Gunsmithing Help with making a dummy round.

[ogonzalez13]

I want to make a dummy round to send to my gunsmith but not sure I have the right method to do so.

Im building a 7 SAUM using using Norma 7 SAUM brass and will be seating 180 grain Berger hunting hybrid bullets.

I plan on using Alpha type 3 magazines that state they have an internal COAL of 2.97"

The action is a defiance deviant medium action.

I saw a video where Greg Tannel suggested to seat the bullet so it is 0.100" less than that COAL length so the lands could be chased as the throat wears and still feed reliably from a magazine.

So if I am understanding his directions correctly I should seat my bullets into my brass so my dummy round has a cartridge over all length of 2.87" which is 0.100" less than the internal COAL available using the Alpha type 3 magazine?

I'm wanting a .015" jump as suggested by Bryan litz from Berger bullets so using the above will my gunsmith have enough information to set a proper freebore, etc...?

Thanks.

 

[Mordamer]

With your particular cartridge choice you probably don't want to start .100" short of mag length. I would seat a bullet to an overall length of 2.920" and use that. You likely won't chase the lands .100". You will end up with a very short freebore on this reamer.

 

[ogonzalez13]

With your particular cartridge choice you probably don't want to start .100" short of mag length. I would seat a bullet to an overall length of 2.920" and use that. You likely won't chase the lands .100". You will end up with a very short freebore on this reamer.

Ok. Good information. So .050" less than COAL of 2.97" should be sufficient for this cartridge.

I know that using this caliber in a short action while using the 180 Berger hybrids set to a depth that still feeds out of a magazine really eats up a lot case space and I won't be able to drive the bullets as fast as I would in a long Action but I am ok with that. I don't need max speed for my application as this will mainly be a hunting rifle first and bench gun for fun second.

I do plan on also using the 168 class of bullets and possibly 140 as well so I don't mind if the free bore is a little short for the 180s as I think it should be just about right for the lighter classes of bullets.

Is my way of thinking sound on this?

If anyone knows an idea freebore for the original setup I stated could you please share that info with me as well. I have read a lot of people are using a .188 freebore with good success but I believe that is from a long Action and may prove to be too long for my needs unless I single feed them all the time.

 

[Mordamer]

0.188 freebore is waaaaaaaaaay too long for a short action. Mine is cut with a SAAMI spec reamer which has a freebore of 0.090". I am using the 162 ELD-M seated about 0.020" off the lands and I am at 2.925" if I remember correctly.

With your loaded dummy round, take a pair of calipers locked at .282" and slide them down the bullet ogive until they stop. Rotate the calipers around the bullet scribing the smallest of lines. Measure from this point to the base of the cartridge and you will get a close estimate to where your "lead" dimension should end on a reamer print. Add 0.015" to this dimension if that is how far you want to be from the lands.

 

[ogonzalez13]

0.188 freebore is waaaaaaaaaay too long for a short action. Mine is cut with a SAAMI spec reamer which has a freebore of 0.090". I am using the 162 ELD-M seated about 0.020" off the lands and I am at 2.925" if I remember correctly.

With your loaded dummy round, take a pair of calipers locked at .282" and slide them down the bullet ogive until they stop. Rotate the calipers around the bullet scribing the smallest of lines. Measure from this point to the base of the cartridge and you will get a close estimate to where your "lead" dimension should end on a reamer print. Add 0.015" to this dimension if that is how far you want to be from the lands.

Never heard of this technique before. Seems perfect. I will do just that. I appreciate the info.

GAP provided me a copy of the the reamer print they will be using to chamber my Barrel and it appears that their reamer has a .110 freebore. Seems like that should be about right if I am too use 180 Berger Hybrids.

Ill use your method and see what I come up with.

I see that you mention your COAL with the 162 ELD-M is 2.925" which is what you suggested more or less I set my dummy cartridge to with the 180s. I assume at this length you are having no issues with feeding from a magazine?

 

[Mordamer]

Never heard of this technique before. Seems perfect. I will do just that. I appreciate the info.

GAP provided me a copy of the the reamer print they will be using to chamber my Barrel and it appears that their reamer has a .110 freebore. Seems like that should be about right if I am too use 180 Berger Hybrids.

Ill use your method and see what I come up with.

I see that you mention your COAL with the 162 ELD-M is 2.925" which is what you suggested more or less I set my dummy cartridge to with the 180s. I assume at this length you are having no issues with feeding from a magazine?

Feeds from an Accurate WSM mag perfectly. I have not ordered any of the 180's to try, but I imagine that I would have to seat them a little farther off the lands to keep them in the mag. My accurate mag measures 2.985" inside.

 

[ogonzalez13]

Feeds from an Accurate WSM mag perfectly. I have not ordered any of the 180's to try, but I imagine that I would have to seat them a little farther off the lands to keep them in the mag. My accurate mag measures 2.985" inside.

Wow. Ok. 2.985". I thought the Alpha type 3 mag had the longest COAL for a short action WSM/SAUM. There website list 2.97" COAL and you are seeing slightly longer with your accurate mag. I will have to look into those also as every little bit counts I belive when feeding this cartridge from a SA.

 

[Aeon1]

Depending on bullet lot a 7mm RSUAM w/Berger 180 Hyb w/.040" FB = 2.950 OAL touching lands.

 

[ogonzalez13]

Depending on bullet lot a 7mm RSUAM w/Berger 180 Hyb w/.040" FB = 2.950 OAL touching lands.

So armed with that info would it be safe say that if I add just another .015" of freebore to the .040 FB number your provided I would have the .015 jump I am looking for if I use a 2.950" COAL as my dummy round. So basically a .055 FB would be what I want more or less?

 

[Aeon1]

Maybe, you might end up with .055" FB and maybe not. It's why I referenced bullet lot. Berger can easily vary that .015" and sometimes more in lot to lot variation. What I have may not be what you have and what you buy today may not be what you buy tomorrow. As an example the current Berger spec sheet says a 7mm 180 Hyb is 1.527" OAL and an older lot I currently have averages 1.540" OAL. This is the main problem trying to run the heavy hybrids with this cartridge in a short action repeater, there is not much room to play with. Btw you reference a 180gn Hunting Hybrid, do they make that bullet? I am not aware of one, only the 180 Hyb target. Make your dummy and send it to the gunsmith and if he's good it'll be alright.

 

[ogonzalez13]

Maybe, you might end up with .055" FB and maybe not. It's why I referenced bullet lot. Berger can easily vary that .015" and sometimes more in lot to lot variation. What I have may not be what you have and what you buy today may not be what you buy tomorrow. As an example the current Berger spec sheet says a 7mm 180 Hyb is 1.527" OAL and an older lot I currently have averages 1.540" OAL. This is the main problem trying to run the heavy hybrids with this cartridge in a short action repeater, there is not much room to play with. Btw you reference a 180gn Hunting Hybrid, do they make that bullet? I am not aware of one, only the 180 Hyb target. Make your dummy and send it to the gunsmith and if he's good it'll be alright.

This is the bullet I ordered. It is listed as a Berger Elite Hunter Hybrid.

https://www.midwayusa.com/product/10...ail-box-of-100

You bring up a good point when you stated that this chambering has some issues with this class of bullet when utilizing it in a short action. So I ask, would It be better for me to have this rifle chambered with the 162-168 class of bullets considering the range I would be using this for will most likely be under 1000 and mostly used as a hunting rifle for deer, elk, stage, etc...?

Would this allow me a better flexibility?

I figured I would chamber for the 180s and that would allow me plenty of freebore to seat the 162-168 class of. Bullets to a depth that would maximize case validity since I would still try and seat them at a MAX COAL of 2.950 or so. Does that make sense?

 

[Aeon1]

The bullet link from Midway is a 30 Cal. You building a 7 or 30? The closest 7mm hunting hyb to the 7mm 180 Target Hybrid is the 175 Elite Hunter. The Elite Hunters are a hybrid design.

 

[ogonzalez13]

The bullet link from Midway is a 30 Cal. You building a 7 or 30? The closest 7mm hunting hyb to the 7mm 180 Target Hybrid is the 175 Elite Hunter. The Elite Hunters are a hybrid design.

Dang friend!!! Good catch on that. I just checked my Midway order and you are absolutely correct! I ordered 30 cal bullets. Big oversight on my party. Need to reorder some of the 180 Hybrid target bullets in 7mm.


Unless people feel like I'm better off going with lighter class of 162-168 for my intended purpose of hunting game up to the size of elk and shots less than 1000. Probably more realistic 600-800 at max.

 

[Aeon1]

You can kill elk out to 1K with the 168 class bullet. The heavy hybrids advantage is wind across big canyons and such. I'd try the 175 Elite if you think your needs will be long and windy and if not go the easier route with 168's. Put a dummy together at your desired OAL, mark the bullet @ .282" as referenced above, subtract .0477" from the case base to the .282" mark dimension and the answer will be the base to throat dimension on a reamer print. The FB can be deduced from there depending on the rest of the reamer dimensions. This will get you to approx .010" of your desired FB. Note: this works with a 1°-30 throat angle only, other throat angles will be shorter or longer.

Most throw FB dimensions around with no regard to other important reamer dimensions so many times you are unwittingly comparing Apples to Oranges.

 

[ogonzalez13]

You can kill elk out to 1K with the 168 class bullet. The heavy hybrids advantage is wind across big canyons and such. I'd try the 175 Elite if you think your needs will be long and windy and if not go the easier route with 168's. Put a dummy together at your desired OAL, mark the bullet @ .282" as referenced above, subtract .0477" from the case base to the .282" mark dimension and the answer will be the base to throat dimension on a reamer print. The FB can be deduced from there depending on the rest of the reamer dimensions. This will get you to approx .010" of your desired FB. Note: this works with a 1°-30 throat angle only, other throat angles will be shorter or longer.

Most throw FB dimensions around with no regard to other important reamer dimensions so many times you are unwittingly comparing Apples to Oranges.

Lots of good advice here and so much I still need to learn. I'll do as you all have mentioned. May take a little longer now as I obviously ordered the wrong bullets but as soon as I do I will report with my results.

I really do appreciate all the information.

 

[idahoorion]

ogonzalez, In my 284 on a long action and my 7 RM, the 175 elite hunters and 180 seem to be interchangable. I just subbed the 175's in for the 180's using all the 180 data and BTO length and they appear to shoot the same.....not saying this optimizes the 175 only saying it was one easy transition. Testing in the 284, they shoot as well to 500yards and I will go further but haven't yet. If they provide the same accuracy I'll just drop the 180's so I don't have to switch off them in the fall for hunting bullets. have yet to test them at distance in the 7RM as well.
course ymmv.
Idahoorion

 

[ogonzalez13]

ogonzalez, In my 284 on a long action and my 7 RM, the 175 elite hunters and 180 seem to be interchangable. I just subbed the 175's in for the 180's using all the 180 data and BTO length and they appear to shoot the same.....not saying this optimizes the 175 only saying it was one easy transition. Testing in the 284, they shoot as well to 500yards and I will go further but haven't yet. If they provide the same accuracy I'll just drop the 180's so I don't have to switch off them in the fall for hunting bullets. have yet to test them at distance in the 7RM as well.
course ymmv.
Idahoorion

I like this approach and I agree. If the 175 grain elite hunting bullets shoot just as good and give up little to nothing ballisticaly to the 180 VLD target bullets at distance, than it would also be wise for me to stick with those so I can hunt with the same round that I practice with.

Great to know. Thanks.

 

[FCS]

Inside of 1K, you don't gain enough to go 180s over 162 / 168. Much easier to make the 162/168 run from a SA than the 180s. 180s you are caught between powders, pressure up with faster burn rate and can't get enough of next slower burn rate in case. YMMV.

 

[ogonzalez13]

Inside of 1K, you don't gain enough to go 180s over 162 / 168. Much easier to make the 162/168 run from a SA than the 180s. 180s you are caught between powders, pressure up with faster burn rate and can't get enough of next slower burn rate in case. YMMV.

Been looking hard at this and thinking I'll go with either a 162 Hornady ELD-X or the 168 Berger VLD.

 

[FCS]

Just loaded up a bunch of 7 SAUM with 168 VLD H.
You have my phone #, text me and I'll help ya out on dummy round for your next project. I know it won't be that far out before you are off to new project.

 

[ogonzalez13]

Just loaded up a bunch of 7 SAUM with 168 VLD H.
You have my phone #, text me and I'll help ya out on dummy round for your next project. I know it won't be that far out before you are off to new project.

Thanks brother. PM sent.