent case stretching in the base web area even when you have tight cartridge headspace in your chamber due to the bolt compression.

You will also see longer throats on the newer "short" magnums because these cases cause more bolt thrust because they have less case body to grip the chamber walls.

I know this from collecting and studied the British Enfield rifle and it also has rear locking lugs and a longer throat.

Don't worry about your throat as long as the rifle shoots good groups, my Enfield rifles used cordite powder that had more nitroglycerin in it than some modern pistol powders. (Cordite is a very hot burning double base powder) Any used Enfield rifle will have throat erosion and the secret is to shoot flat base bullets that expand when kicked in the seat of the pants and fill and seal the worn bore. If you do not see a difference in group size between a boat tail bullet and a flat base bullet then chances are your throat is OK.

[limige]

Thanks for the info. Just trying to find out why the groups deteriorated. Was beginning to think the barrel was blown out. Yes I have bolt issues as well. I have to bump the shoulder back on once fired brass to get the bolt to close right. It must be allowing the case to stretch out. 001-.002 over normal. I'm debating about selling it for a new savage so I can shoot bugholes. My standards have risen a bit.