Thought I would start a new thread so as not to distract from the Joe's HV thread even though bullet design comes into it.
I have drawn up what I believe will be a good bullet for my 6.5 grendel max and would welcome a discussion on the subject.
I wanted to incorporate terminal performance on game with all the accuracy I could draw into it. I started at the meplat and while the usual wisdom (sic) is a 60% meplat I dropped it back to 53% to make sure of feeding.
The transition length from meplat to minor dia is bore dia and the minor nose dia is at 1 thou under bore dia with straight taper to major dia at leading edge of drive band.
Hoping it is the 135-140gn weight ( but not sure how to calculate this except by extrapolating my 7mm bullet data) so it can be run in the 1900-2000fps range in the 6.5 GM. Will cast it from 95-4-1 so it should do well for both meat and paper.
Keep in mind it is drawn with my chamber reamer as a base for sizing of aprotriate dimensions.

So here it is for your consideration and recomendations on who would be the best to aproach to get the mould made (and who doesn't charge the earth for the work either)

Drawing deleted and new pic in new post.

Your bullet body/bearing length is about 50% of your bullet with an unsupported nose. I don't think you'll get the accuracy you expect with it. You really need to have a finished rifle and take a lead impact throat slug to design a proper bullet that fits right.

If the minor nose dia that is .245 was increased to .2555 (bore dia) and nose taper shortened would that make the bearing length long enough to ensure directional integrity - ie accuracy as it would have positive land engagment at that point going to full engagment. Apreciate the informed comment.

Revised drawing for comment

Von,

Couple things on your build. Was looking at the reamer diagram you sent me. Okay when AA made the first rifles they had two different neck dimensions on the chamber. One was .300 and the other was .295. I have the .295. I see yours is .293. I know for a semi auto that's going to be mighty tight, but I believe you're building a bolt action. Another thing is the brass. You can't beat the Lapua brass in that caliber. With the 7.62 brass you're going to have a definite donut at the neck base area. The Hornady brass isn't no ways as good as the Lapua and they had some problems in the early stage as they were given the wrong dimensions from AA. They have since readjusted the case and now it's too much under head space. Hornady also seems not to be able to make a sharp cornered neck/shoulder junction. It was more radius as compared to Lapua. AA sales Lapua pretty cheap if they still have it. That radius was a chambering problem in the first lot of Hornady.

In the early days most everyone had to cam over their press ram or take some metal off the shell holder or bottom of the dies to get the brass to chamber in the rifles. That's all changed now.

There is a different reamer dimension between bolt rifle and semi auto.

quote:

Originally posted by SmokinJ:
Von,

Couple things on your build. Was looking at the reamer diagram you sent me. Okay when AA made the first rifles they had two different neck dimensions on the chamber. One was .300 and the other was .295. I have the .295. I see yours is .293. I know for a semi auto that's going to be mighty tight, but I believe you're building a bolt action. Another thing is the brass. You can't beat the Lapua brass in that caliber. With the 7.62 brass you're going to have a definite donut at the neck base area. The Hornady brass isn't no ways as good as the Lapua and they had some problems in the early stage as they were given the wrong dimensions from AA. They have since readjusted the case and now it's too much under head space. Hornady also seems not to be able to make a sharp cornered neck/shoulder junction. It was more radius as compared to Lapua. AA sales Lapua pretty cheap if they still have it. That radius was a chambering problem in the first lot of Hornady.

In the early days most everyone had to cam over their press ram or take some metal off the shell holder or bottom of the dies to get the brass to chamber in the rifles. That's all changed now.

There is a different reamer dimension between bolt rifle and semi auto.

Yes our reamer spec is most definately for bolt action only aplication and because I have pushed the shoulder forward I am reforming anyway so dont see a problem with the brass. Am used to turning necks for another couple of rifles so an aware of possibilities and will deal with them if they arrise.
Also can load long to 2.4 - 2.45 with a lengthened magazine in my Mark X mini mauser so the bullet design is strictly with thsi in mind.

quote:

Originally posted by Von Gruff:

quote:

Originally posted by SmokinJ:
Von,

Couple things on your build. Was looking at the reamer diagram you sent me. Okay when AA made the first rifles they had two different neck dimensions on the chamber. One was .300 and the other was .295. I have the .295. I see yours is .293. I know for a semi auto that's going to be mighty tight, but I believe you're building a bolt action. Another thing is the brass. You can't beat the Lapua brass in that caliber. With the 7.62 brass you're going to have a definite donut at the neck base area. The Hornady brass isn't no ways as good as the Lapua and they had some problems in the early stage as they were given the wrong dimensions from AA. They have since readjusted the case and now it's too much under head space. Hornady also seems not to be able to make a sharp cornered neck/shoulder junction. It was more radius as compared to Lapua. AA sales Lapua pretty cheap if they still have it. That radius was a chambering problem in the first lot of Hornady.

In the early days most everyone had to cam over their press ram or take some metal off the shell holder or bottom of the dies to get the brass to chamber in the rifles. That's all changed now.

There is a different reamer dimension between bolt rifle and semi auto.

Yes our reamer spec is most definately for bolt action only aplication and because I have pushed the shoulder forward I am reforming anyway so dont see a problem with the brass. Am used to turning necks for another couple of rifles so an aware of possibilities and will deal with them if they arrise.
Also can load long to 2.4 - 2.45 with a lengthened magazine in my Mark X mini mauser so the bullet design is strictly with thsi in mind.

My friend did about all the design on that round. Then AA got in the act and submitted it to Lapua. Ironically their engineer moved the should forward, and he said for manufacturing reasons, and now you're moving it even more. Already a short neck to start with. Lapua also blew out the front of the case too.

I still think I'd go with the Lapua brass as it's a true PPC case with small rifle primer. They are proven to be more efficient and they do seem to win the matches. The 7.62 brass is okay for playing around. I use it when I'm some non important varmint because I'm worried if I lose the case in doing so. Don't like losing my Lapua brass. One last thing, the round was initially loaded with small rifle magnum primers.

I forgot to ask, what twist you going with? Mine is an 8.

quote:

Originally posted by SmokinJ:


I forgot to ask, what twist you going with? Mine is an 8.

I have an 8 twist as well. While I have Win 7.62x39 and some Hornady Grendel brass for playing with and initial trials Zi will get some lapua brass when I get serious about testing what this cartridge will offer. Not hot rodded but definately looking to get some performance gains on the AR chambered Grendel.

quote:

Originally posted by Von Gruff:

quote:

Originally posted by SmokinJ:


I forgot to ask, what twist you going with? Mine is an 8.

I have an 8 twist as well. While I have Win 7.62x39 and some Hornady Grendel brass for playing with and initial trials Zi will get some lapua brass when I get serious about testing what this cartridge will offer. Not hot rodded but definately looking to get some performance gains on the AR chambered Grendel.

The guys I know that have bolt gun Grendels get gains over the auto with the standard cartridge. The problem with the auto is the AR bolt is hogged out too much for the much larger rim then it was designed for.

quote:

Originally posted by Von Gruff:
If the minor nose dia that is .245 was increased to .2555 (bore dia) and nose taper shortened would that make the bearing length long enough to ensure directional integrity - ie accuracy as it would have positive land engagment at that point going to full engagment. Apreciate the informed comment.

Revised drawing for comment

Its not so much changing the nose diameter up front as in matching the rifles throat just in front of the driving bands. A very close fit for 75% of the bullets length should give good accuracy. The nose at bore should be ok as long as it chambers.

Von

This is one of the groups I got from my 6.5G

Not about the bullet design but about the case design and the Mini Mk X action. I have one in 7.62x39 so am very familiar with it. Is that blown out and straight tapered case going to feed? I ask because I tried the 22 and 6mm PPCs for feeding in mine and they would not unless the action feed rails are altered. The feed rails on my mini Mk X are definately for the tapered 7.62x39 cse.

Larry Gibson

quote:

Its not so much changing the nose diameter up front as in matching the rifles throat just in front of the driving bands. A very close fit for 75% of the bullets length should give good accuracy. The nose at bore should be ok as long as it chambers.

45 2.1 I have taken that into account. I know what the chamber specs are as I have drawn the reamer print. The throat is .2645 (I will lap a .264 sizeing die to .26445) I have a 1 degree taper from the drive band to the bore dia shoulder and will be able to seat for a kissing engagment into the 1.30 taper of the lead ( without the risk of a de-bullet if extraced unfired) with just the rear edge of the front drive band in the neck of the case and only have the rear edge of the GC below the neck of the case.


Not about the bullet design but about the case design and the Mini Mk X action. I have one in 7.62x39 so am very familiar with it. Is that blown out and straight tapered case going to feed? I ask because I tried the 22 and 6mm PPCs for feeding in mine and they would not unless the action feed rails are altered. The feed rails on my mini Mk X are definately for the tapered 7.62x39 cse.

Larry Gibson

I have not stumbled into this build as a first project and have taken these aspect of the action into account. I havent even started with a 7.62x39 action but a 223 but the GS who dose my work had my 98 FN (in 30-06) working slickly after re working to 404 Jeffery so I dont think a 223 to 6.5 GM is going to stretch his abilities too far. I have lengthened the magazine so I can load to 2.45 and then I made and fitted another lengthened bolt handle before sending it off to the GS where it sits waiting for the reamer.



You will note that the magazine extension has only been spot welded as the full weld is something that the GS will do.

I have thought this project through over many sleepless nights and intend for it be be a creditable shooter when done. Be good to get groups (with cast) like you have showed Joe and this is what my cast bullet design is working toward.

Von,

I think you may have an error in your last sentence. I think you may have meant 45 2.1 as Mr Gibson has showed me nothing. I have learned much off of 45 2.1.

quote:

Originally posted by SmokinJ:
Von,

I think you may have an error in your last sentence. I think you may have meant 45 2.1 as Mr Gibson has showed me nothing. I have learned much off of 45 2.1.

I have read and re-read my post and for the life of me can not see I have atributed anything to anyone, (except your shooting to you) and my GS's work to my GS. Stand to be corrected though

My mistake Von, it was I that read it wrong. Here's a pic of my 140 grain Saeco and some loaded ammo on SKS strippers:




This next picture is a little project of mine if I get around to building the rifle. It's an 8mmGrendel. I wanted to do the original 8mmKurtz on an AR 15 but the case head is too fat. A Lothar Walther friend of mine said neck up the Grendel. Here's a picture of the round:



Last but not least my friends that built the bolt guns for the Grendels used the CZ 527. AA at one time tried to get CZ interested in building that rifle in 6.5 Grendel, but they weren't interested unfortunately.

One more 6.5 caliber target and this is from a 260Rem that I build on a Japanese Type 38 Arisaka. Wears an E.R. Shaw barrel. How about that, not a Lothar Walther. This is using a standard production mold from Lyman #266455. Was testing some loads and the bad load is obvious. The load that did the trick is to the right and there is one bullet from the bad load in that group because of my bad habit of shooting at bullet holes in the target:

quote:

Originally posted by Von Gruff:
45 2.1 I have taken that into account. I know what the chamber specs are as I have drawn the reamer print. The throat is .2645 (I will lap a .264 sizeing die to .26445) I have a 1 degree taper from the drive band to the bore dia shoulder and will be able to seat for a kissing engagment into the 1.30 taper of the lead ( without the risk of a de-bullet if extraced unfired) with just the rear edge of the front drive band in the neck of the case and only have the rear edge of the GC below the neck of the case.

OK.... with that you should be fine on the nose if you match tapers exactly. A lot of CBA members did that due to the efforts of John Ardito in the 80's.

Von Gruff

Definately my bad for the assumption you started with the 7.62x39 Mini Mk X action. The much straighter feed rails of the .223 action should work fine with he straighter taper cases. Looks like you are all over the project and have thought it out very well indeed. Definately should be an interesting project.

I've often thought of rebarreling my own Mini action to 6mm PPC for a varminit rifle if I ever shoot out the 7.62x39 barrel. That magazine lengthening will mke it possible to set the bullets out, definate got to take a relook at mine now!

I've also thought of rebarelling to a 14 or 16" twist barrel to use a shorter 125 - 140 gr full caliber with no bore riding nose in it. With a 24 - 26" barrel 2400 - 2600 fps whould be quite possible.

Larry Gibson

Von,

Here's a link you might be interested in viewing. As sharp as you are I'll bet you've been there already.

http://www.65grendel.com/forum...b36dbe245d2eeb869f88

quote:

Originally posted by SmokinJ:
Von,

Here's a link you might be interested in viewing. As sharp as you are I'll bet you've been there already.

http://www.65grendel.com/forum...b36dbe245d2eeb869f88

Yep, found them quite a while back and was an irregular on the old site as well before the meltdown.

quote:

Originally posted by Von Gruff:

quote:

Originally posted by SmokinJ:
Von,

Here's a link you might be interested in viewing. As sharp as you are I'll bet you've been there already.

http://www.65grendel.com/forum...b36dbe245d2eeb869f88

Yep, found them quite a while back and was an irregular on the old site as well before the meltdown.

Well the melt down is over and they are back. Bill when back to England. Might give them another look see.

quote:

Originally posted by SmokinJ:

Well the melt down is over and they are back. Bill when back to England. Might give them another look see.

And we have just convinced Hanka to give us a bolt rifle forum as well where for a long time on the new forum it was the AR platform almost exclusively.

Von,

Have you shot cast in a twist as fast as 8?

I posted on your HV thread that my 7x57 has an 8 in twist and I run it over 2400fps.

quote:

Originally posted by Von Gruff:
I posted on your HV thread that my 7x57 has an 8 in twist and I run it over 2400fps.

Yes you did, I should have phrased that "fast as an 8 twist in the smaller bore calibers".

Then your homework fitting the bullet and assembling the cartridges becomes more critical.
There is a smaller cross section area of the smaller diameter bullets that plays havoc on things.

Why did you choose an 8 twist for your 7x57?

quote:

Originally posted by SmokinJ:

quote:

Originally posted by Von Gruff:
I posted on your HV thread that my 7x57 has an 8 in twist and I run it over 2400fps.

Yes you did, I should have phrased that "fast as an 8 twist in the smaller bore calibers".

Then your homework fitting the bullet and assembling the cartridges becomes more critical.
There is a smaller cross section area of the smaller diameter bullets that plays havoc on things.

Why did you choose an 8 twist for your 7x57?

I think that having worked through the "difficulties associated with the fast twist 7mm with no mentor other than my own findings I should be able to muddle my way through with the 6.5.
I didn't initially build my 7x57 rifle for cast bullets and wanted to run the heavier jacketed bullets in the 160gn-175gn weight range, (I had visions of taking it and its companion 404 Jeffery to Africa but circumstances have rulled that out. When I got it sorted with them I thought the chalenges were over untill I got a mould to "TRY OUT". I had cast for my 44's but they were fairly traditional single and lever actions that and were very simple to get where I wanted to go with them. It took quite a bit to get the 7x57 perking but it has been verry sucessful and again I am building the 6.5 GM predominately for the 123gn A Max and possibly the 130gn Scirocco but could not have it and not try it with cast so this is why I am looking for a suitable cast bullet design. Have had a preliminary exchange with Dan at Mountain moulds so unless there are constructive suguestions from the forum I will see what Dan can offer.

quote:

Originally posted by Von Gruff:

quote:

Originally posted by SmokinJ:

quote:

Originally posted by Von Gruff:
I posted on your HV thread that my 7x57 has an 8 in twist and I run it over 2400fps.

Yes you did, I should have phrased that "fast as an 8 twist in the smaller bore calibers".

Then your homework fitting the bullet and assembling the cartridges becomes more critical.
There is a smaller cross section area of the smaller diameter bullets that plays havoc on things.

Why did you choose an 8 twist for your 7x57?

I think that having worked through the "difficulties associated with the fast twist 7mm with no mentor other than my own findings I should be able to muddle my way through with the 6.5.
I didn't initially build my 7x57 rifle for cast bullets and wanted to run the heavier jacketed bullets in the 160gn-175gn weight range, (I had visions of taking it and its companion 404 Jeffery to Africa but circumstances have rulled that out. When I got it sorted with them I thought the chalenges were over untill I got a mould to "TRY OUT". I had cast for my 44's but they were fairly traditional single and lever actions that and were very simple to get where I wanted to go with them. It took quite a bit to get the 7x57 perking but it has been verry sucessful and again I am building the 6.5 GM predominately for the 123gn A Max and possibly the 130gn Scirocco but could not have it and not try it with cast so this is why I am looking for a suitable cast bullet design. Have had a preliminary exchange with Dan at Mountain moulds so unless there are constructive suguestions from the forum I will see what Dan can offer.

You can also take your bullet drawing dimensions to Accurate Mold and Tom there may be able to cut it. Another alternative is when you get the rifle take a throat pound cast and send it to 45 2.1 and maybe he can get a group buy going on it. I'll have to say the 6.5G may not be popular enough though.

The standard twist that the barrel makers make for the 7x57, such as 9 to 10, in my opinion, good enough for the bullet weights you mentions. I've had them and have no problem with heavy long bullets in that caliber.

This is on Accurate moulds web site so he cant do a 6.5

My current tooling is limited to these design features:
•A flat meplat of at least 0.18 inch diameter.
•Overall bullet length no greater than 1.375 inches.
30 caliber minimum
•Base pour molds only.
•No flat-sided lube grooves. All side angles must be at least 35 degrees.

Ordered body diameter tolerance is (+.0015,-.000).

If you have a specific design in mind, e-mail or mail me a drawing. All new designs will be recorded in the catalog.

If an existing catalog design is about right, let me know the your specific dimensional requirements.

[QUOTE]Originally posted by Von Gruff:
This is on Accurate moulds web site so he cant do a 6.5

My current tooling is limited to these design features:
•A flat meplat of at least 0.18 inch diameter.
•Overall bullet length no greater than 1.375 inches.
30 caliber minimum
•Base pour molds only.
•No flat-sided lube grooves. All side angles must be at least 35 degrees.

Ordered body diameter tolerance is (+.0015,-.000).

If you have a specific design in mind, e-mail or mail me a drawing. All new designs will be recorded in the catalog.

If an existing catalog design is about right, let me know the your specific dimensional requirements.[/QUOTE

The guy at Accurate is still learning how to cut molds on a CNC lathe. If you email him he may be able to do a 6.5 by now.

Will send an email and see what he says

If the throat begins life as a straight taper, do we expect it to remain so for long? I don't know. The straight taper throat and matched bullet concept is well over a hundred years old and seemed to work quite well, but if it changes to a parabolic taper through erosion, the cast bullets must be changed to match if accuracy is to be maintained.

Tom has indicated in the past that his tooling limits work to a minimum of .260", that being the bottom of the lube grooves. My belief is he isn't interested in making the smaller-caliber moulds, but we shall see. My suspicion about the meplat restriction is that it's a product of not wanting to change cutters for each hole to finish the noses to a smaller point, although I believe Joe persuaded him to tell that the true minimum is .125", not .180". The .180" just gives a larger margin of error, and works better with Tom's flat sizing punch system.

Gear

Yes, his reply indicated he is only able to do 30 cal and up so that is a wash. Have a letter in the post away to Hoch moulds although the last one I got from them was quite a bit behind the delivery date expectation. Have three strikeouts so far with mountain, accurate and CBE all unable to help. Will have to wait for Hoch as they only have mail and ph conatct.

That is a shame. Even LEE can cut a 6.5 mold. They lathe cut too. You don't see them standard production, but they've done special group buys in that and 22 caliber.