Longest overall cartridge length when converting?

[Naphtali]

I have acquired a M1895 stainless steel rifle that I intend to have converted to 470 Turnbull, 475 Turnbull, 50 Alaskan, or 50-110. Figuring strongly is the overall cartridge length that is safely available for a converted rifle. I believe 2.550 inches is the maximum OAL available in a standard M1895 45-70 rifle. I also understand that this OAL can be safely increased during conversion.

All cartridges I am considering are based on a 348 WCF-sized cartridge base. The 50-110 has significantly longer brass and cartridge OAL than the others; 475 Turnbull has shorter brass with similar OAL. 470 Turnbull and 50 Alaskan are satisfactory for M1895 without altering available cartridge length. While I am nearly certain the 50-110 is too long for safe conversion, where does the M1895 action top out for length of cartridge for this class of cartridge?

My other rifles are USRAC/Winchester M1886 and Browning M71. I am accustomed to being able to use ammunition longer than M1895's standard. While I believe these actions will more easily accept a longer cartridge in conversion, this query pertains to the Marlin M1895 45-70 in stainless steel. Oh, nearly forgot. Conversion will include a new stainless steel barrel. This may make a difference?

[Rimfire McNutjob]

What's a 470 Turnbull? I read the article on the 475 Turnbull but have never heard of the 470.

[Naphtali]

What's a 470 Turnbull? I read the article on the 475 Turnbull but have never heard of the 470.

Mr. Turnbull has announced a slightly shortened version of the 475 Turnbull. It can be fired in 475 Turnbull-chambered rifles. Think of the 480 Ruger's relationship with 475 Linebaugh and you'll be about right. Here's a link to see a rifle and some cartridges http://forums.accuratereloading.com/eve ... /247100478

[Rimfire McNutjob]

Ah, so it's a bit of a re-do specifically for the Marlin guns ... in order to accommodate their 2.55 Cartridge OAL. I suppose it makes sense in that the Marlins are a lot easier to come by than say a 71 or an 1886. At least they are more plentiful and affordable.

Don't feel like having your 86 or 71 converted?

[Hobie]

I think RM is right (offhand), 2.55" is the limit due to the length of the ejection port.

[Rimfire McNutjob]

I think there may be some gunsmiths (and likely Turnbull is one) that could possibly squeeze a bit more OAL from the Marlin. The thing is ... what's the cost / work involved in doing so versus starting with a gun that already sports the OAL you're looking for.

I can load 450 Alaskan for the Marlin if I use (for example) the Hornady #4503 where the top of the cannelure is about 0.5" above the bullet base and the ogive of the bullet itself is rather abrupt leading to a shorter bullet overall. I give up powder capacity though ... but the case will still hold max loads of RL7 without compression. The COAL is right at 2.55".

If I load the Speer #2478 and crimp near the top of the cannelure, I'm at a COAL of 2.75". But I have a good bit more room in the case because the distance from the bullet base to the top of the cannelure is only about 0.4". The ogive is much longer on that bullet and the bullet is longer overall and I believe has a marginally better BC because of it. With that bullet I can load up max using 3031 and not get into powder compression ... barely.

I'm guessing that Turnbull came out with the 475 ... which is a nice cartridge ... then he realized that the market is mostly in Marlins and had to step back and call a mulligan (470) so he could get into the cartridge game in a bigger way. He'll certainly sell more conversions and ammo (if he gets into making it or licensing it) by supporting the Marlin platform.

Honestly though, the guy's got his hands full with the business he already does. If he expands into Marlin conversions, I hope he adds some heads. There definitely seems to be a market that has developed in the bigger and louder cartridge gun arena.

I'll hobble along in the 348 Winchester / 450 Alaskan zone and leave the bigger stuff to younger people with more fresh cartilage in their shoulders.

[Naphtali]

Wouldn't you know it. . . . Just got an E-mail from Mic McPherson. He makes for the Marlin M1895 the 510 Kodiak Express http://www.levergun.com/KodiakExpress.htm. Equally important is his additional information that [he has determined] the Marlin M1895 action can accept cartridges as long as 2.73 inches. The 510 KE is 2.68 inches OAL. While my first impulse was to doubt his sanity, I understand he is one of the premier Marlin gunsmiths. Unless there are shrieks of "NO-NO-NO" with sensible reasoning following, I think 2.65-2.70 inches of cartridge OAL is feasible.

[Rimfire McNutjob]

Yeah, you had to figure someone could do it. I had read his page a long while back on this conversion but I couldn't recall who it was that was going over 2.55". Looks like you found him. Note ... "Through the application of significant receiver modification and with the use of a special high-strength barrel, it is feasible to adapt the basic Marlin-336 action to accommodate this massive cartridge." Apparently it's a lot of work. At least the gun is heavier (10lbs) to help with the recoil from the top loads in that cartridge. I wonder how many of these he has built to date.