Heavy bullet 140gr in the 257 Roberts

[brstevns]

I was given some cast 6.5 bullets that weight 140gr. These are of .263 diameter I was wondering if I could size them down to .259-.260 for use in a 257 Ackley Improved?

[bruce drake]

what is the twist rate for your 257 Ackley Improved?

Will it handle the heavier bullet?

I have a 257 Roberts (parent to the 257 AI) and my rifle's twist is 1-10" which doesn't care for jacketed bullets heavier than 140gr. My rifle prefers both 100 and 117gr bullets and I don't intend to try to make a 25-06 out of the rifle either.

Bruce

[brstevns]

what is the twist rate for your 257 Ackley Improved?

Will it handle the heavier bullet?

I have a 257 Roberts (parent to the 257 AI) and my rifle's twist is 1-10" which doesn't care for jacketed bullets heavier than 140gr. My rifle prefers both 100 and 117gr bullets and I don't intend to try to make a 25-06 out of the rifle either.

Bruce

Twist is 1-9, do not intend to make a 25-06 out of this either. Relative loads it to the high end of the regular 257 roberts or the starting loads listed for the IMP. when he does load for it. In fact most of the time he just shoots factory .257 roberts.

[frnkeore]

I have sucessfully re-sized 8mm cast bullets (.325) down to .321 for my 32/40. But, to do it you have to have a die, in your case that is .2635-.264 for about 1/2", then tappering at no more than 2 deg down to .259 and highly polished. The .264 starting dia, keeps it aligned to the tapper so, it won't shift to the side and has to start straight into the sizing area. Lube them first then push them nose first through the die. You can install the GC at the same time if you tapper the beginging at 2-5 deg at a dia larger than the GC. The lube will keep the grooves from distorting. It's something that you'll have to have custom made. I use a arbor press but, you could have it made out of 7/8 x 14 all thread stock and a plunger to fit the press ram.

Frank

[brstevns]

Any suggestions for a starting load?

[303Guy]

I would think that boolit length would be the deciding factor. Cast boolits usually have lube groove and the like that make them longer. Sizing down a 6.5 boolit would close up the lube grooves so that boolit itself might not elongate. All of which increases the likelyhood of it working. Personally, I would like for you try and see how it turns out and let us know! (I thought my 257 PP boolits were rather long at 121grs but they are within predicted weights and length at the max for a 1-in-10 twist. The max can often be stretched out quite a lot!)

[brstevns]

I would think that boolit length would be the deciding factor. Cast boolits usually have lube groove and the like that make them longer. Sizing down a 6.5 boolit would close up the lube grooves so that boolit itself might not elongate. All of which increases the likelyhood of it working. Personally, I would like for you try and see how it turns out and let us know! (I thought my 257 PP boolits were rather long at 121grs but they are within predicted weights and length at the max for a 1-in-10 twist. The max can often be stretched out quite a lot!)

I will see how it goes. Might try to size down to .250 and paper patch as well. Cousin has a 25-06 he would like to try them in.

[41mag]

Not trying to dissuade you in trying these out as stranger things have happened, but I cannot get a 142gr Wildcat RBBT ULD, to stabilize in my 25-06 AI at 3K fps. It has a 28" 1.9 Broughton 5c on it.

You probably stand a better chance however as these are 1.422" from base to tip.

Wishing you luck.

[brstevns]

Not trying to dissuade you in trying these out as stranger things have happened, but I cannot get a 142gr Wildcat RBBT ULD, to stabilize in my 25-06 AI at 3K fps. It has a 28" 1.9 Broughton 5c on it.

You probably stand a better chance however as these are 1.422" from base to tip.

Wishing you luck.

Will measure and see what length these are. Not sure if it will work either but will give it a try.

[41mag]

Will measure and see what length these are. Not sure if it will work either but will give it a try.

Well hopefully yours will be a bit shorter than these I have. I have run a 125gr RBBT ULD, and a 130gr Bonded FB, with no issues what so ever. I was REALLY hopeful those 142's would shoot as they would be similar to some of the heavier weight 6.5 and 7mm's that shoot very far so well.

Anyway, good luck, wishing the best for you.

[brstevns]

Well hopefully yours will be a bit shorter than these I have. I have run a 125gr RBBT ULD, and a 130gr Bonded FB, with no issues what so ever. I was REALLY hopeful those 142's would shoot as they would be similar to some of the heavier weight 6.5 and 7mm's that shoot very far so well.

Anyway, good luck, wishing the best for you.

I measured some of them, it looks like 1.170. I would think the length will grow once sized down.

[41mag]

Just using a basic calculator,

Calculator for Barrel Twist Rate (http://kwk.us/twist.html)

You might have to get it up to 1900 - 2000fps to completely stabilize it.

Thee again it said I needed to get 3K to stabilize the 142's I have, but so far they only make nice silhouette imprints on the target.

[brstevns]

Just using a basic calculator,

Calculator for Barrel Twist Rate (http://kwk.us/twist.html)

You might have to get it up to 1900 - 2000fps to completely stabilize it.

Thee again it said I needed to get 3K to stabilize the 142's I have, but so far they only make nice silhouette imprints on the target.

Thanks for the link and information. Will past all of this on and see what happens.